Two Dartmouth researchers are part of the worldwide team that is studying the comet material collected by NASA's Stardust spacecraft. Studies about the dust-like particles appear in the journal Science on Dec. 15 in an issue that highlights the results from the preliminary examination team. The research concerns the basic chemical and physical makeup of the comet's particles, which reveals valuable information about our solar system and how it was made.
"One of the most exciting results so far is finding high-temperature minerals in this comet called Wild 2," says Susan Taylor, one of the authors on the study who is an adjunct professor of earth sciences at Dartmouth and a research physical scientist at the U.S. Army Corps of Engineers' Cold Regions Research and Engineering Laboratory. "Because Wild 2 is thought to have formed beyond the orbit of Pluto, it was expected to have only low-temperatures minerals. Finding the high-temperature minerals like pyroxenes and olivines, suggests that there was more mixing of matter in the early Solar System, when the sun and planets were forming, than previously thought."
Launched in 1999 and returning to Earth earlier this year, Stardust flew in the wake of the comet Wild 2. The tiny samples were captured using a material called aerogel, also called solid smoke, which slowed down, cushioned, and stored the material from the comet's tail. These comet particles hit the aerogel at speeds of six kilometers per second (more than 11,000 miles per hour).
"We had the opportunity to image and chemically analyze three particles," says Charles Daghlian, another member of the team and the director of Dartmouth's Electron Microscope Facility. "The largest particle was 10 microns [an average human hair is about 100 microns in diameter], and it proved to be very rich in carbon, one of the basic building blocks of life."
Daghlian and Taylor also worked with student Emily Koepsell, a member of the Dartmouth Class of 2009. As part of Dartmouth's Women in Science Project, or WISP, Koepsell helped analyze the particles from Wild 2 using the scanning electron microscope, a skill she learned as a WISP intern.