based virtual microscope starting in mid-March. Mission experts are holding their breath for a safe landing after last year's ill-fated return of the Genesis space probe carrying solar wind particles, which crashed after its parachute failed to open. Volunteer scanners must pass a test to find the particle tracks in a few test samples, the scientists said. The particles "will have made carrot-shaped trails" in the aerogel - the gummy substance that captured and immobilized the small grains. "Searching each picture should take just a few seconds, but the close attention required as the viewer repeatedly focuses up and down through image after image will probably limit the number a person can scan in one sitting," a statement said. The interstellar grains were collected from the "interstellar dust stream" that travels about 20 kilometres per second through the solar system. Eventually, the identified grains will be extracted for analysis. NASA took a "risk" with the programme, because it allowed Stardust to launch "without anyone having a clue as to how to get particles out of the aerogel after it came back," Westphal said. During the seven-year space journey, Westphal and others back on Earth developed microtweezers and what he calls "micro-pickle forks" to pull out the grains. Stardust is the first mission to return dust samples from a comet and from the galaxy. The leading interest in the Stardust mission is the larger comet particles, which NASA scientists say could shed more light on the origins of the solar system and how oceans and an atmosphere developed on Earth. Scientists also believe the aerogel cells captured minuscule interstellar dust from stars millions of light years away - a sprinkling of dust from distant stars or supernova explosions from the past 10 million years. The interstellar dust was produced by the same dynamic growth of supernovas, flaring red giants or neutron stars that produced heavy elements like carbon, nitrogen and oxygen, scientists believe. --SP 00 03 Local Time 21 03 GMT
