Washington, March 21 : A team of scientists has identified three asteroids that appear to be among our Solar System's oldest objects.
These asteroids were discovered using visible and infrared data collected from telescopes on Hawaii's Mauna Kea by a team of scientists led by University of Maryland's Jessica Sunshine.
According to Sunshine and colleagues from the City University of New York, the Smithsonian Institution, and the University of Hawaii, evidence indicates that these ancient asteroids are relatively unchanged since they formed some 4.55 billion years ago and are older than the oldest meteorites ever found on Earth.
"We have identified asteroids that are not represented in our meteorite collection and which date from the earliest periods of the Solar System," said Sunshine.
Though astronomers have thought that at least some of the Solar System's oldest asteroids should be more enriched in calcium and aluminum, but, until the current study, none had been identified.
Now, using the SpeX instrument at the NASA Infrared Telescope Facility in Hawaii, the scientists looked at the surface of asteroids for evidence of the presence of early bits of high-temperature rock. In particular, they looked for spectral "fingerprints" indicative of the presence of CAIs (Calcium, Aluminum-rich inclusions).
Because different minerals have different reflective properties, the spectrum, or color of light reflected from a surface, reveals information about its composition enabling telescopic compositional analysis.
"Several CAI-rich asteroids have been identified that contain 2-3 times more CAI material than any known meteorite," said Sunshine. "Thus it appears ancient asteroids have indeed survived, and we know where they are," she added.
According to Sunshine, "These asteroids are prime candidates for future space missions that could collect and return samples to Earth providing a more detailed understanding of the Solar System's first few millions of years."