 |
 |
||
 |
|
||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
||||||||
 |
Projects: Stardust@homeStardust@home Team Extracts First Particle Track from Stardust CollectorStardust@home Update, February 15, 2008
It has been more than two years since the Stardust sample return capsule made a perfect landing in the Nevada desert, bringing with precious samples collected on its 7 year journey through the solar system; it has been more a year and a half since volunteer dusters began scanning Stardust@home movies of the aerogel collector, in search of interstellar dust particles; and it has been only six months since Stardust@home team finalized the list of the first 50 particle candidates discovered by volunteer "dusters." And now, at last, results: on the morning of Wednesday, February 13 2008, at the Johnson Space Center in Houston, Andrew Westphal and Dave Frank extracted the first keystone containing a particle identified by Stardust@home from the Stardust aerogel collector. For Westphal and his team, and for thousands of "dusters" around the world, this the culmination of years of hard work, and a vindication of the Stardust@home approach. The first particle extracted, Westphal noted, was one of the larger ones among the 50 candidates, but even so was many times smaller than the typical Stardust cometary grains with which scientists have dealt so far. "This shows how fantastically Stardust@home has worked" Westphal said. Noting that many of his colleagues were initially skeptical of the scientific value of inviting the public to search for the miniscule particles, he added: "that such a tiny track has been unambiguously identified shows how sensitive Stardust@home is, and what a sensible way it is for finding particles." The first particle extracted belongs to a group of "high-angle" tracks detected by the Stardust@home volunteers. Particles in this category did not strike the collector head-on, but at an angle to the plane of the aerogel tray. Since the tray was aimed directly at the path of the dust particles coming from interstellar space, scientists think it unlikely that these high-angle candidates are of interstellar origin. More likely they are the ejecta of impacts by micrometeorites, which struck the spacecraft and deflected into the collector. Naturally, scientists won't know for sure until they test the particles, but of one thing they are certain: whether they come from interstellar space or from our own solar system, these precious grains, collected in deep space, have a fascinating tale to tell. As is often the case when working with new methods, the extraction of the first particle was not without some surprises. After cutting out the aerogel keystone over several hours on February 12, Westphal and Frank were ready to pull it out using the miniscule picklefork. That was when they found out that the aerogel "quarry" surrounding the keystone was pressing down on it and holding it in place. "This had never happened before," Westphal said; "usually the keystone comes right out when the cutting is finished." It seems that the particle was embedded in a section of compressed aerogel, unlike any that the Stardust@home team had encountered before. They decided to leave the keystone in place overnight, and come back the next morning with fresh energy and hopefully some new ideas.
It was a good plan. During the night Dave Frank dreamt up a new method of extraction, in which the quarry walls would be pulled apart with the cutting needle, enabling the keystone to be pulled out. It wasn't easy, but it worked. By mid morning the researchers had managed to pull the keystone cleanly out of the tray with the picklefork. The first particle track detected by Stardust@home volunteers had been extracted from the Stardust aerogel collector. With the first particle out, Westphal and Frank immediately set to work on cutting out a second track, which was extracted later the same day. A third track, named "Spero" by its discoverer was being cut out the following day, February 14. All of these early extractions, Westphal explained, are of high-angle particles that most likely originated in our own solar system. "We'll move on to the interstellar candidate tracks when we gain more experience in this" Westphal said.
Did you like this article? Send
it to a friend or share it at:
Slashdot - Digg this - Reddit - Del.icio.us - Newsvine - NowPublic
|
||||||||
 |
 |
||||||||
[ what is this? ]