| Stardust |
home
topic index |
||
Stardust was scheduled to encounter comet Wild-2 early in 2004 and collect samples of cometary dust and volatiles while flying through the coma at a distance of 100 km on the sunlit side of the nucleus. It would then return the samples to Earth for analysis in 2006. The Stardust spacecraft was derived from the SpaceProbe deep space bus developed by Lockheed Martin Astronautics. This new lightweight spacecraft incorporated components which were either operating in space or flight qualified and manifested to fly. The total weight of the spacecraft including the propellant needed for deep space maneuvers was 380 kilograms. The overall length of the main bus was 1.7 meters. Science Payload
Sample Return Capsule The Sample Return Capsule (SRC) was a 60-degree blunt body re-entry capsule for landing the returned sample on Earth. The capsule was encased in PICA and SLA-561 ablator materials to protect the samples stowed in its interior from the heat of re-entry. A parachute slowed its descent to the Earth's surface to prevent damage to the cargo of comet samples. Propulsion - Because it was on a low-energy trajectory for its flyby of comet Wild 2 and return to Earth, aided by a gravity-assisted boost maneuver as it flew by the Earth for the first time, the Stardust spacecraft needed only a relatively modest propulsion system. This was provided by ultra pure hydrazine (N2H4) monopropellant. Attitude Control - The Stardust spacecraft was 3-axis stabilized in all mission phases, following separation from the launch vehicle. Stabilization was accomplished using eight 0.45 kgf thrusters and eight 0.1 kgf thrusters mounted in four clusters of 4 thrusters each. The primary attitude determination was via the star camera and the inertial measurement unit (IMU), and was backed up by analogue sun sensors. The IMUs were needed only during trajectory correction maneuvers, and during the fly-through of the cometary coma when stars might be difficult to detect. Otherwise, the vehicle could be operated in an all-stellar mode. The Stardust spacecraft was 3-axis stabilized in all mission phases, following separation from the launch vehicle. The primary attitude determination was via the star camera and the inertial measurement unit (IMU), and was backed up by analogue sun sensors. The IMUs were needed only during trajectory correction maneuvers, and during the fly-through of the cometary coma when stars may be difficult to detect. Otherwise, the vehicle can be operated in an all-stellar mode. Command & Data Handling - The RAD6000 central processing 32-bit unit embedded in the spacecraft's Command and Data Handling (C&DH) subsystem provided computing capability for all spacecraft subsystems, including the payload elements. Electronic cards were provided to interface instruments and subsystems to the C&DH subsystem. 128 Mbytes of data storage was provided on the processor card, although the spacecraft used approximately 20% of this for its own internal programs. The rest of the space in the memory was used for science programs and data storage for sending back to Earth 600 megabits (Mb) of images taken by the navigation camera, 100 Mb by the Comet Interstellar Dust Analyzer (CIDA) instrument, and 16 Mb by the Dust Flux Monitor (DFM). Telecommunications - Primary communication between the Earth and the orbiter was by use of the Deep Space Network (DSN) X-band (up/down) link and the orbiter's deep space transponder developed for the Cassini spacecraft, a 15 Watt RF solid state amplifier, and a 0.6 meter (2 ft) diameter fixed high gain parabolic antenna. Power - Two non-gimbaled solar arrays were deployed immediately after launch. They provided 6.6 square meters of solar energy to power the Stardust spacecraft. One nickel-hydrogen (NiH2) 16 amp-hour battery using common pressure vessel (CPV) cell pairs provided power during eclipses and for peak power operations. The electrical power control electronics were derived primarily from the Small Spacecraft Technology Initiative (SSTI) spacecraft development. Thermal Control - The thermal control subsystem used passive methods and louvers to control the temperature of the batteries and the solid state power amplifiers. Passive coatings as well as multi-layer insulation blankets were used to control other temperatures. Where needed, radiators were used to take the excess heat out of the spacecraft components to keep them at their proper operating temperature. Structure - The Stardust spacecraft structure was in the form of a rectangular box, with approximate dimensions of 1.6 meters long by a square cross-section of 0.66 meters on each side. Panels used graphite fibers with polycyanate as face sheets and aluminum honeycomb as the core. Redundancy - Virtually all spacecraft subsystem components were redundant with critical items cross-strapped. The battery included an extra pair of cells. A software fault protection system was used to protect the spacecraft from reasonable, credible faults but also had resiliency built into it so many faults not anticipated could be accommodated without taking the spacecraft down. Whipple Shield - The Whipple shield shadowed the spacecraft to protect it during the high speed encounter with particles in the cometary coma. Bumper shields were composite panels which disrupt particles as they impact. Nextel blankets of ceramic cloth further dissipated and spread the particle debris. Three blankets were used in the main body shield, and two were used in the solar array shields. The composite Catcher absorbed all of the debris for primary particles up to 1 cm in diameter for the shield protecting the spacecraft main body. Mass: 370 kg (810 lb). Stardust Chronology
Bibliography:
Contact us with any corrections, additions, or comments. Conditions for use of drawings, pictures, or other materials from this site.. To contact astronauts or cosmonauts. © Mark Wade, 1997 - 2008 except where otherwise noted. |
