[meteorite-list] Stardust Prepares to Make History

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:18:05 2004
Message-ID: <200312310324.TAA16112_at_zagami.jpl.nasa.gov>

http://space.com/scienceastronomy/stardust_update_031230.html

Stardust Prepares to Make History
By Tariq Malik
space.com
30 December 2003

A NASA spacecraft is preparing to not only get close and personal with a
comet this week, but also fly through object's tail and steal pieces of it
for scientists on Earth.

On Jan. 2, the Stardust spacecraft is scheduled spend 12 hours studying the
comet Wild 2 -- pronounced Vilt-2 -- after a five-year journey to the far
side of the Sun, 242 million miles (389 million kilometers) from Earth.
During the flyby, scientists hope it will collect cometary material and stow
them in a reentry capsule to be sent Earthward later.

"Comets are among the most beautiful things in the universe," said Donald
Brownlee, Stardust's principal investigator and an astronomer with the
University of Washington. "But in addition to [that] they are containers
that have preserved the fundamental solar system, the planets and even
ourselves are made of." Brownlee spoke to reporters during a mission
briefing held at NASA's Jet Propulsion Laboratory (JPL) in Pasadena,
California, home to Stardust's control center.

Stardust is not the first spacecraft to visit a comet, but it is the first
mission to use a collector the size of a tennis racket and a foamy
glass-like material called Aerogel to return a sample from outside the orbit
of Mars. In 1986, Russian, European, Japan and NASA vehicles met or flew by
the famed Halley's Comet. None of them returned samples to Earth.

But Stardust's success could be a boon for scientists who believe comets
contain organic material that may have played a role in the origin of life
on Earth. Much of Earth's water is also thought to originate from icy comets
that impacted the planet eons ago. Since Wild 2 only recently began orbiting
closer the Sun, it may have preserved material from the birth of the Solar
System -or even other stars - making it an attractive target for a
rendezvous mission.

"We are basically bringing our own building blocks back to the lab and
studying them at the atomic scale," Brownlee said.

Stardust researchers hope their spacecraft will sweep up less than ounce of
comet dust, each particle of which is smaller than a grains of sand, in the
Aerogel collector as Wild 2 passes by at about 13,650 miles (21,967
kilometers) an hour. The dust should be moving past their spacecraft at
speeds of five times that of a rifle bullet. But since the Aerogel is 99.8
percent empty space, it shouldn't damage the grains or the collector.

"We just stick this collector up into the dust stream - and it will stop these
particles," explained Stardust project manager Thomas Duxbury. The Aerogel,
which is the lightest solid on Earth, gets denser the further in an object
goes, though comet dust particles should only penetrate about 100 times
their own diameter, Duxbury added.

Stardust's reentry capsule should then deliver the Wild 2 grain and
interstellar dust samples to Earth in 2006 in a parachute plunge down to the
desert floor of the U.S. Air Force Utah Test and Training Range.

Stardust is positioned so that as Wild 2 overtakes it, onboard instruments
should be able to record data and take close-up images of the comet. At its
closest, Stardust will come within 186 miles (300 kilometers) of Wild 2,
with a trio of bumpers protecting the spacecraft from cometary debris as it
enters Wild 2's coma, an envelope of gas and dust surrounding the nucleus.

Mission scientists are confident Stardust is ready for its date with Wild 2.
In November 2002 the spacecraft was able to test onboard instruments it
would use during the comet rendezvous when it swung past Asteroid 5535
Annefrank. Mission controllers even had a chance to test the Aerogel system
by scooping up interstellar dust on the opposite side of comet grain
collector.

"We're ready as a team, so we say bring on Wild 2," Duxbury said.

Stardust is expected to return to Earth in January 2006, eight years after
its launch on Feb. 7 1999.

AP wire reports contributed to this story.
Received on Tue 30 Dec 2003 10:24:39 PM PST