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:''Not to be confused with InterPlanetary Network'' The Interplanetary Transport Network (ITN) is a collection of gravitationally determined pathways through the Solar System that require very little energy for an object to follow. The ITN makes particular use of Lagrange points as locations where trajectories through space are redirected using little or no energy. These points have the peculiar property of allowing objects to orbit around them, despite lacking an object to orbit. While they use little energy, the transport can take a very long time. ==History== The key to discovering the Interplanetary Transport Network was the investigation of the exact nature of the winding paths near the Earth-Sun and Earth-Moon Lagrange points. They were first investigated by Jules-Henri Poincaré in the 1890s. He noticed that the paths leading to and from any of those points would almost always settle, for a time, on an orbit about that point. There are in fact an infinite number of paths taking one to the point and away from it, and all of which require no change in energy to reach. When plotted, they form a tube with the orbit about the Lagrange point at one end. The derivation of these paths traces back to mathematicians Charles C. Conley and Richard P. McGehee. ''Hiten'', Japan's first lunar probe, was moved into lunar orbit using similar insight into the nature of paths between the Earth and the Moon. Beginning in 1997, Martin Lo, Shane D. Ross, and others wrote a series of papers identifying the mathematical basis that applied the technique to the Genesis solar wind sample return, and to lunar and Jovian missions. They referred to it as an Interplanetary Superhighway (IPS)〔Lo, Martin W. and Ross, Shane D. 2001. (The Lunar L1 Gateway: Portal to the Stars and Beyond ), AIAA Space 2001 Conference, Albequerque, New Mexico.〕 As it turns out, it is very easy to transit from a path leading to the point to one leading back out. This makes sense, since the orbit is unstable, which implies one will eventually end up on one of the outbound paths after spending no energy at all. However, with careful calculation, one can pick ''which'' outbound path one wants. This turned out to be useful, as many of these paths lead to some interesting points in space, such as the Earth's Moon or the Galilean moons of Jupiter.〔Ross, S.D., W.S. Koon, M.W. Lo and J.E. Marsden. 2003. (Design of a Multi-Moon Orbiter ). 13th AAS/AIAA Space Flight Mechanics Meeting, Ponce, Puerto Rico. Paper No. AAS 03–143.〕 As a result, for the cost of reaching the Earth–Sun point, which is rather low energy value, one can travel to a huge number of very interesting points for a little or no additional fuel cost . The transfers are so low-energy that they make travel to almost any point in the Solar System possible. On the downside, these transfers are very slow, and only useful for automated probes. Nevertheless, they have already been used to transfer spacecraft to the Earth–Sun point, a useful point for studying the Sun that was employed in a number of recent missions, including the Genesis mission, the first to return solar wind samples to Earth.〔Lo, M. W., et al. 2001. Genesis Mission Design, The Journal of the Astronautical Sciences 49:169–184.〕 The Solar and Heliospheric Observatory began operations at L1 in 1996. The network is also relevant to understanding Solar System dynamics;〔Belbruno, E., and B.G. Marsden. 1997. (Resonance Hopping in Comets ). The Astronomical Journal 113:1433–1444〕〔W.S. Koon, M.W. Lo, J.E. Marsden, and S.D. Ross. 2000. ( Heteroclinic connections between periodic orbits and resonance transitions in celestial mechanics ). Chaos 10:427–469〕 Comet Shoemaker–Levy 9 followed such a trajectory on its collision path with Jupiter.〔Smith, D. L. 2002. (Next Exit 0.5 Million Kilometers ). Engineering and Science LXV(4):6–15〕〔Ross, S. D. 2003. (Statistical theory of interior–exterior transition and collision probabilities for minor bodies in the solar system ), Libration Point Orbits and Applications (Eds. G Gomez, M.W. Lo and J.J. Masdemont), World Scientific, pp. 637–652.〕 In a more recent example, the Chinese spacecraft Chang'e 2 used the ITN to travel from lunar orbit to the Earth-Sun L2 point, then on to fly by the asteroid 4179 Toutatis. 