STS-61-B was NASA's 23rd Space Shuttle mission, and its second using Space Shuttle Atlantis. The shuttle was launched from Kennedy Space Center, Florida, on 26 November 1985. During STS-61-B, the shuttle crew deployed three communications satellites, and tested techniques of constructing structures in orbit. Atlantis landed at Edwards Air Force Base, California, at 16:33 EST on 3 December 1985, after 6 days and 21 hours in orbit.