Archive for December 6th, 2011


Another new planet…here in our solar system.

December 6, 2011

Vesta - asteroid, or baby planet?

Maybe we aren’t traveling to these places in person – not yet, anyway – but the robot explorers are doing incredible stuff. Nobody expected the second-largest asteroid in the Belt to look like these images. What caused these parallel grooves?


The NASA Dawn spacecraft, powered by an ion drive like something out of science fiction, is orbiting Vesta and has taken 500 photos so far. The asteroid/planetoid is about 330 miles in diameter. It’s currently 117 million miles from Earth, and Dawn is about 1700 miles away, moving in until it will come as close as 100 miles from the surface. After a year studying Vesta, Dawn moves on to Ceres, the “big enchilada” of the Belt. It should arrive there in 2015.

Dawn spacecraft

With a low-thrust but long-duration ion engine and hardware validated on other spacecraft and satellites, the craft cost about $ 350 million not including the launch vehicle. The ion engine uses electricity from the solar panels to accelerate ionized xenon gas to very high speeds. The spacecraft has less than a thousand pounds of xenon fuel to take it from Earth, past Mars, to Vesta, and onward to Ceres over a period of nine years.

In 2009 Dawn did a close pass of Mars to use the planet as a gravity assist. Without it the spacecraft couldn’t go to both Vesta and Ceres for lack of fuel.

Callibration image of Mars made by Dawn on its closest approach in 2009

It may not be planet-sized, but it’s pretty big. Asteroids may be the space outposts of the future. Using one reduces the amount of structure, and perhaps water and fuel, to be hauled up from Earth.The main Dawn JPL/NASA page.