Moon bang: NASA confirms twin satellite smash

Dec 18, 2012
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NASA has successfully smashed two satellites into the dark side of the moon, the space agency has confirmed, naming the new crater after Sally Ride, the first American woman in low Earth orbit. The mission, to crash the spent GRAIL spacecraft and glean some valuable internal structure and composition data about the moon from their demise, culminated in impact at 5:28pm EST and 5:29pm, at a speed of 3,760 mph, though the scale of the crater they created won't be known until the Lunar Reconnaissance Orbiter catches sight of it in a few weeks time.

The Gravity Recovery and Interior Laboratory (GRAIL) mission saw two satellites, Ebb and Flow, orbit the moon for nearly a year, snapping more than 115,000 images of the moon's surface. NASA has said the results of GRAIL is the highest-resolution gravity field map of any celestial body; "the scientists tell me it will take years to analyze all the great data they got," project manager David Lehman said in a statement, "and that is why we came to the moon in the first place."

However, neither satellite was equipped with sufficient fuel to continue with the scientific mission, and Ebb and Flow's orbits were decreasing past the point of usefulness. The decision was made to crash both into a specific point on the lunar surface, with the destruction opening up new opportunities for investigating what makes up the crust of the moon.

Even the final fuel burn - intended to deplete the GRAIL satellite's onboard stores to the bare minimum for the crash - will contribute to NASA's future missions. The length of time it took for the engines to drain supplies to that minimum will be used to check NASA computer simulations of fuel tank modeling. In the end, Ebb required a 4 minute 3 second burn, while Flow took longer at 5 minutes 7 seconds.

The subsequent crash took place on the southern face of a 1.5 mile tall mountain; the Jet Propulsion Lab team responsible for the GRAIL project estimates that most of the debris will have been buried in shallow craters around the area. Since the site is in the dark side of the moon, no photos or video showing it taking place has been captured. Instead, NASA will wait until the Lunar Reconnaissance Orbiter is nearby to snap some shots from orbit.

NASA's decision to name the new crater after astronaut Sally Ride follows her death in July this year. Ride was member of the GRAIL mission team, and was the first American woman in space back in 1983. After her time with NASA, Ride established Sally Ride Science, an organization dedicated to promoting science learning among girls, as well as writing a number of science-themed children's books with partner Tam O'Shaughnessy.


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