By Ron Cowen
FAJARDO, Puerto Rico — Space rocks may be dead as doornails but some contain ingredients that could have given life on Earth a foothold.
Planetary scientists reported October 7 that they have, for the first time, confirmed that an asteroid contains frozen water on its surface. Evidence of water-ice, along with organic compounds, on the surface of the asteroid 24 Themis supports the theory that asteroids brought both water and organic compounds to the early Earth, helping lay the foundation for life on the planet.
Humberto Campins of the University of Central Florida in Orlando and his colleagues recorded spectra of the asteroid 24 Themis over a seven-hour period, corresponding to 84 percent of the rotational period of the spinning rock. The spectra, taken with NASA’s Infrared Telescope Facility on Hawaii’s Mauna Kea, revealed the consistent presence of frozen water as different parts of the asteroid’s surface came into view, Campins reported at the annual meeting of the American Astronomical Society’s Division for Planetary Sciences.
The finding corroborates earlier observations (SN Online: 7/18/08) of the same asteroid by Andrew S. Rivkin of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., and Joshua Emery of the University of Tennessee in Knoxville, who also used the Infrared Telescope Facility. Over several years, Rivkin and Emery had found evidence of frozen water in single spots on 24 Themis but had not studied the asteroid as it made one entire rotation. Together, the two teams’ findings reveal that the asteroid’s entire surface is coated with frozen water, Campins says.