The Sample Return Capsule is a compact system, consisting primarily of a sample canister with an aeroshield/basecover, plus navigation recovery aids, an event sequencer and a small parachute system.
The sample canister is designed to hold and protect the dust particles collected during the Stardust flight - the most important goal of the mission being to bring these back safely. On its base, an aeroshield serves as a cover. In flight this opens like a clamshell, allowing the aerogel dust collector grid to encounter dust.
Earth Return Sequence
The return capsule stores the samples of cometary and interstellar dust securely in the sample canister, by folding it inside and tightly closing. Just prior to Earth encounter, the capsule is released, once the spacecraft sets up the proper flight trajectory and entry angle, and imparts a stabilizing spin to the capsule. The spin adds to the capsule stability in flight.
Image above: Diagram of Stardust Sample Return Capsule. Image credit: NASA/JPL.
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Upon entering Earth's atmosphere the capsule passively stabilizes as a result of its center of gravity, spin rate and aerodynamic shape. After entry the capsule will continue to free-fall until approximately 2 miles (3 km) above the ground, at which point the parachute deployment sequence will initiate. The planned landing site is the Utah Test and Training Range.
The reentry landing accuracy has been analyzed and it is believed to be possible to achieve a landing footprint of 84 km by 30 km - well within the Range area. To slow the capsule, a reinforced ring-slot descent chute will be deployed with the aid of a pilot chute. The descending capsule will have a UHF beacon and the parachute will be tracked by ground radar, so it is expected to be easy to locate.
Following touchdown, the capsule will be recovered by helicopter or ground vehicles and transported to a staging area at the range for retrieval of the sample canister. The canister will then be transported to the planetary materials curatorial facility at Johnson Space Center for examination.