As if
scanning the moon's surface for impact blemishes were not enough, NASA
now plans to visualize its internal imperfections to solve longstanding mysteries about the moon's insides.
NASA said
this week that it selected the Gravity Recovery and Interior Laboratory (GRAIL)
mission from two dozen proposals. GRAIL's twin spacecraft are slated to launch
around Sept. 6, 2011 and, after a few weeks of settling into orbit, map the
lunar gravity field for 90 days.
Scientists
hope to use the data to pick apart its insides from crust to core, much like a medical X-ray that shows the insides of a person.
"We're
looking forward to the data," Michael New, GRAIL's lead project scientist,
told SPACE.com. "It's really going to open up new understanding
of the particular history and internal structure of the moon."
Crust to
core
NASA
previously launched a mission to map Earth's gravitational fields, called
GRACE—the Gravity Recovery and Climate Experiment. Over the years, it measured minute
differences in gravitational pull at different points around our planet,
revealing glacial melt, migrating magma and tectonic plate movement, among other
curiosities.
Similarly,
GRAIL will measure gravity at different points around the moon, which should
reveal any gravity differences as slight as 1 million times weaker than the
Earth's overall gravity.
New said
the data will be about 1,000 times better than any other measurements of lunar
gravity, explaining that such data can be processed to peer beneath the moon's
surface and locate any significant structures related to early lunar history.
"We're
talking about things like relaxation of lunar crust to ... a big lava flow,"
New said. "The other thing that may become a little clearer will be a
little bound on the size of any lunar
core, if there is one."
Besting
the competition
GRAIL beat out
23 elaborate competitors in NASA's Discovery mission selection process, and
will cost at least $375 million for the whole package—design, launch and
staffing included.
"GRAIL
also offers to bring innovative Earth studies techniques to the moon as a precursor
to their possible later use at Mars and other planets," said Alan Stern,
NASA's associate administrator for science, at this week's American Geophysical
Union's 2007 meeting.
New said
the money is set aside in NASA's budget, which means intricate engineering of
GRAIL's twin spacecraft can begin.
"The
money's there," he said. "Unless something really horrific
happens—like another Katrina—we have money in our budget to support mission all
the way out."
The Lunar
Reconnaissance Orbiter (LRO), set to launch in 2008, will
precede GRAIL's spaceshot. LRO will scan the moon's pockmarked surface for
future robotic and human landing sites and will be accompanied by another
spacecraft, called the Lunar Crater Observation and Sensing Satellite (LCROSS)
mission—which will impact the lunar south pole to search for polar water.
"As
NASA moves forward with exploration endeavors, our lunar science missions will
be the light buoy leading the path for future human
activities," said Jim Green, NASA's planetary division
director in Washington, D.C.
Lockheed
Martin Space Systems in Denver will build GRAIL and NASA's Jet Propulsion
Laboratory in Pasadena, Calif., will manage GRAIL's mission.
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