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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Launch loop</span></span>

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<p>A <b>launch loop</b>, or <b>Lofstrom loop</b>, is a proposed system for <a href="Orbital_launch" class="mw-redirect" title="Orbital launch">launching objects into orbit</a> using a moving cable-like system situated inside a sheath attached to the <a href="Earth" title="Earth">Earth</a> at two ends and suspended above the <a href="Atmosphere" title="Atmosphere">atmosphere</a> in the middle. The design concept was published by <a href="Keith_Lofstrom" title="Keith Lofstrom">Keith Lofstrom</a> and describes an <a href="Active_structure" title="Active structure">active structure</a> <a href="Maglev" title="Maglev">maglev</a> <a href="Cable_transport" title="Cable transport">cable transport</a> system that would be around 2,000 km (1,240 mi) long and maintained at an altitude of up to 80 km (50 mi). A launch loop would be held up at this altitude by the <a href="Self-siphoning_beads" class="mw-redirect" title="Self-siphoning beads">momentum of a belt</a> that circulates around the structure. This circulation, in effect, transfers the weight of the structure onto a pair of magnetic bearings, one at each end, which support it.

</p><p>Launch loops are intended to achieve <a href="Non-rocket_spacelaunch" title="Non-rocket spacelaunch">non-rocket spacelaunch</a> of <a href="Spacecraft" title="Spacecraft">vehicles</a> weighing 5 metric tons by <a href="Maglev" title="Maglev">electromagnetically accelerating</a> them so that they are projected into Earth <a href="Orbit" title="Orbit">orbit</a> or even beyond. This would be achieved by the flat part of the cable which forms an acceleration track above the atmosphere.<sup id="cite_ref-Forward_1-0" class="reference"><a href="#cite_note-Forward-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>

</p><p>The system is designed to be suitable for launching humans for <a href="Space_tourism" title="Space tourism">space tourism</a>, <a href="Space_exploration" title="Space exploration">space exploration</a> and <a href="Space_colonization" title="Space colonization">space colonization</a>, and provides a relatively low <a href="G-force" title="G-force">3<i>g</i> acceleration</a>.<sup id="cite_ref-launch1985_2-0" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

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

<p>Launch loops were described by <a href="Keith_Lofstrom" title="Keith Lofstrom">Keith Lofstrom</a> in November 1981 Reader's Forum of the <a href="American_Astronautical_Society" title="American Astronautical Society">American Astronautical Society</a> News Letter, and in the August 1982 <a href="L5_Society" title="L5 Society">L5</a> News.

</p><p>In 1982, <a href="Paul_Birch_(writer)" title="Paul Birch (writer)">Paul Birch</a> published a series of papers in <i><a href="Journal_of_the_British_Interplanetary_Society" title="Journal of the British Interplanetary Society">Journal of the British Interplanetary Society</a></i> which described <a href="Orbital_ring" title="Orbital ring">orbital rings</a> and described a form which he called Partial Orbital Ring System (PORS).<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>

The launch loop idea was worked on in more detail around 1983–1985 by Lofstrom.<sup id="cite_ref-launch1985_2-1" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> It is a fleshed-out version of PORS specifically arranged to form a mag-lev acceleration track suitable for launching humans into space, but whereas the orbital ring used superconducting <a href="Magnetic_levitation" title="Magnetic levitation">magnetic levitation</a>, launch loops use <a href="Electromagnetic_suspension" title="Electromagnetic suspension">electromagnetic suspension</a> (EMS).

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

<p>Consider a large cannon on an island that shoots a shell into the high atmosphere. The shell will follow a roughly parabolic path for the initial flight, but drag will slow the shell and cause it to return to Earth in a much more vertical path. One could make the path purely ballistic by enclosing the predicted path in a tube and removing the air. Suspending such a tube would be a significant problem depending on the length of the path. However, one can use the shell to provide this lift force, at least temporarily. If the tube is not exactly along the flight path of the shell, but slightly below it, as the shell passes through the tube, it will be forced downward, thereby producing an upward force on the tube. To stay aloft, the system would require the shells to be fired continually.

