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Since its launch in February 1999, Stardust has covered 3.2 billion kilometres. It is the first mission designed to bring samples back from a known comet. The study of comets provides a window into the past as they are the best preserved raw materials in the Solar System. The cometary and interstellar dust samples collected will help provide answers to fundamental questions about the origins of the solar system.
Professor Tony McDonnell and Dr Simon Green from the UK Open University's Planetary and Space Science Research Institute (PSSRI) are currently at the mission command centre, the Jet Propulsion Laboratory in California, USA, where they are beginning to receive data from their instrument.
Dr Simon Green said: "Early indications show that the encounter with Comet Wild 2 has been successful. The sensors on the DFMI have detected a significant number of impacts. Some of these, as expected, have penetrated the spacecraft dust shield, hopefully this should result in a good number of samples being returned to Earth."
Professor Tony McDonnell added, "The whole process seems to have gone to plan and we look forward to receiving more data over the next day or so. The telemetry received so far includes an image from the onboard camera, which shows a roughly spherical comet nucleus that was pockmarked with large "sinkholes". Four or five jets of material could be seen bursting from the object."
At the time of the encounter the 5.4 kilometre sailed past the 5 metre long spacecraft at a distance of 240 kilometres and at a relative speed of 21,960 kilometres per hour. A tennis racket shaped collector was extended on 24 December in preparation for the encounter. Now that this has taken place a clam like shell will have encased the aerogel collector keeping safe the particles until they return to Earth in January 2006.
"Stardust could provide a new window into the distant past," said Dr Green. "Comets are made of ice and are very cold and have been very cold since they were formed. That protects the material of which they were made from any process of heating, so they haven't been changed since they were formed, right at the beginning of the formation of the Solar System. So we can have almost a little time capsule of what things were like 4.5 billion years ago."
UK scientists, including a team from the Open University, are also involved with the European Space Agency's Rosetta Mission which will follow and land on Comet Churyumov-Gerasimenko. This mission is due to be launched on 26th February 2004.
The DFMI, part funded by the Particle Physics and Astronomy Research Council (PPARC) records the distribution and sizes of particles on its journey through the centre, or coma, of the comet. This will help tell us more about comets and the evolution of our own solar system and, critical for Stardust, its survival in the close fly-by of the comet.
The distance between Earth and Comet Wild 2 was 390 million kilometres at the time of the encounter. Wild-2 is pronounced “Vilt-2”. Named after the Swiss discoverer. The spacecraft was protected from debris and rocks by a number of shields in order to guard its solar panels and body. In preparation for this journey the craft was pelted with rocks and debris travelling at six times the speed of a bullet.
The cometary particles were captured on a tennis racket like grid which contains a substance called aerogel, the lightest solid in the Universe! This is a porous material that allows the particles to become embedded with minimum damage. This means that on their return to Earth they will be as near as possible to their original state.
Once the samples are captured a clam like shell closes around them. The capsule then returns to Earth in January 2006 where it will land at the US Air Force Utah Test and Training Range. Once collected, the samples will be taken to the planetary material curatorial facility at NASA's Johnson Space Centre, Houston, where they will be carefully stored and examined.
More info: Space Now
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