出典:Wikipedia
出典:『Wikipedia』 (2010/11/22 22:37 UTC 版)
Explorer 33 (also known as IMP-D) was a spacecraft launched by NASA on July 1, 1966 on a mission of scientific exploration. Originally intended for a lunar orbit, mission controllers worried that the spacecraft's trajectory was too fast to guarantee lunar capture. Consequently, mission managers opted for a backup plan of placing the craft into an eccentric Earth orbit with a perigee of 265,679 km and an apogee of 480,762 km — still reaching distances beyond the Moon's orbit.