Missions about NEOs
Stardust spacecraft was built by Lockheed Martin Astronautics under contract to the NASA/Jet Propulsion Laboratory.
|The STARDUST spacecraft was launched on February 6, 1999. Stardust will fly through the dust atmosphere of comet Wild 2 on January 2, 2004 (within approximately 100 kilometers ). STARDUST will image the icy cometary nucleus (dict.), collect dust samples, and return these samples to Earth in January 2006. The special dust collectors will also trap some of the dust particles that recently came to our solar system from the interstellar medium, and bring them also back to Earth for laboratory analyses. Once the STARDUST spacecraft has made return to Earth in January of 2006, the samples will be dropped using a streamlined, low-cost reentry capsule designed to separate from the main body of the spacecraft and re-enter Earth's atmosphere. The capsule will be protected from the heat of atmosphere by a new, carbon-based shield. The main body of the spacecraft will go on to travel in a long-lived orbit through space.|
Why Comet Wild 2 ?
Periodic comet Wild 2 is new to the inner solar system. In 1974, the comet, that before that day was no closer to the sun than Jupiter's orbit, was captured by the massive planet's gravitational force which changed the comet's orbit (see this issue of T.S. to know more about this mechanism). Now, Wild2 travels between Jupiter and the Earth. This is very important, because it means that Wild 2, at the time STARDUST will meet it, will have passed near the Sun only a few times . For a parallelism, Wild 2 will have passed near the Sun about 5 times, while the most famous comet, Comet Halley, has already passed the sun more than 100 times.
|Since when a comet comes close enough to the sun it gets heated up, loosing some of its material through sublimation, Wild 2 will be a very good subject of study. In fact, having passed the sun only a few times, it will still have most of its dust and gases containing much of the primordial, unchanged meaterial that made the solar system.|
STARDUST scientific instruments
|Of course the main scientific objective will be the
sample collection during the encounter with Wild 2, when
high resolution pictures of the comet will also be taken.
But STARDUST objectives are not limited to this: scientific instruments have also been studied to work during flight. Throughout the voyage, in fact, a Dust Flux Monitor Instrument will be used to monitor constantly the dust particle impacts and transmit information about particles' flux (or in other words the number of particles that hit a certain surface ) directly back to Earth. In addition, a Cometary and Interstellar Dust Analyzer instrument will intercept and perform real-time compositional analysis of dust as it is encountered by the spacecraft for transmission back to Earth.
Aerogel : a new exciting material
|Collecting material from a comet is not so easy,
considering the high impact velocity of the particles
(thata should be to 9 times the speed of a bullet fired
from a rifle) and the size of the grains, smaller than a
grain of sand. How can these high-speed particle be
captured without altering their shape and chemical
To solve this problem, STARDUST sample collection will make use of an exciting new substance, called aerogel, which is a silicon-based solid with a porous, sponge-like structure. Being the 99% of the volume of this material made of empty space, aerogel is the lowest density solid material in the world: it is 1000 times lighter than glass, another silicon-based solid. Furthermore, aerogel is 39 times more insulating than fiberglass, which is currently the best insulation on the market. Par example, 1 inch of aerogel could insulate a house 5 times better than 6 inches of fiberglass!.
This material, which has already been used to protect the Pathfinder Rover's electronics from the harsh, cold climate of Mars, will also play an important role on the STARDUST mission, being used to catch dust grains. In fact, when a particle hits the aerogel, it buries itself in the material, creating a visible track that measures up to 200 times its own length, slowing down and coming to a gentle stop. These tracks are easy to find in the almost transparent aerogel, and are therefore used to locate the tiny particles.
Images on this page: courtesy of JPL. Image
of the spacecraft provided by Engineered Multimedia Inc.
For additional information on the STARDUST
To know more about the scientific results: