STS042-27-037 (22-30 Jan. 1992) --- Astronaut David C. Hilmers, STS-42 mission specialist, wearing a helmet assembly, sits in the Microgravity Vestibular Investigation (MVI) rotating chair. The scene is in the International Microgravity Laboratory (IML-1) science module aboard Discovery. Hilmers, a mission specialist, and six other crewmembers spent more than eight days in Earth-orbit conducting experiments. Hilmer's helmet assembly is outfitted with accelerometers to measure head movements and visors that fit over each eye independently to provide visual stimuli. The chair system has three movement patterns: "sinusoidal" or traveling predictably back and forth over the same distance at a constant speed; "pseudorandom" or moving back and forth over the varying distances; and "stepped" or varying speeds beginning and stopping suddenly.