NASA honored late astronaut Sally Ride by lending her name to the mountainous area of the moon where two probes crash landed on Monday to complete their one-year gravity mapping mission.
Ride, who died of cancer this year, took a major role in the Gravity Recovery and Interior Laboratory mission by leading a classroom-oriented camera program on the two probes through her education company, Sally Ride Science.
Named Ebb and Flow, the GRAIL probes slammed into a massif - a mountainous section of planetary crust - near the moon's north pole at 2:28 and 2:29 p.m. Monday, traveling 3,760 mph, at what is now called the Sally K. Ride Impact Site.
"It's a living testimony that keep on giving," said Ride's sister, Bear, who was at Jet Propulsion Laboratory mission control for the crash countdown.
Jet Propulsion Laboratory tracked the probes until their final moments, but the impact wasn't visible from Earth because the area was in shadow at the time.
GRAIL principal investigator Maria Zuber said she hopes to eventually name the entire massif after Ride, although that process takes at least three years through the International Astronomical Union.
Ebb and Flow each had a MoonKAM, or Moon Knowledge Acquired by Middle School Students, that gave students the opportunity to take their own photos of the lunar surface. Students took about 115,000 photos that are available online.
"The vision that Sally had was that a student who took their own image of the moon would go to any length to try to understand what was on it," Zuber said.
GRAIL's primary mission was measuring the irregular gravity fields on the moon's surface, doing so by orbiting at about airplane altitude.
Ebb and Flow's first flybys were from an altitude of 55 kilometers. There was enough fuel left for a second tour, so JPL lowered the probes to an altitude of 23 kilometers, firing their engines about three times per week to maneuver around higher terrain.
With the fuel depleted and seeking a crash zone to keep the probes from becoming an orbital navigation hazard, the team picked out the Sally K. Ride Impact Site because it is far enough away from 23 historical sites on the moon where the U.S. and Russia landed, GRAIL project manager David Lehman said.
The initial results of GRAIL's gravity mapping, announced this month, showed that the moon's crust was thinner than previously thought, and gave clues about its bombardment by meteors early in its formation.
The findings could also pave the way for future lunar missions by providing accurate navigational data, within 50 meters of a landing site rather than several kilometers, Zuber said.
GRAIL's data showed the fractures and underground features of the moon, which can aid studies of Mars and other planets. Scientists are keeping a sharp eye out for empty lava tubes, where astronauts living on a moon base might be able to seek protection during a solar storm, Zuber said.