“So long, Ebb and Flow, and we thank you,” said GRAIL project manager David Lehman of NASA’s Jet Propulsion Laboratory after the twin GRAIL spacecraft completed a planned formation-flying double impact into the southern face of 2.5-kilometer- (1.5-mile-) tall mountain on a crater rim near the Moon’s north pole.
Mission team members estimate the two spacecraft were traveling at a speed of 1.7 kilometers per second (3,760 mph), and likely broke apart on impact. NASA said that most of what remains of the washing machine-sized spacecraft are probably buried in shallow craters, and the size of those craters will hopefully be determined when NASA’s Lunar Reconnaissance Orbiter is able to image the impact site in about two weeks.
Launched in September 2011, Ebb and Flow had been orbiting the moon since Jan. 1, 2012. The probes were intentionally crashed into the lunar surface because they did not have sufficient altitude or fuel to continue science operations.
Fourth grade students at Emily Dickinson Elementary School in Bozeman, Montana suggested names Ebb and Flow for the twin orbiters winning out over nearly 900 classrooms from 45 states, Puerto Rico and the District of Columbia that participated in a contest to name the spacecraft.
NASA has honored the GRAIL team’s request to name Ebb and Flow’s impact sites after astronaut Sally Ride, who passed away earlier this year. She was America’s first woman in space and a member of the GRAIL mission team.
GRAIL was NASA’s first planetary mission to carry cameras fully dedicated to education and public outreach. Ride, who died in July, led GRAIL’s MoonKAM (Moon Knowledge Acquired by Middle School Students) Program through her company, Sally Ride Science. The camera took more than 115,000 total images of the lunar surface, and imaging targets were proposed by middle school students from across the country and the resulting images returned for them to study.
“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 Zuber. “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 two spacecraft impacted on the lunar surface at 2:28:51 p.m. PST) and 2:29:21 p.m. PST. NASA’s Lunar Reconnaissance Orbiter will start imaging the impact sites in the next couple of weeks.
The GRAIL mission generated the highest-resolution gravity field map of any celestial body — including Earth — and determined the inner crust of the Moon is nearly pulverized.
“Ebb and Flow have removed a veil from the Moon,” said GRAIL principal investigator Maria Zuber during a televised commentary of the impacts today, adding that the mission will enable discoveries for years to come.
– Ex astris, scientia –
I am and avid amateur astronomer and intellectual property attorney. As a former Chief Petty Officer in the U.S. Navy, I am a proud member of the Armed Service Committee of the Los Angeles County Bar Association working to aid all active duty and veterans in our communities. Connect with me on Google +