Carnegie scientists breathed a sigh of relief on Sunday, January 15 when NASA’s Stardust mission landed safely with the first solid comet samples ever brought back to Earth. As members of the mission’s Preliminary Examination Team, Larry Nittler and Conel Alexander (both Department of Terrestrial Magnetism) with Marc Fries and George Cody (both Geophysical Laboratory) will be among the first to get their hands on these precious samples, captured from the coma of comet Wild-2. These tiny bits hold clues to the formation of the solar system, and might even reveal how organic molecules—the ingredients of life—first arrived on Earth.

“It has been an exciting week,” Nittler said. “No one quite knew what to expect when the team at Johnson Space Center opened the capsule, so when we heard the collection grid was filled with particles, we could hardly contain ourselves.”

Scientists believe comets like Wild-2 are the oldest solid bodies in the solar system. Yet until now, no one has seen a piece of a comet up close. Researchers expect to retrieve less than one thousandth of an ounce of material from Stardust’s collection grid. By comparing the structure and chemistry of Stardust grains to interstellar dust and rare meteorites rich in organic material, researchers may be able to fill in some significant holes concerning the evolution and history of our solar system.

“It is likely that some of the carbon in our bodies was originally bound up in comets and delivered to the early Earth through impacts,” Fries explained. “So when we say that ‘we are stardust’ we are literally talking about the type of material that Stardust has returned to our laboratories for analysis.”

Carnegie’s share of the bounty is due to arrive in early February, and the researchers are ready with a brand new, $2.8 million NanoSIMS ion probe. Ion probes can reveal the chemical makeup of a sample by vaporizing tiny target areas with a stream of ions, allowing an accurate count of the elements emitted as a result; with much greater sensitivity than previous ion probes, the NanoSIMS is an ideal tool for analyzing minuscule Stardust grains.

Nittler, Alexander, Fries, and Cody also plan to study the physical and chemical details of Stardust grains using two different spectroscopic techniques. First, by analyzing laser light reflected from a sample, Raman spectroscopy can reveal both the structure of minerals and the forms of carbon present.

Second, a unique soft X-ray microscope at Lawrence Berkeley National Laboratory’s Advanced Light Source facility in California enables a technique called XANES spectroscopy, which can help characterize the carbon, nitrogen, and oxygen species in organic matter. Since the carbon-containing materials from Wild-2 are likely to be unchanged since the birth of the solar system, these analyses are especially important.

“We can’t wait to get going on these experiments,” Cody said. “Stardust is really just the beginning; Carnegie now has the tools to take a leading role in sample-return analysis for decades to come.”

NASA provided funds in support of this work through the Stardust Participating Scientist Program. NASA’s Sample Return Laboratory Instrument and Data Analysis (SRLIDA) program funded both the Raman instrument and a portion of the cost of the NanoSIMS ion probe. NASA also provided partial support for work at the Advanced Light Source, a facility funded by the U.S. Department of Energy.

More information about the Stardust mission may be found at the following two sites:
http://stardust.jpl.nasa.gov/home/index.html
http://www.nasa.gov/mission_pages/stardust/main/