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<title>Explorers Program</title>

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Explorers Program

</h1>

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The Explorers Program<a href="#cite_note-1">[1]</a> is a <a href="NASA" title="NASA">NASA</a> exploration program that provides flight opportunities for physics, <a href="Geophysics" title="Geophysics">geophysics</a>, <a href="Heliophysics" title="Heliophysics">heliophysics</a>, and <a href="Astrophysics" title="Astrophysics">astrophysics</a> investigations from space. Launched in 1958, <a href="Explorer_1" title="Explorer 1">Explorer 1</a> was the first spacecraft of the United States to achieve orbit. Over 90 space missions have been launched since. Starting with <a href="Explorer_6" title="Explorer 6">Explorer 6</a>, it has been operated by NASA, with regular collaboration with a variety of other institutions, including many international partners.

Launchers for the Explorers Program have included <a href="Juno_I" title="Juno I">Juno I</a>, <a href="Juno_II" title="Juno II">Juno II</a>, various <a href="Thor_(rocket_family)" title="Thor (rocket family)">Thor</a>, <a href="Scout_(rocket_family)" title="Scout (rocket family)">Scout</a>, <a href="Delta_(rocket_family)" title="Delta (rocket family)">Delta</a> and <a href="Northrop_Grumman_Pegasus" title="Northrop Grumman Pegasus">Pegasus</a> launch vehicles, and <a href="Falcon_9" title="Falcon 9">Falcon 9</a>.

The program has three classes: Medium-Class Explorers (MIDEX), Small Explorers (SMEX), and University-Class Explorers (UNEX), with select Missions of Opportunity operated with other agencies.

<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Early_Explorer_satellites">Early Explorer satellites</h3></div>

The Explorers Program began as a <a href="United_States_Army" title="United States Army">U.S. Army</a> proposal (<a href="Project_Orbiter" title="Project Orbiter">Project Orbiter</a>) to place a "civilian" <a href="Satellite" title="Satellite">artificial satellite</a> into orbit during the <a href="International_Geophysical_Year" title="International Geophysical Year">International Geophysical Year</a> (IGY). Although that proposal was rejected in favor of the <a href="United_States_Navy" title="United States Navy">U.S. Navy</a>'s <a href="Project_Vanguard" title="Project Vanguard">Project Vanguard</a>, which made the first sub-orbital flight <a href="Vanguard_TV0" class="mw-redirect" title="Vanguard TV0">Vanguard TV0</a> in December 1956, the <a href="Soviet_Union" title="Soviet Union">Soviet Union</a>'s launch of <a href="Sputnik_1" title="Sputnik 1">Sputnik 1</a> on 4 October 1957 (and the resulting "<a href="Sputnik_crisis" title="Sputnik crisis">Sputnik crisis</a>") and the failure of the <a href="Vanguard_1" title="Vanguard 1">Vanguard 1</a> launch attempt resulted in the Army program being funded to match the Soviet space achievements. <a href="Explorer_1" title="Explorer 1">Explorer 1</a> was launched on the Juno I on 1 February 1958, becoming the first U.S. satellite, as well as discovering the <a href="Van_Allen_radiation_belt" title="Van Allen radiation belt">Van Allen radiation belt</a>.

Four follow-up satellites of the Explorer series were launched by the Juno I launch vehicle in 1958, of which <a href="Explorer_3" title="Explorer 3">Explorer 3</a> and <a href="Explorer_4" title="Explorer 4">Explorer 4</a> were successful, while <a href="Explorer_2" title="Explorer 2">Explorer 2</a> and <a href="Explorer_5" title="Explorer 5">Explorer 5</a> failed to reach orbit.<a href="#cite_note-Boehm-NASA-2">[2]</a> The Juno I vehicle was replaced by the <a href="Juno_II" title="Juno II">Juno II</a> in 1959.

<div class="mw-heading mw-heading3"><h3 id="Continuation_of_the_Explorers_Program">Continuation of the Explorers Program</h3></div>

With the establishment of NASA in 1958, the Explorers Program was transferred to NASA from the <a href="United_States_Army" title="United States Army">U.S. Army</a>. NASA continued to use the name for an ongoing series of relatively small space missions, typically an artificial satellite with a specific science focus. <a href="Explorer_6" title="Explorer 6">Explorer 6</a> in 1959 was the first scientific satellite under the project direction of NASA's <a href="Goddard_Space_Flight_Center" title="Goddard Space Flight Center">Goddard Space Flight Center</a> (GSFC) in <a href="Greenbelt%2C_Maryland" title="Greenbelt, Maryland">Greenbelt, Maryland</a>.<a href="#cite_note-3">[3]</a><a href="#cite_note-4">[4]</a>

The <a href="Interplanetary_Monitoring_Platform" title="Interplanetary Monitoring Platform">Interplanetary Monitoring Platform</a> (IMP) was launched in 1963 and involved a network of eleven Explorer satellites designed to collect data on space radiation in support of the <a href="Apollo_program" title="Apollo program">Apollo program</a>. The IMP program was a major step forward in spacecraft <a href="Electronics" title="Electronics">electronics</a> design, as it was the first space program to use <a href="Integrated_circuit" title="Integrated circuit">integrated circuit</a> (IC) chips and <a href="MOSFET" title="MOSFET">MOSFETs</a> (MOS transistors).<a href="#cite_note-Butrica-5">[5]</a><a href="#cite_note-nasa-6">[6]</a> The IMP-A (<a href="Explorer_18" title="Explorer 18">Explorer 18</a>) in 1963 was the first spacecraft to use IC chips, and the IMP-D (<a href="Explorer_33" title="Explorer 33">Explorer 33</a>) in 1966 was the first to use MOSFETs.<a href="#cite_note-Butrica-5">[5]</a>

<caption>List of <a href="Interplanetary_Monitoring_Platform" title="Interplanetary Monitoring Platform">Interplanetary Monitoring Platform</a> (IMP) missions

</caption>

<th rowspan="2">Mission

</th>

<th rowspan="2">Photo

</th>

<th colspan="2">Satellite

</th>

<th rowspan="2">Launch date

</th>

<th rowspan="2">Decay date

</th>

<th rowspan="2">Notes

</th></tr>

<tr>

<th>Explorer

</th>

<th>IMP

</th></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 18

</td>

<td>IMP-A

</td>

<td>27 November 1963, 02:30 UTC<a href="#cite_note-jonathan-7">[7]</a>

</td>

<td>December 30, 1965

</td>

<td>First use of <a href="Integrated_circuit" title="Integrated circuit">integrated circuits</a> in a spacecraft. First satellite in IMP-A/-B/-C design series.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 21

</td>

<td>IMP-B

</td>

<td>4 October 1964, 03:45 UTC<a href="#cite_note-jonathan-7">[7]</a>

</td>

<td>January 1, 1966

</td>

<td>Second satellite in IMP-A/-B/-C design series.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 28

</td>

<td>IMP-C

</td>

</td>

<td>4 July 1968

</td>

<td>Third satellite in IMP-A/-B/-C design series.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 33

</td>

<td>IMP-D

</td>

</td>

<td>In orbit

</td>

<td>First use of <a href="MOSFET" title="MOSFET">MOSFET</a> integrated circuits in a spacecraft, similar design to IMP-E. Originally intended to orbit the Moon, but placed in an elliptical high orbit instead.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 34

</td>

<td>IMP-F

</td>

</td>

<td>May 3, 1969

</td>

<td>Similar design to IMP-G.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 35

</td>

<td>IMP-E

</td>

</td>

<td>After June 24, 1973

</td>

<td>Similar design to IMP-D. Positioned in <a href="Moon" title="Moon">Selenocentric orbit</a>.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 41

</td>

<td>IMP-G

</td>

</td>

<td>December 23, 1972

</td>

<td>Similar design to IMP-F.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 43

</td>

<td>IMP-I

</td>

<td>13 March 1971, 16:15 UTC<a href="#cite_note-jonathan-7">[7]</a>

</td>

<td>October 2, 1974

</td>

<td>First spacecraft in IMP-I/-H/-J series.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 47

</td>

<td>IMP-H

</td>

<td>23 September 1972, 01:20 UTC<a href="#cite_note-jonathan-7">[7]</a>

</td>

<td>In orbit

</td>

<td>Second spacecraft in IMP-I/-H/-J series.

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer 50

</td>

<td>IMP-J

</td>

<td>26 October 1973, 02:26 UTC<a href="#cite_note-jonathan-7">[7]</a>

</td>

<td>In orbit

</td>

<td>Third spacecraft in IMP-I/-H/-J series, remained in service until 2006

</td></tr></tbody></table>

Over the following two decades, NASA has launched over 50 Explorer missions,<a href="#cite_note-nssdc_list-8">[8]</a> some in conjunction to military programs, usually of an exploratory or survey nature or had specific objectives not requiring the capabilities of a major space observatory. Explorer satellites have made many important discoveries on: Earth's <a href="Magnetosphere" title="Magnetosphere">magnetosphere</a> and the shape of its <a href="Gravitational_field" title="Gravitational field">gravity field</a>; the <a href="Solar_wind" title="Solar wind">solar wind</a>; properties of <a href="Micrometeoroids" class="mw-redirect" title="Micrometeoroids">micrometeoroids</a> raining down on the <a href="Earth" title="Earth">Earth</a>; ultraviolet, cosmic and X-rays from the <a href="Solar_System" title="Solar System">Solar System</a> and beyond; <a href="Ionosphere" title="Ionosphere">ionospheric physics</a>; <a href="Solar_flare" title="Solar flare">Solar plasma</a>; <a href="Solar_energetic_particles" title="Solar energetic particles">solar energetic particles</a>; and <a href="Atmospheric_science" title="Atmospheric science">atmospheric physics</a>. These missions have also investigated air density, radio astronomy, <a href="Geodesy" title="Geodesy">geodesy</a>, and <a href="Gamma-ray_astronomy" title="Gamma-ray astronomy">gamma-ray astronomy</a>.

With decreases in NASA's budget, Explorer missions became infrequent in the early 1980s.

<div class="mw-heading mw-heading3"><h3 id="SMEX,_MIDEX,_and_Student_Explorers_Programs">SMEX, MIDEX, and Student Explorers Programs</h3></div>

In 1988, the Small Explorer (SMEX) class was established with a focus on frequent flight opportunities for highly focused and relatively inexpensive space science missions in the disciplines of astrophysics and space physics.<a href="#cite_note-NASAhistory-9">[9]</a><a href="#cite_note-10">[10]</a> The first three SMEX missions were chosen in April 1989 out of 51 candidates, and launched in 1992, 1996 and 1998<a href="#cite_note-IEEE-11">[11]</a> The second set of two missions were announced in September 1994 and launched in 1998 and 1999.<a href="#cite_note-NASAhistory-9">[9]</a>

In the mid-1990s, NASA initiated the Medium-class Explorers (MIDEX) to enable more frequent flights. These are larger than SMEX missions and were to be launched aboard a new kind of medium-light class launch vehicle.<a href="#cite_note-NASAhistory-9">[9]</a> This new launch vehicle was not developed and instead, these missions were flown on a modified <a href="Delta_II" title="Delta II">Delta II</a> rocket.<a href="#cite_note-12">[12]</a><a href="#cite_note-13">[13]</a> The first announcement opportunity for MIDEX was issued in March 1995, and the first launch under this new class was <a href="Far_Ultraviolet_Spectroscopic_Explorer" title="Far Ultraviolet Spectroscopic Explorer">FUSE</a> in 1999.<a href="#cite_note-NASAhistory-9">[9]</a>

In May 1994, NASA started the Student Explorer Demonstration Initiative (STEDI) pilot program, to demonstrate that high-quality space science can be carried out with small, low-cost missions. Of the three selected missions, SNOE was launched in 1998 and TERRIERS in 1999, but the latter failed after launch. The STEDI program was terminated in 2001.<a href="#cite_note-NASAhistory-9">[9]</a> Later, NASA established the University-Class Explorer (UNEX) program for much cheaper missions, which is regarded as a successor to STEDI.<a href="#cite_note-14">[14]</a>

The Explorer missions were at first managed by the Small Explorers Project Office at NASA's Goddard Space Flight Center (GSFC). In early 1999, that office was closed and with the announcement of opportunity for the third set of SMEX missions NASA converted the SMEX class so that each mission was managed by its <a href="Principal_investigator" title="Principal investigator">principal investigator</a>, with oversight by the GSFC Explorer Project.<a href="#cite_note-welcome-15">[15]</a> The Explorers Program Office at Goddard Space Flight Center, provides management of the many operational scientific exploration missions that are characterized by relatively moderate costs and small to medium-sized missions that are capable of being built, tested, and launched in a short time interval compared to larger observatories like NASA's <a href="Great_Observatories" class="mw-redirect" title="Great Observatories">Great Observatories</a>.<a href="#cite_note-16">[16]</a>

Excluding the launches, the MIDEX class has a current mission cap cost of US$250 million in 2018,<a href="#cite_note-Midex19-17">[17]</a> with future MIDEX missions being capped at US$350 million.<a href="#cite_note-18">[18]</a> The cost cap for SMEX missions in 2017 was US$165 million.<a href="#cite_note-19">[19]</a> UNEX missions are capped at US$15 million.<a href="#cite_note-missions-20">[20]</a> A sub-project called Missions of Opportunity (MO) has funded science instruments or hardware components of onboard non-NASA space missions, and have a total NASA cost cap of US$70 million.<a href="#cite_note-Midex19-17">[17]</a><a href="#cite_note-missions-20">[20]</a>

<div class="mw-heading mw-heading2"><h2 id="Classes">Classes</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Medium-Class_(MIDEX)">Medium-Class (MIDEX)</h3></div>

<caption>List of MIDEX missions<a href="#cite_note-21">[21]</a><a href="#cite_note-:0-22">[22]</a><a href="#cite_note-23">[23]</a>

</caption>

<th>Name

</th>

<th>MIDEX number

</th>

<th>Explorer number

</th>

<th>Launch (UTC)

</th>

<th>Status

</th></tr>

<tr>

</td>

<td>

</td>

<td>Explorer-69

</td>

<td>30 December 1995

</td>

<td>Ended in 2012 / Reentered on 30 April 2018

</td></tr>

<tr>

</td>

<td>

</td>

<td>Explorer-71

</td>

<td>25 August 1997

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td>MIDEX-0

</td>

<td>Explorer-77

</td>

<td>23 June 1999

</td>

<td>Ended in 2007

</td></tr>

<tr>

<td><a href="IMAGE_(spacecraft)" title="IMAGE (spacecraft)">IMAGE</a>

</td>

<td>MIDEX-1

</td>

<td>Explorer-78

</td>

<td>25 March 2000

</td>

<td>Lost contact in 2005. Partial contact reestablished in January 2018

</td></tr>

<tr>

</td>

<td>MIDEX-2

</td>

<td>Explorer-80

</td>

<td>30 June 2001

</td>

<td>Ended in 2010

</td></tr>

<tr>

<td><a href="Neil_Gehrels_Swift_Observatory" title="Neil Gehrels Swift Observatory">Swift</a>

</td>

<td>MIDEX-3

</td>

<td>Explorer-84

</td>

<td>20 November 2004

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td>MIDEX-4

</td>

</td>

<td>Scheduled for 2004

</td>

<td>Cancelled in 2002 (cost)

</td></tr>

<tr>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> A

</td>

<td>MIDEX-5A

</td>

<td>Explorer-85

</td>

<td>17 February 2007

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> B

</td>

<td>MIDEX-5B

</td>

<td>Explorer-86

</td>

<td>17 February 2007

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> C

</td>

<td>MIDEX-5C

</td>

<td>Explorer-87

</td>

<td>17 February 2007

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> D

</td>

<td>MIDEX-5D

</td>

<td>Explorer-88

</td>

<td>17 February 2007

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> E

</td>

<td>MIDEX-5E

</td>

<td>Explorer-89

</td>

<td>17 February 2007

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="Wide-field_Infrared_Survey_Explorer" title="Wide-field Infrared Survey Explorer">WISE / NEOWISE</a>

</td>

<td>MIDEX-6

</td>

<td>Explorer-92

</td>

<td>14 December 2009

</td>

<td>Mission operations Completed on 31 July 2024.<a href="#cite_note-24">[24]</a> Reentered on 2 November 2024

</td></tr>

<tr>

</td>

<td>MIDEX-7

</td>

<td>Explorer-95

</td>

<td>18 April 2018

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td>MIDEX-8

</td>

<td>Explorer-96

</td>

<td>11 October 2019

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="SPHEREx" title="SPHEREx">SPHEREx</a>

