This animation shows the final flight path
for NASA’s twin Gravity Recovery and Interior Laboratory (GRAIL)
mission spacecraft, which will impact the moon on Dec. 17, 2012, around
2:28 p.m. PST.
Download Image
GRAIL's Final Resting Spot
These maps of Earth's moon highlight the region where the twin spacecraft of NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission will impact on Dec. 17, marking the end of its successful endeavor to map the moon's gravity. The two washing-machine-sized spacecraft, named Ebb and Flow, will impact at an unnamed mountain near the moon's North Pole.These maps are from NASA's Lunar Reconnaissance Orbiter.
Image credit: NASA/GSFC
Lunar Heritage Sites and GRAIL's Final Mile
This graphic highlights locations on the moon NASA considers "lunar heritage sites" and the path NASA's Gravity Recovery and Interior Laboratory spacecraft will take on their final flight. Navigators on the GRAIL team have designed an end of mission plan that rules out the extremely remote possibility of either of the two GRAIL spacecraft impacting near any of these historic locations. The Apollo 11, 12, 14, 16 and 17 landing sites are indicated with green circles. The Surveyor sites are indicated with yellow squares. The Soviet Union's Luna and Lunakhod landing sites are indicated with red diamonds and red squares, respectively.The ground track for the Ebb and Flow spacecraft during their final half-orbits is shown in black. The maps are color-coded by topography. Red and white indicate the high areas. Blue and violet indicate low areas.
Image credit: NASA/JPL-Caltech
Ebb and Flow's Final Moments
These side-by-side, 3-D comparisons depict the unnamed lunar mountain targeted by the NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission for controlled impact of They also include the ground tracks the spacecraft are expected to follow into the lunar terrain. These graphics were generated using data from the Lunar Orbiter Laser Altimeter instrument aboard NASA's Lunar Reconnaissance Orbiter spacecraft.On the left is the mountain with the ground track and mission termination point for the Ebb spacecraft. On the right is the mountain, ground track and mission termination point for the Flow spacecraft.
Image credit: NASA/JPL-Caltech/MIT/GSFC
PASADENA, Calif. -- Twin lunar-orbiting NASA spacecraft that have
allowed scientists to learn more about the internal structure and
composition of the moon are being prepared for their controlled descent
and impact on a mountain near the moon's north pole at about 2:28 p.m.
PST (5:28 p.m. EST) Monday, Dec. 17.
Ebb and Flow, the Gravity Recovery and Interior Laboratory (GRAIL)
mission probes, are being sent purposely into the lunar surface because
their low orbit and low fuel levels preclude further scientific
operations. The duo's successful prime and extended science missions
generated the highest-resolution gravity field map of any celestial
body. The map will provide a better understanding of how Earth and other
rocky planets in the solar system formed and evolved.
"It is going to be difficult to say goodbye," said GRAIL principal
investigator Maria Zuber of the Massachusetts Institute of Technology in
Cambridge. "Our little robotic twins have been exemplary members of the
GRAIL family, and planetary science has advanced in a major way because
of their contributions."
The mountain where the two spacecraft will make contact is located near a
crater named Goldschmidt. Both spacecraft have been flying in formation
around the moon since Jan. 1, 2012. They were named by elementary
school students in Bozeman, Mont., who won a contest. The first probe to
reach the moon, Ebb, also will be the first to go down, at 2:28:40 p.m.
PST. Flow will follow Ebb about 20 seconds later.
Both spacecraft will hit the surface at 3,760 mph (1.7 kilometers per
second). No imagery of the impact is expected because the region will be
in shadow at the time.
Ebb and Flow will conduct one final experiment before their mission
ends. They will fire their main engines until their propellant tanks are
empty to determine precisely the amount of fuel remaining in their
tanks. This will help NASA engineers validate fuel consumption computer
models to improve predictions of fuel needs for future missions.
"Our lunar twins may be in the twilight of their operational lives, but
one thing is for sure, they are going down swinging," said GRAIL project
manager David Lehman of NASA's Jet Propulsion Laboratory in Pasadena,
Calif. "Even during the last half of their last orbit, we are going to
do an engineering experiment that could help future missions operate
more efficiently."
Because the exact amount of fuel remaining aboard each spacecraft is
unknown, mission navigators and engineers designed the depletion burn to
allow the probes to descend gradually for several hours and skim the
surface of the moon until the elevated terrain of the target mountain
gets in their way.
The burn that will change the spacecrafts' orbit and ensure the impact is scheduled to take place Friday morning, Dec. 14.
"Such a unique end-of-mission scenario requires extensive and detailed
mission planning and navigation," said Lehman. "We've had our share of
challenges during this mission and always come through in flying colors,
but nobody I know around here has ever flown into a moon mountain
before. It'll be a first for us, that's for sure."
During their prime mission, from March through May, Ebb and Flow
collected data while orbiting at an average altitude of 34 miles (55
kilometers). Their altitude was lowered to 14 miles (23 kilometers) for
their extended mission, which began Aug. 30 and sometimes placed them
within a few miles of the moon's tallest surface features.
JPL manages the GRAIL mission for NASA's Science Mission Directorate in
Washington. The 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
California Institute of Technology in Pasadena.
For more information about GRAIL, visit: http://www.nasa.gov/grail .
DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
Dwayne.c.brown@nasa.gov
Sarah McDonnell 617-253-8923
Massachusetts Institute of Technology, Cambridge
s_mcd@mit.edu
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
Dwayne.c.brown@nasa.gov
Sarah McDonnell 617-253-8923
Massachusetts Institute of Technology, Cambridge
s_mcd@mit.edu
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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