On January 15, 2006, the Stardust spacecraft's sample return capsule parachuted gently onto the Utah desert. Nestled within the capsule were precious particles collected during Stardust's dramatic encounter with comet Wild 2 in January of 2004; and something else, even rarer and no less precious: tiny particles of interstellar dust that originated in distant stars, light-years away. They are the first such contemporary interstellar dust particles ever collected in space and returned to Earth for study.
Before they can be studied, though, these tiny interstellar grains have to be found. As we have discovered since we started the Stardust@home project in 2006, this is not easy. Unlike the thousands of particles of varying sizes collected from the comet, scientists originally estimated that Stardust would collect only around 45 interstellar dust particles. After a thorough search of about one-third of the collector, we have so far found only four particles that appear to be interstellar. So they are incredibly rare and precious. They are tiny only about a micron (a millionth of a meter) in size! These miniscule particles are embedded in an aerogel collector 1,000 square centimeters in size. To make things worse the collector plates are interspersed with flaws, cracks, and an uneven surface. All this makes the interstellar dust particles extremely difficult to locate.
If we were doing this project twenty years ago, we would have searched for the tracks through a typical laboratory microscope of the era. Because the view of the microscope is so small, we would have had to move the microscope more than 1.6 million times to search the whole collector. And in each field of view, we would have had to focus up and down by hand to look for the tracks. This is so much work, that even starting twenty years ago, we would still be doing it today!
This is where you come in:
Since we cannot do this by ourselves, we are asking for help from talented volunteers like you from all over the world. Of course, we can't invite hundreds of people to our lab to do this search-we only have two microscopes! To find the elusive particles , therefore, we are using an automated scanning microscope to automatically collect images of the entire Stardust interstellar collector at the Curatorial Facility at Johnson Space Center in Houston. We call these stacks of images focus movies. All in all there will be nearly a million such focus movies. These are available to Stardust@home users like you around the world. You can then view them with the aid of a special Virtual Microscope (VM) that works in your web browser.
Together, you and thousands of other Stardust@home participants will find the first pristine interstellar dust particles ever brought to Earth.
In recognition of the critical importance of the Stardust@home volunteers, the discoverer of an interstellar dust particle appears as a co-author on any scientific paper by the Stardust@home team announcing the discovery of the particle. The discoverer also has the privilege of naming the particle! Each particle, as it is discovered, will be given some kind of alpha-numeric identifier (an address of sorts) for book-keeping purposes. But the name that people will actually call each particle will be given to it by its discoverer. For example, Bruce Hudson of Ontario, Canada, discovered our first candidate interstellar dust track. Its official NASA "phone number" is "I1043,1,30,0,0" - which is very hard to remember and doesn't exactly roll off the tongue. So we asked Bruce to give it a name to publish it by, and he decided on "Orion", and then later "Sirius" for the accompanying upstream particle that was discovered very nearby. Bruce was featured in a recent article in Nature on Citizen Science projects. To also recognize the efforts of our volunteers who work hard, but may not have found a particle, we will invite the top-ranked volunteers to come visit our lab in Berkeley for a special tour. (Unfortunately, we are legally precluded from covering travel expenses.)