Close Encounter of a Cometary Kind – STARDUST flies through Comet Wild 2

At 19.44 hours GMT on 2nd January NASA’s space probe, STARDUST, successfully flew through Comet Wild 2, collecting interstellar particles and dust on its way. One of the instruments on board, the Dust Flux Monitor Instrument (DFMI), has been built by a team which include space scientists from the Open University.

Since its launch in February 1999, STARDUST has covered 3.2 billion km (2.3 billion miles). 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 Open University’s Planetary and Space Science Research Institute (PSSRI) are currently at the mission command centre, the Jet Propulsion Laboratory in California, 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 3.3 mile wide comet (5.4 km) sailed past the 5 metre long spacecraft at a distance of 186 miles (240 km) and at a relative speed of 21,960 km per hour (13,650 miles/hour). The 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.