</td>

<td>MIDEX-9

</td>

<td>Explorer-102

</td>

<td>12 March 2025

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td>MIDEX-10

</td>

<td>

</td>

<td>2027

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development

</td></tr>

<tr>

<td><a href="HelioSwarm" title="HelioSwarm">HelioSwarm</a>

</td>

<td>MIDEX-11

</td>

<td>

</td>

<td>2028

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development

</td></tr>

<tr>

</td>

<td>MIDEX-12

</td>

<td>

</td>

<td>2030

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development

</td></tr></tbody></table>

<div class="mw-heading mw-heading3"><h3 id="Small_Explorers_(SMEX)">Small Explorers (SMEX)</h3></div>

The Small Explorers class was implemented in 1989 specifically to fund space exploration missions that cost no more than US$120 million.<a href="#cite_note-missions-20">[20]</a><a href="#cite_note-IEEE-11">[11]</a> The missions are managed by the Explorers Project at the <a href="Goddard_Space_Flight_Center" title="Goddard Space Flight Center">Goddard Space Flight Center</a> (GSFC).<a href="#cite_note-welcome-15">[15]</a>

The first set of three SMEX missions were launched between 1992 and 1998. The second set of two missions were launched in 1998 and 1999. These early missions were managed by the Small Explorers Project Office at Goddard Space Flight Center. In early 1999, that office was closed and with the announcement of opportunity for the third set of SMEX missions NASA converted the program so that each mission was managed by its <a href="Principal_investigator" title="Principal investigator">Principal Investigator</a>, with oversight by the GSFC Explorers Project.<a href="#cite_note-welcome-15">[15]</a>

NASA funded a competitive study of five candidate heliophysics Small Explorers missions for flight in 2022. The proposals were Mechanisms of Energetic Mass Ejection – eXplorer (MEME-X), Focusing Optics X-ray Solar Imager (FOXSI), Multi-Slit Solar Explorer (MUSE), Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS), and Polarimeter to Unify the Corona and Heliosphere (PUNCH).<a href="#cite_note-25">[25]</a><a href="#cite_note-26">[26]</a><a href="#cite_note-27">[27]</a> In June 2019 NASA selected TRACERS and PUNCH for flight.<a href="#cite_note-28">[28]</a>

<caption>List of SMEX missions <a href="#cite_note-:0-22">[22]</a><a href="#cite_note-29">[29]</a>

</caption>

<th>Name

</th>

<th>SMEX number

</th>

<th>Explorer number

</th>

<th>Launch (UTC)

</th>

<th>End of mission

</th>

<th>Status

</th></tr>

<tr>

<td><a href="Solar_Anomalous_and_Magnetospheric_Particle_Explorer" title="Solar Anomalous and Magnetospheric Particle Explorer">SAMPEX</a>

</td>

<td>SMEX-1

</td>

<td>Explorer-68

</td>

<td>3 July 1992

</td>

<td>30 June 2004

</td>

<td>Reentered on 13 November 2012

</td></tr>

<tr>

</td>

<td>SMEX-2

</td>

<td>Explorer-70

</td>

<td>21 August 1996

</td>

<td>4 May 2009

</td>

<td>

</td></tr>

<tr>

</td>

<td>SMEX-3

</td>

<td>Explorer-74

</td>

<td>6 December 1998

</td>

<td>21 July 2004

</td>

<td>

</td></tr>

<tr>

<td><a href="TRACE" title="TRACE">TRACE</a>

</td>

<td>SMEX-4

</td>

<td>Explorer-73

</td>

<td>2 April 1998

</td>

<td>21 June 2010

</td>

<td>Reentered on 18 July 2025<a href="#cite_note-30">[30]</a>

</td></tr>

<tr>

</td>

<td>SMEX-5

</td>

<td>Explorer-75

</td>

<td>5 March 1999

</td>

<td data-sort-value="" style="background: var(--background-color-interactive, #ececec); color: var(--color-base, inherit); vertical-align: middle; text-align: center;" class="table-na">—

</td>

<td>Spacecraft equipment failure; reentered on 10 May 2011

</td></tr>

<tr>

<td><a href="Reuven_Ramaty_High_Energy_Solar_Spectroscopic_Imager" title="Reuven Ramaty High Energy Solar Spectroscopic Imager">RHESSI</a>

</td>

<td>SMEX-6

</td>

<td>Explorer-81

</td>

<td>5 February 2002

</td>

<td>April 2018

</td>

<td>Deorbited on 20 April 2023

</td></tr>

<tr>

<td><a href="GALEX" title="GALEX">GALEX</a>

</td>

<td>SMEX-7

</td>

<td>Explorer-83

</td>

<td>28 April 2003

</td>

<td>May 2012

</td>

<td>Decommissioned on 28 June 2013

</td></tr>

<tr>

<td>SPIDR

</td>

<td>SMEX-8

</td>

</td>

<td>Scheduled for 2005

</td>

<td data-sort-value="" style="background: var(--background-color-interactive, #ececec); color: var(--color-base, inherit); vertical-align: middle; text-align: center;" class="table-na">—

</td>

<td>Cancelled in 2003 due to poor instrument sensitivity <a href="#cite_note-31">[31]</a>

</td></tr>

<tr>

<td><a href="Aeronomy_of_Ice_in_the_Mesosphere" title="Aeronomy of Ice in the Mesosphere">Aeronomy of Ice in the Mesosphere</a> (AIM)

</td>

<td>SMEX-9

</td>

<td>Explorer-90

</td>

<td>25 April 2007

</td>

<td>19 August 2024

</td>

<td>Reentered on 19 August 2024

</td></tr>

<tr>

</td>

<td>SMEX-10

</td>

<td>Explorer-91

</td>

<td>19 October 2008

</td>

<td>

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="NuSTAR" title="NuSTAR">NuSTAR</a>

</td>

<td>SMEX-11

</td>

<td>Explorer-93

</td>

<td>13 June 2012

</td>

<td>

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td>SMEX-12

</td>

<td>Explorer-94

</td>

<td>28 June 2013

</td>

<td>

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td>SMEX-13

</td>

</td>

<td>Scheduled for 2014

</td>

<td data-sort-value="" style="background: var(--background-color-interactive, #ececec); color: var(--color-base, inherit); vertical-align: middle; text-align: center;" class="table-na">—

</td>

<td>Cancelled in 2012 due to expected cost overruns<a href="#cite_note-32">[32]</a>

</td></tr>

<tr>

<td><a href="Imaging_X-ray_Polarimetry_Explorer" class="mw-redirect" title="Imaging X-ray Polarimetry Explorer">Imaging X-ray Polarimetry Explorer</a> (IXPE)

</td>

<td>SMEX-14

</td>

<td>Explorer-97

</td>

<td>9 December 2021

</td>

<td>

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="Polarimeter_to_Unify_the_Corona_and_Heliosphere" title="Polarimeter to Unify the Corona and Heliosphere">PUNCH</a>

</td>

<td>SMEX-15

</td>

<td>

</td>

<td>12 March 2025<a href="#cite_note-nasa-lspedu-33">[33]</a>

</td>

<td>

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational<a href="#cite_note-nasa-20220803-34">[34]</a>

</td></tr>

<tr>

<td><a href="Tandem_Reconnection_and_Cusp_Electrodynamics_Reconnaissance_Satellites" title="Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites">TRACERS</a>

</td>

<td>SMEX-16

</td>

<td>

</td>

<td>22 July 2025

</td>

<td>

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">Pending launch

</td></tr>

<tr>

</td>

<td>SMEX-17

</td>

<td>

</td>

<td>August 2027<a href="#cite_note-35">[35]</a>

</td>

<td>

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development

</td></tr></tbody></table>

<div class="gallerytext">SAMPEX</div>

</li>

<div class="gallerytext">RHESSI</div>

</li>

</li>

</li>

</ul>

<div class="mw-heading mw-heading3"><h3 id="University-Class_Explorers_(UNEX)">University-Class Explorers (UNEX)</h3></div>

<caption>List of UNEX missions<a href="#cite_note-:1-36">[36]</a>

</caption>

<th>Name

</th>

<th>UNEX number

</th>

<th>Explorer number

</th>

<th>Launch (UTC)

</th>

<th>Status

</th></tr>

<tr>

</td>

<td>UNEX-1

</td>

<td>Explorer-72

</td>

<td>26 February 1998

</td>

<td>Ended in 2000

</td></tr>

<tr>

<td>IMEX

</td>

<td>UNEX-2

</td>

</td>

<td>Scheduled for 2003

</td>

<td>Cancelled before 2005 (cost)<a href="#cite_note-nap-37">[37]</a>

</td></tr>

<tr>

<td><a href="Cosmic_Hot_Interstellar_Plasma_Spectrometer" class="mw-redirect" title="Cosmic Hot Interstellar Plasma Spectrometer">CHIPS</a>

</td>

<td>UNEX-3

</td>

<td>Explorer-82

</td>

<td>12 January 2003

</td>

<td>Ended in 2008

</td></tr></tbody></table>

<div class="mw-heading mw-heading3"><h3 id="Missions_of_Opportunity_(MO)">Missions of Opportunity (MO)</h3></div>

Missions of Opportunity (MO) are investigations characterized by being part of a non-NASA space mission of any size and having a total NASA cost of under $55 million. These missions are conducted on a no-exchange-of-funds basis with the organization sponsoring the mission. NASA solicits proposals for Missions of Opportunity on SMEX, MIDEX and UNEX investigations.<a href="#cite_note-38">[38]</a>

</caption>

<th>Name

</th>

<th>Launcher (mission)

</th>

<th>Launch (UTC)

</th>

<th>Status

</th></tr>

<tr>

</td>

<td>NASA (Explorer-79)

</td>

<td>9 October 2000

</td>

<td>Ended in 2008<a href="#cite_note-39">[39]</a>

</td></tr>

<tr>

<td><a href="INTEGRAL" title="INTEGRAL">INTEGRAL</a>

</td>

</td>

<td>17 October 2002

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="Suzaku_(satellite)" title="Suzaku (satellite)">Suzaku</a> (Astro-E2)

</td>

</td>

<td>10 July 2005

</td>

<td>Ended in 2015

</td></tr>

<tr>

<td><a href="TWINS" title="TWINS">TWINS</a>

</td>

<td><a href="National_Reconnaissance_Office" title="National Reconnaissance Office">NRO</a> (<a href="USA-184" title="USA-184">USA-184</a>;<a href="#cite_note-42">[42]</a> <a href="USA-200" title="USA-200">USA-200</a><a href="#cite_note-43">[43]</a>)

</td>

<td>TWINS-1: 28 June 2006 TWINS-2: 13 March 2008

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="CINDI" title="CINDI">CINDI</a>

</td>

</td>

<td>16 April 2008

</td>

<td>Ended in 2015

</td></tr>

<tr>

<td><a href="Hitomi_(satellite)" title="Hitomi (satellite)">Hitomi</a> (Astro-H)

</td>

</td>

<td>17 February 2016

</td>

<td style="background: #FFC7C7; color:black; vertical-align: middle; text-align: center;" class="table-failure">Failed

</td></tr>

<tr>

<td><a href="Neutron_Star_Interior_Composition_Explorer" title="Neutron Star Interior Composition Explorer">NICER</a>

</td>

<td><a href="ISS" class="mw-redirect" title="ISS">ISS</a> (<a href="SpaceX_CRS-11" title="SpaceX CRS-11">CRS-11</a>)

</td>

<td>3 June 2017

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td><a href="SES_(company)" title="SES (company)">SES</a> (<a href="SES-14" title="SES-14">SES-14</a>)

</td>

<td>25 January 2018

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="X-Ray_Imaging_and_Spectroscopy_Mission" title="X-Ray Imaging and Spectroscopy Mission">XRISM</a>

</td>

</td>

<td>6 September 2023

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

</td>

<td><a href="ISS" class="mw-redirect" title="ISS">ISS</a> (<a href="SpaceX_CRS-29" title="SpaceX CRS-29">CRS-29</a>)

</td>

<td>December 2023

</td>

<td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="table-success">Operational

</td></tr>

<tr>

<td><a href="GUSTO_(telescope)" title="GUSTO (telescope)">GUSTO</a>

</td>

<td><a href="NASA" title="NASA">NASA</a> (<a href="High-altitude_balloon" title="High-altitude balloon">high-altitude balloon</a>)

</td>

<td>31 December 2023

</td>

<td>Ended on 26 February 2024<a href="#cite_note-46">[46]</a>

</td></tr>

<tr>

<td><a href="Sun_Radio_Interferometer_Space_Experiment" title="Sun Radio Interferometer Space Experiment">SunRISE</a>

</td>

<td><a href="NASA" title="NASA">NASA</a> (<a href="Maxar" class="mw-redirect" title="Maxar">Maxar</a> satellite)

</td>

<td>2024

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development<a href="#cite_note-47">[47]</a><a href="#cite_note-48">[48]</a>

</td></tr>

<tr>

</td>

<td><a href="NASA" title="NASA">NASA</a>, <a href="JHUAPL" class="mw-redirect" title="JHUAPL">JHUAPL</a>

</td>

<td>2024

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development<a href="#cite_note-49">[49]</a>

</td></tr>

<tr>

<td><a href="Solar-C_EUVST" class="mw-redirect" title="Solar-C EUVST">Solar-C EUVST</a>

</td>

</td>

<td>July 2028

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development<a href="#cite_note-50">[50]</a><a href="#cite_note-51">[51]</a>

</td></tr>

<tr>

</td>

<td><a href="ESA" class="mw-redirect" title="ESA">ESA</a> (<a href="Cosmic_Vision" title="Cosmic Vision">Cosmic Vision</a> <a href="ARIEL" title="ARIEL">M4</a>)

</td>

<td>2029

</td>

<td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">In development<a href="#cite_note-52">[52]</a><a href="#cite_note-53">[53]</a>

</td></tr></tbody></table>

<div class="mw-heading mw-heading3"><h3 id="Beacon_Explorers">Beacon Explorers</h3></div>

Three satellites were planned in this series: <a href="Beacon_Explorer-A" class="mw-redirect" title="Beacon Explorer-A">Beacon Explorer-A</a>, <a href="Beacon_Explorer-B" class="mw-redirect" title="Beacon Explorer-B">Beacon Explorer-B</a>, <a href="Beacon_Explorer-C" class="mw-redirect" title="Beacon Explorer-C">Beacon Explorer-C</a>.

<div class="mw-heading mw-heading3"><h3 id="GEOS_series">GEOS series</h3></div>

A series of three Geodetic Earth Orbiting Satellite (GEOS) were put in orbit: <a href="GEOS_1" class="mw-redirect" title="GEOS 1">GEOS 1</a>, <a href="GEOS_2" class="mw-redirect" title="GEOS 2">GEOS 2</a>, <a href="GEOS_3" class="mw-redirect" title="GEOS 3">GEOS 3</a>.

<div class="mw-heading mw-heading2"><h2 id="Launched_spacecraft">Launched spacecraft</h2></div>

Explorers Program name numbers can be found in the <a href="NASA_Space_Science_Data_Coordinated_Archive" title="NASA Space Science Data Coordinated Archive">NSSDC master catalog</a>, typically assigned to each spacecraft in a mission. These numbers were not officially assigned until after 1975.<a href="#cite_note-54">[54]</a>

<caption>Explorers Program satellites<a href="#cite_note-nssdc_list-8">[8]</a><a href="#cite_note-55">[55]</a><a href="#cite_note-56">[56]</a><a href="#cite_note-skyrocket-57">[57]</a>

</caption>

<th>No.

