Grail Mission: Twin Satellites to Make Revolutionary Study of the Moon

It has played a significant part in our planets history, but our moon has been ultimately unexplored, except for a few locations where humanity has left their footprints. So an MIT study costing $375 million will attempt to rectify that matter, by conducted a study using a pair of satellites.

The Gravity Recovery and Interior Laboratory (GRAIL) mission is to be led by MIT professor Maria Zuber, and launched in 2011. Two separate satellites will be launched in to space, to orbit the moon. Their mission will be to precisely map the variations in the moons gravitational pull.

"After the three-month mission is completed, we will know the lunar gravitational field better than we know Earth's," says Zuber, who is head of MIT's Department of Earth, Atmospheric and Planetary Sciences and the E.A. Griswold Professor of Geophysics. She will be the principal investigator for the GRAIL mission.

Fundamental questions as whether or not the moon has a separate, differentiated core, as Earth does, are unknown, Zuber says. In addition to answering that question, the new mission should reveal details about lunar history, including the relative timing and effects of the myriads of huge impacts that created the craters and basins seen on the surface today. The moon, with its airless, un-eroded surface, serves as a kind of Rosetta Stone for understanding the history of all the solar system's inner planets--Mercury, Venus, Earth and Mars--so the mission should also help to unlock secrets of the evolution of all these planets.

"The moon has the best-preserved record of the solar system's early history," Zuber says, while on other planets much of that record has been lost through erosion and other surface changes.

In addition, the gravitational studies will also provide future moon-landings with better information, helping to control decent and target desirable landing sites.

The technology to be used in the twin satellites is a direct spinoff from the highly successful Gravity Recovery and Climate Experiment (GRACE) which has been mapping Earth’s own gravitational field since 2002. This made the GRAIL mission a no-brainer for NASA, as there was “no risk” in already tested and proven systems.

However, in designing this new system there was one technological hill to climb. The GRACE satellites use the Global Positioning System to direct the movement of the satellites; for our moon, there is obviously no such help. Thus, the MIT team had to design a system that used radio frequencies to bypass such a problem.

This same technology subsequently allows this type of mission to be carried out on other planets obviously lacking a comprehensive GPS system. "We could learn amazing things" from such follow-up missions, Zuber says. "Since we solved the GPS problem for the moon, we could propose this with little modification for other planets."

This could be a big step forward in the study of Mars, our closest interstellar neighbor and the one we have focused much of our attention of late. Zuber believes that the GRAIL system could be used to reveal the exchange of carbon dioxide between the polar caps and atmosphere or the movement of flowing subsurface water.

Operated by Lockheed Martin Space Systems of Denver, Colorado, the GRAIL satellites will be handled from the NASA Jet Propulsion Laboratory in Pasadena, Calif., who is in line to design the communications and navigation systems.

Posted by Josh Hill.