Astronauts had to swim before they could walk.
- By Rebecca Maksel
- AirSpaceMag.com, August 11, 2009
Although underwater training for extravehicular activity—spacewalks—is now the norm, NASA started out using aircraft to simulate weightlessness. Boeing KC-135 Stratotankers were used for this purpose, along with Convair C-131 Samaritans. The basic technique is the same today as it was then: The airplane makes a series of steep, roller-coaster-like climbs and dives, producing about 30 seconds of weightlessness at the top of each arc. These maneuvers frequently provoked airsickness, which led to the aircraft being nicknamed the “Vomit Comet.”