[meteorite-list] NASA Study Finds New Kind of Organics in Stardust Mission

[Ron Baalke]

http://stardust.jpl.nasa.gov/news/news108.html

NASA Study Finds New Kind of Organics in Stardust Mission 
December 14, 2006

A team of scientists found a new class of organics in 
comet dust captured from comet Wild 2 in 2004 by NASA's 
Stardust spacecraft.

The discovery is described in a technical paper, 
"Organics Captured from Comet Wild 2 by the Stardust 
Spacecraft," in the Dec. 15 issue of Science Express, 
the online edition of the journal Science.

In January 2004, the Stardust spacecraft flew through 
comet dust and captured specks of it in a very light, 
low-density substance called aerogel. Stardust's return 
capsule parachuted to the Utah Test and Training Range 
on Jan. 15, 2006, after a seven-year mission. The 
science canister containing the comet particles and 
interstellar dust particles arrived at Johnson Space 
Center on Jan. 17. From there, the cometary samples 
have been processed and distributed to about 150 
scientists worldwide who are using a variety of 
techniques to determine the properties of the 
cometary grains. 

"A portion of the organic material in the samples is 
unlike anything seen before in extraterrestrial 
materials," said Scott Sandford, the study's lead 
author and a scientist from NASA's Ames Research 
Center in California's Silicon Valley. "Capturing 
the particles in aerogel was a little bit like 
collecting BBs by shooting them into Styrofoam."

The comet organics collected by the Stardust spacecraft 
are more "primitive" than those seen in meteorites and 
may have formed by processes in nebulae, either in space 
clouds between the stars, or in the disk-shaped cloud of 
gas and dust from which our solar system formed, the 
study's authors found. 

"Comets are a major source of the water and carbon on 
the moon," said S. Pete Worden, NASA Ames director. 
"Therefore, understanding comets will help scientists 
learn what natural resources to search for on our 
nearest neighbor in space -- resources that will aid 
astronauts in exploration beyond Earth," Worden 
explained.

The study's scientists used many highly sophisticated, 
state-of-the-art techniques to analyze the Stardust 
samples.

Several of the analyses indicated that the samples 
contain polycyclic aromatic hydrocarbons (PAHs), 
scientists said. PAHs are molecules made of carbon 
and hydrogen that are common in interstellar space - 
and in barbeque grill soot.

Certain PAHs chemical varieties also contain oxygen 
and nitrogen. Some scientists believe that these PAHs 
variants exist in interstellar space as well. They 
are of interest to astrobiologists because these kinds 
of compounds play important roles in terrestrial 
biochemistry, according to Sandford.

"Our studies of the comet dust show that the organics 
are very rich in oxygen and nitrogen," Sandford said. 
"The data are not incompatible with some of it being 
in the PAHs, but we still have a lot to learn in this 
area."

Although some of the other organics captured by the 
Stardust spacecraft look somewhat similar to the 
fairly stable organics found in meteorites, Sandford 
noted that many of the organic compounds appear to be 
very volatile. One sample even showed an abundance of 
material containing alcohols.

Many scientists believe that comets are largely made 
of the original material from which our solar system 
formed and could contain pre-solar system, interstellar 
grains. According to scientists, continued analysis of 
these celestial specks may well yield important insights 
into the evolution of the sun, its planets and possibly, 
even the origin of life.

"I anticipate that people will be asking for and working 
on these samples for decades to come," said Sandford. 
"What we report in the papers that appear this week is 
just the beginning of what we will learn from these 
samples. One of the advantages of returned samples is 
that they are available for study into the future, a 
gift that keeps on giving."

The organics paper is one of seven in the journal Science 
reporting the findings of the preliminary examination 
team that made the initial study of the cometary samples.

The Jet Propulsion Laboratory, Pasadena, Calif., manages 
the Stardust mission for NASA's Science Mission 
Directorate, Washington. Dr. Peter Tsou of JPL is 
deputy principal investigator and is a co-author of the 
paper.   

For more information about Stardust studies and other 
mission information, visit:  

http://stardust.jpl.nasa.gov/ .

JPL Media Contact for Stardust:
DC Agle
Phone: 818-393-9011
agle at jpl.nasa.gov