</p><p>The launch loop is essentially a continuous version of this concept. Instead of a cannon firing a shell, a <a href="Mass_driver" title="Mass driver">mass driver</a> accelerates a cable into a similar trajectory. The cable is surrounded by an evacuated tube, which is held aloft by pushing down on the cable using <a href="Electromagnet" title="Electromagnet">electromagnets</a>. When the cable falls back to Earth at the other end of the trajectory, it is captured by a second mass driver, bent through 180 degrees, and sent back up on the opposite trajectory. The result is a single loop that is continually travelling and keeping the tube aloft.

</p><p>To use the system as a space launcher, a launch loop would be about 2,000 km long and 80 km high. The loop would be in the form of a tube, known as the <i>sheath</i>. Floating within the sheath is another continuous tube, known as the <i>rotor</i> which is a sort of belt or chain. The rotor is an <a href="Iron" title="Iron">iron</a> tube approximately 5 cm (2 inches) in diameter, moving around the loop at 14 km/s (31,000 miles per hour). Keeping the system aloft requires a significant amount of lift, and the resulting path is much flatter than the natural ballistic path of the rotor.<sup id="cite_ref-launch1985_2-2" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>Due to the possibility of the loop failing and falling to Earth, it is normally considered as running between two islands outside of heavy shipping routes.

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<div class="mw-heading mw-heading3"><h3 id="Ability_to_stay_aloft">Ability to stay aloft</h3></div>

<p>When at rest, the loop is at ground level. The rotor is then accelerated up to speed. As the rotor speed increases, it curves to form an arc. The structure is held up by the force from the rotor, which attempts to follow a parabolic trajectory. The ground anchors force it to go parallel to the earth upon reaching the height of 80 kilometers. Once raised, the structure requires continuous power to overcome the energy dissipated. Additional energy would be needed to power any vehicles that are launched.<sup id="cite_ref-launch1985_2-3" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="Launching_payloads">Launching payloads</h3></div>

<p>To launch, vehicles are raised up on an 'elevator' cable that hangs down from the West station loading dock at 80 km, and placed on the track. The payload applies a magnetic field that generates <a href="Eddy_current" title="Eddy current">eddy currents</a> in the fast-moving rotor. This both lifts the payload away from the cable, as well as pulls the payload along with 3<i>g</i> (30 m/s²) acceleration. The payload then rides the rotor until it reaches the required <a href="Orbital_speed" title="Orbital speed">orbital velocity</a>, and leaves the track.<sup id="cite_ref-launch1985_2-4" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>If a stable or circular orbit is needed, once the payload reaches the highest part of its trajectory then an on-board <a href="Rocket_engine" title="Rocket engine">rocket engine</a> ("kick motor") or other means is needed to circularize the trajectory to the appropriate Earth orbit.<sup id="cite_ref-launch1985_2-5" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>The eddy current technique is compact, lightweight and powerful, but inefficient. With each launch the rotor temperature increases by 80 <a href="Kelvin" title="Kelvin">kelvins</a> due to power dissipation. If launches are spaced too close together, the rotor temperature can approach 770 °C (1043 K), at which <a href="Curie_point" class="mw-redirect" title="Curie point">point</a> the iron rotor loses its <a href="Ferromagnetism" title="Ferromagnetism">ferromagnetic</a> properties and rotor containment is lost.<sup id="cite_ref-launch1985_2-6" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="Capacity_and_capabilities">Capacity and capabilities</h3></div>

<p>Closed orbits with a perigee of 80 km quite quickly decay and re-enter, but in addition to such orbits, a launch loop by itself would also be capable of directly injecting payloads into <a href="Escape_velocity" title="Escape velocity">escape orbits</a>, <a href="Gravity_assist" title="Gravity assist">gravity assist</a> trajectories past the <a href="Moon" title="Moon">Moon</a>, and other non closed orbits such as close to the <a href="Trojan_points" class="mw-redirect" title="Trojan points">Trojan points</a>.

