GRACE mission: map the moons gravity

The Gravity Recovery and Interior Laboratory (GRAIL) mission will be led by MIT professor Maria Zuber and NASA's Jet Propulsion Laboratory, will be launched in 2011. It will put two separate satellites into orbit around the moon to precisely map variations in the moon's gravitational pull. These changes will reveal differences in density of the moon's crust and mantle, and can be used to answer fundamental questions about the moon's internal structure and its history of collisions with asteroids.

The detailed information about lunar gravity will also significantly facilitate any future manned or unmanned missions to land on the moon. Such data will be used to program the descent to the surface to avoid a crash landing and will also help target desirable landing sites. Moreover, the mission's novel technology could eventually be used to explore other interesting worlds such as Mars.

Former astronaut Sally Ride, the first U.S. woman in space, will lead the project's educational outreach phase, which will include five live MoonKam cameras on each satellite that will be targeted by young students--especially middle-school girls--in their classrooms to get close-up still and video views of the moon's surface.
The mission will help the scientific community to answer fundamental questions as
# Whether or not the moon has a separate, differentiated core, as Earth does.
# Lunar history, including the relative timing and effects of the myriads of huge impacts that created the craters and basins

The technology used in the mission is a direct spinoff from the Gravity Recovery and Climate Experiment (GRACE) mission, which has been mapping Earth's gravitational field since 2002. . With GRACE, scientists of GFZ Potsdam (Germany’s National Lab for Geosciences, member of the Helmholtz Association) have been able to determine globally the water balance of the continents in seasonal change from satellites.

Using that technology made this a "low risk" mission for NASA because the necessary instruments had already been developed and tested. The measurements of the moons gravitational field will come from very precise monitoring of changes in the distance between the two satellites that will be a part of the GRAIL mission. The resulting measurements will map the moon's gravitational field up to 1,000 times more accurately than any previous mapping.

The main difference in this project from GRACE is the new technology needed to make GRAIL possible was a way to calibrate the timing of the satellites accurately. The Earth-orbiting GRACE satellites use the GPS satellite navigation system. As there is no such system for moon, a new technique has been adapted which involves precise monitoring of radio signals. Zuber says. "We could learn amazing things" from such follow-up missions, she says. "Since we solved the GPS problem for the moon, we could propose this with little modification for other planets."

The GRAIL satellites will be built and operated by Lockheed Martin Space Systems of Denver, Colo. NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., will handle project management and development of the communications and navigation systems.

At a different event held as a part of the "Fall Meeting of the AGU (American Geophysical Union)" in San Francisco the German-American GRACE-Team was presented with the William T. Pecora Award. This prize is awarded for extraordinary achievement in better understanding our planet with the aid of remote sensing. It is dedicated in commemoration of the former Director of the U.S. Geological Survey, William T. Pecora.

"This award for the GRACE team demonstrates that with innovative satellite missions such as the GRACE satellite tandem, new insights into the System Earth become available to science. And especially in view of the current discussion on the climate change such data provide us with a reliable data base" specifies Professor Dr. Reinhard Hüttl, Scientific Executive Director of the GFZ Potsdam with respect to this award. "I congratulate the GRACE-Team on this well-deserved award."

Source : http://web.mit.edu ,www.eurekalert.org