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A low-energy transfer, or low-energy trajectory, is a route in space that allows spacecraft to change orbits using very little fuel. These routes work in the Earth–Moon system and also in other systems, such as traveling from Earth to Mars or between the moons of Jupiter. The drawback of such trajectories is that they take longer to complete than higher-energy (more-fuel) transfers, such as Hohmann transfer orbits. Low-energy transfers are also known as weak stability boundary trajectories, or ballistic capture trajectories. Low-energy transfers follow special pathways in space, sometimes referred to as the Interplanetary Transport Network. Following these pathways allows for long distances to be traversed for little change in velocity, or . Missions that have used low-energy transfers include: * ''Hiten'', from JAXA * ''SMART-1'', from ESA * ''Mars Orbiter Mission'', from ISRO * ''Genesis'', from NASA.〔(Interplanetary Superhighway Makes Space Travel Simpler ) // NASA 07.17.02: "Lo conceived the theory of the Interplanetary Superhighway. Lo and his colleagues have turned the underlying mathematics of the Interplanetary Superhighway into a tool for mission design called "LTool," ... The new LTool was used by JPL engineers to redesign the flight path for the Genesis mission"〕 * ''GRAIL'', from NASA.〔(【引用サイトリンク】title=GRAIL Design at MIT Website )〕〔(【引用サイトリンク】title=Spaceflight101 GRAIL Mission Design )〕 Proposed missions using low-energy transfers include: * European Student Moon Orbiter (ESMO) * Mars Direct ==History== Low-energy transfers to the Moon were first demonstrated in 1991 by the Japanese spacecraft ''Hiten'', which was designed to swing by the Moon but not to enter orbit. The Hagoromo subsatellite was released by Hiten on its first swing-by and successfully entered lunar orbit, but suffered a communications failure. Edward Belbruno and James Miller of the Jet Propulsion Laboratory had heard of the failure, and helped to salvage the mission by developing a ballistic capture trajectory that would enable the main Hiten probe to itself enter lunar orbit. The trajectory they developed for ''Hiten'' used Weak Stability Boundary Theory and required only a small perturbation to the elliptical swing-by orbit, sufficiently small to be achievable by the spacecraft's thrusters.〔 This course would result in the probe being captured into lunar orbit using zero , but required five months instead of the usual three days for a Hohmann transfer. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Low-energy transfer」の詳細全文を読む スポンサード リンク
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