Stardust to a Comet
Stardust was JPL's second Discovery mission. This and another Discovery mission, Genesis, returned the first samples from space since the Apollo program ended.
Proposed by Donald Brownlee of the University of Washington, Stardust's goal was to collect dust from a comet, Wild 2, and return it to Earth for study. Most scientists believe that comets are remnants of the material the planets are made from, and are the oldest surviving material in the solar system. But returning samples of comet dust was extremely challenging for two reasons. Despite having to be inexpensive, the spacecraft had to survive a seven-year mission. And its return to Earth would be at the highest re-entry velocity NASA had attempted. Launched Feb. 7, 1999, Stardust made its sample collection in 2004. Its sample return capsule parachuted into the Utah desert on Jan. 15, 2006.
Scientific analysis for this mission is just beginning.
Genesis and the Solar Wind
Genesis, JPL's third Discovery project, was also a sample return mission. Proposed by Donald Burnett of Caltech, Genesis collected particles of the solar wind at the "L1" point, where the gravitational pulls of Earth and the sun balance exactly. Genesis was launched Aug. 8, 2001, and began collecting particles that December. Its sample return capsule entered the atmosphere Sept. 8, 2004, but its parachute system failed, and the capsule hit the ground at 311 kilometers per hour (193 miles per hour). The damaged capsule's contents were still mostly retrievable, and the mission's scientists turned to finding ways to remove Earthly contamination from the samples.