</p><p>To access circular orbits using a launch loop a relatively small 'kick motor' would need to be launched with the payload which would fire at <a href="Apogee" class="mw-redirect" title="Apogee">apogee</a> and would circularise the orbit. For <a href="Geosynchronous_orbit" title="Geosynchronous orbit">GEO</a> insertion this would need to provide a <a href="Delta-v" title="Delta-v">delta-v</a> of about 1.6 km/s, for <a href="Low_Earth_orbit" title="Low Earth orbit">LEO</a> to circularise at 500 km would require a delta-v of just 120 m/s. Conventional <a href="Rocket" title="Rocket">rockets</a> require delta-vs of roughly 14 and 10 km/s to reach GEO and LEO respectively.<sup id="cite_ref-launch1985_2-7" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>Launch loops in Lofstrom's design are placed close to the equator<sup id="cite_ref-launch1985_2-8" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> and can only directly access equatorial orbits. However other orbital planes might be reached via high altitude plane changes, lunar perturbations or aerodynamic techniques.

</p><p>Launch rate capacity of a launch loop is ultimately limited by the temperature and cooling rate of the rotor to 80 per hour, but that would require a 17 <a href="Gigawatt" class="mw-redirect" title="Gigawatt">GW</a> power station; a more modest 500 MW power station is sufficient for 35 launches per day.<sup id="cite_ref-launch1985_2-9" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="Economics">Economics</h3></div>

<p>For a launch loop to be economically viable it would require customers with sufficiently large payload launch requirements.

</p><p>Lofstrom estimates that an initial loop costing roughly $10 <a href="1000000000_(number)" class="mw-redirect" title="1000000000 (number)">billion</a> with a one-year payback could launch 40,000 metric tons per year, and cut launch costs to $300/kg. For $30 billion, with a larger power generation capacity, the loop would be capable of launching 6 million metric tons per year, and given a five-year payback period, the costs for accessing space with a launch loop could be as low as $3/kg.<sup id="cite_ref-isdc_5-0" class="reference"><a href="#cite_note-isdc-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup>

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

<div class="mw-heading mw-heading3"><h3 id="Advantages_of_launch_loops">Advantages of launch loops</h3></div>

<p>Compared to space elevators, no new high-tensile strength materials have to be developed, since the structure resists Earth's gravity by supporting its own weight with the kinetic energy of the moving loop, and not by tensile strength.

</p><p>Lofstrom's launch loops are expected to launch at high rates (many launches per hour, independent of weather), and are not inherently polluting. Rockets create pollution such as nitrates in their exhausts due to high exhaust temperature, and can create greenhouse gases depending on propellant choices. Launch loops as a form of electric propulsion can be clean, and can be run on geothermal, nuclear, wind, solar or any other power source, even intermittent ones, as the system has huge built-in power storage capacity.

</p><p>Unlike space elevators which would have to travel through the <a href="Van_Allen_belts" class="mw-redirect" title="Van Allen belts">Van Allen belts</a> over several days, launch loop passengers can be launched to low Earth orbit, which is below the belts, or through them in a few hours. This would be a similar situation to that faced by the Apollo astronauts, who had radiation doses about 0.5% of what the space elevator would give.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>

</p><p>Unlike space elevators which are subjected to the risks of space debris and meteorites along their whole length, launch loops are to be situated at an altitude where orbits are unstable due to air drag. Since debris does not persist, it only has one chance to impact the structure. Whereas the collapse period of space elevators is expected to be of the order of years, damage or collapse of loops in this way is expected to be rare. In addition, launch loops themselves are not a significant source of space debris, even in an accident. All debris generated has a perigee that intersects the atmosphere or is at escape velocity.

</p><p>Launch loops are intended for human transportation, to give a safe 3<i>g</i> acceleration which the vast majority of people would be capable of tolerating well,<sup id="cite_ref-launch1985_2-10" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> and would be a much faster way of reaching space than space elevators.

