On Friday, NASA’s Dawn spacecraft will make history by becoming the first spacecraft to reach a dwarf planet, said Robert Mase, project manager for the Dawn mission at NASA’s Jet Propulsion Laboratory in Pasadena, California, during a NASA press conference today.
While Pluto might be the most famous of the dwarf planets, Ceres is the closest at 257 million miles from Earth — just about 100 million miles farther than Mars.
Ceres is the largest object in the asteroid belt — a strip of rocky debris floating in space between Mars and Jupiter. The Dawn spacecraft has been jetting toward Ceres since it was launched in 2007, finally set to approach and orbit its destination around 7:20 am Friday, March 6, after 8 years of travel.
“At its closest approach [on Friday], Dawn is within 25,000 miles to Ceres,” Mase said during the press conference. That’s about 10 times closer than the Moon is to Earth.
Over the next year, Dawn will descend even closer to Ceres until it’s only 230 miles above the surface — lower than the height of International Space Station above Earth. During that time, the spacecraft will study the dwarf planet’s rocky surface and its many intriguing features including its mysterious bright spots, craters, and smooth features. The mission will last through June 2016.
Here is a map of the surface of the planet, where you can see its different features:
The smooth features on Ceres, including shallow craters that likely eroded over time, make scientists like Carol Raymond, the Dawn deputy principal investigator at JPL, suspect that Ceres once had a vast ocean beneath its surface. Since Ceres has, at best, a very thin atmosphere, the way these craters likely eroded was by underground water movement stretching and, therefore, flattening them over time.
“It retained a lot of water when it was formed,” Raymond said during the press conference. In this sense, it’s a lot like the icy moons in the outer solar system, like Saturn’s moon Eneceldus and Jupiter’s moon Europa — some of the most likely places in the solar system where life could exist.
It’s not likely that Ceres still harbours liquid water today, Raymond said, but Dawn will ultimately determine that over the months following its orbit. It will search for any evidence of cracks in the surface where plumes might be gushing water vapor into space.
Here’s the latest GIF of the dwarf planet, compiled from recent images taken by the camera aboard Dawn:
Whether it finds evidence of liquid water, or not, Dawn will still undoubtedly find important information about the early solar system during its time with Ceres, Raymond said.
“One of the prime motivations of the dawn mission is to examine these building blocks of the planets… formed at the very dawn of the solar system,” she said.
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