Out beyond the orbit of Mars, a space probe destined to land in Utah has begun its job.
NASA's Stardust probe, programmed to land in Utah in 2006, began gathering samples last week of the grains of interstellar dust whizzing through outer space.Scientists believe the dust is from outside our solar system. It is part of a stream of material moving through the galaxy in the direction opposite to the motion of the sun.
The interstellar dust cloud is rarefied, with a low density of dust particles. Stardust officials expect to gather about 100 particles during two collection periods.
In two years, when the spacecraft is again oriented correctly relative to the dust stream, it will gather more of the grains. Two years later, it will grab samples from Comet Wild 2.
The spacecraft, launched from Cape Canaveral in January 1999, has two assignments: to collect interstellar dust from the depths of the solar system and to gather dust erupting off Comet Wild 2. The cometary rendezvous is scheduled for Jan. 1, 2004.
In January 2006, the probe's Sample Return Capsule should make a parachute descent to the Utah Test and Training Range, an Air Force bombing and firing range about 100 miles west of Salt Lake City.
"Following touchdown, the sample container will be recovered by helicopter or ground vehicles and transported to a staging area at (the) test and training range," according to a NASA briefing. The canister's next stop is Johnson Space Center, Houston, where scientists will begin examining the contents.
After a year hurtling through space, the probe opened its heat shield on Feb. 22. Then the dust-collecting instrument moved out of the Sample Return Capsule, extending on a metal arm, where it began capturing grains of dust.
This collecting will continue until at least May 25, and possibly for a few more weeks. After that, the probe will fly by Earth en route to the rendezvous with Comet Wild 2.
An exotic material called an aerogel is used to capture the dust. Aerogel is an ultra-low density "foam" material that is something like clear glass. But aerogel is 95 percent air, the lowest-density material ever made by man.
When a fast-moving particle strikes a dust collector, it plows through the aerogel for up to 200 times its own length and then is trapped in the material. The collector devices have two faces, side A for interstellar dust and side B for cometary dust.
What do scientists hope to discover?
According to NASA, clouds of gas and dust drift outside the solar system. In this type of material, stars develop and chemical reactions form organic molecules.
A stream of this cosmic dust shoots past Earth, and NASA believes the source is a cloud of gas between the stars.
If Stardust succeeds in gathering some of these tiny grains, they may learn much about chemistry in the distant reaches of our galaxy.