NASA Moon Mission in Final Preparations for September Launch

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DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

Dwayne Brown 202-358-1726
Headquarters, Washington
dwayne.c.brown@nasa.gov

Caroline McCall 617-253-1682
Massachusetts Institute of Technology, Cambridge
cmcall5@mit.edu

News release: 2011-265 August 25, 2011

NASA Moon Mission in Final Preparations for September Launch

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-265&cid=release_2011-265

CAPE CANAVERAL, Fla. -- NASA's Gravity Recovery And Interior Laboratory (GRAIL) mission
to study the moon is in final launch preparations for a scheduled Sept. 8 launch from Cape Canaveral
Air Force Station in Florida.

GRAIL's twin spacecraft are tasked for a nine-month mission to explore Earth's nearest neighbor in
unprecedented detail. They will determine the structure of the lunar interior from crust to core and
advance our understanding of the thermal evolution of the moon.

"Yesterday's final encapsulation of the spacecraft is an important mission milestone," said David
Lehman, GRAIL project manager for NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Our
two spacecraft are now sitting comfortably inside the payload fairing which will protect them during
ascent. Next time the GRAIL twins will see the light of day, they will be about 95 miles up and
accelerating."

The spacecraft twins, GRAIL-A and GRAIL-B, will fly aboard a Delta II rocket launched from
Florida. The twins' circuitous route to lunar orbit will take 3.5 months and cover approximately 2.6
million miles (4.2 million kilometers) for GRAIL-A, and 2.7 million miles (4.3 million kilometers)
for GRAIL-B.

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," said Maria Zuber, GRAIL principal investigator from the Massachusetts
Institute of Technology in Cambridge.

GRAIL's launch period opens Sept. 8 and extends through Oct. 19. On each day, there are two
separate launch opportunities separated by approximately 39 minutes. On Sept. 8, the first launch
opportunity is 8:37 a.m. EDT (5:37 a.m. PDT); the second is 9:16 a.m. EDT (6:16 a.m. PDT).

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the GRAIL mission. The
Massachusetts Institute of Technology, Cambridge, is home to the mission's principal investigator,
Maria Zuber. The GRAIL mission is part of the Discovery Program managed at NASA's Marshall
Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft.
Launch management for the mission is the responsibility of NASA's Launch Services Program at the
Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in
Pasadena.

For extensive pre-launch and launch day coverage of the GRAIL spacecraft, visit:
http://www.nasa.gov .

A prelaunch webcast for the mission will be streamed at noon on Wednesday, Sept. 7. Live
countdown coverage through NASA's Launch Blog begins at 6:30 a.m. EDT (3:30 am PDT) on Sept.
8. Coverage features live updates as countdown milestones occur and streaming video clips
highlighting launch preparations and liftoff.

To view the webcast and the blog or to learn more about the GRAIL mission, visit:
http://www.nasa.gov/grail and http://grail.nasa.gov .

The launch will also be streamed live, with a chat available, on http://www.ustream.tv/nasajpl2 .

To view live interviews with lunar scientists from noon to 5 p.m. EDT (2 p.m. PDT) on Sept. 8 and 9,
visit: http://www.livestream.com/grail .

-end-

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