A department of NASA’s Goddard Space Flight Center, founded in 1966 as the National Space Science Data Center; it changed to its present name in 2014. NSSDCA is the repository for data from US space science missions—astronomy and astrophysics, solar physics, space plasma physics, and lunar and planetary science.

http://nssdc.gsfc.nasa.gov/ Official website, with links to many information pages on spacecraft and space exploration.