NASA's Twin Grail Spacecraft Reunite in Lunar Orbit

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
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http://www.jpl.nasa.gov

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: 2012-001 Jan. 1, 2012

NASA's Twin Grail Spacecraft Reunite in Lunar Orbit

The full version of this story with accompanying images is at:

http://www.jpl.nasa.gov/news/news.cfm?release=2012-001&cid=release_2012-001

NASA'S TWIN GRAIL SPACECRAFT REUNITE IN LUNAR ORBIT

PASADENA, Calif. -- The second of NASA's two Gravity Recovery And Interior Laboratory (GRAIL)
spacecraft has successfully completed its planned main engine burn and is now in lunar orbit. Working
together, GRAIL-A and GRAIL-B will study the moon as never before.

"NASA greets the new year with a new mission of exploration," said NASA Administrator Charles Bolden.
"The twin GRAIL spacecraft will vastly expand our knowledge of our moon and the evolution of our own
planet. We begin this year reminding people around the world that NASA does big, bold things in order to
reach for new heights and reveal the unknown."

GRAIL-B achieved lunar orbit at 2:43 p.m. PST (5:43 p.m. EST) today. GRAIL-A successfully completed
its burn yesterday at 2 p.m. PST (5 p.m. EST). The insertion maneuvers placed the spacecraft into a near-
polar, elliptical orbit with an orbital period of approximately 11.5 hours. Over the coming weeks, the GRAIL
team will execute a series of burns with each spacecraft to reduce their orbital period to just under two
hours. At the start of the science phase in March 2012, the two GRAILs will be in a near-polar, near-
circular orbit with an altitude of about 34 miles (55 kilometers).

During GRAIL's science mission, the two spacecraft will transmit radio signals precisely defining the distance
between them. As they fly over areas of greater and lesser gravity caused by visible features such as
mountains and craters, and masses hidden beneath the lunar surface, the distance between the two
spacecraft will change slightly.

Scientists will translate this information into a high-resolution map of the moon's gravitational field. The data
will allow scientists to understand what goes on below the lunar surface. This information will increase
knowledge of how Earth and its rocky neighbors in the inner solar system developed into the diverse worlds
we see today.

Each spacecraft carries a small camera called GRAIL MoonKAM (Moon Knowledge Acquired by Middle
school students) with the sole purpose of education and public outreach. The MoonKAM program is led by
Sally Ride, America's first woman in space, and her team at Sally Ride Science in collaboration with
undergraduate students at the University of California in San Diego.

GRAIL MoonKAM will engage middle schools across the country in the GRAIL mission and lunar
exploration. Thousands of fifth- to eighth-grade students will select target areas on the lunar surface and send
requests to the GRAIL MoonKAM Mission Operations Center in San Diego. Photos of the target areas will
be sent back by the GRAIL satellites for students to study.

A student contest that began in October 2011 also will choose new names for the spacecraft. The new
names are scheduled to be announced in January 2012. Ride and Maria Zuber, the mission's principal
investigator at the Massachusetts Institute of Technology in Cambridge, chaired the final round of judging.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the GRAIL mission for NASA's Science
Mission Directorate, Washington. The GRAIL mission is part of the Discovery Program managed at
NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built
the spacecraft. JPL is a division of the Çalifornia Institute of Technology in Pasadena.

For more information about GRAIL, visit:

http://www.nasa.gov/grail

Information about MoonKAM is available online at:

http://solarsystem.nasa.gov/grail/education.cfm

-end-

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