</th>

<th>Name(s)

</th>

<th>Launch date (UTC)

</th>

<th>Rocket

</th>

<th>Mass (kg)

</th>

<th>Orbit regime

</th>

<th>End of data

</th>

<th>Re-entry <a href="#cite_note-58">[58]</a>

</th>

<th>Mission/Notes

</th></tr>

<tr>

<th>1

</th>

<td><a href="Explorer_1" title="Explorer 1">Explorer 1</a>

</td>

<td>1 February 1958

</td>

</td>

<td>14

</td>

<td>MEO

</td>

<td>23 May 1958

</td>

<td>31 March 1970

</td>

<td>First American satellite, third satellite to achieve orbit; discovered the <a href="Van_Allen_radiation_belt" title="Van Allen radiation belt">Van Allen radiation belt</a>; launched by the <a href="United_States_Army" title="United States Army">U.S. Army</a><a href="#cite_note-59">[59]</a>

</td></tr>

<th style="background:#fbb;">2

</th>

<td><a href="Explorer_2" title="Explorer 2">Explorer 2</a>

</td>

<td>5 March 1958

</td>

</td>

<td>15

</td>

<td>Failed

</td>

<td>—

</td>

<td>—

</td>

<td>Failed to achieve orbit.<a href="#cite_note-60">[60]</a>

</td></tr>

<tr>

<th>3

</th>

<td><a href="Explorer_3" title="Explorer 3">Explorer 3</a>

</td>

<td>26 March 1958

</td>

</td>

<td>14

</td>

<td>MEO

</td>

<td>27 June 1958

</td>

<td>27 June 1958

</td>

<td>Energetic particle studies helped confirm the presence of <a href="Van_Allen_radiation_belt" title="Van Allen radiation belt">Van Allen radiation belt</a><a href="#cite_note-61">[61]</a>

</td></tr>

<tr>

<th>4

</th>

<td><a href="Explorer_4" title="Explorer 4">Explorer 4</a>

</td>

<td>26 July 1958

</td>

</td>

<td>26

</td>

<td>MEO

</td>

<td>5 October 1958

</td>

<td>23 October 1959

</td>

<td>Monitor charged particles inside Van Allen belts from nuclear detonations (during <a href="Operation_Argus" title="Operation Argus">Operation Argus</a>)<a href="#cite_note-62">[62]</a>

</td></tr>

<th style="background:#fbb;">5

</th>

<td><a href="Explorer_5" title="Explorer 5">Explorer 5</a>

</td>

<td>24 August 1958

</td>

</td>

<td>17

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Planned in conjunction with Explorer 4, but launch failed<a href="#cite_note-63">[63]</a>

</td></tr>

<th style="background:#fbb;">—

</th>

<td><a href="Explorer_S-1" class="mw-redirect" title="Explorer S-1">Explorer S-1</a> (7X)

</td>

<td>16 July 1959

</td>

</td>

<td>42

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Planned to measure Earth's radiation balance, but destroyed within seconds by range safety<a href="#cite_note-64">[64]</a>

</td></tr>

<tr>

<th>6

</th>

<td><a href="Explorer_6" title="Explorer 6">Explorer 6</a> (S-2, Able 3)

</td>

<td>7 August 1959

</td>

</td>

<td>64

</td>

<td>HEO

</td>

<td>6 October 1959

</td>

<td>12 July 1961

</td>

<td>Magnetosphere research and digital telemetry; first NASA launch, first Earth photo from orbit<a href="#cite_note-65">[65]</a><a href="#cite_note-space-timeline-66">[66]</a>

</td></tr>

<tr>

<th>7

</th>

<td><a href="Explorer_7" title="Explorer 7">Explorer 7</a> (S-1A)

</td>

<td>13 October 1959

</td>

</td>

<td>42

</td>

<td>LEO

</td>

<td>24 August 1961

</td>

<td>In orbit

</td>

<td>Micrometeoroids and energetic particle studies, first satellite to measure Earth's climate<a href="#cite_note-67">[67]</a><a href="#cite_note-68">[68]</a><a href="#cite_note-69">[69]</a>

</td></tr>

<th style="background:#fbb;">–

</th>

<td><a href="Explorer_S-46_(satellite)" title="Explorer S-46 (satellite)">S-46A</a> (IE-B)

</td>

<td>23 March 1960

</td>

</td>

<td>16

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Analyze electron and proton radiation energies, failed to achieve orbit<a href="#cite_note-70">[70]</a>

</td></tr>

<tr>

<th>8

</th>

<td><a href="Explorer_8" title="Explorer 8">Explorer 8</a> (S-30)

</td>

<td>3 November 1960

</td>

</td>

<td>41

</td>

<td>LEO

</td>

<td>27 December 1960

</td>

<td>27 March 2012

</td>

<td>Measured atmospheric composition of the ionosphere<a href="#cite_note-71">[71]</a>

</td></tr>

<th style="background:#fbb;">–

</th>

</td>

<td>4 December 1960

</td>

<td><a href="Scout_X-1" title="Scout X-1">Scout X-1</a>

</td>

<td>6

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Atmosphere density measurement, but failed to achieve orbit<a href="#cite_note-72">[72]</a>

</td></tr>

<tr>

<th>9

</th>

<td><a href="Explorer_9" title="Explorer 9">Explorer 9</a> (S-56A)

</td>

<td>16 February 1961

</td>

<td><a href="Scout_X-1" title="Scout X-1">Scout X-1</a>

</td>

<td>36

</td>

<td>LEO

</td>

<td>9 April 1964

</td>

<td>9 April 1964

</td>

<td>Atmospheric density measurements, first spacecraft placed in orbit by a solid-fuel rocket<a href="#cite_note-73">[73]</a>

</td></tr>

<th style="background:#fbb;">–

</th>

</td>

<td>24 February 1961

</td>

</td>

<td>34

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Ionosphere research, but failed to achieve orbit<a href="#cite_note-74">[74]</a>

</td></tr>

<tr>

<th>10

</th>

<td><a href="Explorer_10" title="Explorer 10">Explorer 10</a> (P 14)

</td>

<td>25 March 1961

</td>

<td><a href="Delta_(rocket_family)" title="Delta (rocket family)">Thor-Delta</a>

</td>

<td>79

</td>

<td>HEO

</td>

<td>25 March 1961

</td>

<td>1 June 1968

</td>

<td>Investigated the magnetic field between the Earth and Moon<a href="#cite_note-75">[75]</a>

</td></tr>

<tr>

<th>11

</th>

<td><a href="Explorer_11" title="Explorer 11">Explorer 11</a> (S 15)

</td>

<td>27 April 1961

</td>

</td>

<td>37

</td>

<td>LEO

</td>

<td>17 November 1961

</td>

<td>In orbit

</td>

<td>Gamma ray astronomy<a href="#cite_note-76">[76]</a>

</td></tr>

<th style="background:#fbb;">–

</th>

</td>

<td>25 May 1961

</td>

</td>

<td>34

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Ionosphere research, failed to achieve orbit. Last Juno II launch.<a href="#cite_note-77">[77]</a>

</td></tr>

<th style="background:#fbb;">–

</th>

<td><a href="S-55_(satellite)" class="mw-redirect" title="S-55 (satellite)">S-55 (satellite)</a> (Meteoroid Satellite-A, Micrometeorite Explorer)

</td>

<td>30 June 1961

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-1</a>

</td>

<td>85

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Micrometeoroid research, failed to achieve orbit<a href="#cite_note-78">[78]</a>

</td></tr>

<tr>

<th>12

</th>

<td><a href="Explorer_12" title="Explorer 12">EPE-A</a> (S 3, Energetic Particle Explorer-A)

</td>

<td>16 August 1961

</td>

<td><a href="Thor-Delta" title="Thor-Delta">Thor-Delta</a>

</td>

<td>38

</td>

<td>HEO

</td>

<td>6 December 1961

</td>

<td>1 September 1963

</td>

<td>Energetic particle research<a href="#cite_note-79">[79]</a>

</td></tr>

<th style="background: #FFB;">13

</th>

<td><a href="Explorer_13" title="Explorer 13">Explorer 13</a> (S-55A)

</td>

<td>25 August 1961

</td>

<td><a href="Scout_X-1" title="Scout X-1">Scout X-1</a>

</td>

<td>86

</td>

<td>LEO

</td>

<td>28 August 1961

</td>

<td>28 August 1961

</td>

<td>Micrometeoroid research; partial failure<a href="#cite_note-80">[80]</a>

</td></tr>

<tr>

<th>14

</th>

<td><a href="Explorer_14" title="Explorer 14">EPE-B</a> (Energetic Particle Explorer-B)

</td>

<td>2 October 1962

</td>

<td><a href="Delta_A" title="Delta A">Delta A</a>

</td>

<td>40

</td>

<td>HEO

</td>

<td>11 August 1963

</td>

<td>1 July 1966

</td>

<td>Energetic particle research<a href="#cite_note-81">[81]</a>

</td></tr>

<tr>

<th>15

</th>

<td><a href="Explorer_15" title="Explorer 15">EPE-C</a> (S-3B, Energetic Particle Explorer-C)

</td>

<td>27 October 1962

</td>

<td><a href="Delta_A" title="Delta A">Delta A</a>

</td>

<td>44

</td>

<td>HEO

</td>

<td>30 January 1963

</td>

<td>15 January 1978

</td>

<td>Energetic particle research<a href="#cite_note-82">[82]</a>

</td></tr>

<tr>

<th>16

</th>

</td>

<td>16 December 1962

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-3</a>

</td>

<td>101

</td>

<td>LEO

</td>

<td>22 July 1963

</td>

<td>In orbit

</td>

<td>Micrometeoroid research<a href="#cite_note-83">[83]</a>

</td></tr>

<tr>

<th>17

</th>

<td><a href="Explorer_17" title="Explorer 17">AE-A (S-6, Atmosphere Explorer-A)</a>

</td>

<td>3 April 1963

</td>

<td><a href="Delta_B" title="Delta B">Delta B</a>

</td>

<td>184

</td>

<td>LEO

</td>

<td>10 July 1963

</td>

<td>24 November 1966

</td>

<td>Atmospheric research<a href="#cite_note-84">[84]</a>

</td></tr>

<tr>

<th>18

</th>

<td><a href="Explorer_18" title="Explorer 18">IMP-A</a> (IMP 1, Interplanetary Monitoring Platform-A)

</td>

<td>27 November 1963

</td>

<td><a href="Delta_C" title="Delta C">Delta C</a>

</td>

<td>138

</td>

<td>HEO

</td>

<td>10 May 1965

</td>

<td>30 December 1965

</td>

<td>Magnetospheric research<a href="#cite_note-85">[85]</a>

</td></tr>

<tr>

<th>19

</th>

<td><a href="Explorer_19" title="Explorer 19">AD-A (Atmospheric Density-A)</a>

</td>

<td>19 December 1963

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-4</a>

</td>

<td>8

</td>

<td>LEO

</td>

<td>10 May 1981

</td>

<td>10 May 1981

</td>

<td>Atmospheric density measurements<a href="#cite_note-86">[86]</a>

</td></tr>

<th style="background:#fbb;">–

</th>

<td>BE-A (<a href="Beacon_Explorer-A" class="mw-redirect" title="Beacon Explorer-A">Beacon Explorer-A</a>, S-66A)

</td>

<td>19 March 1964

</td>

<td><a href="Delta_B" title="Delta B">Delta B</a>

</td>

<td>114

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Launch failure<a href="#cite_note-87">[87]</a>

</td></tr>

<tr>

<th>20

</th>

<td><a href="Explorer_20" title="Explorer 20">IE-A</a> (S 48, TOPSI, Ionosphere Explorer-A)

</td>

<td>25 August 1964

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-4</a>

</td>

<td>45

</td>

<td>LEO

</td>

<td>29 December 1965

</td>

<td>In orbit

</td>

<td>Ionosphere research<a href="#cite_note-88">[88]</a>

</td></tr>

<tr>

<th>21

</th>

<td><a href="Explorer_21" title="Explorer 21">IMP-B</a> (IMP 2, Interplanetary Monitoring Platform-B)

</td>

<td>4 October 1964

</td>

<td><a href="Delta_C" title="Delta C">Delta C</a>

</td>

<td>135

</td>

<td>HEO

</td>

<td>13 October 1965

</td>

<td>30 January 1966

</td>

<td>Magnetospheric research<a href="#cite_note-89">[89]</a>

</td></tr>

<tr>

<th>22

</th>

<td><a href="Explorer_22" title="Explorer 22">BE-B</a> (Beacon Explorer-B, S-66B)

</td>

<td>10 October 1964

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-4</a>

</td>

<td>53

</td>

<td>LEO

</td>

<td>February 1970

</td>

<td>In orbit

</td>

<td>Ionospheric and geodetic research<a href="#cite_note-90">[90]</a>

</td></tr>

<tr>

<th>23

</th>

</td>

<td>6 November 1964

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-4</a>

</td>

<td>134

</td>

<td>LEO

</td>

<td>7 November 1965

</td>

<td>29 June 1983

</td>

<td>Micrometeoric research<a href="#cite_note-91">[91]</a>

</td></tr>

<tr>

<th>24

</th>

<td><a href="Explorer_24" title="Explorer 24">AD-B</a> (Atmospheric Density-B)

</td>

<td>21 November 1964

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-4</a>

</td>

<td>9

</td>

<td>MEO

</td>

<td>18 October 1968

</td>

<td>18 October 1968

</td>

<td>Atmospheric density measurements<a href="#cite_note-92">[92]</a>

</td></tr>

<tr>

<th>25

</th>

<td><a href="Injun_(satellite)" title="Injun (satellite)">Injun 4</a> (IE-B, Ionosphere Explorer-B)

</td>

<td>21 November 1964

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-4</a>

</td>

<td>40

</td>

<td>LEO

</td>

<td>December 1966

</td>

<td>In orbit

</td>

<td>Ionospheric research<a href="#cite_note-93">[93]</a>

</td></tr>

<tr>

<th>26

</th>

<td><a href="Explorer_26" title="Explorer 26">EPE-D (Energetic Particle Explorer-D)</a>

</td>

<td>21 December 1964

</td>

<td><a href="Delta_C" title="Delta C">Delta C</a>

</td>

<td>46

</td>

<td>MEO

</td>

<td>27 December 1967

</td>

<td>23 August 2021

</td>

<td>High energy particle observations<a href="#cite_note-94">[94]</a>

</td></tr>

<tr>

<th>27

</th>

<td><a href="Explorer_27" title="Explorer 27">BE-C (Beacon Explorer-C, S-66C)</a>

</td>

<td>29 April 1965

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout X-4</a>

</td>

<td>61

</td>

<td>LEO

</td>

<td>20 July 1973

</td>

<td>In orbit

</td>

<td>Magnetospheric research<a href="#cite_note-95">[95]</a>

</td></tr>

<tr>

<th>28

</th>

<td><a href="Explorer_28" title="Explorer 28">IMP-C</a> (IMP 3, Interplanetary Monitoring Platform-C)

</td>

<td>29 May 1965

</td>

<td><a href="Delta_C" title="Delta C">Delta C</a>

</td>

<td>128

</td>

<td>HEO

</td>

<td>12 May 1967

</td>

<td>4 July 1968

</td>

<td>Magnetospheric research<a href="#cite_note-96">[96]</a>

</td></tr>

<tr>

<th>29

</th>

<td><a href="Explorer_29" title="Explorer 29">GEOS 1</a> (GEOS-A, Geodetic Earth Orbiting Satellite-1)

</td>

<td>6 November 1965

</td>

<td><a href="Delta_E" title="Delta E">Delta E</a>

</td>

<td>387

</td>

<td>LEO

</td>

<td>23 June 1978

</td>

<td>In orbit

</td>

<td>Geodetic Earth monitoring<a href="#cite_note-97">[97]</a>

</td></tr>

<tr>

<th>30

</th>

<td><a href="Solrad_8" class="mw-redirect" title="Solrad 8">SOLRAD 8</a> (SE-A)

</td>

<td>19 November 1965

</td>

<td><a href="Scout_(rocket_family)" title="Scout (rocket family)">Scout X-4</a>

</td>

<td>57

</td>

<td>LEO

</td>

<td>5 November 1967

</td>

<td>In orbit

</td>

<td>Solar radiation monitoring (Cover for covert <a href="Signals_intelligence" title="Signals intelligence">ELINT</a> mission)<a href="#cite_note-98">[98]</a>

</td></tr>

<tr>

<th>31

</th>

<td><a href="Explorer_31" title="Explorer 31">DME-A</a> (Direct Measurements Explorer)

</td>

<td>29 November 1965

</td>

<td><a href="Thor-Agena" title="Thor-Agena">Thor-Agena</a> B

</td>

<td>99

</td>

<td>LEO

</td>

<td>1 October 1969

</td>

<td>In orbit

</td>

<td>Ionospheric research<a href="#cite_note-99">[99]</a>

</td></tr>

<tr>

<th>32

</th>

<td><a href="Explorer_32" title="Explorer 32">AE-B (Atmosphere Explorer-B)</a>

</td>

<td>25 May 1966

</td>

<td><a href="Delta_C" title="Delta C">Delta C</a>1

</td>

<td>225

</td>

<td>LEO

</td>

<td>March 1967

</td>

<td>22 February 1985

</td>

<td>Atmospheric research<a href="#cite_note-100">[100]</a>

</td></tr>

<tr>

<th>33

</th>

<td><a href="Explorer_33" title="Explorer 33">IMP-D (AIMP 1, Interplanetary Monitoring Platform-D)</a>

</td>

<td>1 July 1966

</td>

<td><a href="Delta_E" title="Delta E">Delta E</a>1

</td>

<td>212

</td>

<td>HEO

</td>

<td>21 September 1971<a href="#cite_note-101">[101]</a>

</td>

<td>In orbit

</td>

<td>Magnetospheric research

</td></tr>

<tr>

<th>34

</th>

<td><a href="Explorer_34" title="Explorer 34">IMP-F</a> (IMP 4, Interplanetary Monitoring Platform-F)

