[meteorite-list] First Of NASA'S Two Grail Spacecraft Enters Orbit Around Moon

[Ron Baalke]

Dec. 31, 2011

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

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

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

RELEASE: 11-427

FIRST OF NASA'S TWO GRAIL SPACECRAFT ENTERS ORBIT AROUND MOON

PASADENA, Calif. -- The first of two NASA spacecraft to study the moon 
in unprecedented detail has entered lunar orbit. 

NASA's Gravity Recovery And Interior Laboratory (GRAIL)-A spacecraft 
successfully completed its planned main engine burn at 2 p.m. PST (5 
p.m. EST) today. As of 3 p.m. PST (6 p.m. EST), GRAIL-A is in a 
56-mile (90-kilometer) by 5,197-mile (8,363-kilometer) orbit around 
the moon that takes approximately 11.5 hours to complete. 

"My resolution for the new year is to unlock lunar mysteries and 
understand how the moon, Earth and other rocky planets evolved," said 
Maria Zuber, GRAIL principal investigator at the Massachusetts 
Institute of Technology in Cambridge. "Now, with GRAIL-A successfully 
placed in orbit around the moon, we are one step closer to achieving 
that goal." 

The next mission milestone occurs tomorrow when GRAIL-A's mirror twin, 
GRAIL-B, performs its own main engine burn to place it in lunar 
orbit. At 3 p.m. PST (6 p.m. EST) today, GRAIL-B was 30,018 miles 
(48,309 kilometers) from the moon and closing at a rate of 896 mph 
(1,442 kph). GRAIL-B's insertion burn is scheduled to begin tomorrow 
at 2:05 p.m. PST (5:05 p.m. EST) and will last about 39 minutes. 

"With GRAIL-A in lunar orbit we are halfway home," said David Lehman, 
GRAIL project manager at NASA's Jet Propulsion Laboratory (JPL) in 
Pasadena, Calif. "Tomorrow may be New Year's everywhere else, but 
it's another work day around the moon and here at JPL for the GRAIL 
team." 

Once both spacecraft are confirmed in orbit and operating, science 
work will begin in March. The spacecraft will transmit radio signals 
precisely defining the distance between them as they orbit the moon 
in formation. As they fly over areas of greater and lesser gravity 
caused by both 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. 

JPL manages the GRAIL mission for NASA's Science Mission Directorate 
at the agency's headquarters in 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. 

For more information about GRAIL, visit: 

http://www.nasa.gov/grail 
	
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