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「:''Not to be confused with InterPlanetary Network''The Interplanetary Transport Network (ITN) is a collection of gravitationally determined pathways through the Solar System that require very little energy for an object to follow. The ITN makes particular use of Lagrange points as locations where trajectories through space are redirected using little or no energy. These points have the peculiar property of allowing objects to orbit around them, despite lacking an object to orbit. While they use little energy, the transport can take a very long time.==History==The key to discovering the Interplanetary Transport Network was the investigation of the exact nature of the winding paths near the Earth-Sun and Earth-Moon Lagrange points. They were first investigated by Jules-Henri Poincaré in the 1890s. He noticed that the paths leading to and from any of those points would almost always settle, for a time, on an orbit about that point. There are in fact an infinite number of paths taking one to the point and away from it, and all of which require no change in energy to reach. When plotted, they form a tube with the orbit about the Lagrange point at one end. The derivation of these paths traces back to mathematicians Charles C. Conley and Richard P. McGehee. ''Hiten'', Japan's first lunar probe, was moved into lunar orbit using similar insight into the nature of paths between the Earth and the Moon. Beginning in 1997, Martin Lo, Shane D. Ross, and others wrote a series of papers identifying the mathematical basis that applied the technique to the Genesis solar wind sample return, and to lunar and Jovian missions. They referred to it as an Interplanetary Superhighway (IPS)Lo, Martin W. and Ross, Shane D. 2001. (The Lunar L1 Gateway: Portal to the Stars and Beyond ), AIAA Space 2001 Conference, Albequerque, New Mexico.As it turns out, it is very easy to transit from a path leading to the point to one leading back out. This makes sense, since the orbit is unstable, which implies one will eventually end up on one of the outbound paths after spending no energy at all. However, with careful calculation, one can pick ''which'' outbound path one wants. This turned out to be useful, as many of these paths lead to some interesting points in space, such as the Earth's Moon or the Galilean moons of Jupiter.Ross, S.D., W.S. Koon, M.W. Lo and J.E. Marsden. 2003. (Design of a Multi-Moon Orbiter ). 13th AAS/AIAA Space Flight Mechanics Meeting, Ponce, Puerto Rico. Paper No. AAS 03–143. As a result, for the cost of reaching the Earth–Sun point, which is rather low energy value, one can travel to a huge number of very interesting points for a little or no additional fuel cost .The transfers are so low-energy that they make travel to almost any point in the Solar System possible. On the downside, these transfers are very slow, and only useful for automated probes. Nevertheless, they have already been used to transfer spacecraft to the Earth–Sun point, a useful point for studying the Sun that was employed in a number of recent missions, including the Genesis mission, the first to return solar wind samples to Earth.Lo, M. W., et al. 2001. Genesis Mission Design, The Journal of the Astronautical Sciences 49:169–184. The Solar and Heliospheric Observatory began operations at L1 in 1996. The network is also relevant to understanding Solar System dynamics;Belbruno, E., and B.G. Marsden. 1997. (Resonance Hopping in Comets ). The Astronomical Journal 113:1433–1444W.S. Koon, M.W. Lo, J.E. Marsden, and S.D. Ross. 2000. ( Heteroclinic connections between periodic orbits and resonance transitions in celestial mechanics ). Chaos 10:427–469 Comet Shoemaker–Levy 9 followed such a trajectory on its collision path with Jupiter.Smith, D. L. 2002. (Next Exit 0.5 Million Kilometers ). Engineering and Science LXV(4):6–15Ross, S. D. 2003. (Statistical theory of interior–exterior transition and collision probabilities for minor bodies in the solar system ), Libration Point Orbits and Applications (Eds. G Gomez, M.W. Lo and J.J. Masdemont), World Scientific, pp. 637–652. In a more recent example, the Chinese spacecraft Chang'e 2 used the ITN to travel from lunar orbit to the Earth-Sun L2 point, then on to fly by the asteroid 4179 Toutatis.」の詳細全文を読む スポンサード リンク
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