September 6, 2011
NASA To Launch GRAIL Moon Mission Thursday
NASA will usher in another Moon mission on Thursday when it launches twin probes to measure gravity on Earth's closest cosmic neighbor.
Near-identical twins GRAIL A and GRAIL B are set to launch on Thursday aboard a small Delta II rocket.
The two spacecraft will separate an hour after launch and will travel independently to the moon.
NASA said its robotic twins will travel over 2 million miles to get to the moon during the $496 million mission.
Grail-A is scheduled to arrive at the Moon on New Year's Eve, while Grail-B will arrive New Year's Day. Both the spacecraft will go into orbit around the lunar poles and eventually wind up circling just 34 miles above the surface.
The spacecraft will chase one another around the moon for nearly three months, about 40 miles to 140 miles apart.
In lunar orbit, the spacecraft will transmit radio signals precisely defining the distance between them. Regional gravitational differences on the moon are expected to expand and contract that distance. GRAIL scientists will use these accurate measurements to define the moon´s gravity field. The data will allow mission scientists to understand what goes on below the surface of our natural satellite.
“GRAIL will unlock lunar mysteries and help us understand how the moon, Earth and other rocky planets evolved as well,” Maria Zuber, GRAIL principal investigator from the Massachusetts Institute of Technology in Cambridge, said in a press release.
Image Caption: Artist´s interpretation of the GRAIL tandem spacecraft above the lunar surface. Credit: NASA
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