Asteroid Vesta will be visited by the DAWN spacecraft starring in 2011. We are fortunate to have samples of Vesta on Earth. January 24 this blog told the tale of a meteorite that came from Vesta all the way to Australia. This week researchers at University of Toronto reported on another Vesta meteorite found in Antarctica. They studied zircon crystals formed in eucrites, meteors formed by volcanic activity. Billions of years ago these rocks erupted free of Vesta's gravity and eventually made their way to Earth.
By studying the abundance of isotopes such as Tungsten 182, researchers can determine how long these rocks were molten. Experiments indicate that Vesta grew molten and solidified within the first 10 million years of the solar system's existence. Zircons on Earth and Vesta have the same characteristics. Asteroids and planets may have formed in the remarkably short time of 10 million years.
In January 2005 the Opportunity Rover found the first meteorite identified on another planet (above). It was nicknamed "Heat Shield Rock" because Opportunity's heat shield fell just 6 meters away. As in dry Antarctica, meteorites on Mars can be preserved a long time. If they had contacted water in their history, the meteorites should have become red and oxidised. The fact that they are not rusty may indicate that Mars' surface has been dry.
Presently Spirit and Opportunity are both threatened by an enormous dust storm. Already they have exceed their design lifetime and gathered far more data than expected. Who knows what further surprises await on Mars? DAWN will likely make similiar discoveries among the asteroids.