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| [Image credit: NASA/JPL-Caltech/GSFC/ASU /Sally Ride Science] |
Pasadena, California: NASA has named the site where twin agency spacecraft
impacted the moon Monday in honor of the late astronaut, Sally K. Ride, who was
America's first woman in space and a member of the probes' mission team.
Last Friday, Ebb and
Flow, the two spacecraft comprising NASA's Gravity Recovery and Interior
Laboratory (GRAIL) mission, were commanded to descend into a lower orbit that
would result in an impact Monday on a mountain near the moon's north pole. The
formation-flying duo hit the lunar surface as planned at 2:28:51 p.m. PST
(5:28:51 p.m. EST) and 2:29:21 p.m. PST (5:29:21 p.m. EST) at a speed of 3,760
mph (1.7 kilometers per second). The location of the Sally K. Ride Impact Site
is on the southern face of an approximately 1.5 mile- (2.5 -kilometer) tall
mountain near a crater named Goldschmidt.
"Sally was all
about getting the job done, whether it be in exploring space, inspiring the
next generation, or helping make the GRAIL mission the resounding success it is
today," said GRAIL principal investigator Maria Zuber of the Massachusetts
Institute of Technology in Cambridge. "As we complete our lunar mission,
we are proud we can honor Sally Ride's contributions by naming this corner of
the moon after her."
The impact marked a
successful end to the GRAIL mission, which was NASA's first planetary mission
to carry cameras fully dedicated to education and public outreach. Ride, who
died in July after a 17-month battle with pancreatic cancer, led GRAIL's
MoonKAM (Moon Knowledge Acquired by Middle School Students) Program through her
company, Sally Ride Science, in San Diego.
Along with its
primary science instrument, each spacecraft carried a MoonKAM camera that took
more than 115,000 total images of the lunar surface. Imaging targets were
proposed by middle school students from across the country and the resulting
images returned for them to study. The names of the spacecraft were selected by
Ride and the mission team from student submissions in a nationwide contest.
"Sally Ride worked
tirelessly throughout her life to remind all of us, especially girls, to keep
questioning and learning," said Sen. Barbara Mikulski of Maryland.
"Today her passion for making students part of NASA's science is honored
by naming the impact site for her."
Fifty minutes prior
to impact, the spacecraft fired their engines until the propellant was
depleted. The maneuver was designed to determine precisely the amount of fuel
remaining in the tanks. This will help NASA engineers validate computer models
to improve predictions of fuel needs for future missions.
"Ebb fired its
engines for 4 minutes, 3 seconds and Flow fired its for 5 minutes, 7
seconds," said GRAIL project manager David Lehman of NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, Calif. "It was one final important set of
data from a mission that was filled with great science and engineering
data."
The mission team
deduced that much of the material aboard each spacecraft was broken up in the
energy released during the impacts. Most of what remained probably is buried in
shallow craters. The craters' size may be determined when NASA's Lunar
Reconnaissance Orbiter returns images of the area in several weeks.
Launched in September
2011, Ebb and Flow had been orbiting the moon since Jan. 1, 2012. The probes
intentionally were sent into the lunar surface because they did not have
sufficient altitude or fuel to continue science operations. Their 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.
"We will miss
our lunar twins, but the scientists tell me it will take years to analyze all
the great data they got, and that is why we came to the moon in the first
place," Lehman said. "So long, Ebb and Flow, and we thank you."