[meteorite-list] NASA's Twin Grail Spacecraft Begin Collecting Lunar Science Data

[Ron Baalke]

March 7, 2012

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: 12-070

NASA'S TWIN GRAIL SPACECRAFT BEGIN COLLECTING LUNAR SCIENCE DATA

WASHINGTON -- NASA's Gravity Recovery And Interior Laboratory (GRAIL) 
spacecraft orbiting the moon officially have begun their science 
collection phase. During the next 84 days, scientists will obtain a 
high-resolution map of the lunar gravitational field to learn about 
the moon's internal structure and composition in unprecedented 
detail. The data also will provide a better understanding of how 
Earth and other rocky planets in the solar system formed and evolved. 

"The initiation of science data collection is a time when the team 
lets out a collective sigh of relief because we are finally doing 
what we came to do," said Maria Zuber, principal investigator for the 
GRAIL mission at the Massachusetts Institute of Technology in 
Cambridge. "But it is also a time where we have to put the coffee pot 
on, roll up our sleeves and get to work." 

The GRAIL mission's twin, washing-machine-sized spacecraft, named Ebb 
and Flow, entered lunar orbit on New Year's Eve and New Years Day. 
GRAIL's science phase began yesterday at 8:15 p.m. EST (5:15 p.m. 
PST). During this mission phase, the 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, craters and masses hidden beneath the lunar 
surface, the distance between the two spacecraft will change 
slightly. Science activities are expected to conclude on May 29, 
after GRAIL maps the gravity field of the moon three times. 

"We are in a near-polar, near-circular orbit with an average altitude 
of about 34 miles (55 kilometers) right now," said David Lehman, 
GRAIL project manager from NASA's Jet Propulsion Laboratory (JPL) in 
Pasadena, Calif. "During the science phase, our spacecraft will orbit 
the moon as high as 31 miles (51 kilometers) and as low as 10 miles 
(16 kilometers). They will get as close to each other as 40 miles (65 
kilometers) and as far apart as 140 miles (225 kilometers)." 

Previously named GRAIL A and B, the names Ebb and Flow were the result 
of a nation-wide student contest to choose new names for the 
spacecraft. The winning entry was submitted by fourth graders from 
the Emily Dickinson Elementary School in Bozeman, Mont. Nearly 900 
classrooms with more than 11,000 students from 45 states, Puerto Rico 
and the District of Columbia, participated in the contest. 

JPL manages the GRAIL mission for NASA's Science Mission Directorate 
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 

-end-