Stardust Probe Collects Samples of Comet
On 2nd January a NASA space probe called STARDUST successfully intercepted Comet Wild 2 and collected samples interstellar particles and dust which will now be returned to the earth for analysis. Comets are essentially 'icy dirt balls' and provide a valuable snapshot of our past, rather like a time-capsule, because their low temperature means that they contain well-preserved raw materials which gave rise to our solar system 4.5 billion years ago. Analysis of the dust samples that they contain will help to answer important questions about how the solar system formed. So how did STARDUST collect the samples from Wild 2 ? The 5 metre long probe got to within 186 miles of the 3 and a half mile wide comet which sailed past at a speed of over 13,000 miles an hour. Before the encounter the probe deployed a collector with a tennis-racket shaped grid containing a substance called aerogel, 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. After the samples were captured a clam like shell closed 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. The UK's Open University, which also helped to build one of the instruments on board the probe, hope to be involved in the analysis of the comet dust.