ROYAL ASTRONOMICAL SOCIETY PRESS INFORMATION NOTE
Date: 2 February 1999
Ref. PN 99/04

Issued by:
Peter Bond,
RAS Space Science Advisor.
10 Harrier Close,
Cranleigh,
Surrey, GU6 7BS,
United Kingdom.
Phone: +44 (0)1483-268672
Fax: +44 (0)1483-274047
E-mail: 100604.1111@compuserve.com

http://www.ras.org.uk/ras

INFORMATION ON CONTACTS AND ILLUSTRATIONS IS GIVEN AT THE END OF THIS
RELEASE.

UNIVERSITY OF KENT ON A WILD COMET CHASE!

Stardust is currently set for launch on Saturday, February 6. After a five year voyage to reach its target, Stardust will fly past the comet in January 2004. Approaching at a speed of 6 km/s (14,000 mph), Stardust will capture the tiny dust particles that make up the comet's tail, eventually returning them to Earth in January 2006. In order to avoid damaging the fragile particles, panels of aerogel - sometimes called 'solid smoke' because of its extreme lightness - will be exposed to the dust stream and used to entrap them.

The overall dust environment around the comet will also be studied in detail. One of the instruments used to measure the characteristics of this dust is a sensitive dust detection system.

This Large Area Momentum Sensor (LAMS) is mounted on Stardust's front bumper shield. The circular shield, which consists of three layers, is used to protect the vulnerable spacecraft from high speed impacts. At the rear of the shield is a set of microphones, designed by Kent in collaboration with the University of Chicago. These will listen to the 'sound' of the dust particles as they strike the spacecraft.

The microphone attached to the back of the external aluminium layer will record impacts from smaller particles. Larger grains which penetrate the aluminium will be detected by a second microphone fixed to a layer of Nextel cloth. The number of impacts on the shield will be counted from the number of electrical pulses picked up by the Kent sensors, while the voltage of each pulse will enable particle mass to be calculated.

UKC team member Dr. Mark Burchell said, "Using the special facilities in our laboratory, we have been able to recreate the high speed impacts on a mock-up of the Stardust spacecraft. This allowed us to test the microphones which will 'listen' to the impacts on the real spacecraft as it flies past the comet."

Dust particles ejected by comets are thought to have been preserved in almost pristine condition since our Solar System formed some 4,600,000,000 years ago. Professor Tony McDonnell, Director of the Unit for Space Sciences, pointed out that "since comets are probably the most primitive objects in our Solar System, this is a very important mission which will greatly extend our understanding of them and of the conditions out of which our Solar System developed".

Also involved in the team is postgraduate student Bryan Vaughan, who will be basing his doctorate thesis on the University of Kent Stardust research.

The University of Kent involvement with this NASA mission is funded by a grant from PPARC, the UK Particle Physics and Astronomy Research Council.

Stardust is a prelude to an even more ambitious European Space Agency mission called Rosetta. A number of UK groups are involved in this mission, including the University of Kent, the Open University, and Rutherford Appleton Laboratory. Scheduled for launch in 2003, Rosetta will actually land a probe on the surface of a comet, but not until the year 2011!

NOTES. Stardust will be the first spacecraft ever to bring cometary material back to Earth for analysis by scientists worldwide. Its main objective is to collect return particles flying off the nucleus of Comet Wild-2. It will also bring back samples of interstellar dust, including the recently discovered dust streaming into the Solar System from other stars. Ground-based analysis of these samples after their return in January 2006 should yield important insights into the evolution of the Sun and planets, and possibly into the origin of life itself.

Other objectives are to take pictures of the comet, count the comet particles striking the spacecraft, and produce real-time analyses of the composition of the material ejected by the comet.

Stardust is the fourth of NASA's low-cost Discovery missions.