</p><p>Launch loops would be quiet in operation, and would not cause any sound pollution, unlike rockets.

</p><p>Finally, their low payload costs are compatible with large-scale commercial <a href="Space_tourism" title="Space tourism">space tourism</a> and even <a href="Space_colonisation" class="mw-redirect" title="Space colonisation">space colonisation</a>.

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<div class="mw-heading mw-heading3"><h3 id="Difficulties_of_launch_loops">Difficulties of launch loops</h3></div>

<p>A running loop would have an extremely large amount of energy in its linear momentum. While the magnetic suspension system would be highly redundant, with failures of small sections having essentially no effect, if a major failure did occur the energy in the loop (1.5×10<sup>15</sup> <a href="Joule" title="Joule">joules</a> or 1.5 petajoules) would approach the same total energy release as a <a href="Nuclear_bomb" class="mw-redirect" title="Nuclear bomb">nuclear bomb</a> explosion (350 kilotons of <a href="TNT_equivalent" title="TNT equivalent">TNT equivalent</a>), although not emitting nuclear radiation.

</p><p>While this is a significant amount of energy, it is unlikely that this would destroy much of the structure due to its very large size, and because most of the energy would be deliberately dumped at preselected places when the failure is detected. Steps might need to be taken to lower the cable down from 80 km altitude with minimal damage, such as by the use of parachutes.

</p><p>Therefore, for safety and <a href="Astrodynamics" class="mw-redirect" title="Astrodynamics">astrodynamic</a> reasons, launch loops are intended to be installed over an ocean near the equator, well away from habitation.

</p><p>The published design of a launch loop requires electronic control of the magnetic levitation to minimize power dissipation and to stabilize the otherwise under-damped cable.

</p><p>The two main points of instability are the turnaround sections and the cable.

</p><p>The turnaround sections are potentially unstable, since movement of the rotor away from the magnets gives reduced magnetic attraction, whereas movements closer gives increased attraction. In either case, instability occurs.<sup id="cite_ref-launch1985_2-11" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> This problem is routinely solved with existing servo control systems that vary the strength of the magnets. Although servo reliability is a potential issue, at the high speed of the rotor, many consecutive sections would need to fail for the rotor containment to be lost.<sup id="cite_ref-launch1985_2-12" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>The cable sections also share this potential issue, although the forces are much lower.<sup id="cite_ref-launch1985_2-13" class="reference"><a href="#cite_note-launch1985-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> However, an additional instability is present in that the cable/sheath/rotor may undergo <a href="Meander" title="Meander">meandering</a> modes (similar to a <a href="Lariat_chain" title="Lariat chain">Lariat chain</a>) that grow in amplitude without limit. Lofstrom believes that this instability also can be controlled in real time by servo mechanisms, although this has never been attempted.

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<div class="mw-heading mw-heading3"><h3 id="Competing_and_similar_designs">Competing and similar designs</h3></div>

<p>In works by <a href="Alexander_Bolonkin" title="Alexander Bolonkin">Alexander Bolonkin</a> it is suggested that Lofstrom's project has many unsolved problems and that it is very far from a current technology.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> For example, the Lofstrom project has expansion joints between 1.5 meter iron plates. Their speeds (under gravitation, friction) can be different and Bolonkin claims that they could wedge in the tube; and the force and friction in the ground 28 km diameter turnaround sections are gigantic. In 2008,<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Bolonkin proposed a simple rotated close-loop cable to launch the space apparatus in a way suitable for current technology.