</td>

<td>24 May 1967

</td>

<td><a href="Delta_E" title="Delta E">Delta E</a>1

</td>

<td>163

</td>

<td>MEO

</td>

<td>3 May 1969

</td>

<td>3 May 1969

</td>

<td>Magnetospheric research<a href="#cite_note-102">[102]</a>

</td></tr>

<tr>

<th>35

</th>

<td><a href="Explorer_35" title="Explorer 35">IMP-E (AIMP 2, Interplanetary Monitoring Platform-E)</a>

</td>

<td>19 July 1967

</td>

<td><a href="Delta_E" title="Delta E">Delta E</a>1

</td>

<td>230

</td>

<td><a href="Lunar_orbit" title="Lunar orbit">Lunar</a>

</td>

<td>24 June 1973

</td>

<td>Lunar orbit

</td>

<td>Magnetospheric research<a href="#cite_note-103">[103]</a>

</td></tr>

<tr>

<th>36

</th>

<td><a href="GEOS_2" class="mw-redirect" title="GEOS 2">GEOS 2</a> (GEOS-B, Geodetic Earth Orbiting Satellite-2)

</td>

<td>11 January 1968

</td>

<td><a href="Delta_E" title="Delta E">Delta E</a>1

</td>

<td>469

</td>

<td>LEO

</td>

<td>1 July 1982

</td>

<td>In orbit

</td>

<td>Geodetic Earth monitoring<a href="#cite_note-104">[104]</a>

</td></tr>

<tr>

<th>37

</th>

<td><a href="SOLRAD_9" title="SOLRAD 9">SOLRAD 9</a> (SE B)

</td>

<td>5 March 1968

</td>

<td><a href="Scout_B" class="mw-redirect" title="Scout B">Scout B</a>

</td>

<td>198

</td>

<td>LEO

</td>

<td>30 April 1974

</td>

<td>16 November 1990

</td>

<td>Solar radiation monitoring (Cover for covert <a href="ELINT" class="mw-redirect" title="ELINT">ELINT</a> mission)<a href="#cite_note-105">[105]</a>

</td></tr>

<tr>

<th>38

</th>

<td><a href="Explorer_38" title="Explorer 38">RAE-A (RAE 1, Radio Astronomy Explorer-A)</a>

</td>

<td>4 July 1968

</td>

<td><a href="Delta_J" title="Delta J">Delta J</a>

</td>

<td>602

</td>

<td>MEO

</td>

<td>(~1969)

</td>

<td>In orbit

</td>

<td>Radio astronomy<a href="#cite_note-106">[106]</a>

</td></tr>

<tr>

<th>39

</th>

<td><a href="Explorer_39" title="Explorer 39">AD-C</a> (Atmospheric Density-C)

</td>

<td>8 August 1968

</td>

<td><a href="Scout_B" class="mw-redirect" title="Scout B">Scout B</a>

</td>

<td>9

</td>

<td>LEO

</td>

<td>23 June 1971

</td>

<td>22 June 1981

</td>

<td>Atmospheric density measurements<a href="#cite_note-107">[107]</a>

</td></tr>

<tr>

<th>40

</th>

<td><a href="Injun_(satellite)" title="Injun (satellite)">Injun 5</a> (Injun C, IE-C, Ionosphere Explorer-C)

</td>

<td>8 August 1968

</td>

<td><a href="Scout_B" class="mw-redirect" title="Scout B">Scout B</a>

</td>

<td>71

</td>

<td>LEO

</td>

<td>June 1971

</td>

<td>In orbit

</td>

<td>Magnetospheric Research<a href="#cite_note-108">[108]</a>

</td></tr>

<tr>

<th>41

</th>

<td><a href="Explorer_41" title="Explorer 41">IMP-G</a> (IMP 5, Interplanetary Monitoring Platform-G)

</td>

<td>21 June 1969

</td>

<td><a href="Delta_E" title="Delta E">Delta E</a>1

</td>

<td>145

</td>

<td>HEO

</td>

<td>23 December 1972

</td>

<td>23 December 1972

</td>

<td>Magnetospheric research<a href="#cite_note-109">[109]</a>

</td></tr>

<tr>

<th>42

</th>

<td><a href="Uhuru_(satellite)" title="Uhuru (satellite)">Uhuru</a> (SAS-A, SAS 1)

</td>

<td>12 December 1970

</td>

<td><a href="Scout_B" class="mw-redirect" title="Scout B">Scout B</a>

</td>

<td>142

</td>

<td>LEO

</td>

<td>4 January 1975

</td>

<td>5 April 1979

</td>

<td>X-ray astronomy<a href="#cite_note-110">[110]</a>

</td></tr>

<tr>

<th>43

</th>

<td><a href="Explorer_43" title="Explorer 43">IMP-H</a> (IMP 7, Interplanetary Monitoring Platform-H)

</td>

<td>13 March 1971

</td>

<td><a href="Delta_M" title="Delta M">Delta M</a>6

</td>

<td>635

</td>

<td>MEO

</td>

<td>2 October 1974

</td>

<td>2 October 1974

</td>

<td>Magnetospheric research<a href="#cite_note-111">[111]</a>

</td></tr>

<tr>

<th>44

</th>

<td><a href="SOLRAD_10" title="SOLRAD 10">SOLRAD 10</a> (SE-C, SOLRAD-C)

</td>

<td>8 July 1971

</td>

<td><a href="Scout_B" class="mw-redirect" title="Scout B">Scout B</a>

</td>

<td>260

</td>

<td>LEO

</td>

<td>30 June 1973

</td>

<td>15 December 1979

</td>

<td>Solar radiation monitoring (Cover for covert <a href="ELINT" class="mw-redirect" title="ELINT">ELINT</a> mission)<a href="#cite_note-112">[112]</a>

</td></tr>

<tr>

<th>45

</th>

<td><a href="Explorer_45" title="Explorer 45">SSS-A</a> (S-Cubed A)

</td>

<td>15 November 1971

</td>

<td><a href="Scout_B" class="mw-redirect" title="Scout B">Scout B</a>

</td>

<td>52

</td>

<td>MEO

</td>

<td>30 September 1974

</td>

<td>10 January 1992

</td>

<td>Magnetospheric research<a href="#cite_note-113">[113]</a>

</td></tr>

<tr>

<th>46

</th>

<td>MTS (<a href="Meteoroid_Technology_Satellite" class="mw-redirect" title="Meteoroid Technology Satellite">Meteoroid Technology Satellite</a>, METEC)<a href="#cite_note-114">[114]</a>

</td>

<td>13 August 1972

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout D-1</a>

</td>

<td>90

</td>

<td>LEO

</td>

<td>4 November 1974

</td>

<td>2 November 1979

</td>

<td>Micrometeoroids research<a href="#cite_note-115">[115]</a>

</td></tr>

<tr>

<th>47

</th>

<td><a href="Explorer_47" title="Explorer 47">IMP-I</a> (IMP 6, Interplanetary Monitoring Platform-I)

</td>

<td>23 September 1972

</td>

<td><a href="Delta_1000" title="Delta 1000">Delta 1604</a>

</td>

<td>635

</td>

<td>HEO

</td>

<td>31 October 1978

</td>

<td>In orbit

</td>

<td>Magnetospheric research<a href="#cite_note-116">[116]</a>

</td></tr>

<tr>

<th>48

</th>

<td><a href="Second_Small_Astronomy_Satellite" class="mw-redirect" title="Second Small Astronomy Satellite">SAS-B (Small Astronomy Satellite-B, SAS 2)</a>

</td>

<td>15 November 1972

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout D-1</a>

</td>

<td>166

</td>

<td>LEO

</td>

<td>8 June 1973

</td>

<td>20 August 1980

</td>

<td>X-ray astronomy<a href="#cite_note-117">[117]</a>

</td></tr>

<tr>

<th>49

</th>

<td><a href="Explorer_49" title="Explorer 49">RAE-B (RAE 2, Radio Astronomy Explorer-B)</a>

</td>

<td>10 June 1973

</td>

<td><a href="Delta_1000" title="Delta 1000">Delta 1913</a>

</td>

<td>328

</td>

<td><a href="Lunar_orbit" title="Lunar orbit">Lunar</a>

</td>

<td>26 April 1977

</td>

<td>Presumed crashed into Moon sometime after August 1977<a href="#cite_note-explorer49nssdc-118">[118]</a>

</td>

<td>Radio astronomy<a href="#cite_note-explorer49nssdc-118">[118]</a>

</td></tr>

<tr>

<th>50

</th>

<td><a href="Explorer_50" title="Explorer 50">IMP-J</a> (IMP 8, Interplanetary Monitoring Platform-J)

</td>

<td>26 October 1973

</td>

<td><a href="Delta_1000" title="Delta 1000">Delta 1604</a>

</td>

<td>371

</td>

<td>HEO

</td>

<td>7 October 2006

</td>

<td>In orbit

</td>

<td>Magnetospheric research<a href="#cite_note-119">[119]</a>

</td></tr>

<tr>

<th>51

</th>

<td><a href="Explorer_51" title="Explorer 51">AE-C</a> (Atmosphere Explorer-C)

</td>

<td>16 December 1973

</td>

<td><a href="Delta_1000" title="Delta 1000">Delta 1900</a>

</td>

<td>658

</td>

<td>LEO

</td>

<td>(12 December 1978)

</td>

<td>12 December 1978

</td>

<td>Atmospheric research<a href="#cite_note-120">[120]</a>

</td></tr>

<tr>

<th>52

</th>

<td><a href="Explorer_52" title="Explorer 52">Hawkeye 1</a> (Injun-F, Injun 6, IE-D, Ionosphere Explorer-D)

</td>

<td>3 June 1974

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout E-1</a>

</td>

<td>23

</td>

<td>HEO

</td>

<td>28 April 1978

</td>

<td>28 April 1978

</td>

<td>Magnetospheric research<a href="#cite_note-121">[121]</a>

</td></tr>

<tr>

<th>53

</th>

<td><a href="Third_Small_Astronomy_Satellite" class="mw-redirect" title="Third Small Astronomy Satellite">SAS-C (Small Astronomy Satellite-C, SAS 3)</a>

</td>

<td>7 May 1975

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout F-1</a>

</td>

<td>197

</td>

<td>LEO

</td>

<td>7 April 1979

</td>

<td>9 April 1979

</td>

<td>X-ray astronomy<a href="#cite_note-122">[122]</a>

</td></tr>

<tr>

<th>54

</th>

<td><a href="Explorer_54" title="Explorer 54">AE-D</a> (Atmosphere Explorer-D)

</td>

<td>6 October 1975

</td>

<td><a href="Delta_2000" title="Delta 2000">Delta 2910</a>

</td>

<td>681

</td>

<td>LEO

</td>

<td>29 January 1976

</td>

<td>12 March 1976

</td>

<td>Atmospheric research<a href="#cite_note-123">[123]</a>

</td></tr>

<tr>

<th>55

</th>

<td><a href="Explorer_55" title="Explorer 55">AE-E</a> (Atmosphere Explorer-E)

</td>

<td>20 November 1975

</td>

<td><a href="Delta_2000" title="Delta 2000">Delta 2910</a>

</td>

<td>735

</td>

<td>LEO

</td>

<td>25 September 1980

</td>

<td>10 June 1981

</td>

<td>Atmospheric research<a href="#cite_note-124">[124]</a>

</td></tr>

<th style="background:#fbb;">—

</th>

<td><a href="Dual_Air_Density_Explorer" title="Dual Air Density Explorer">DADE-A</a> (Dual Air Density Explorer-A)

</td>

<td>5 December 1975

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout F-1</a>

</td>

<td>40

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Atmospheric research; failed during launch<a href="#cite_note-125">[125]</a>

</td></tr>

<th style="background:#fbb;">—

</th>

<td><a href="Dual_Air_Density_Explorer" title="Dual Air Density Explorer">DADE-B</a> (Dual Air Density Explorer-B)

</td>

<td>5 December 1975

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout F-1</a>

</td>

<td>43

</td>

<td>failed

</td>

<td>—

</td>

<td>—

</td>

<td>Atmospheric research; failed during launch<a href="#cite_note-126">[126]</a>

</td></tr>

<tr>

<th>56

</th>

<td><a href="ISEE-1" title="ISEE-1">ISEE-1</a> (ISEE-A)

</td>

<td>22 October 1977

</td>

<td><a href="Delta_2000" title="Delta 2000">Delta 2914</a>

</td>

<td>340

</td>

<td>HEO

</td>

<td>26 September 1987

</td>

<td>26 September 1987

</td>

<td>Magnetospheric research; launched with ESA's <a href="ISEE-2" title="ISEE-2">ISEE-2</a>; co-mission with ISEE 3<a href="#cite_note-127">[127]</a>

</td></tr>

<tr>

<th>57

</th>

</td>

<td>26 January 1978

</td>

<td><a href="Delta_2000" title="Delta 2000">Delta 2914</a>

</td>

<td>669

</td>

<td>MEO

</td>

<td>30 September 1996

</td>

<td>In orbit

</td>

<td>Ultraviolet astronomy<a href="#cite_note-128">[128]</a>

</td></tr>

<tr>

<th>58

</th>

<td><a href="Heat_Capacity_Mapping_Mission" title="Heat Capacity Mapping Mission">HCMM</a> (AEM-A)

</td>

<td>26 April 1978

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout F</a>

</td>

<td>117

</td>

<td>LEO

</td>

<td>30 September 1980

</td>

<td>December 22, 1981

</td>

<td>Thermal mapping of the Earth<a href="#cite_note-129">[129]</a>

</td></tr>

<tr>

<th>59

</th>

<td><a href="International_Cometary_Explorer" title="International Cometary Explorer">ICE</a> (ISEE 3, ISEE-C)

</td>

<td>12 August 1978

</td>

<td><a href="Delta_2000" title="Delta 2000">Delta 2914</a>

</td>

<td>390

</td>

<td><a href="Lissajous_orbit" title="Lissajous orbit">Sun–Earth L1</a>

</td>

<td>16 September 2014

</td>

<td><a href="Heliocentric_orbit" title="Heliocentric orbit">Heliocentric orbit</a>

</td>

<td>Magnetospheric research; heliocentric mission, re-purposed in 1982 as a cometary probe (renamed International Cometary Explorer). First spacecraft to be placed at a libration point, and first one to perform a flyby of a comet.<a href="#cite_note-130">[130]</a><a href="#cite_note-space-timeline-66">[66]</a>

</td></tr>

<tr>

<th>60

</th>

<td><a href="Stratospheric_Aerosol_and_Gas_Experiment" title="Stratospheric Aerosol and Gas Experiment">SAGE</a> (AEM-B)

</td>

<td>18 February 1979

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout D-1</a>

</td>

<td>149

</td>

<td>LEO

</td>

<td>7 January 1982

</td>

<td>11 April 1989

</td>

<td>Stratospheric aerosol and ozone data<a href="#cite_note-131">[131]</a>

</td></tr>

<tr>

<th>61

</th>

<td><a href="Magsat" class="mw-redirect" title="Magsat">MAGSAT</a> (AEM-C)

</td>

<td>30 October 1979

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout G-1</a>

</td>

<td>158

</td>

<td>LEO

</td>

<td>6 May 1980

</td>

<td>11 June 1980

</td>

<td>Mapped the near surface magnetic field of the Earth<a href="#cite_note-132">[132]</a>

</td></tr>

<tr>

<th>62

</th>

<td><a href="Dynamics_Explorer_1" title="Dynamics Explorer 1">Dynamics Explorer 1</a> (DE-1)

</td>

<td>3 August 1981

</td>

<td><a href="Delta_(rocket)" class="mw-redirect" title="Delta (rocket)">Delta 3913</a>

</td>

<td>424

</td>

<td>MEO

</td>

<td>28 February 1991

</td>

<td>In orbit

</td>

<td>Magnetospheric research<a href="#cite_note-133">[133]</a>

</td></tr>

<tr>

<th>63

</th>

<td><a href="Dynamics_Explorer_2" title="Dynamics Explorer 2">Dynamics Explorer 2</a> (DE-2)

</td>

<td>3 August 1981

</td>

<td><a href="Delta_(rocket)" class="mw-redirect" title="Delta (rocket)">Delta 3913</a>

</td>

<td>420

</td>

<td>LEO

</td>

<td>19 February 1983

</td>

<td>19 February 1983

</td>

<td>Magnetospheric research<a href="#cite_note-134">[134]</a>

</td></tr>

<tr>

<th>64

</th>

</td>

<td>6 October 1981

</td>

<td><a href="Delta_(rocket)" class="mw-redirect" title="Delta (rocket)">Delta 2310</a>

