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


image 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.

The Particle Physics and Astronomy Research Council (PPARC) is the UK's strategic science investment agency. It funds research, education and public understanding in four broad areas of science -- particle physics, astronomy, cosmology and space science.

PPARC is government funded and provides research grants and studentships to scientists in British universities, gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Organisation for Nuclear Research, CERN, the European Space Agency and the European Southern Observatory. It also contributes money for the UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, the UK Astronomy Technology Centre at the Royal Observatory, Edinburgh and the MERLIN/VLBI National Facility.

Notes for editor:

Background information

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 (242 million miles) at the time of the encounter.

Wild-2 is pronounced Vilt-2. The comet is 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.

The Open University team hope to be involved in analysing the samples that return to Earth in January 2006.

STARDUST, is part of NASA's Discovery Programme of low cost, highly focused science missions, was built by Lockheed Martin Astronautics and Operations, Denver, Colorado, and is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington D.C.

Images

Images of STARDUST flying through Comet Wild 2 and the unusual aerogel material that will capture the interstellar dust can be found on the PPARC website at http://www.pparc.ac.uk/Nw/images.asp Further images, including those taken from the onboard camera can be found on the NASA website -- address below.

Websites

* NASA http://stardust.jpl.nasa.gov

* Open University http://pssri.open.ac.uk/missions/index.htm

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