NASA Mission Returns Cosmic Dust
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JEFFREY KAYE: Today scientists are preparing to analyze ancient particles from outer space. Particles that arrived special delivery Sunday morning. Almost exactly on time and on target, a tiny payload of cosmic dust particles landed in a Utah desert after a seven-year journey through space.
JOE VELLINGA, Lockheed Martin Space Systems: Everything was intact. It was fine. There was a little bit of mud on the nose; the paint around the corner of the capsule is still on.
JEFFREY KAYE: As it ended its 3-billion-mile odyssey, the Stardust spacecraft ejected its return capsule into the upper atmosphere late Saturday and sped to Earth at nearly 49,000 miles an hour, faster than anything that’s ever returned from space.
SPOKESMAN: We have confirmation — (cheers and applause)
JEFFREY KAYE: There were cheers in the control room at NASA’s Jet Propulsion Lab, JPL, in California when the parachute slowed the capsule.
SPOKESMAN: From the ground.
JEFFREY KAYE: And a touchdown, a second cheer.
SPOKESMAN: All stations we have touchdown!
JEFFREY KAYE: Now the real science remains to be done, analyzing the contents of the time capsule to learn more about the formation of our solar system. Don Brownlee of the University of Washington is the project’s principal investigator.
DON BROWNLEE: Much of the science of this mission hasn’t been done yet. It’s going to be done in laboratories all over the world doing things that you really can’t do in space.
SPOKESMAN: Three, two, one…
JEFFREY KAYE: NASA’s $170 million Stardust mission launched in 1999. It’s one of a series of missions to explore the makeup of comets, one of the best known phenomena in the skies and one of the least understood. Paul Weissman is a JPL comet scientist.
PAUL WEISSMAN: Comets are the most primitive bodies in the solar system. They are frozen ice balls, dirty snowballs left over from the origins of the solar system and they have been unprocessed by the normal things that we see on Earth. So this is the original material out of which the solar system formed.
JEFFREY KAYE: The Stardust mission orbited the sun three times, using its own thrusters, as well as the Earth’s gravity as a sling shot to gain speed and distance. In 2004 it moved in on the relatively unknown comet Wild 2. The spacecraft flew alongside the halo of gas and dust surrounding Wild 2 to collect samples and return them to Earth.
DON BROWNLEE: It is a very, very bizarre thing. It had on the order of two dozen jets. I mean, the dust we collected was squirted out of little spots on the surface of the comet at — by high-speed gas escaping.
JEFFREY KAYE: Scientists believe [the solar system] formed out of a cloud of gas and dust 4.6 billion years ago. But how? It’s hard to find the answers by studying material on Earth or on the planets because that material has changed so much over time.
PAUL WEISSMAN: All of the planets and the moons of the giant planets have gone through extremely violent histories with the impacts from asteroids and comets, the actual formation process which literally melts the planet and differentiates it so that we have an iron core and a silicate or stony mantel. These processes totally destroy the initial record of what was there.
JEFFREY KAYE: Most comets are made up of relatively pristine material essentially unchanged from the early days of the solar system. As a well-preserved comet within easy reach, Wild 2 made a good comet.
PAUL WEISSMAN: The material can tell us first of all, what the composition of the original solar nebula was for the heavier elements, the silicates, the dust and some of the organics that were in the original solar system. So it is a starting point for all future calculations of how the solar system formed and how the solar system evolved.
JEFFREY KAYE: To collect the particles, Stardust extended a grid-shaped target filled with an exotic substance called Aerogel, a kind of spun glass honeycombed with air pockets. It looks like a hologram or a piece of solid smoke. Steven Jones heads JPL’s Aerogel Lab.
STEVEN JONES: You have to think of the comet sweeping by the spacecraft, basically, at six kilometers per second. And there is a cloud of particles given off, basically, or jets of particles around the comet. And all those are moving at the same relative velocity through the spacecraft. So as the comet swept by the spacecraft, these particles, some of them impacted on the Aerogel collector grid.
JEFFREY KAYE: The dust particles burrowed into the Aerogel. Most should be undamaged by the impact.
STEVEN JONES: It is a little bit like catching a bullet in a bale of hay. So the bullet is very hard and dense and much larger than the pieces of hay. So even though the bullet destroys the individual pieces of hay in the hay bale, there are so many pieces of hay that they slow down the bullet and stop it.
JEFFREY KAYE: One side of the collector was used to gather material from the comet. The other side picked up particles entering the solar system from interstellar space.
Yesterday handlers used protective gloves because of residual heat from reentry to recover the capsule containing the particles and flew it to a nearby clean room.
The cargo will be transferred to the Johnson Space Center in Houston and from there the space particles will go to laboratories all over the world.
DON BROWNLEE: We believe that the typical particle we will be working on will actually be a collection of tens of thousands to hundreds of thousands of the grains we really want to study. Most of the particles we will be extracting; one of the first things we will do is cut them into slices and send it to people all around the world and do a sequential analyses.
JEFFREY KAYE: Some 180 scientists will use instruments as small as microscopes and as big as Stanford University’s two mile long particle accelerator to examine each grain. Among the many questions is how the cometary particles gathered by the Stardust mission compare to other materials extracted from meteorites that fell to Earth thousands of years ago.
DON BROWNLEE: We want to compare the ones that were at the edge of the solar system and the least changed to things that formed in other parts of the solar system and have been changed by all the different processes that have happened inside the solar system.
JEFFREY KAYE: Though the samples collected weigh just a fraction of a gram total, they are expected to keep analysts busy for years to come.