</td>

<td>145

</td>

<td>LEO

</td>

<td>4 April 1989

</td>

<td>5 March 1991

</td>

<td>Atmospheric research<a href="#cite_note-135">[135]</a>

</td></tr>

<tr>

<th>65

</th>

<td><a href="AMPTE-CCE" title="AMPTE-CCE">AMPTE-CCE</a>

</td>

<td>16 August 1984

</td>

<td><a href="Delta_(rocket)" class="mw-redirect" title="Delta (rocket)">Delta 3924</a>

</td>

<td>242

</td>

<td>MEO

</td>

<td>12 July 1989

</td>

<td>In orbit

</td>

<td><a href="Magnetosphere" title="Magnetosphere">Magnetosphere research</a><a href="#cite_note-Display-136">[136]</a>

</td></tr>

<tr>

<th>66

</th>

</td>

<td>18 November 1989

</td>

<td><a href="Delta_(rocket)" class="mw-redirect" title="Delta (rocket)">Delta 5920</a>

</td>

<td>2,206

</td>

<td>LEO

</td>

<td>23 December 1993

</td>

<td>In orbit

</td>

<td>Microwave astronomy<a href="#cite_note-137">[137]</a>

</td></tr>

<tr>

<th>67

</th>

<td><a href="Extreme_Ultraviolet_Explorer" title="Extreme Ultraviolet Explorer">EUVE</a> (BERKSAT)

</td>

<td>7 June 1992

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 6920-X

</td>

<td>3,275

</td>

<td>LEO

</td>

<td>31 January 2001

</td>

<td>30 January 2002

</td>

<td>Ultraviolet astronomy<a href="#cite_note-138">[138]</a>

</td></tr>

<tr>

<th>68

</th>

<td><a href="Solar_Anomalous_and_Magnetospheric_Particle_Explorer" title="Solar Anomalous and Magnetospheric Particle Explorer">SAMPEX</a>

</td>

<td>3 July 1992

</td>

<td><a href="Scout_(rocket)" class="mw-redirect" title="Scout (rocket)">Scout G-1</a>

</td>

<td>158

</td>

<td>LEO

</td>

</td>

<td>13 November 2012.<a href="#cite_note-140">[140]</a>

</td>

<td>SMEX: magnetospheric research<a href="#cite_note-141">[141]</a>

</td></tr>

<tr>

<th>69

</th>

</td>

<td>30 December 1995

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7920

</td>

<td>3,200

</td>

<td>LEO

</td>

<td>3 January 2012

</td>

<td>30 April 2018<a href="#cite_note-142">[142]</a>

</td>

<td>MIDEX: X-ray astronomy<a href="#cite_note-143">[143]</a>

</td></tr>

<tr>

<th>70

</th>

</td>

<td>21 August 1996

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>187

</td>

<td>LEO

</td>

<td>4 May 2009

</td>

<td>In orbit

</td>

<td>SMEX: auroral phenomena<a href="#cite_note-144">[144]</a>

</td></tr>

<th style="background:#fbb;">—

</th>

</td>

<td>4 November 1996

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>128

</td>

<td>LEO

</td>

<td>—

</td>

<td>7 April 2002

</td>

<td>Separation failure, mission relaunched as HETE 2<a href="#cite_note-145">[145]</a>

</td></tr>

<th style="background:#bfb;">71

</th>

</td>

<td>25 August 1997

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7920

</td>

<td>596

</td>

<td><a href="Lissajous_orbit" title="Lissajous orbit">Sun–Earth L1</a>

</td>

<td>Operational

</td>

<td>In <a href="Lissajous_orbit" title="Lissajous orbit">L1 orbit</a>

</td>

<td>MIDEX: solar/interplanetary/interstellar particle research<a href="#cite_note-146">[146]</a>

</td></tr>

<tr>

<th>72

</th>

</td>

<td>26 February 1998

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>120

</td>

<td>LEO

</td>

<td>13 December 2003

</td>

<td>13 December 2003

</td>

<td>STEDI, UNEX: atmospheric research<a href="#cite_note-147">[147]</a>

</td></tr>

<tr>

<th>73

</th>

<td><a href="TRACE" title="TRACE">TRACE</a>

</td>

<td>2 April 1998

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>250

</td>

<td>LEO

</td>

</td>

<td>In orbit

</td>

<td>SMEX: solar observatory<a href="#cite_note-149">[149]</a>

</td></tr>

<tr>

<th>74

</th>

</td>

<td>6 December 1998

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>288

</td>

<td>LEO

</td>

<td>1 September 2005

</td>

<td>In orbit

</td>

<td>SMEX: submillimeter astronomy<a href="#cite_note-150">[150]</a>

</td></tr>

<th style="background: #FFB;">75

</th>

</td>

<td>5 March 1999

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>250

</td>

</td>

<td>30 September 2000<a href="#cite_note-151">[151]</a>

</td>

</td>

<td>SMEX, Infrared astronomy, primary mission failed due to loss of coolant<a href="#cite_note-153">[153]</a>

</td></tr>

<th style="background:#fbb;">76

</th>

<td>TERRIERS

</td>

<td>18 May 1999

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>120

</td>

<td>Polar LEO

</td>

<td>18 May 1999

</td>

<td>In orbit

</td>

<td>STEDI: atmospheric research, satellite failed shortly after achieving orbit<a href="#cite_note-154">[154]</a>

</td></tr>

<tr>

<th>77

</th>

</td>

<td>23 June 1999

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7320

</td>

<td>1,400

</td>

<td>LEO

</td>

<td>18 October 2007

</td>

<td>In orbit

</td>

<td>MIDEX: ultraviolet astronomy<a href="#cite_note-155">[155]</a>

</td></tr>

<tr>

<th>78

</th>

<td><a href="IMAGE_(spacecraft)" title="IMAGE (spacecraft)">IMAGE</a>

</td>

<td>25 March 2000

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7326

</td>

<td>536

</td>

<td>Polar MEO

</td>

<td>18 December 2005<a href="#cite_note-156">[156]</a>

</td>

<td>In orbit

</td>

<td>MIDEX: magnetospheric research<a href="#cite_note-157">[157]</a>

</td></tr>

<tr>

<th>79

</th>

</td>

<td>9 October 2000

</td>

<td><a href="Pegasus_(rocket)" class="mw-redirect" title="Pegasus (rocket)">Pegasus-H</a>

</td>

<td>124

</td>

<td>LEO

</td>

<td>28 March 2007<a href="#cite_note-158">[158]</a>

</td>

<td>In orbit

</td>

<td>MO: UV, X-ray, and gamma ray astronomy<a href="#cite_note-159">[159]</a>

</td></tr>

<tr>

<th>80

</th>

</td>

<td>30 June 2001

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7425-10

</td>

<td>840

</td>

<td><a href="Lissajous_orbit" title="Lissajous orbit">Sun–Earth L2</a>

</td>

<td>October 2010<a href="#cite_note-graveyard-160">[160]</a>

</td>

<td>Heliocentric orbit

</td>

<td>MIDEX: microwave astronomy<a href="#cite_note-161">[161]</a>

</td></tr>

<tr>

<th>81

</th>

<td><a href="RHESSI" class="mw-redirect" title="RHESSI">RHESSI</a>

</td>

<td>5 February 2002

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>230

</td>

<td>LEO

</td>

<td>16 August 2018

</td>

<td>Deorbited

</td>

<td>SMEX: X-ray and gamma ray solar flare imaging<a href="#cite_note-162">[162]</a>

</td></tr>

<th style="background:#bfb;">—

</th>

<td><a href="INTEGRAL" title="INTEGRAL">INTEGRAL</a>

</td>

<td>17 October 2002

</td>

<td><a href="Proton-K" title="Proton-K">Proton-K</a> <a href="Blok_D" title="Blok D">Blok DM-2</a>

</td>

<td>4,000

</td>

<td>HEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>International: space telescope for observing gamma rays<a href="#cite_note-163">[163]</a>

</td></tr>

<tr>

<th>82

</th>

<td><a href="CHIPSat" class="mw-redirect" title="CHIPSat">CHIPSat</a>

</td>

<td>13 January 2003

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7320-10

</td>

<td>60

</td>

<td>LEO

</td>

<td>11 April 2008<a href="#cite_note-164">[164]</a>

</td>

<td>In orbit

</td>

<td>UNEX: ultraviolet spectroscopy and astronomy<a href="#cite_note-165">[165]</a>

</td></tr>

<tr>

<th>83

</th>

<td><a href="GALEX" title="GALEX">GALEX</a>

</td>

<td>28 April 2003

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>280

</td>

<td>LEO

</td>

</td>

<td>In orbit

</td>

<td>SMEX: ultraviolet astronomy<a href="#cite_note-167">[167]</a>

</td></tr>

<th style="background:#bfb;">84

</th>

<td><a href="Neil_Gehrels_Swift_Observatory" title="Neil Gehrels Swift Observatory">Swift</a>

</td>

<td>20 November 2004

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7320-10C

</td>

<td>1,470

</td>

<td>LEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MIDEX: gamma ray astronomy<a href="#cite_note-168">[168]</a>

</td></tr>

<tr>

<th>—

</th>

<td><a href="Suzaku_(satellite)" title="Suzaku (satellite)">Suzaku</a> (Astro E2)

</td>

<td>10 July 2005

</td>

</td>

<td>1,706

</td>

<td>LEO

</td>

<td>2 September 2015

</td>

<td>In orbit

</td>

<td>MO: instrument on JAXA's Suzaku mission<a href="#cite_note-169">[169]</a>

</td></tr>

<th style="background:#bfb;">—

</th>

<td><a href="TWINS" title="TWINS">TWINS</a> A

</td>

<td>28 June 2006

</td>

<td><a href="Delta_IV" title="Delta IV">Delta IV</a> M+(4,2)

</td>

<td>classified

</td>

<td><a href="Molniya_orbit" title="Molniya orbit">Molniya</a>

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MO: payload on Trumpet-F/O-1 1 (<a href="USA-184" title="USA-184">USA-184</a>)

</td></tr>

<th style="background:#bfb;">85

</th>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> A

</td>

<td>17 February 2007

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7925

</td>

<td>77

</td>

<td>HEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MIDEX: magnetospheric research<a href="#cite_note-170">[170]</a>

</td></tr>

<th style="background:#bfb;">86

</th>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> B (ARTEMIS P1)

</td>

<td>17 February 2007

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7925

</td>

<td>77

</td>

<td><a href="Lunar_orbit" title="Lunar orbit">Lunar</a>

</td>

<td>Operational

</td>

<td>Lunar orbit

</td>

<td>MIDEX; Magnetospheric research<a href="#cite_note-171">[171]</a>

</td></tr>

<th style="background:#bfb;">87

</th>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> C (ARTEMIS P2)

</td>

<td>17 February 2007

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7925

</td>

<td>77

</td>

<td><a href="Lunar_orbit" title="Lunar orbit">Lunar</a>

</td>

<td>Operational

</td>

<td>Lunar orbit

</td>

<td>MIDEX: magnetospheric research<a href="#cite_note-172">[172]</a>

</td></tr>

<th style="background:#bfb;">88

</th>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> D

</td>

<td>17 February 2007

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7925

</td>

<td>77

</td>

<td>HEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MIDEX: magnetospheric research<a href="#cite_note-173">[173]</a>

</td></tr>

<th style="background:#bfb;">89

</th>

<td><a href="THEMIS_(satellite)" class="mw-redirect" title="THEMIS (satellite)">THEMIS</a> E

</td>

<td>17 February 2007

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7925

</td>

<td>77

</td>

<td>HEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MIDEX: magnetospheric research<a href="#cite_note-174">[174]</a>

</td></tr>

<tr>

<th>90

</th>

</td>

<td>25 April 2007

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>197

</td>

</td>

<td>March 2023

</td>

<td>19 August 2024

</td>

<td>SMEX: <a href="Noctilucent_cloud" title="Noctilucent cloud">noctilucent cloud</a> observation<a href="#cite_note-175">[175]</a>

</td></tr>

<th style="background:#bfb;">—

</th>

<td><a href="TWINS" title="TWINS">TWINS</a> B

</td>

<td>13 March 2008

</td>

<td><a href="Atlas_V" title="Atlas V">Atlas V</a> 411

</td>

<td>classified

</td>

<td><a href="Molniya_orbit" title="Molniya orbit">Molniya</a>

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MO: payload on Trumpet-F/O-1 2 (<a href="USA-200" title="USA-200">USA-200</a>)

</td></tr>

<tr>

<th>—

</th>

<td><a href="CINDI" title="CINDI">CINDI</a>

</td>

<td>16 April 2008

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>395

</td>

<td>LEO

</td>

<td>28 November 2015

</td>

<td>28 November 2015

</td>

<td>MO: instruments on <a href="C/NOFS" title="C/NOFS">C/NOFS</a>

</td></tr>

<th style="background:#bfb;">91

</th>

</td>

<td>19 October 2008

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>107

</td>

<td>MEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>SMEX: mapping the boundary between the Solar System and interstellar space.<a href="#cite_note-176">[176]</a>

</td></tr>

<tr>

<th>92

</th>

</td>

<td>14 December 2009

</td>

<td><a href="Delta_II" title="Delta II">Delta II</a> 7320

</td>

<td>661

</td>

<td>LEO

</td>

<td>August 2024

</td>

<td>2 November 2024

</td>

<td>MIDEX: infrared astronomy, NEOWISE extension. Discovered first <a href="Earth_trojan" title="Earth trojan">Earth trojan</a>.<a href="#cite_note-177">[177]</a>

</td></tr>

<th style="background:#bfb;">93

</th>

<td><a href="Nuclear_Spectroscopic_Telescope_Array" class="mw-redirect" title="Nuclear Spectroscopic Telescope Array">NuSTAR</a>

</td>

<td>13 June 2012

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>350

</td>

<td>LEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>SMEX: high-energy X-ray astronomy<a href="#cite_note-178">[178]</a>

</td></tr>

<th style="background:#bfb;">94

</th>

</td>

<td>27 June 2013

</td>

<td><a href="Pegasus_XL" class="mw-redirect" title="Pegasus XL">Pegasus XL</a>

</td>

<td>183

</td>

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>SMEX: solar UV astronomy<a href="#cite_note-179">[179]</a>

</td></tr>

<tr>

<th>—

</th>

<td><a href="Hitomi_(satellite)" title="Hitomi (satellite)">Hitomi</a> (NeXT, ASTRO-H)

</td>

<td>7 February 2016

</td>

<td><a href="H-2A" class="mw-redirect" title="H-2A">H-2A</a>-202

</td>

<td>2,700

</td>

<td>LEO

</td>

<td>26 March 2016

</td>

<td>In orbit

</td>

<td>MO: X-ray instrument on JAXA's Hitomi, but spacecraft failed after initial checkouts<a href="#cite_note-180">[180]</a>

</td></tr>

<th style="background:#bfb;">—

</th>

<td><a href="NICER" class="mw-redirect" title="NICER">NICER</a>

</td>

<td>3 May 2017

</td>

<td><a href="Falcon_9" title="Falcon 9">Falcon 9</a> FT

</td>

<td>372

</td>

</td>

<td>Operational

</td>

<td>ISS

</td>

<td>MO: instrument on ISS for <a href="Neutron_star" title="Neutron star">neutron star</a> observations

</td></tr>

<th style="background:#bfb;">—

</th>

</td>

<td>25 January 2018

</td>

<td><a href="Ariane_5" title="Ariane 5">Ariane 5</a> ECA

</td>

<td>37

</td>

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MO: instrument on <a href="SES-14" title="SES-14">SES-14</a> comsat for studying Earth–space boundary

</td></tr>

<th style="background:#bfb;">95

</th>

</td>

<td>18 April 2018

</td>

<td><a href="Falcon_9" title="Falcon 9">Falcon 9</a> FT

</td>

<td>362

</td>

<td>HEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MIDEX: survey for transiting exoplanets

</td></tr>

<th style="background:#bfb;">96

</th>

</td>

<td>11 October 2019

</td>

<td><a href="Pegasus_(rocket)" class="mw-redirect" title="Pegasus (rocket)">Pegasus</a> XL

</td>

<td>287

</td>

<td>LEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MIDEX: ionospheric studies

</td></tr>

<th style="background:#bfb;">97

</th>

</td>

<td>9 December 2021

</td>

<td><a href="Falcon_9" title="Falcon 9">Falcon 9</a> Block 5

</td>

<td>330

</td>

<td>LEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>SMEX: X-ray studies

</td></tr>

<th style="background:#bfb;">—

</th>

<td><a href="X-Ray_Imaging_and_Spectroscopy_Mission" title="X-Ray Imaging and Spectroscopy Mission">XRISM</a>

</td>

<td>6 September 2023

</td>

<td><a href="H-IIA" title="H-IIA">H-IIA</a> 202

</td>

<td>2,300

</td>

<td>LEO

</td>

<td>Operational

</td>

<td>In orbit

</td>

<td>MO: instruments on <a href="JAXA" title="JAXA">JAXA</a>'s XRISM x-ray space telescope

</td></tr></tbody></table>

<div class="mw-heading mw-heading2"><h2 id="Cancelled_missions">Cancelled missions</h2></div>

Many missions are proposed, but not selected. For example, in 2011, the Explorers Program received 22 full missions solicitations, 20 Missions of Opportunity, and 8 USPI.<a href="#cite_note-181">[181]</a> Sometimes mission are only partially developed but must be stopped for financial, technological, or bureaucratic reasons. Some missions failed upon reaching orbit including WIRE and TERRIERS.

