Synchrotron light sources have helped researchers discover that interstellar space dust is more complex in composition and structure than previously thought. Researchers from the Argonne, Lawrence Berkeley and Brookhaven national laboratories used synchrotrons in concert with various microscopy techniques to examine seven particles collected by the Stardust space probe and returned to Earth in 2006. Synchrotrons produce extremely bright light beams that enable “unprecedented chemical identification” at the microscale, according to Dr. Hans Bechtel, principal scientific engineering associate at Berkeley Lab. The bulbous impact from a vaporized dust particle called Sorok can barely be seen as the thin black line in the upper right corner of this section of aerogel from the Stardust spacecraft. Courtesy of Lawrence Berkeley National Laboratory. The dust was found to contain a crystalline material called olivine, a mineral made of magnesium, iron and silicon. This suggests that the particles came from other stars and were modified in the interstellar medium, according to the researchers. “The analysis of these particles captured by Stardust is our first glimpse into the complexity of interstellar dust, and the surprise is that each of the particles is quite different from each other,” said Dr. Andrew Westphal, a physicist at the Space Sciences Laboratory at the University of California, Berkeley. A team at Berkeley’s Advanced Light Source used Fourier transform infrared (FTIR) spectroscopy, which identified sample contamination, as well as scanning transmission x-ray microscopy, which ruled out many interstellar dust candidates that contained aluminum, which is not found in space. A group at Argonne’s Advanced Photon Source (APS) performed elemental imaging and analysis to create a map of the locations and abundances of the different elements in each tiny particle. All analysis was nondestructive, meaning that it preserved the structural and chemical properties of the particles. While the samples are suspected to be from beyond the solar system, Westphal said, potential confirmation of their origin must come from subsequent tests for oxygen isotopes, which will destroy some of the particles. “Despite all the work we've done, we have limited the analyses on purpose,” Westphal said. “These particles are so precious. We have to think very carefully about what we do with each particle.” The research was supported by NASA, the Klaus Tschira Foundation, the Tawani Foundation, the German Science Foundation and the Funds for Scientific Research (Belgium). The research was published in Science (doi: 10.1126/science.1252496). For more information, visit www.lbl.gov.