</p><p>Another project, the space cable, is a smaller design by John Knapman that is intended for launch assist for conventional rockets and suborbital tourism. The space cable design uses discrete bolts rather than a continuous rotor, as with the launch loop architecture. Knapman has also mathematically shown that the meander instability can be tamed.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup>

</p><p>The <a href="Skyhook_(structure)" title="Skyhook (structure)">skyhook</a> is another launch system concept. A skyhook could be either rotating or non-rotating. The non-rotating skyhook hangs from a <a href="Low_Earth_orbit" title="Low Earth orbit">low Earth orbit</a> down to just above the Earth's atmosphere (skyhook cable is not attached to Earth).<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> The rotating skyhook changes this design to decrease the speed of the lower end; the entire cable rotates around its center of gravity. The advantage of this is an even greater velocity reduction for the launch vehicle flying to the bottom end of the rotating skyhook which makes for an even larger payload and a lower launch cost. The two disadvantages of this are: the greatly reduced time available for the arriving launch vehicle to hook up at the lower end of the rotating skyhook (approximately 3 to 5 seconds), and the lack of choice regarding the destination orbit.

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<ul><li><a href="Belt_(mechanical)" title="Belt (mechanical)">Belt (mechanical)</a></li>

<li><a href="Cable_transport" title="Cable transport">Cable transport</a></li>

<li><a href="Magnetic_levitation" title="Magnetic levitation">Magnetic levitation</a></li>

<li><a href="Mass_driver" title="Mass driver">Mass driver</a></li>

<li><a href="Megascale_engineering" title="Megascale engineering">Megascale engineering</a></li>

<li><a href="Non-rocket_spacelaunch" title="Non-rocket spacelaunch">Non-rocket spacelaunch</a></li>

<li><a href="Orbital_ring" title="Orbital ring">Orbital ring</a></li>

<li><a href="Space_elevator" title="Space elevator">Space elevator</a></li>

<li><a href="Space_gun" title="Space gun">Space gun</a></li>

<li><a href="Space_fountain" title="Space fountain">Space fountain</a></li>

<li><a href="Space_tourism" title="Space tourism">Space tourism</a></li>

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

<li><a href="Tether_propulsion" class="mw-redirect" title="Tether propulsion">Tether propulsion</a></li></ul>

</div>

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

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</style><cite id="CITEREFForward1995" class="citation cs2"><a href="Robert_L._Forward" title="Robert L. Forward">Forward, Robert L.</a> (1995), "Beanstalks", <i>Indistinguishable From Magic</i>, <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-671-87686-4</bdi></cite></span>

</li>

<li id="cite_note-launch1985-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-launch1985_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-launch1985_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-launch1985_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-launch1985_2-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-launch1985_2-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-launch1985_2-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-launch1985_2-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-launch1985_2-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-launch1985_2-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-launch1985_2-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-launch1985_2-10"><sup><i><b>k</b></i></sup></a> <a href="#cite_ref-launch1985_2-11"><sup><i><b>l</b></i></sup></a> <a href="#cite_ref-launch1985_2-12"><sup><i><b>m</b></i></sup></a> <a href="#cite_ref-launch1985_2-13"><sup><i><b>n</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://launchloop.com/slides/launchloop.pdf">PDF version of Lofstrom's 1985 launch loop publication (AIAA conference)</a></span>

</li>

<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><a href="Paul_Birch_(writer)" title="Paul Birch (writer)">Paul Birch</a> • <a rel="nofollow" class="external text" href="http://www.paulbirch.net/OrbitalRings-II.zip">Orbital Rings - I 12</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20070707213633/http://www.paulbirch.net/OrbitalRings-II.zip">Archived</a> 2007-07-07 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span>

</li>

<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text">December 1983 Analog magazine</span>

</li>

<li id="cite_note-isdc-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-isdc_5-0">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://launchloop.com/LaunchLoop?action=AttachFile&do=view&target=isdc2002loop.pdf">Launch Loop slides for the ISDC2002 conference</a></span>

</li>

<li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><cite id="CITEREFYoung2006" class="citation web cs1">Young, Kelly (13 November 2006). <a rel="nofollow" class="external text" href="https://www.newscientist.com/article/dn10520-space-elevators-first-floor-deadly-radiation.html">"Space elevators: 'First floor, deadly radiation!'"</a>. <i>New Scientist</i>.</cite></span>