Examples of missions that were not developed or cancelled were:<a href="#cite_note-skyrocket-57">[57]</a>

<li>MSS A (Magnetic Storm Satellite, Explorer-A, 1970)<a href="#cite_note-183">[183]</a><a href="#cite_note-184">[184]</a></li>

<li>CATSAT (STEDI 3) (cost)<a href="#cite_note-nap-37">[37]</a></li>

<li><a href="Full-sky_Astrometric_Mapping_Explorer" title="Full-sky Astrometric Mapping Explorer">FAME</a> (MIDEX 4)</li>

<li>SPIDR (SMEX 8) (technical, 2003)<a href="#cite_note-nap-37">[37]</a></li>

Recent examples of conclusions of launched missions, cancelled due to budgetary constraints:

<li><a href="TRACE" title="TRACE">TRACE</a> - 2010 (Solar observatory, see <a href="Solar_Dynamics_Observatory" title="Solar Dynamics Observatory">Solar Dynamics Observatory</a>)</li>

<li><a href="Wilkinson_Microwave_Anisotropy_Probe" title="Wilkinson Microwave Anisotropy Probe">Wilkinson MAP</a> - 2010</li>

<li><a href="Wide-field_Infrared_Survey_Explorer" title="Wide-field Infrared Survey Explorer">WISE</a> - 2011 (extended in 2013 as NEOWISE mission)</li>

<li><a href="GALEX" title="GALEX">Galaxy Evolution Explorer</a> - 2013</li></ul>

<div class="mw-heading mw-heading2"><h2 id="Launch_statistics">Launch statistics</h2></div>

Number of launches per decade:<a href="#cite_note-185">[185]</a>

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<caption>Number of Explorer launches by decade

</caption>

<th scope="col" class="bar-chart-label-type">Decade

</th>

</th></tr>

<tr>

<th scope="row">1950s

</th>

</td></tr>

<tr>

<th scope="row">1960s

</th>

</td></tr>

<tr>

<th scope="row">1970s

</th>

</td></tr>

<tr>

<th scope="row">1980s

</th>

</td></tr>

<tr>

<th scope="row">1990s

</th>

</td></tr>

<tr>

<th scope="row">2000s

</th>

</td></tr>

<tr>

<th scope="row">2010s

</th>

</td></tr>

<tr>

<th scope="row">2020s

</th>

</td></tr>

</tbody></table>

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<ul><li><a href="Cosmic_Vision" title="Cosmic Vision">Cosmic Vision</a>, a <a href="European_Space_Agency" title="European Space Agency">European Space Agency</a> (ESA) programme</li>

<li><a href="Cosmic_Vision#Small_class" title="Cosmic Vision">Cosmic Vision S-class missions</a>, the European Space Agency equivalent to the Small Explorers Program</li>

<li><a href="Discovery_program" class="mw-redirect" title="Discovery program">Discovery program</a> – Solar system exploration program by NASAPages displaying short descriptions of redirect targets</li>

<li><a href="New_Frontiers_program" title="New Frontiers program">New Frontiers program</a> – Series of space exploration missions being conducted by NASA</li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

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<div class="side-box-text plainlist">Wikimedia Commons has media related to <a href="https://commons.wikimedia.org/wiki/Category:Explorer_program" class="extiw external" title="commons:Category:Explorer program">Explorer program</a>.</div></div>

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<ul><li><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20091031051247/http://explorers.gsfc.nasa.gov/index.html">"Explorers Program"</a>. Goddard Space Flight Center. <a href="NASA" title="NASA">NASA</a>. 2009. Archived from <a rel="nofollow" class="external text" href="https://explorers.gsfc.nasa.gov/index.html">the original</a> on 31 October 2009. Retrieved 5 December 2009.</cite></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100323182500/http://explorers.gsfc.nasa.gov/missions.html">NASA Explorers Program missions page</a></li>

<li><a rel="nofollow" class="external text" href="https://nssdc.gsfc.nasa.gov/multi/explorer.html">NSSDC updated list of Explorers missions</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20151220110322/http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Explorer_Moon">Explorers Program Profile</a> by <a rel="nofollow" class="external text" href="https://solarsystem.nasa.gov">NASA's Solar System Exploration</a></li>

<li><a rel="nofollow" class="external text" href="https://explorers.gsfc.nasa.gov/smex.html">Small Explorers Missions</a> by <a href="Goddard_Space_Flight_Center" title="Goddard Space Flight Center">Goddard Space Flight Center</a></li>

<li><a rel="nofollow" class="external text" href="http://rammb.cira.colostate.edu/dev/hillger/SMEX.htm">SMEX-series satellites</a> by Colorado State University</li></ul>

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</style><div id="Explorers_Program494" style="font-size:114%;margin:0 4em"></div></th></tr><tr><td class="navbox-abovebelow" colspan="3"><div><a href="List_of_Explorers_Program_missions" class="mw-redirect" title="List of Explorers Program missions">List of Explorers Program missions</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Missions</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:5em">1958–1992</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Explorer_1" title="Explorer 1">Explorer 1</a></li>

<li><a href="Injun_(satellite)" title="Injun (satellite)">25 (Injun 4, IE-B)</a></li>

<li><a href="Solrad_8" class="mw-redirect" title="Solrad 8">30 (Solrad 8)</a></li>

<li><a href="Solrad_9" class="mw-redirect" title="Solrad 9">37 (Solrad 9)</a></li>

<li><a href="Injun_(satellite)" title="Injun (satellite)">40 (Injun 5)</a></li>

<li><a href="Uhuru_(satellite)" title="Uhuru (satellite)">42 (Uhuru, SAS-A)</a></li>

<li><a href="Solrad_10" class="mw-redirect" title="Solrad 10">44 (Solrad 10)</a></li>

<li><a href="Explorer_52" title="Explorer 52">52 (Hawkeye 1)</a></li>

<li><a href="Magsat" class="mw-redirect" title="Magsat">61 (Magsat)</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Medium class (since 1992)</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<li><a href="IMAGE_(spacecraft)" title="IMAGE (spacecraft)">78 (IMAGE)</a></li>

<li><a href="Neil_Gehrels_Swift_Observatory" title="Neil Gehrels Swift Observatory">84 (Swift)</a></li>

<li><a href="THEMIS" title="THEMIS">85–89 (THEMIS)</a></li>

<li><a href="SPHEREx" title="SPHEREx">SPHEREx</a></li>

<li><a href="HelioSwarm" title="HelioSwarm">HelioSwarm</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Small class (since 1992)</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Solar_Anomalous_and_Magnetospheric_Particle_Explorer" title="Solar Anomalous and Magnetospheric Particle Explorer">68 (SAMPEX)</a></li>

<li><a href="TRACE" title="TRACE">73 (TRACE)</a></li>

<li><a href="Reuven_Ramaty_High_Energy_Solar_Spectroscopic_Imager" title="Reuven Ramaty High Energy Solar Spectroscopic Imager">81 (RHESSI)</a></li>

<li><a href="GALEX" title="GALEX">83 (GALEX)</a></li>

<li><a href="NuSTAR" title="NuSTAR">93 (NuSTAR)</a></li>

<li><a href="Polarimeter_to_Unify_the_Corona_and_Heliosphere" title="Polarimeter to Unify the Corona and Heliosphere">PUNCH</a></li>

<li><a href="Tandem_Reconnection_and_Cusp_Electrodynamics_Reconnaissance_Satellites" title="Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites">TRACERS</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">University-class/ Missions of opportunity/ International missions</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<li><a href="TERRIERS" class="mw-redirect" title="TERRIERS">76 (TERRIERS)</a>†</li>

<li><a href="INTEGRAL" title="INTEGRAL">INTEGRAL</a></li>

<li><a href="CHIPSat" class="mw-redirect" title="CHIPSat">82 (CHIPSat)</a></li>

<li><a href="CINDI" title="CINDI">CINDI</a></li>

<li><a href="Suzaku_(satellite)" title="Suzaku (satellite)">Suzaku</a></li>

<li><a href="TWINS" title="TWINS">TWINS</a></li>

<li><a href="Hitomi_(satellite)" title="Hitomi (satellite)">Hitomi</a>†</li>

<li><a href="Neutron_Star_Interior_Composition_Explorer" title="Neutron Star Interior Composition Explorer">NICER</a></li>

<li><a href="X-Ray_Imaging_and_Spectroscopy_Mission" title="X-Ray Imaging and Spectroscopy Mission">XRISM</a></li>

<li><a href="GUSTO_(telescope)" title="GUSTO (telescope)">GUSTO</a></li>

<li><a href="Sun_Radio_Interferometer_Space_Experiment" title="Sun Radio Interferometer Space Experiment">SunRISE</a></li>

</div></td></tr></tbody></table><div></div></td><td class="noviewer navbox-image" rowspan="2" style="width:1px;padding:0 0 0 2px"><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Proposals</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Arcus_(satellite)" title="Arcus (satellite)">Arcus</a></li>

<li><a href="Atmosphere-Space_Transition_Region_Explorer" title="Atmosphere-Space Transition Region Explorer">ASTRE</a></li>

<li><a href="Extreme-ultraviolet_Stellar_Characterization_for_Atmospheric_Physics_and_Evolution" title="Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution">ESCAPE</a></li>

<li><a href="Exoplanetary_Circumstellar_Environments_and_Disk_Explorer" title="Exoplanetary Circumstellar Environments and Disk Explorer">EXCEDE</a></li>

<li><a href="Fast_Infrared_Exoplanet_Spectroscopy_Survey_Explorer" title="Fast Infrared Exoplanet Spectroscopy Survey Explorer">FINESSE</a></li>

<li><a href="Observatory_for_Heteroscale_Magnetosphere-Ionosphere_Coupling" title="Observatory for Heteroscale Magnetosphere-Ionosphere Coupling">OHMIC</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="3"><div>

<ul><li>Green titles indicates active current missions</li>

<li>Grey titles indicates cancelled missions</li>

<li>Italics indicate missions yet to launch</li>

<li>Symbol † indicates failure en route or before intended mission data returned</li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="NASA_planetary_exploration_programs138" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="NASA_planetary_exploration_programs138" style="font-size:114%;margin:0 4em"><a href="NASA" title="NASA">NASA</a> <a href="Timeline_of_Solar_System_exploration" title="Timeline of Solar System exploration">planetary exploration</a> programs</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Active</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Large_strategic_science_missions" class="mw-redirect" title="Large strategic science missions">Large strategic science missions</a></li>

<li><a href="Lunar_Discovery_and_Exploration_Program" title="Lunar Discovery and Exploration Program">Lunar Discovery & Exploration</a></li>

<li><a href="Mars_Exploration_Program" title="Mars Exploration Program">Mars Exploration</a></li>

<li><a href="Planetary_Missions_Program_Office" title="Planetary Missions Program Office">Planetary Missions</a>

<ul><li><a href="Discovery_Program" title="Discovery Program">Discovery</a></li>

<li><a href="New_Frontiers_program" title="New Frontiers program">New Frontiers</a></li>

<li><a href="Planetary_Missions_Program_Office#Solar_System_Exploration" title="Planetary Missions Program Office">Solar System Exploration</a></li></ul></li>

<li><a href="Ocean_Worlds_Exploration_Program" title="Ocean Worlds Exploration Program">Ocean Worlds Exploration</a></li>

<li><a href="Voyager_program" title="Voyager program">Voyager</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Completed</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Lunar_Orbiter_program" title="Lunar Orbiter program">Lunar Orbiter</a></li>

<li><a href="Lunar_Precursor_Robotic_Program" title="Lunar Precursor Robotic Program">Lunar Precursor</a></li>

<li><a href="Mariner_program" title="Mariner program">Mariner</a></li>

<li><a href="MESUR" title="MESUR">MESUR</a></li>

<li><a href="New_Millennium_Program" title="New Millennium Program">New Millennium</a></li>

<li><a href="Pioneer_program" title="Pioneer program">Pioneer</a></li>

<li><a href="Planetary_Observer_program" title="Planetary Observer program">Planetary Observer</a></li>

<li><a href="Ranger_program" title="Ranger program">Ranger</a></li>

<li><a href="Surveyor_program" title="Surveyor program">Surveyor</a></li>

<li><a href="Viking_program" title="Viking program">Viking</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Cancelled</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Grand_Tour_program" title="Grand Tour program">Grand Tour</a></li>

<li><a href="Mariner_Mark_II" title="Mariner Mark II">Mariner Mark II</a></li>

<li><a href="Project_Prometheus" title="Project Prometheus">Project Prometheus</a></li>

<li><a href="Voyager_program_(Mars)" title="Voyager program (Mars)">Voyager (Mars)</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

<ul><li><a href="List_of_NASA_missions" title="List of NASA missions">List of NASA missions</a></li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="NASA578" style="padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2" style="text-align: center;"><div id="NASA578" style="font-size:114%;margin:0 4em"><a href="NASA" title="NASA">NASA</a></div></th></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Space_policy_of_the_United_States" title="Space policy of the United States">Policy</a> and history</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">History (<a href="Creation_of_NASA" title="Creation of NASA">creation</a>)</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="National_Aeronautics_and_Space_Act" title="National Aeronautics and Space Act">National Aeronautics and Space Act</a> (1958)</li>

<li><a href="Space_Task_Group" title="Space Task Group">Space Task Group</a> (1958)</li>

<li><a href="Thomas_O._Paine#National_Commission_on_Space" title="Thomas O. Paine">Paine</a> (1986)</li>

<li><a href="Rogers_Commission_Report" title="Rogers Commission Report">Rogers</a> (1986)</li>

<li><a href="Space_Exploration_Initiative" title="Space Exploration Initiative">Space Exploration Initiative</a> (1989)</li>

<li><a href="Augustine_Committee" title="Augustine Committee">Augustine</a> (1990)</li>

<li><a href="Space_policy_of_the_United_States#Clinton_administration" title="Space policy of the United States">U.S. National Space Policy</a> (1996)</li>

<li><a href="Commission_on_the_Future_of_the_United_States_Aerospace_Industry" title="Commission on the Future of the United States Aerospace Industry">CFUSAI</a> (2002)</li>

<li><a href="Vision_for_Space_Exploration" title="Vision for Space Exploration">Vision for Space Exploration</a> (2004)</li>

<li><a href="President's_Commission_on_Implementation_of_United_States_Space_Exploration_Policy" title="President's Commission on Implementation of United States Space Exploration Policy">Aldridge</a> (2004)</li>

<li><a href="Review_of_United_States_Human_Space_Flight_Plans_Committee" title="Review of United States Human Space Flight Plans Committee">Augustine</a> (2009)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">General</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Space_Race" title="Space Race">Space Race</a></li>

<li><a href="List_of_administrators_and_deputy_administrators_of_NASA" class="mw-redirect" title="List of administrators and deputy administrators of NASA">Administrator and Deputy Administrator</a></li>

<li><a href="NASA_Chief_Scientist" title="NASA Chief Scientist">Chief Scientist</a></li>

<li><a href="NASA_Astronaut_Corps" title="NASA Astronaut Corps">Astronaut Corps</a>

<ul><li><a href="Astronaut_ranks_and_positions" title="Astronaut ranks and positions">Ranks and positions</a></li>

<li><a href="Chief_of_the_Astronaut_Office" title="Chief of the Astronaut Office">Chief</a></li></ul></li>

<li><a href="Budget_of_NASA" title="Budget of NASA">Budget</a></li>

<li><a href="NASA_research" title="NASA research">NASA research</a>

<ul><li><a href="NASA_spinoff_technologies" class="mw-redirect" title="NASA spinoff technologies">spinoff technologies</a></li></ul></li>

<li><a href="NASA_Social" title="NASA Social">NASA Social</a></li>

<li><a href="Launch_Services_Program" class="mw-redirect" title="Launch Services Program">Launch Services Program</a></li>

<li><a href="Mercury_Control_Center" title="Mercury Control Center">Mercury Control Center</a></li>

<li><a href="Manned_Space_Flight_Network" title="Manned Space Flight Network">Manned Space Flight Network</a></li>

<li><a href="Kennedy_Space_Center" title="Kennedy Space Center">Kennedy Space Center</a>

