Sample Return Capsule (SRC)

Aerogel Collector

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.

The SRC 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 SRC 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 SRC stability in flight.

Upon entering the Earth's atmosphere the capsule passively stabilizes as a result of its center of gravity, spin rate and aerodynamic shape. After entry the SRC 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 (UTTR).

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 SRC will be recovered by helicopter or ground vehicles and transported to a staging area at UTTR for retrieval of the sample canister. The canister will then be transported to the planetary materials curatorial facility at Johnson Space Center for examination.

Collector Grid

Collection of cometary particle samples is accomplished by simply exposing blocks of aerogel to the material it encounters during spaceflight.

The dust collector media consists of blocks of 1 and 3 cm thick underdense, microporous silica aerogel mounted in modular aluminum cells. This is similar to what was used for previous exposures during Shuttle and MIR experiments. For the Stardust mission, cells in a grid holding aerogel are mounted on a two-sided, tennis racket-shaped array that will deploy from the Sample Return Capsule (SRC). After exposure, the array will fold compactly for stowage inside the sample Earth return capsule for the trip back to Earth.

One side of the aerogel will be used to collect samples during the comet encounter and the reverse side - sometimes called the "B-side" - will be used for interstellar collection. The useful collecting areas are identical, with 1000 cm2 for interstellar dust grains and 1000 cm2 for cometary dust. These collectors are totally inert and only need to be exposed and then stowed after they are used.

Earth Return Sequence

The Sample Return Capsule will perform a direct entry at Earth. After entry the SRC will continue to free-fall until approximately 3 km, at which point the parachute deployment sequence will initiate. The planned landing site is the Utah Test and Training Range (UTTR).

The reentry to landing accuracy has been analyzed and found to be sufficient to achieve a landing footprint of 84 km by 30 km. - well within the Utah Test and Training Range. 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.

Following touchdown, the SRC will be recovered by helicopter or ground vehicles and transported to a staging area at UTTR for retrieval of the sample canister. The canister will then be transported to the planetary materials curatorial facility at Johnson Space Center.