</li>

<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite id="CITEREFBolonkin2006" class="citation book cs1">Bolonkin, Alexander (2006). <a rel="nofollow" class="external text" href="https://www.elsevier.com/books/non-rocket-space-launch-and-flight/bolonkin/978-0-08-044731-5"><i>Non-Rocket Space Launch and Flight</i></a>. Elsevier. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9780080447315</bdi>.</cite></span>

</li>

<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><cite id="CITEREFBolonkin2002" class="citation conference cs1">Bolonkin, Alexander (10–19 October 2002). <i>Optimal inflatable space towers with 3–100 km height</i>. World Space Congress. Houston, TX, USA. IAC–02–IAA.1.3.03.</cite></span>

</li>

<li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text">Journal of the British Interplanetary Society, Vol. 56, 2003, No.9/10, pp.314-327</span>

</li>

<li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text">Bolonkin A.A., New Concepts, Ideas, and Innovations in Aerospace, Technology and Human Science, NOVA, 2008, 400 pgs.</span>

</li>

<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><cite id="CITEREFKnapman2009" class="citation journal cs1">Knapman, J. (2009-01-01). <a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2009JBIS...62..202K">"The Space Cable - Capability and Stability"</a>. <i>Journal of the British Interplanetary Society</i>. <b>62</b>: <span class="nowrap">202–</span>210. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2009JBIS...62..202K">2009JBIS...62..202K</a>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0007-084X">0007-084X</a>.</cite></span>

</li>

<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><cite id="CITEREFKnapman2009" class="citation journal cs1">Knapman, John (2009). <span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="https://linkinghub.elsevier.com/retrieve/pii/S0094576509000824">"Stability of the space cable"</a></span>. <i>Acta Astronautica</i>. <b>65</b> (<span class="nowrap">1–</span>2): <span class="nowrap">123–</span>130. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2009AcAau..65..123K">2009AcAau..65..123K</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.actaastro.2009.01.047">10.1016/j.actaastro.2009.01.047</a>.</cite></span>

</li>

<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><cite id="CITEREFSmitherman" class="citation web cs1">Smitherman, D. V. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20070221162221/http://www.affordablespaceflight.com/spaceelevator.html">"Space Elevators: An Advanced Earth-Space Infrastructure for the New Millennium"</a>. NASA/CP-2000-210429. Archived from <a rel="nofollow" class="external text" href="http://www.affordablespaceflight.com/spaceelevator.html">the original</a> on 2007-02-21.</cite></span>

</li>

</ol></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 <span style="font-weight: bold; font-style: italic;"><a href="https://commons.wikimedia.org/wiki/Category:Launch_loop" class="extiw external" title="commons:Category:Launch loop">Launch loop</a></span>.</div></div>

</div>

<ul><li><a rel="nofollow" class="external text" href="http://www.launchloop.com/">www.launchloop.com</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20111002153532/http://www.spacecable.org.uk/Stability%20IAC.pdf">SpaceCable</a> Another similar idea for launch assist/short range travel/recreational extremely high altitude trips</li>

<li><a rel="nofollow" class="external text" href="http://server-sky.com/slides/SEplatform/">Space Elevator Stage 1: Through the Stratosphere</a>, John Knapman, Keith Lofstrom, presentation at Microsoft conference center, August 2011.</li></ul>

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</style><div id="Non-rocket_spacelaunch389" style="font-size:114%;margin:0 4em"><a href="Non-rocket_spacelaunch" title="Non-rocket spacelaunch">Non-rocket spacelaunch</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="3"><div><a href="Spaceflight" title="Spaceflight">Spaceflight</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Static structures</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%">Compressive</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="Space_tower" class="mw-redirect" title="Space tower">Space tower</a></li>

<li><a href="Pneumatic_freestanding_tower" class="mw-redirect" title="Pneumatic freestanding tower">Pneumatic freestanding tower</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Tensile</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%">Orbiting skyhooks</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="Skyhook_(structure)" title="Skyhook (structure)">Skyhook</a></li>

