The 66th space shuttle flight began with a nearly on-time liftoff of Space Shuttle Mission STS-66 into clear Florida skies. The orbiter Atlantis returned to space after an approximately two-year absence with a liftoff from Launch Pad 39B at 11:59:43 am EST, about four minutes after the launch window opened. The planned 11-day flight continued NASA's Mission to Planet Earth, a comprehensive international collaboration to study how Earth's environment is changing and how human beings affect that change. Primary payloads for the shuttle flight of 1994 include the Atmospheric Laboratory for Applications and Science (ATLAS-3), making its third flight, and the German-built Cryogenic infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite (CRISTA-SPAS), which was deployed and later retrieved during the mission. Mission commander was Donald R. McMonagle; Curtis L. Brown Jr. is the pilot; Ellen Ochoa was the payload commander, and the three mission specialists were Joseph R. Tanner, Scott E. Parzynski, and Jean-Francois Clervoy, a French citizen who is the European Space Agency.