A speck of dust smaller than the eye can see from a place where no humans have ventured may reveal clues to the birth of our solar system.

By tailing a comet - serendipitously called Wild 2 - that was shooting material into space at 6.1 kilometers a second, NASA's Stardust spacecraft managed to pick up cometary and interplanetary dust particles that contain the very iron that is found in every human being's hemoglobin, and may provide hints to how life started on Earth.

"It's dirt," said John Bradley, director of the Lawrence Livermore National Laboratory's Institute for Geophysics and Planetary Physics. "Basically, it's cosmic crud".

But that cosmic crud found in deep space also makes up most of the contents of the human body. And it arrived on Earth from the Stardust spacecraft's seven-year mission just before 2 a.m. Sunday, Jan. 15, in the middle of a Utah desert. The sample return capsule (SRC) touched down at the correct velocity (10 mph), bounced five times, and then released the chute. The chute settled to the ground about 30 feet away.

"The landing surface was smooth, dry mud-flat with a somewhat surreal appearance," Bradley said after the landing. "Everyone involved is elated but exhausted".

For a perspective of the amount of dust gathered on the two-year mission, the Apollo moon missions brought back about 280 kilograms of material; on Stardust, less than a milligram of material was returned.

Bradley is among nearly 150 researchers on an international team that will dissect the dust particles collected in a tennis-racquet-shaped collector engulfed in aerogel. Aerogel - a material that is made up of 99.8 percent air, provides 39 times more insulation than the best fiberglass insulation, and is 1,000 times less dense than glass - was used to ensure the samples would stay intact as the capsule slammed into the Earth's atmosphere at 29,000 miles per hour.

Other Livermore team members include Giles Graham, Hope Ishii, Zurong Dai, Sasa Bajt, Patrick Grant, Ian Hutcheon, Jerome Aleon, Alice Tappani, Peter Weber and Nick Teslich.

In the early part of 1990s, with funding from NASA and the Jet Propulsion Laboratory, Laboratory researchers from the Chemistry and Materials Science Directorate developed the chemistry and process methods subsequently used by JPL to produce the ultra-low-density silica aerogel for Stardust. The Laboratory also assisted JPL by teaching the process and contributing to the design of the equipment needed to produce the aerogels at JPL.

The analysis is a very detailed and precise exercise in which some tracks are carved out of the aerogel with ultrasonic diamond blades. Researchers then use microscopic needles to extract the dust from the tracks.

"We do something not unlike a colonoscopy with the tracks," Bradley said.

After the Jan. 15 early landing, Bradley said the capsule's heat shield was in excellent condition, which boded well for the contents of the SRC. It was flown to NASA'S Johnson Space Center (NASA-JSC) in Houston the following Tuesday, where the capsule was opened that evening. The first few days were devoted to optical scanning of the aerogel tiles. Extractions of particles from aerogel cells began the next week, after which samples were distributed to Livermore and other research labs around the world.

"It's unbelievable. It's almost surreal," Bradley said. "We've collected so much stuff. We can see it. With a needle and a spatula, I could put it on the tip of my fingernail."



Posted by: Edwin    Source