basis, the technical value of launching the spacecraft - particularly after the successful launch of both Genesis I and II - is somewhat marginal. Therefore
spaceflight in the mid-twentieth century, only nation states developed and flew spacecraft above the Kármán line, the nominal boundary of space. Both the U.S. civilian
Osiris-Rex Spacecraft to Asteroid Bennu. The New York Times. 2016-09-08 [2018-02-20]. (原始内容存档于2018-02-20) (美国英语). Wall, Mike. NASA Spacecraft Buzzes Earth