Oldest-Known Asteroids in Solar System Identified

Three rocks hurtling through space appear to be among oursolar system's oldest objects.

The ancient asteroidsseem to have formed some 4.55 billion years ago, making them older than theoldest meteorites ever found on Earth, said Jessica Sunshine, an astronomer atthe University of Maryland who led the team that discovered the objects.

"We have identified asteroids that are not representedin our meteorite collection and which date from the earliestperiods of the solar system," Sunshine said. "These asteroids areprime candidates for future space missions that could collect and returnsamples to Earth providing a more detailed understanding of the Solar System'sfirst few millions of years."

The scientists observed the asteroids with infrared andvisible light telescopes on Hawaii's Mauna Kea. They measured the variousamounts of different colors of light reflected from the surface and foundevidence that the asteroids contain bits of material rich with calcium andaluminum.

An abundance of these elements indicates that the objects wereformed when the solar system was young because during that time the firstmaterials to condense into solid particles were rich in calcium and aluminum.

These three asteroidscontain two to three times the amount of calcium- and aluminum-rich material ofany space rock found on Earth.

The discovery was detailed in the March 20 online edition of thejournal Science.

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