Komeet Wild 2 gezien door de Stardust navigatiecamera
tijdens de passage op 2 januari. De foto werd genomen van 500 kilometer afstand
met een belichtingstijd van 10-milliseconden. Tijdens de flyby werden
in totaal 72 foto's gemaakt.
Jet Propulsion Laboratory
January 3, 2004
NASA Spacecraft Makes Great Catch...Heads for Touchdown
Team Stardust, NASA's first dedicated sample return mission to a comet, passed a huge milestone today by successfully navigating through the particle and gas-laden coma around comet Wild 2 (pronounced "Vilt-2"). During the hazardous traverse, the spacecraft flew within 240 kilometers (149 miles) of the comet, catching samples of comet particles and scoring detailed pictures of Wild 2's pockmarked surface.
"Things couldn't have worked better in a fairy tale," said Tom Duxbury, Stardust project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"These images are better than we had hoped for in our wildest dreams," said Ray Newburn of JPL, a co-investigator for Stardust. "They will help us better understand the mechanisms that drive conditions on comets."
"These are the best pictures ever taken of a comet," said Principal Investigator Dr. Don Brownlee of the University of Washington, Seattle. "Although Stardust was designed to be a comet sample return mission, the fantastic details shown in these images greatly exceed our expectations."
The collected particles, stowed in a sample return capsule onboard Stardust, will be returned to Earth for in-depth analysis. That dramatic event will occur on January 15, 2006, when the capsule makes a soft landing at the U.S. Air Force Utah Test and Training Range. The microscopic particle samples of comet and interstellar dust collected by Stardust will be taken to the planetary material curatorial facility at NASA's Johnson Space Center, Houston, Texas, for analysis.
Stardust has traveled about 3.22 billion kilometers (2 billion miles) since its launch on February 7, 1999. As it closed the final gap with its cometary quarry, it endured a bombardment of particles surrounding the nucleus of comet Wild 2. To protect Stardust against the blast of expected cometary particles and rocks, the spacecraft rotated so it was flying in the shadow of its "Whipple Shields." The shields are named for American astronomer Dr. Fred L. Whipple, who, in the 1950s, came up with the idea of shielding spacecraft from high-speed collisions with the bits and pieces ejected from comets. The system includes two bumpers at the front of the spacecraft -- which protect Stardust's solar panels -- and another shield protecting the main spacecraft body. Each shield is built around composite panels designed to disperse particles as they impact, augmented by blankets of a ceramic cloth called Nextel that further dissipate and spread particle debris.
"Everything occurred pretty much to the minute," said Duxbury. "And with our cometary encounter complete, we invite everybody to tune in about one million, 71 thousand minutes from now when Stardust returns to Earth, bringing with it the first comet samples in the history of space exploration."
Scientists believe in-depth terrestrial analysis of the samples will reveal much about comets and the earliest history of the solar system. Chemical and physical information locked within the cometary particles could be the record of the formation of the planets and the materials from which they were made.
Stardust, a part of NASA's Discovery Program of low-cost, highly focused science missions, was built by Lockheed Martin Space Systems, Denver, Colo., and is managed by JPL for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
Particle Physics and Astronomy Research Council
3 January 2004
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.
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.
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 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