STS040-S-176 (14 June 1991) --- The main landing gear of the Space Shuttle Columbia touches down, on Runway 22 at Edwards Air Force Base in California, to complete a successful nine-day mission. The Spacelab Life Sciences (SLS-1) mission was the first ever devoted exclusively to life sciences research. Onboard the spacecraft were astronauts Bryan D. O'Connor, Sidney M. Gutierrez, Rhea Seddon, James P. Bagian and Tamara E. Jernigan; and payload specialists F. Drew Gaffney and Millie Hughes-Fulford. Landing occurred at 8:39:11 a.m. (PDT), June 14, 1991.