Posted on 01/02/2004 4:56:00 PM PST by Brett66
January 02, 2004
Stardust Space Probe Flies By Comet
The Stardust space probe, the first mission to collect a sample from a body beyond the moon and return it to Earth, has successfully made its close approach to Comet Wild-2 (pictured at right).
"We’ve flown through the worst of it, and we’re still in contact with our spacecraft," says project manager Tom Duxbury of NASA’s Jet Propulsion Laboratory (JPL).
Zipping through the comet’s coma—its dusty atmosphere—the probe passed about 230 kilometers from the solid body, or nucleus. The previous close-approach record-holder was the European Space Agency’s Giotto spacecraft, which in 1986 came within 600 kilometers of the nucleus of Comet Halley. During the encounter, Stardust deployed a dust collector roughly the size and shape of a large-head tennis racket. The collector will soon be folded into a capsule for the return journey to Earth. In January 2006, the capsule is scheduled to separate from Stardust and land in an Air Force test range in Utah.
The collected dust, ranging in size from a few to a few hundred micron, is thought to be a piece of the swirling cloud from which the planets emerged. Comets, like asteroids, are planetary building blocks that were never incorporated into planets. In the intervening 4.6 billion years, they languished in the deep freeze of the outer solar system, little changed. By comparison, material on Earth and other planets was thoroughly reworked by geological processes, erasing the record of the formative early period.
For those watching the Stardust encounter from mission control, it was a case of no news is good news. Relative to the comet, the space probe was moving at six kilometers per second. Shields—multiple layers of carbon and ceramic sheets—protected the solar panels and main body from damage by colliding dust grains. Stardust did not send images in real time, so all scientists and engineers could do was watch the radio carrier signal to see whether the spacecraft survived the bombardment. The signal from the moment of closest approach was scheduled to reach Earth at 11:44 a.m. Pacific time, and as this time came and went, the carrier held steady. Applause went up in the control room. "We’ve passed the closest approach without any injury, apparently," says Donald Yeomans, a comet scientist at JPL. Over the ensuing hours, Stardust transmitted its data back to Earth.
Stardust is one of the mid-price spacecraft in NASA’s Discovery program, running $130 million plus launch rocket and operations costs. It was launched in February 1999 and, during its journey, also collected interstellar dust that had infiltrated interplanetary space.
Comet Wild-2 used to orbit beyond the orbit of Jupiter, but it made an unusually close approch to the giant planet in September 1974 and got catapulted into the inner solar system. Since then, the comet has passed near the sun five times—compared to over 100 times for Comet Halley. Consequently, the sun has hardly had a chance to boil off or otherwise alter the cometary material, making Wild-2 an especially pristine sample from the genesis of planets. --George Musser in Pasadena, Calif.
| Rank | Location | Receipts | Donors/Avg | Freepers/Avg | Monthlies | |||
|---|---|---|---|---|---|---|---|---|
| Louisiana |
|
|
|
|
|
38.00 |
5 |
|
Thanks for donating to Free Republic!
Move your locale up the leaderboard!
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.