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Capsule brings comet
dust to Earth
Jan. 15,
2006
Special to World Science
A space capsule containing dust from a comet has returned to Earth after a seven-year mission.
The capsule landed in
the Utah desert at At 5:10 a.m. Eastern U.S. time this morning, according to NASA officials.
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An artist's concept of Stardust encounter with comet Wild 2.
(NASA/JPL)
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Scientists around the world were awaiting the arrival of particles from Comet Wild 2, carried by the NASA spacecraft Stardust.
In January 2004, the spacecraft encountered the comet to collect samples of particles ejected from its nucleus, or core.
This was achieved with a sample canister containing cells filled with Aerogel, an extremely lightweight, porous material that slowed down the fast-moving dust particles and collected them, scientists said. These particles
were speeding at up to seven kilometres (more than 4 miles) per second.
During the encounter, the canister was exposed to the cometary particles and then retracted inside the spacecraft and stored in
a special return capsule, scientists said. The spacecraft then began its two-year journey back to Earth to return carrying its cargo. Also a sample of interstellar dust was collected during the journey.
Studying comets is among the best ways to understand the origin and evolution of the Solar System, astronomers say. Comets formed four and a half thousand million years ago and have remained almost unchanged since then. Thus they can provide important clues about the origin of the material out of which the Solar System formed, and could even help in understanding the origins of life on Earth.
“We feel like parents awaiting the return of a child who left us young and innocent, who now returns holding answers to the most profound questions of our solar system,” said Stardust Project Manager Tom Duxbury of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., earlier this week.
The mission has traveled about 4.5 billion kilometers (2.88 billion miles) during its round trip odyssey. The journey carried it around the sun three times and beyond Mars and the asteroid belt —as far out as half-way to Jupiter, NASA scientists said.
Missions like Stardust provide “valuable data by the first-ever study in terrestrial laboratories of particles ejected from a known comet and collected in the very close vicinity to it,” said Gerhard Schwehm of the European Space Agency. Schwehm is project scientist for Rosetta, a mission launched in 2004 to deliver a lander onto Comet Churyumov-Gerasimenko in 2014.
Stardust will give scientists access to information about particles collected from the
coma, the halo of dust and gas surrounding the comet tail, researchers said.
“These tiny particles, mostly micrometres [thousandths of a millimeter] in size, will be cut into even finer pieces and will be analysed with the very best instruments and at the highest level of detail for Earth-based labs,” continued Schwehm.
This “will provide the whole scientific community with an unprecedented close-up view” of a comet, he added. For instance, a study of what fraction of the elements in the dust grain have undergone radioactive breakdown helps reveal where and how the material was formed, he explained.
He added that Rosetta will employ a different strategy from Stardust.
“With Rosetta, we will study the comet in situ [in place] in all its aspects – the tail, the coma and even the surface, the comet ‘mantle’. Instead of bringing the comet material to our laboratories, Rosetta will take the ‘laboratory’ to the comet.”
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