andrew yee

American Chemical Society
Washington, D.C.

CONTACT:
Jes Martez Frs, Ph.D.
Center for Astrobiology CSIC/INTA
Madrid, Spain
Phone: 34-91-5206418

Delphine Nna-Mvondo, Ph.D.
Center for Astrobiology CSIC/INTA
Madrid, Spain
Phone: +34-91-5206434

Michael Woods
News and Information Department
American Chemical Society
202-872-4400

EMBARGOED FOR 9 A.M., EASTERN TIME, April 9, 2007

Key "Stardust" spacecraft discovery may have been contamination

One of the biggest scientific surprises from last year's "Stardust" space
mission may have resulted from contamination from the spacecraft's rocket
boosters, scientists in Spain are cautioning in a report scheduled for
publication in the May 16 issue of ACS' Energy & Fuels, a bi-monthly
journal.

Stardust was the first U.S. mission to capture samples of a comet (Comet
Wild 2) and return that material, believed to hold clues to the origin of
the solar system, to Earth for scientific ****ysis. In the report, Jesus
Martinez-Frias and colleagues point out that scientists were surprised to
find that Stardust had collected tiny grains of the mineral osbornite, which
chemically is titanium nitride. Osbornite forms only at ultra-hot
temperatures of about 3,140 Fahrenheit. Scientists thus concluded that the
osbornite could have formed near the sun, and ejected to the outer reaches
of the solar system -- an indication that the infant solar system was a much
more violent and tumultuous place then previous believed.

Martinez-Frias and colleagues stress the plausibility and significance of
such hypothesis, but suggest another possible explanation for osbornite
presence, which they say has not yet been considered. They point out that
Stardust's rocket thrusters used a propellant of ultra-pure hydrazine, which
chemists long have used for the so-called nitration reactions used to make
titanium nitride on Earth. The propellant likewise could have reacted in
space with titanium from the comet or spacecraft to form titanium nitride,
the researchers state. They recommend that laboratory simulation ****yses
and further studies are needed before reaching a final conclusion on
osbornite origin.

"Stardust's Hydrazine (N2H4) Fuel: A Potential Contaminant for the
Formation of Titanium Nitride (Osbornite)"

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