<ul><li><a href="Vehicle_Assembly_Building" title="Vehicle Assembly Building">Vehicle Assembly Building</a></li>

<li><a href="Kennedy_Space_Center_Launch_Complex_39" title="Kennedy Space Center Launch Complex 39">Launch Complex 39</a></li>

<li><a href="Kennedy_Space_Center_Launch_Complex_48" title="Kennedy Space Center Launch Complex 48">Launch Complex 48</a></li>

<li><a href="Launch_Control_Center" title="Launch Control Center">Launch Control Center</a></li>

<li><a href="Operations_and_Checkout_Building" title="Operations and Checkout Building">Operations and Checkout Building</a></li></ul></li>

<li><a href="Johnson_Space_Center" title="Johnson Space Center">Johnson Space Center</a>

<ul><li><a href="Christopher_C._Kraft_Jr._Mission_Control_Center" title="Christopher C. Kraft Jr. Mission Control Center">Mission Control</a></li>

<li><a href="Lunar_Sample_Laboratory_Facility" title="Lunar Sample Laboratory Facility">Lunar Sample Laboratory</a></li></ul></li>

<li><a href="Science_Mission_Directorate" title="Science Mission Directorate">Science Mission Directorate</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Human_spaceflight" title="Human spaceflight">Human spaceflight</a> programs</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Past</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="North_American_X-15" title="North American X-15">X-15</a> (<a href="Sub-orbital_spaceflight" title="Sub-orbital spaceflight">suborbital</a>)</li>

<li><a href="Project_Mercury" title="Project Mercury">Mercury</a></li>

<li><a href="Project_Gemini" title="Project Gemini">Gemini</a></li>

<li><a href="Apollo_program" title="Apollo program">Apollo</a></li>

<li><a href="Skylab" title="Skylab">Skylab</a></li>

<li><a href="Apollo%E2%80%93Soyuz" title="Apollo–Soyuz">Apollo–Soyuz</a> (with the <a href="Soviet_space_program" title="Soviet space program">Soviet space program</a>)</li>

<li><a href="Space_Shuttle_program" title="Space Shuttle program">Space Shuttle</a></li>

<li><a href="Shuttle%E2%80%93Mir_program" title="Shuttle–Mir program">Shuttle–Mir</a> (with <a href="Roscosmos" title="Roscosmos">Roscosmos</a>)</li>

<li><a href="Constellation_program" title="Constellation program">Constellation</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Current</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="International_Space_Station_programme" title="International Space Station programme">International Space Station</a></li>

<li><a href="Commercial_Orbital_Transportation_Services" title="Commercial Orbital Transportation Services">Commercial Orbital Transportation Services</a></li>

<li><a href="Commercial_Crew_Program" title="Commercial Crew Program">Commercial Crew</a></li>

<li><a href="Orion_(spacecraft)" title="Orion (spacecraft)">Orion</a></li>

<li><a href="Artemis_program" title="Artemis program">Artemis</a></li>

<li><a href="Lunar_Gateway" title="Lunar Gateway">Lunar Gateway</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Robotic_spacecraft" class="mw-redirect" title="Robotic spacecraft">Robotic</a> programs</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Past</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Hitchhiker_Program" title="Hitchhiker Program">Hitchhiker</a></li>

<li><a href="Mariner_program" title="Mariner program">Mariner</a></li>

<li><a href="Mariner_Mark_II" title="Mariner Mark II">Mariner Mark II</a></li>

<li><a href="MESUR" title="MESUR">MESUR</a></li>

<li><a href="Mars_Surveyor_'98" title="Mars Surveyor '98">Mars Surveyor '98</a></li>

<li><a href="New_Millennium_Program" title="New Millennium Program">New Millennium</a></li>

<li><a href="Lunar_Orbiter_program" title="Lunar Orbiter program">Lunar Orbiter</a></li>

<li><a href="Pioneer_program" title="Pioneer program">Pioneer</a></li>

<li><a href="Planetary_Observer_program" title="Planetary Observer program">Planetary Observer</a></li>

<li><a href="Ranger_program" title="Ranger program">Ranger</a></li>

<li><a href="Surveyor_program" title="Surveyor program">Surveyor</a></li>

<li><a href="Viking_program" title="Viking program">Viking</a></li>

<li><a href="Project_Prometheus" title="Project Prometheus">Project Prometheus</a></li>

<li><a href="Mars_Exploration_Program" title="Mars Exploration Program">Mars Exploration</a></li>

<li><a href="Mars_Exploration_Rover" title="Mars Exploration Rover">Mars Exploration Rover</a></li></ul>

<ul><li><a href="Living_With_a_Star" title="Living With a Star">Living With a Star</a></li>

<li><a href="Lunar_Precursor_Robotic_Program" title="Lunar Precursor Robotic Program">Lunar Precursor Robotic Program</a></li>

<li><a href="Earth_Observing_System" title="Earth Observing System">Earth Observing System</a></li>

<li><a href="Great_Observatories_program" title="Great Observatories program">Great Observatories program</a></li>

<li><a href="Voyager_program" title="Voyager program">Voyager</a></li>

<li><a href="Discovery_Program" title="Discovery Program">Discovery</a></li>

<li><a href="New_Frontiers_program" title="New Frontiers program">New Frontiers</a></li>

<li><a href="Solar_Terrestrial_Probes_program" title="Solar Terrestrial Probes program">Solar Terrestrial Probes</a></li>

<li><a href="Commercial_Lunar_Payload_Services" title="Commercial Lunar Payload Services">Commercial Lunar Payload Services</a></li>

<li><a href="Small_Innovative_Missions_for_Planetary_Exploration" title="Small Innovative Missions for Planetary Exploration">SIMPLEx</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%">Individual featured <a href="List_of_NASA_missions" title="List of NASA missions">missions</a> (human and robotic)</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Past</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Apollo_11" title="Apollo 11">Apollo 11</a></li>

<li><a href="Mercury-Redstone_3" title="Mercury-Redstone 3">Mercury 3</a></li>

<li><a href="Mercury-Atlas_6" title="Mercury-Atlas 6">Mercury-Atlas 6</a></li>

<li><a href="Magellan_(spacecraft)" title="Magellan (spacecraft)">Magellan</a></li>

<li><a href="Pioneer_10" title="Pioneer 10">Pioneer 10</a></li>

<li><a href="Pioneer_11" title="Pioneer 11">Pioneer 11</a></li>

<li><a href="Galileo_project" title="Galileo project">Galileo</a>

<ul><li><a href="Timeline_of_Galileo_(spacecraft)" title="Timeline of Galileo (spacecraft)">timeline</a></li></ul></li>

<li><a href="GALEX" title="GALEX">GALEX</a></li>

<li><a href="GRAIL" title="GRAIL">GRAIL</a></li>

<li><a href="Space_Shuttle" title="Space Shuttle">Space Shuttle</a></li>

<li><a href="Spitzer_Space_Telescope" title="Spitzer Space Telescope">Spitzer Space Telescope</a></li>

<li><a href="Sojourner_(rover)" title="Sojourner (rover)">Sojourner rover</a></li>

<li><a href="Spirit_(rover)" title="Spirit (rover)">Spirit rover</a></li>

<li><a href="LADEE" title="LADEE">LADEE</a></li>

<li><a href="MESSENGER" title="MESSENGER">MESSENGER</a></li>

<li><a href="Aquarius_(SAC-D_instrument)" title="Aquarius (SAC-D instrument)">Aquarius</a></li>

<li><a href="Cassini%E2%80%93Huygens" title="Cassini–Huygens">Cassini</a></li>

<li><a href="Kepler_space_telescope" title="Kepler space telescope">Kepler space telescope</a></li>

<li><a href="Opportunity_(rover)" title="Opportunity (rover)">Opportunity rover</a>

<ul><li><a href="Timeline_of_Opportunity" title="Timeline of Opportunity">timeline</a></li>

<li><a href="List_of_surface_features_of_Mars_visited_by_Spirit_and_Opportunity" title="List of surface features of Mars visited by Spirit and Opportunity">observed</a></li></ul></li>

<li><a href="Ramaty_High_Energy_Solar_Spectroscopic_Imager" class="mw-redirect" title="Ramaty High Energy Solar Spectroscopic Imager">RHESSI</a></li>

<li><a href="InSight" title="InSight">InSight</a></li>

<li><a href="Ingenuity_(helicopter)" title="Ingenuity (helicopter)">Ingenuity helicopter</a>

<ul><li><a href="List_of_Ingenuity_flights" title="List of Ingenuity flights">flights</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Currently operating</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Mars_Reconnaissance_Orbiter" title="Mars Reconnaissance Orbiter">Mars Reconnaissance Orbiter</a></li>

<li><a href="2001_Mars_Odyssey" title="2001 Mars Odyssey">2001 Mars Odyssey</a></li>

<li><a href="New_Horizons" title="New Horizons">New Horizons</a></li>

<li><a href="International_Space_Station" title="International Space Station">International Space Station</a></li>

<li><a href="Hubble_Space_Telescope" title="Hubble Space Telescope">Hubble Space Telescope</a></li>

<li><a href="Chandra_X-ray_Observatory" title="Chandra X-ray Observatory">Chandra X-ray Observatory</a></li>

<li><a href="Neil_Gehrels_Swift_Observatory" title="Neil Gehrels Swift Observatory">Swift</a></li>

<li><a href="THEMIS" title="THEMIS">THEMIS</a></li>

<li><a href="Mars_Exploration_Rover" title="Mars Exploration Rover">Mars Exploration Rover</a></li>

<li><a href="Curiosity_(rover)" title="Curiosity (rover)">Curiosity rover</a>

<ul><li><a href="Timeline_of_Mars_Science_Laboratory" title="Timeline of Mars Science Laboratory">timeline</a></li></ul></li>

<li><a href="Lunar_Reconnaissance_Orbiter" title="Lunar Reconnaissance Orbiter">Lunar Reconnaissance Orbiter</a></li>

<li><a href="Mars_Science_Laboratory" title="Mars Science Laboratory">Mars Science Laboratory</a>

<ul><li><a href="Timeline_of_Mars_Science_Laboratory" title="Timeline of Mars Science Laboratory">timeline</a></li></ul></li>

<li><a href="NuSTAR" title="NuSTAR">NuSTAR</a></li>

<li><a href="Voyager_1" title="Voyager 1">Voyager 1</a></li>

<li><a href="Voyager_2" title="Voyager 2">Voyager 2</a></li>

<li><a href="MAVEN" title="MAVEN">MAVEN</a></li>

<li><a href="OSIRIS-REx" title="OSIRIS-REx">OSIRIS-APEX</a></li>

<ul><li><a href="Perseverance_(rover)" title="Perseverance (rover)">Perseverance rover</a></li>

<li><a href="Timeline_of_Mars_2020" title="Timeline of Mars 2020">timeline</a></li></ul></li>

<li><a href="James_Webb_Space_Telescope" title="James Webb Space Telescope">James Webb Space Telescope</a>

<ul><li><a href="Timeline_of_the_James_Webb_Space_Telescope" title="Timeline of the James Webb Space Telescope">timeline</a></li></ul></li>

<li><a href="Europa_Clipper" title="Europa Clipper">Europa Clipper</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Future</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="NISAR_(satellite)" title="NISAR (satellite)">NISAR</a></li>

<li><a href="Nancy_Grace_Roman_Space_Telescope" title="Nancy Grace Roman Space Telescope">Nancy Grace Roman Space Telescope</a></li>

<li><a href="DAVINCI" title="DAVINCI">DAVINCI</a></li>

<li><a href="VERITAS_(spacecraft)" title="VERITAS (spacecraft)">VERITAS</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Space_Communications_and_Navigation_Program" title="Space Communications and Navigation Program">Communications and navigation</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Near_Earth_Network" title="Near Earth Network">Near Earth Network</a></li>

<li><a href="Space_Network" title="Space Network">Space Network</a></li>

<li><a href="NASA_Deep_Space_Network" title="NASA Deep Space Network">Deep Space Network</a> (<a href="Goldstone_Deep_Space_Communications_Complex" title="Goldstone Deep Space Communications Complex">Goldstone</a></li>

<li><a href="Madrid_Deep_Space_Communications_Complex" title="Madrid Deep Space Communications Complex">Madrid</a></li>

<li><a href="Canberra_Deep_Space_Communication_Complex" title="Canberra Deep Space Communication Complex">Canberra</a></li>

<li><a href="Space_Flight_Operations_Facility" title="Space Flight Operations Facility">Space Flight Operations Facility</a>)</li>

<li><a href="Deep_Space_Atomic_Clock" title="Deep Space Atomic Clock">Deep Space Atomic Clock</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%">NASA lists</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Astronaut" title="Astronaut">Astronauts</a>

<li><a href="List_of_Gemini_astronauts" title="List of Gemini astronauts">Gemini astronauts</a></li>

<li><a href="List_of_Apollo_astronauts" title="List of Apollo astronauts">Apollo astronauts</a></li>

<li><a href="List_of_Space_Shuttle_crews" title="List of Space Shuttle crews">Space Shuttle crews</a></li></ul></li>

<li><a href="List_of_NASA_aircraft" title="List of NASA aircraft">NASA aircraft</a></li>

<li><a href="List_of_NASA_missions" title="List of NASA missions">NASA missions</a>

<ul><li><a href="List_of_uncrewed_NASA_missions" title="List of uncrewed NASA missions">uncrewed missions</a></li>

<li><a href="List_of_Apollo_missions" title="List of Apollo missions">Apollo missions</a></li>

<li><a href="List_of_Space_Shuttle_missions" title="List of Space Shuttle missions">Space Shuttle missions</a></li></ul></li>

<li><a href="List_of_rockets_of_the_United_States" title="List of rockets of the United States">United States rockets</a></li>

<li><a href="List_of_NASA_cancellations" title="List of NASA cancellations">NASA cancellations</a></li>

<li><a href="List_of_NASA_cameras_on_spacecraft" title="List of NASA cameras on spacecraft">NASA cameras on spacecraft</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%">NASA images and artwork</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Earthrise" title="Earthrise">Earthrise</a></li>

<li><a href="The_Blue_Marble" title="The Blue Marble">The Blue Marble</a></li>

<li><a href="Family_Portrait_(Voyager)" title="Family Portrait (Voyager)">Family Portrait</a>

<li><a href="Pillars_of_Creation" title="Pillars of Creation">Pillars of Creation</a></li>

<li><a href="Mystic_Mountain" title="Mystic Mountain">Mystic Mountain</a></li>

<li><a href="Family_Portrait_(MESSENGER)" title="Family Portrait (MESSENGER)">Solar System Family Portrait</a></li>

<li><a href="The_Day_the_Earth_Smiled" title="The Day the Earth Smiled">The Day the Earth Smiled</a></li>

<li><a href="Fallen_Astronaut" title="Fallen Astronaut">Fallen Astronaut</a></li>

<li><a href="List_of_deep_fields" title="List of deep fields">Deep fields</a></li>

<li><a href="Lunar_plaque" title="Lunar plaque">Lunar plaques</a></li>

<li><a href="Pioneer_plaque" title="Pioneer plaque">Pioneer plaques</a></li>

<li><a href="Voyager_Golden_Record" title="Voyager Golden Record">Voyager Golden Record</a></li>

<li><a href="Apollo_11_goodwill_messages" title="Apollo 11 goodwill messages">Apollo 11 goodwill messages</a></li>

<li><a href="NASA_insignia" title="NASA insignia">NASA insignia</a></li>

<li><a href="NASA_space-flown_Gemini_and_Apollo_medallions" title="NASA space-flown Gemini and Apollo medallions">Gemini and Apollo medallions</a></li>

<li><a href="Mission_patch" title="Mission patch">Mission patches</a></li>

<li><a href="Astronomy_Picture_of_the_Day" title="Astronomy Picture of the Day">Astronomy Picture of the Day</a></li>

<li><a href="List_of_Hubble_Space_Telescope_anniversary_images" title="List of Hubble Space Telescope anniversary images">Hubble Space Telescope anniversary images</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li>"<a href="We_choose_to_go_to_the_Moon" title="We choose to go to the Moon">We choose to go to the Moon</a>"</li>

<li><a href="Apollo_8_Genesis_reading" title="Apollo 8 Genesis reading">Apollo 8 Genesis reading</a></li>

<li><a href="Apollo_15_postal_covers_incident" title="Apollo 15 postal covers incident">Apollo 15 postal covers incident</a></li>

<li><a href="Apollo_Lunar_Module" title="Apollo Lunar Module">Apollo Lunar Module</a></li>

<li><a href="Space_Mirror_Memorial" title="Space Mirror Memorial">Space Mirror Memorial</a></li>

<li><a href="The_Astronaut_Monument" class="mw-redirect" title="The Astronaut Monument">The Astronaut Monument</a></li>

