| 词条 | Circumlunar trajectory |
| 释义 |
A circumlunar trajectory, trans-lunar trajectory or lunar free return is a type of free return trajectory which takes a spacecraft from Earth, around the far side of the Moon, and back to Earth using only gravity once the initial trajectory is set. BackgroundThe first spacecraft to fly a circumlunar trajectory was Luna 3. Circumlunar trajectories were also used by Apollo missions prior to lunar orbit insertion,[1] to provide a free return to Earth in the event of a propulsion system malfunction on the way to the Moon. This was used on Apollo 13, when an oxygen tank rupture necessitated return to Earth without firing the Service Module engine, although a number of course corrections using the Lunar Module descent engine were required to maintain this trajectory.[2] A number of manned missions were also proposed {{when|date=September 2018}} but not flown to intentionally conduct circumlunar flybys, including the Soviet Soyuz 7K-L1 or Zond programme, and several US proposals, including Gemini-Centaur and an early Apollo proposal.[3] See also
References1. ^{{cite web|url=http://spaceflightnow.com/apollo13/retro/09/launch.html|title=The launch and mission trajectory|work=Apollo 13 Mission Report|publisher=Spaceflight Now|accessdate=2009-06-30}} {{Use British English|date=January 2014}}{{space-stub}}2. ^{{cite web|url=http://spaceflightnow.com/apollo13/retro/14/index3.html|title=Apollo 13 on Free Return Trajectory|last=Turnhill|first=Reginald|publisher=Spaceflight Now|accessdate=2009-06-30}} 3. ^{{cite web|url=http://www.astronautix.com/fam/manlunar.htm|title=Manned Circumlunar|last=Wade|first=Mark|publisher=Encyclopedia Astronautica|accessdate=2015-02-11}} 1 : Exploration of the Moon |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。