This artist's concept shows NASA's Dawn spacecraft arriving at the dwarf planet Ceres, the most massive body in the asteroid belt. Dawn is the first mission to visit a dwarf planet -- a round body that orbits the sun but, unlike a planet, does not clear its orbital path of other objects. Photo courtesy of NASA/JPL-Caltech
LOS ANGELES, March 5 (UPI) -- In less than two days, NASA will provide the closest ever view of a dwarf planet between Mars and Jupiter that has mesmerized, puzzled and tantalized astronomers for more than two centuries.
The administration's Dawn spacecraft is expected to enter Ceres' orbit Friday, finally allowing scientists to begin exploring its existence after a near eight-year voyage.
Launched in September 2007, Dawn has traveled more than 3 billion miles so far, stopped to visit the asteroid Vesta on the way, and has beamed back some incredible photography. On Vesta, the probe captured what's believed to be one of the tallest mountains in the entire solar system -- three times the height of Mount Everest. It also transmitted a photo that revealed craters in the shape of a snowman.
First discovered in 1801 by Italian astronomer Giuseppe Piazzi, Ceres has long been a mystery. Located in an asteroid belt between Mars and Jupiter, the cosmic body was classified as a dwarf planet in 2006. Before that, scientists filed it under both the planet and asteroid designations -- too small to be considered a planet but too large to represent an asteroid. It is one of just five dwarf planets known to man, along with the distant Pluto.
"It is the giant of the main asteroid belt," Dawn project manager Robert Mase told The Wall Street Journal.
One of the most intriguing possibilities of Ceres is that it may, or at one time may have sustained an environment capable of producing life. Scientists believe much of the dwarf planet is composed of ice -- possibly enough ice that, if melted, would amount to more than all the water in the Earth's oceans.
"We suspect there was a subsurface ocean early on in Ceres. At present, it [likely] is an ice layer under a crust," said Carol Raymond, of NASA's Jet Propulsion Laboratory in California.
Also of interest to NASA are two bright flashes of light recently spotted inside a crater on Ceres' surface.
"I am sitting on the edge of my seat," Jim Green, director of NASA's planetary-science division, said in the Journal's report. "Dawn is right now at the doorstep of Ceres."
The first images of the small planet are expected in April.
Dawn is the first NASA exploratory mission that will use ion thrusters to maneuver the spacecraft. Between 2003 and 2006, NASA canceled and reinstated the Dawn mission multiple times. The project cost $446 million.