<li><a href="Lunar_sample_displays" title="Lunar sample displays">Lunar sample displays</a>

<ul><li><a href="Moon_rock" title="Moon rock">Moon rocks</a></li>

<li><a href="Stolen_and_missing_Moon_rocks" title="Stolen and missing Moon rocks">stolen or missing</a></li></ul></li>

<li><a href="United_States_Astronaut_Hall_of_Fame" title="United States Astronaut Hall of Fame">U.S. Astronaut Hall of Fame</a></li>

<li><a href="U.S._space_exploration_history_on_U.S._stamps" title="U.S. space exploration history on U.S. stamps">Space program on U.S. stamps</a></li>

<li><a href="Fe%2C_Fi%2C_Fo%2C_Fum%2C_and_Phooey" title="Fe, Fi, Fo, Fum, and Phooey">Apollo 17 Moon mice</a></li>

<li><a href="Monkeys_and_apes_in_space#United_States" title="Monkeys and apes in space">Other primates in space</a></li>

<li><a href="NASA_International_Space_Apps_Challenge" title="NASA International Space Apps Challenge">NASA International Space Apps Challenge</a></li>

<li><a href="Astronauts_Day" title="Astronauts Day">Astronauts Day</a></li>

<li><a href="National_Astronaut_Day" title="National Astronaut Day">National Astronaut Day</a></li>

<li><a href="Nikon_NASA_F4" title="Nikon NASA F4">Nikon NASA F4</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="text-align: center;"><div>

<ul><li> Category</li>

<li> <a href="https://commons.wikimedia.org/wiki/Category:NASA" class="extiw external" title="commons:Category:NASA">Commons</a></li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="NASA_Goddard_Space_Flight_Center103" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="NASA_Goddard_Space_Flight_Center103" style="font-size:114%;margin:0 4em"><a href="NASA" title="NASA">NASA</a> <a href="Goddard_Space_Flight_Center" title="Goddard Space Flight Center">Goddard Space Flight Center</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Main articles</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Robert_H._Goddard" title="Robert H. Goddard">Robert H. Goddard</a></li>

<li><a href="History_of_the_Goddard_Space_Flight_Center" title="History of the Goddard Space Flight Center">GSFC History</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Facilities</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Wallops_Flight_Facility" title="Wallops Flight Facility">Wallops Flight Facility (WFF)</a></li>

<li><a href="Goddard_Institute_for_Space_Studies" title="Goddard Institute for Space Studies">Goddard Institute for Space Studies (GISS)</a></li>

<li><a href="Columbia_Scientific_Balloon_Facility" title="Columbia Scientific Balloon Facility">Columbia Scientific Balloon Facility (CSBF)</a></li>

<li><a href="Spacecraft_Magnetic_Test_Facility" title="Spacecraft Magnetic Test Facility">Spacecraft Magnetic Test Facility</a></li>

<li><a href="Katherine_Johnson_Independent_Verification_and_Validation_Facility" title="Katherine Johnson Independent Verification and Validation Facility">Katherine Johnson Independent Verification and Validation Facility (IV&V)</a></li>

<li><a href="Spacecraft_Fabrication_Facility_(Goddard)" title="Spacecraft Fabrication Facility (Goddard)">Spacecraft Fabrication Facility</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Notable missions and programs</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul>

<li><a href="Landsat_program" title="Landsat program">Landsat program</a></li>

<li><a href="Getaway_Special" title="Getaway Special">Getaway Special</a></li>

<li><a href="Space_Network" title="Space Network">Space Network</a></li>

<li><a href="Tracking_and_Data_Relay_Satellite_System" title="Tracking and Data Relay Satellite System">Tracking and Data Relay Satellite System (TDRS)</a></li>

<li><a href="Hitchhiker_Program" title="Hitchhiker Program">Hitchhiker Program</a></li>

<li><a href="Cosmic_Background_Explorer" title="Cosmic Background Explorer">Cosmic Background Explorer (COBE)</a></li>

<li><a href="Near_Earth_Network" title="Near Earth Network">Near Earth Network</a></li>

<li><a href="Hubble_Space_Telescope" title="Hubble Space Telescope">Hubble Space Telescope (HST)</a></li>

<li><a href="Compton_Gamma_Ray_Observatory" title="Compton Gamma Ray Observatory">Compton Gamma Ray Observatory (CGRO)</a></li>

<li><a href="Solar_and_Heliospheric_Observatory" title="Solar and Heliospheric Observatory">Solar and Heliospheric Observatory (SOHO)</a></li>

<li><a href="Rossi_X-ray_Timing_Explorer" title="Rossi X-ray Timing Explorer">Rossi X-ray Timing Explorer (RXTE)</a></li>

<li><a href="NASA_Earth_Observatory" title="NASA Earth Observatory">NASA Earth Observatory</a></li>

<li><a href="Goddard_Earth_Observing_System" title="Goddard Earth Observing System">Goddard Earth Observing System</a></li>

<li><a href="Lunar_Reconnaissance_Orbiter" title="Lunar Reconnaissance Orbiter">Lunar Reconnaissance Orbiter (LRO)</a></li>

<li><a href="Solar_Dynamics_Observatory" title="Solar Dynamics Observatory">Solar Dynamics Observatory (SDO)</a></li>

<li><a href="James_Webb_Space_Telescope" title="James Webb Space Telescope">James Webb Space Telescope (JWST)</a></li>

<li><a href="Nancy_Grace_Roman_Space_Telescope" title="Nancy Grace Roman Space Telescope">Nancy Grace Roman Space Telescope</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Leadership</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li>Dennis J. Andrucyk (Director)</li>

<li><a href="Anne_L._Kinney" title="Anne L. Kinney">Anne L. Kinney</a> (Deputy Center Director)</li>

<li>Christyl Johnson (Deputy Director, Technology and Research Investments)</li>

<li>Ray Rubilotta (Associate Center Director)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Notable scientists and engineers</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="David_Louis_Band" title="David Louis Band">David Louis Band</a></li>

<li><a href="Robert_Bindschadler" title="Robert Bindschadler">Robert Bindschadler</a></li>

<li><a href="Fred_Espenak" title="Fred Espenak">Fred Espenak</a></li>

<li><a href="Gene_Carl_Feldman" title="Gene Carl Feldman">Gene Carl Feldman</a></li>

<li><a href="Orlando_Figueroa" title="Orlando Figueroa">Orlando Figueroa</a></li>

<li><a href="James_Hansen" title="James Hansen">James Hansen</a></li>

<li><a href="Marc_Kuchner" title="Marc Kuchner">Marc Kuchner</a></li>

<li><a href="Lissette_Martinez" title="Lissette Martinez">Lissette Martinez</a></li>

<li><a href="John_C._Mather" title="John C. Mather">John C. Mather</a></li>

<li><a href="Nancy_Roman" title="Nancy Roman">Nancy Roman</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Jet_Propulsion_Laboratory230" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Jet_Propulsion_Laboratory230" style="font-size:114%;margin:0 4em"><a href="Jet_Propulsion_Laboratory" title="Jet Propulsion Laboratory">Jet Propulsion Laboratory</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Current missions</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Euclid_(spacecraft)" title="Euclid (spacecraft)">Euclid</a></li>

<li><a href="Psyche_(spacecraft)" title="Psyche (spacecraft)">Psyche</a></li>

<li><a href="ACRIMSAT" title="ACRIMSAT">ACRIMSAT</a></li>

<li><a href="Advanced_Spaceborne_Thermal_Emission_and_Reflection_Radiometer" title="Advanced Spaceborne Thermal Emission and Reflection Radiometer">ASTER</a></li>

<li><a href="Atmospheric_infrared_sounder" title="Atmospheric infrared sounder">Atmospheric infrared sounder</a> (AIRS)</li>

<li><a href="Deep_Space_Atomic_Clock" title="Deep Space Atomic Clock">Deep Space Atomic Clock</a></li>

<li><a href="GRACE-FO" class="mw-redirect" title="GRACE-FO">GRACE-FO</a></li>

<li><a href="InSight" title="InSight">InSight</a></li>

<li><a href="W._M._Keck_Observatory" title="W. M. Keck Observatory">Keck observatory</a></li>

<li><a href="Large_Binocular_Telescope" title="Large Binocular Telescope">Large Binocular Telescope</a> (LBT)</li>

<li><a href="2001_Mars_Odyssey" title="2001 Mars Odyssey">Mars Odyssey</a></li>

<ul><li><a href="Perseverance_(rover)" title="Perseverance (rover)">Perseverance rover</a></li>

<li><a href="Ingenuity_(helicopter)" title="Ingenuity (helicopter)">Ingenuity helicopter</a></li></ul></li>

<li><a href="Mars_Reconnaissance_Orbiter" title="Mars Reconnaissance Orbiter">Mars Reconnaissance Orbiter</a> (MRO)</li>

<li><a href="Mars_Science_Laboratory" title="Mars Science Laboratory">Mars Science Laboratory</a> (MSL)</li>

<li><a href="Microwave_limb_sounder" title="Microwave limb sounder">Microwave limb sounder</a> (MLS)</li>

<li><a href="Multi-angle_imaging_spectroradiometer" title="Multi-angle imaging spectroradiometer">Multi-angle imaging spectroradiometer</a> (MISR)</li>

<li><a href="Soil_Moisture_Active_Passive" title="Soil Moisture Active Passive">Soil Moisture Active Passive</a> (SMAP)</li>

<li><a href="Tropospheric_Emission_Spectrometer" title="Tropospheric Emission Spectrometer">Tropospheric Emission Spectrometer</a> (TES)</li>

<li><a href="Voyager_program" title="Voyager program">Voyager program</a>

<ul><li><a href="Voyager_1" title="Voyager 1">Voyager 1</a></li>

<li><a href="Voyager_2" title="Voyager 2">Voyager 2</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Past missions</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Cassini%E2%80%93Huygens" title="Cassini–Huygens">Cassini-Huygens</a></li>

<li><a href="Deep_Impact_(spacecraft)" title="Deep Impact (spacecraft)">Deep Impact</a></li>

<li><a href="Deep_Space_1" title="Deep Space 1">Deep Space 1</a></li>

<li><a href="Deep_Space_2" title="Deep Space 2">Deep Space 2</a></li>

<li><a href="GALEX" title="GALEX">GALEX</a></li>

<li><a href="Galileo_project" title="Galileo project">Galileo</a>

<ul><li><a href="Galileo_(spacecraft)" title="Galileo (spacecraft)">spacecraft</a></li></ul></li>

<li><a href="Genesis_(spacecraft)" title="Genesis (spacecraft)">Genesis</a></li>

<li><a href="Gravity_Recovery_and_Climate_Experiment" class="mw-redirect" title="Gravity Recovery and Climate Experiment">GRACE</a></li>

<li><a href="Herschel_Space_Observatory" title="Herschel Space Observatory">Herschel</a></li>

<li><a href="Jason-1" title="Jason-1">Jason-1</a></li>

<li><a href="Kepler_space_telescope" title="Kepler space telescope">Kepler</a></li>

<li><a href="Magellan_(spacecraft)" title="Magellan (spacecraft)">Magellan</a></li>

<li><a href="Mariner_program" title="Mariner program">Mariner</a></li>

<li><a href="Mars_Climate_Orbiter" title="Mars Climate Orbiter">Mars Climate Orbiter</a></li>

<li><a href="Mars_Cube_One" title="Mars Cube One">Mars Cube One</a> (MarCO)</li>

<li><a href="Mars_Observer" title="Mars Observer">Mars Observer</a></li>

<li><a href="Mars_Pathfinder" title="Mars Pathfinder">Mars Pathfinder</a></li>

<li><a href="Mars_Polar_Lander" title="Mars Polar Lander">Mars Polar Lander</a></li>

<li><a href="Mars_Global_Surveyor" title="Mars Global Surveyor">Mars Global Surveyor</a></li>

<li><a href="Mars_Exploration_Rover" title="Mars Exploration Rover">Mars Exploration Rovers</a>

<ul><li><a href="Spirit_(rover)" title="Spirit (rover)">Spirit rover</a></li>

<li><a href="Opportunity_(rover)" title="Opportunity (rover)">Opportunity rover</a></li></ul></li>

<li><a href="Near-Earth_Asteroid_Scout" title="Near-Earth Asteroid Scout">Near-Earth Asteroid Scout</a></li>

<li><a href="Scatterometer" title="Scatterometer">NSCAT</a></li>

<li><a href="Phoenix_(spacecraft)" title="Phoenix (spacecraft)">Phoenix</a></li>

<li><a href="Pioneer_program" title="Pioneer program">Pioneer</a></li>

<li><a href="QuikSCAT" title="QuikSCAT">QuikSCAT</a></li>

<li><a href="Ranger_program" title="Ranger program">Ranger</a></li>

<li><a href="Rosetta_(spacecraft)" title="Rosetta (spacecraft)">Rosetta</a></li>

<li><a href="Seasat" title="Seasat">Seasat</a></li>

<li><a href="Shuttle_Radar_Topography_Mission" title="Shuttle Radar Topography Mission">Shuttle Radar Topography Mission</a> (SRTM)</li>

<li><a href="Solar_Mesosphere_Explorer" title="Solar Mesosphere Explorer">Solar Mesosphere Explorer</a> (SME)</li>

<li><a href="Spaceborne_Imaging_Radar" title="Spaceborne Imaging Radar">Spaceborne Imaging Radar</a> (SIR)</li>

<li><a href="Spitzer_Space_Telescope" title="Spitzer Space Telescope">Spitzer Space Telescope</a></li>

<li><a href="Stardust_(spacecraft)" title="Stardust (spacecraft)">Stardust</a></li>

<li><a href="Surveyor_program" title="Surveyor program">Surveyor</a></li>

<li><a href="Very-long-baseline_interferometry" title="Very-long-baseline interferometry">SVLBI</a></li>

<li><a href="TOPEX/Poseidon" title="TOPEX/Poseidon">TOPEX/Poseidon</a></li>

<li><a href="Ulysses_(spacecraft)" title="Ulysses (spacecraft)">Ulysses</a></li>

<li><a href="Viking_program" title="Viking program">Viking</a></li>

<li><a href="Wide_Field_and_Planetary_Camera" title="Wide Field and Planetary Camera">Wide Field and Planetary Camera</a> (WFPC)</li>

<li><a href="Wide_Field_Infrared_Explorer" title="Wide Field Infrared Explorer">Wide Field Infrared Explorer</a> (WIRE)</li>

<li><a href="Lunar_Flashlight" title="Lunar Flashlight">Lunar Flashlight</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Planned missions</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Europa_Clipper" title="Europa Clipper">Europa Clipper</a></li>

<li><a href="Nancy_Grace_Roman_Space_Telescope" title="Nancy Grace Roman Space Telescope">Nancy Grace Roman Space Telescope</a></li>

<li><a href="SPHEREx" title="SPHEREx">SPHEREx</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Proposed missions</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Europa_Lander_(NASA)" class="mw-redirect" title="Europa Lander (NASA)">Europa Lander</a></li>

<li><a href="Fast_Infrared_Exoplanet_Spectroscopy_Survey_Explorer" title="Fast Infrared Exoplanet Spectroscopy Survey Explorer">FINESSE</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Canceled missions</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Astrobiology_Field_Laboratory" title="Astrobiology Field Laboratory">Astrobiology Field Laboratory</a> (AFL)</li>

<li><a href="Mars_Astrobiology_Explorer-Cacher" title="Mars Astrobiology Explorer-Cacher">Mars Astrobiology Explorer-Cacher</a> (MAX-C)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related organizations</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="California_Institute_of_Technology" title="California Institute of Technology">Caltech</a></li>

<li><a href="NASA_Deep_Space_Network" title="NASA Deep Space Network">NASA Deep Space Network</a></li>

<li><a href="Goldstone_Deep_Space_Communications_Complex" title="Goldstone Deep Space Communications Complex">Goldstone Complex</a></li>

<li><a href="Table_Mountain_Observatory" title="Table Mountain Observatory">Table Mountain Observatory</a></li>

<li><a href="Solar_System_Ambassadors" title="Solar System Ambassadors">Solar System Ambassadors</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

<ul><li><a href="JPL_Science_Division" title="JPL Science Division">JPL Science Division</a></li>

<li><a href="Near-Earth_Asteroid_Tracking" title="Near-Earth Asteroid Tracking">Near-Earth Asteroid Tracking</a></li>

<li><a href="Space_Flight_Operations_Facility" title="Space Flight Operations Facility">Space Flight Operations Facility</a></li></ul>

</div></td></tr></tbody></table></div>

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This article is issued from <a class="external text" title="Last edited on 2025-07-19" href="https://en.wikipedia.org/wiki/?title=Explorers_Program&oldid=1301422938">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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