Vesta Sighted

The Dawn spacecraft has taken its first photograph of asteroid Vesta from a distance of 1.21 million km. Dawn was launched on September 27, 2007 from Cape Canaveral Launch Complex 17-B atop a Delta 2 booster. An ion propulsion system gives Dawn the endurance to reach its targets in the asteroid belt. Dawn is scheduled to go into orbit around Vesta, the second largest asteroid, on July 15. The spacecraft will rendezvous with Ceres in 2015.

Bode's Law predicts that another planet should lie between Mars and Jupiter. Ceres is the largest asteroid and first to be discovered. Ceres was thought to be the missing planet until other asteroids were found. Vesta is 530 km in diameter, though today it still looks like a tiny dot. We are fortunate to have samples from Vesta thanks to the Camel Donga meteorite, which can be seen in the Museum of Natural History. (See Night at the Museum!)

Ceres has recently been found to contain water; by some estimates more liquid water than Earth! Observations suggest that Ceres is differentiated into core and mantle, which would mean that it was melted early in its history. Ultraviolet observations have found water vapour near Ceres' North Pole. Liquid water is one indicator that Ceres could be suitable for life. How such a small body could be heated is a complete mystery, though Ceres' 10^{21} kg mass could easily hide a small Black Hole. More than just big rocks, the asteroids are new worlds that could contain Black Holes and even life.