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4660 Nereus ( ; (ギリシア語:''Νηρέας''), provisional designation 1982 DB) is a small (about ) asteroid. It was discovered by Eleanor F. Helin on February 28, 1982, approximately 1 month after a near pass by the Earth.〔 Although the discoverer is given the opportunity to name the asteroid, Helin donated naming rights to the Planetary Society which organized a naming contest.〔Helin, Eleanor F. (Jan/Feb 1991), "Eureka! The Recovery of 1982DB," pp. 12-16, Planetary Report, Planetary Society, Pasadena, CA.〕 The winner, Robert M. Cutler, then an employee of NASA contractor The MITRE Corporation, named the asteroid after the ancient Greek proto-god Nereus who had characteristics later attributed to Apollo (prophecy) and Poseidon (a sea god similar to Nereus but with legs rather than a fish tail). Nereus is potentially a very important asteroid. It is an Apollo and Mars-crosser, with an orbit that frequently comes very close to Earth, and because of this it is exceptionally accessible to spacecraft. Indeed, because of its small size and close orbit, its delta-V for rendezvous of ~5 km/s is smaller than the Moon's, which is about 6.3 km/s. Nereus makes seven approaches to Earth of less than 5 million km between 1900 and 2100.〔 The closest will be in February 2060, at 1.2 million km.〔(【引用サイトリンク】publisher=Department of Mathematics, University of Pisa, ITALY )〕 The next close approach is in December 2021, when it will be 3.9 million km away.〔〔(【引用サイトリンク】 title = Solex )〕 Its orbital period of 1.82 yr〔 also puts it somewhat near a 2:1 orbital resonance with Earth, which means that an approximately 4-year mission could depart for and return from the asteroid on relatively near passes to the Earth. ==Spacecraft== Nereus was proposed for visitation by both the private Near Earth Asteroid Prospector (NEAP) probe, and the Japanese sample return mission Hayabusa. However, the NEAP probe was not realized, and the Hayabusa's launch was delayed by 10 months and the probe had to be redirected to 25143 Itokawa. 4660 Nereus was considered as a flyby target of the NEAR unmanned robotic spacecraft mission.〔(Extended-mission opportunities for a Discovery-class asteroid rendezvous mission )〕 NEAR eventually launched, but visited 253 Mathilde and 433 Eros. 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「4660 Nereus ( ; (ギリシア語:''Νηρέας''), provisional designation 1982 DB) is a small (about ) asteroid. It was discovered by Eleanor F. Helin on February 28, 1982, approximately 1 month after a near pass by the Earth.Although the discoverer is given the opportunity to name the asteroid, Helin donated naming rights to the Planetary Society which organized a naming contest.Helin, Eleanor F. (Jan/Feb 1991), "Eureka! The Recovery of 1982DB," pp. 12-16, Planetary Report, Planetary Society, Pasadena, CA. The winner, Robert M. Cutler, then an employee of NASA contractor The MITRE Corporation, named the asteroid after the ancient Greek proto-god Nereus who had characteristics later attributed to Apollo (prophecy) and Poseidon (a sea god similar to Nereus but with legs rather than a fish tail).Nereus is potentially a very important asteroid. It is an Apollo and Mars-crosser, with an orbit that frequently comes very close to Earth, and because of this it is exceptionally accessible to spacecraft. Indeed, because of its small size and close orbit, its delta-V for rendezvous of ~5 km/s is smaller than the Moon's, which is about 6.3 km/s.Nereus makes seven approaches to Earth of less than 5 million km between 1900 and 2100. The closest will be in February 2060, at 1.2 million km.(【引用サイトリンク】publisher=Department of Mathematics, University of Pisa, ITALY ) The next close approach is in December 2021, when it will be 3.9 million km away.(【引用サイトリンク】 title = Solex ) Its orbital period of 1.82 yr also puts it somewhat near a 2:1 orbital resonance with Earth, which means that an approximately 4-year mission could depart for and return from the asteroid on relatively near passes to the Earth.==Spacecraft==Nereus was proposed for visitation by both the private Near Earth Asteroid Prospector (NEAP) probe, and the Japanese sample return mission Hayabusa. However, the NEAP probe was not realized, and the Hayabusa's launch was delayed by 10 months and the probe had to be redirected to 25143 Itokawa.4660 Nereus was considered as a flyby target of the NEAR unmanned robotic spacecraft mission.(Extended-mission opportunities for a Discovery-class asteroid rendezvous mission ) NEAR eventually launched, but visited 253 Mathilde and 433 Eros.」の詳細全文を読む スポンサード リンク
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