Two materials experiments, which had been designed by high school students, were performed during the flight. These experiments involved melting and resolidifing titanium alloys by growing crystals to test whether materials with improved characteristics can be produced in prolonged low gravity. From high above, the crew photographed lightning during night thunderstorms. Scientists are studying the photographs to better understand the effects of lightning. In another atmospheric experiment, astronauts photographed the twilight glow at sunrise and sunset at Earth's horizon.
Communication satellites use horizon sensors to align themselves properly.
The photos may help scientists design improved horizon sensors. Discovery carried an electronic system in its cargo bay for measuring environmental conditions in the payload area during launch and flight. Discovery was traveling at about 25 times the speed of sound over the Indian Ocean, when the astronauts fired the deorbit engines and started the hour-long descent. Touchdown was to be a point on a dry lake bed at Edwards Air Force Base. More than 100,000 vehicles were parked on the fringes of the air base.