CHICAGO, Feb. 20 (UPI) -- Scientists at the University of Chicago say they are among the first ever to analyze comet dust delivered to Earth via a spacecraft.
Chicago scientists say they routinely examine extraterrestrial material that falls to Earth as meteorites, but never before NASA's Stardust mission have they had access to verified samples from a comet -- the leftover debris from the formation of the solar system 4.5 billion years ago.
The Stardust spacecraft, launched in February 1999, came within 150 miles of the comet Wild 2 on Jan. 2, 2004, and collected thousands of tiny dust particles streaming from its nucleus. The Stardust sample-return canister parachuted onto the Utah desert salt flats Jan. 15 following a journey of nearly 3 million miles.
Scientists estimate the spacecraft collected at least 2,300 particles measuring at least 15 micrometers -- one-third the size of a human hair -- during the fly-by.
University of Chicago researchers say they are studying the dust with an electron microprobe and a scanning electron microscope.
The Stardust spacecraft was put into an orbit around the sun after dropping its canister of comet dust. The spacecraft is expected to come into contact with another comet in February 2011.