<li><a href="Momentum_exchange_tether" title="Momentum exchange tether">Momentum exchange tether</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Space elevators</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><a href="Space_elevator" title="Space elevator">Space elevator</a></div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td><td class="noviewer navbox-image" rowspan="5" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Dynamic structures</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_fountain" title="Space fountain">Space fountain</a></li>

<li><a href="Orbital_ring" title="Orbital ring">Orbital ring</a></li>

<li><a href="Endo-atmospheric_tether" class="mw-redirect" title="Endo-atmospheric tether">Endo-atmospheric tether</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Projectile launchers</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%">Electrical</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="Coilgun" title="Coilgun">Coilgun</a></li>

<li><a href="Mass_driver" title="Mass driver">Mass driver</a></li>

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

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

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Chemical</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_gun" title="Space gun">Space gun</a></li>

<li><a href="Blast_wave_accelerator" class="mw-redirect" title="Blast wave accelerator">Blast wave accelerator</a></li>

<li><a href="Ram_accelerator" title="Ram accelerator">Ram accelerator</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Mechanical</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="Slingatron" class="mw-redirect" title="Slingatron">Slingatron</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Reaction drives</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="Air_launch" title="Air launch">Air launch</a></li>

<li><a href="Spaceplane" title="Spaceplane">Spaceplanes</a></li>

<li><a href="Laser_propulsion" title="Laser propulsion">Laser propulsion</a></li>

<li><a href="Beam-powered_propulsion" title="Beam-powered propulsion">Beam-powered propulsion</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Buoyant lifting</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="Non-rocket_spacelaunch#Balloon" title="Non-rocket spacelaunch">Balloon</a></li>

<li><a href="Buoyant_space_port" class="mw-redirect" title="Buoyant space port">Buoyant space port</a></li>

<li><a href="High-altitude_platform" class="mw-redirect" title="High-altitude platform">High-altitude platform</a></li></ul>

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

<dd><a href="Rocket_sled_launch" title="Rocket sled launch">Rocket sled launch</a></dd>

<dd><a href="Megascale_engineering" title="Megascale engineering">Megascale engineering</a></dd></dl>

<ul><li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> <b>Category</b></li></ul>

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

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Space_elevator164" 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="3"><div id="Space_elevator164" style="font-size:114%;margin:0 4em"><a href="Space_elevator" title="Space elevator">Space elevator</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="Space_elevator_construction" title="Space elevator construction">Construction</a></li>

<li><a href="Space_elevator_economics" title="Space elevator economics">Economics</a></li>

<li><a href="Space_elevator_safety" title="Space elevator safety">Safety</a></li>

<li><a href="Space_elevators_in_fiction" title="Space elevators in fiction">In fiction</a></li></ul>

</div></td><td class="noviewer navbox-image" rowspan="6" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technologies</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="Electromagnetic_propulsion" title="Electromagnetic propulsion">Electromagnetic propulsion</a></li>

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

<li><a href="Carbon_nanotube" title="Carbon nanotube">Carbon nanotube</a></li>

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

<li><a href="Space_tether" title="Space tether">Space tether</a>

<ul><li><a href="Momentum_exchange_tether" title="Momentum exchange tether">Momentum exchange tether</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related concepts</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="Lunar_space_elevator" title="Lunar space elevator">Lunar space elevator</a></li>

<li><a href="Orbital_ring" title="Orbital ring">Orbital ring</a></li>

<li><a href="Skyhook_(structure)" title="Skyhook (structure)">Skyhook</a></li>

<li><a href="Space_fountain" title="Space fountain">Space fountain</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Competitions</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="Space_elevator_competitions" title="Space elevator competitions">List of competitions</a></li>

<li><a href="Elevator%3A2010" title="Elevator:2010">Elevator:2010</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">

<ul><li><a href="Yuri_Artsutanov" title="Yuri Artsutanov">Yuri Artsutanov</a></li>

<li><a href="Bradley_C._Edwards" title="Bradley C. Edwards">Bradley C. Edwards</a></li>

