STS-73 was a Space Shuttle Columbia Spacelab mission carrying the second United States Microgravity Laboratory. After several scrubbed launch attempts, Columbia lifted off from Launch Complex 39B on October 20, 1995. The seven-person crew operated the pressurized Spacelab module for research in materials science, biotechnology, combustion science, fluid physics, and other microgravity investigations. The mission landed at Kennedy Space Center's Shuttle Landing Facility on November 5 after nearly sixteen days in orbit.