Embedded in part of the meteorite were 10-micron diamond grains — much smaller than what is used in diamond rings. But their diminutive size is still bigger than what is usually found in meteorites. The finding hints at what could have existed in the parent cosmic body that eventually broke apart and produced the Sutter's Mill meteoroid before the fragment slammed into Earth's atmosphere. [Photos: Fireball Drops Meteorites on California]
“Sutter's Mill gives us a glimpse of what future NASA spacecraft may find when they bring back samples from a primitive asteroid," researcher Peter Jenniskens, who holds dual affiliations at the SETI Institute and at NASA's Ames Research Center, said in a statement. "From what falls naturally to the ground, much does not survive the violent collision with Earth's atmosphere."
"The formation of the solar system did not fully erase and homogenize these signatures, and Sutter’s Mill provides the clearest record yet," Qing-Zhu Yin, the Sutter's Mill Meteorite Consortium lead in isotope and trace element geochemistry, said in the same statement.
Other unusual elements — such as a calcium sulfide called oldhamite — also indicate heating in the parent body, as well as in areas that were not heated at all. Heating also came when the fragment was sailing on its own. Sometime in the past 100,000 years, the meteoroid was heated up to at least 572 degrees Fahrenheit (300 degrees Celsius). This heating could have happened during the entry into Earth's atmosphere, the researchers said.
"I don't know of any similar meteorites that contain both heated and unheated materials," said team member Mike Zolensky, a space scientist at NASA's Johnson Space Center in Houston.
The heated portions caused other changes inside the meteorite's interior, such as the removal of volatile organic compounds. Scientists also managed to track down amino acids (protein building blocks) inside the meteorite.
source: livescience.com by Elizabeth Howell