<li><a href="Jerome_Pearson" title="Jerome Pearson">Jerome Pearson</a></li>

<li><a href="Konstantin_Tsiolkovsky" title="Konstantin Tsiolkovsky">Konstantin Tsiolkovsky</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Organizations</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="KC_Space_Pirates" title="KC Space Pirates">KC Space Pirates</a></li>

<li><a href="LaserMotive" class="mw-redirect" title="LaserMotive">LaserMotive</a></li>

<li><a href="LiftPort_Group" title="LiftPort Group">LiftPort Group</a></li></ul>

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

<ul><li><a href="Non-rocket_spacelaunch" title="Non-rocket spacelaunch">Non-rocket spacelaunch</a></li>

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

<li><a href="Megascale_engineering" title="Megascale engineering">Megascale engineering</a></li></ul>

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

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Maglev77" 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="Maglev77" style="font-size:114%;margin:0 4em"><a href="Maglev" title="Maglev">Maglev</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technologies</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="Linear_induction_motor" title="Linear induction motor">Linear induction motor</a></li>

<li><a href="Magnetic_levitation" title="Magnetic levitation">Magnetic levitation</a></li>

<li><a href="Electromagnetic_suspension" title="Electromagnetic suspension">Electromagnetic suspension</a> (EMS)</li>

<li><a href="Electrodynamic_suspension" title="Electrodynamic suspension">Electrodynamic suspension</a> (EDS)</li>

<li><a href="Automated_guideway_transit" title="Automated guideway transit">Guideway</a></li>

<li><a href="Magnetic_bearing" title="Magnetic bearing">Magnetic bearing</a></li>

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

<li><a href="Eddy_current_brake" title="Eddy current brake">Eddy current brake</a></li>

<li><a href="Lift-to-drag_ratio" title="Lift-to-drag ratio">Lift-to-drag ratio</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Systems</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="High_Speed_Surface_Transport" title="High Speed Surface Transport">High Speed Surface Transport</a></li>

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

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

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

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

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

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Lines</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="Line_S1_(Beijing_Subway)" title="Line S1 (Beijing Subway)">Beijing line S1</a></li>

<li><a href="Air-Rail_Link" title="Air-Rail Link">Birmingham Maglev</a></li>

<li><i><a href="California%E2%80%93Nevada_Interstate_Maglev" title="California–Nevada Interstate Maglev">California–Nevada Interstate Maglev</a></i></li>

<li><a href="Changsha_Maglev_Express" title="Changsha Maglev Express">Changsha Maglev Express</a></li>

<li><a href="Ch%C5%AB%C5%8D_Shinkansen" title="Chūō Shinkansen">Chūō Shinkansen</a></li>

<li><a href="Incheon_Airport_Maglev" title="Incheon Airport Maglev">Incheon Airport Maglev</a></li>

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

<li><i><a href="Northeast_Maglev" title="Northeast Maglev">Northeast Maglev</a></i></li>

<li><a href="Old_Dominion_University_maglev" title="Old Dominion University maglev">ODU maglev</a></li>

<li><a href="Qingyuan_Maglev_Tourist_Line" title="Qingyuan Maglev Tourist Line">Qingyuan Maglev Tourist Line</a></li>

<li><a href="Shanghai_maglev_train" title="Shanghai maglev train">Shanghai Maglev Train</a></li>

<li><i><a href="Shanghai%E2%80%93Hangzhou_maglev_line" class="mw-redirect" title="Shanghai–Hangzhou maglev line">Shanghai–Hangzhou Maglev Line</a></i></li>

<li><i><a href="UK_Ultraspeed" title="UK Ultraspeed">UK Ultraspeed</a></i></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Transport Accidents</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="Lathen_train_collision" title="Lathen train collision">Lathen train collision</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="font-size:90%;"><div>Proposals in <i>italics</i></div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-05-24" href="https://en.wikipedia.org/wiki/?title=Launch_loop&oldid=1291990025">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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