STS-55 "Columbia" launched from Kennedy Space Center, Florida, on April 26, 1993. Nearly 90 experiments were conducted during this German-sponsored Spacelab D-2 mission to investigate life sciences, materials sciences, physics, robotics, astronomy and the Earth and its atmosphere. STS-55 also flew the Shuttle Amateur Radio Experiment (SAREX) making contact with students in 14 schools around the world. After 160 orbits of the earth in 240 flight hours, the 10-day mission concluded with a landing on Runway 22 at Edwards Air Force Base, California, on May 6, 1993.