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(meteorobs) [ASTRO] Stardust to Begin Sweep of Interstellar Particles
------- Forwarded Message
From: Ron Baalke <BAALKE@KELVIN.JPL.NASAdot gov>
Date: Mon, 21 Feb 2000 4:01:14 GMT
Subject: [ASTRO] Stardust to Begin Sweep of Interstellar Particles
http://www.space.com/science/solarsystem/stardust_update_000219.html
Stardust to Begin Sweep of Interstellar Particles
By Andrew Bridges
19 February 2000
PASADENA, Calif. - Stardust will begin collecting particles of interstellar
dust on Tuesday, sweeping up and capturing microscopic specks of material
that stream into our solar system from faraway stars.
The $165-million NASA spacecraft will keep its dust collector, a waffle
iron-shaped instrument, extended until May and then again during much of
2002. During that time, scientists hope the yard- (meter-) square collector
will sweep up as many as 100 of the particles.
Along with bits of comet dust the flip side of the collector will trap in
2004, Stardust will then return the samples to Earth in 2006, jettisoning
them to a soft landing in Utah.
"This will be the first sample return mission ever beyond the moon," said
Don Brownlee, the mission's principal investigator.
During the two interstellar dust collecting periods - which play second
fiddle to the main task of gathering comet samples - the spacecraft will fly
downwind of the particle stream. That will allow the zippy grains to strike
the dust collector.
There the micron-sized particles will be trapped in any one of 130 blocks of
glass foam, like bugs on a windshield.
"Except you want to catch the bugs very softly," said Kenneth Atkins,
Stardust's project manager at NASA's Jet Propulsion Laboratory. "This is our
butterfly net, if you will."
The mission makes a novel use of a glass foam called aerogel to grab, slow
and trap the zippy particles, which will traveling at a relative speed of
anywhere from 6 to 16 miles (10 to 26 kilometers) a second when they strike
the spacecraft.
The dust particles are literally samples of stars elsewhere in the galaxy,
where they are formed by condensation around those other suns.
The Milky Way is awash with the stuff - just peer upward on a clear night,
Brownlee said.
"You see this dark band running along the middle of it?" Brownlee said.
"That is interstellar dust, blocking the light of some stars."
Their presence inside our solar system was discovered by Ulysses in 1993 and
later confirmed by Galileo.
Throughout Stardust's flight, its Dust Flux Monitor Instrument (DFMI) will
monitor the dust particle impacts and transmit data back to Earth.
Furthermore, Stardust's Cometary and Interstellar Dust Analyzer instrument
(CIDA) will carry out real-time compositional analysis of the dust as it is
strikes the spacecraft.
"We want to know what they are," said Brownlee, who gained renown for the
discovery of cosmic particles in the stratosphere known as "Brownlee
particles."
Once the sample capsule is safely back on Earth, scientists will avail
themselves of an arsenal of instruments - including electron microscopes,
ion microprobes, atomic force microscopes, synchrotron microprobes, and
laser probe mass spectrometers - to study the miniature interstellar grains.
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