GRAIL Impacts the Moon

  • Released Monday, December 17, 2012
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The Gravity Recovery and Interior Laboratory (GRAIL) mission comprises a pair of satellites launched in September, 2011 and placed in orbit around the Moon in January, 2012. The two satellites, named Ebb and Flow, used radio signals to precisely measure their separation as they flew in formation, one following the other in the same nearly circular polar orbit. These measurements allowed mission scientists to build up an accurate and detailed gravity map of the Moon.

GRAIL ends its successful mission by impacting the Moon on December 17, 2012 at approximately 5:27 p.m. EST (22:27 UT). The two spacecraft were placed in an orbit that takes them within a kilometer of the surface, so low that they will hit the side of an unnamed mountain that lies between Mouchez and Philolaus craters, near the north pole at 75°45'N, 26°11'W. Ebb strikes first, followed 24 seconds later by Flow.

This animation shows the last three orbits of the two spacecraft, with views of the impact site. The impact occurs on the night side of a waxing crescent Moon, so the view shifts from a natural color Moon to a false-color elevation map.

One of GRAIL's last orbits across the night side of a waxing crescent Moon.

One of GRAIL's last orbits across the night side of a waxing crescent Moon.

On their penultimate orbit, Ebb and Flow just miss the mountain they will hit on their next pass.

On their penultimate orbit, Ebb and Flow just miss the mountain they will hit on their next pass.

A more distant view of the impact site, just seconds before the impact of Ebb.

A more distant view of the impact site, just seconds before the impact of Ebb.



Credits

Please give credit for this item to:
NASA's Goddard Space Flight Center Scientific Visualization Studio

Release date

This page was originally published on Monday, December 17, 2012.
This page was last updated on Tuesday, November 14, 2023 at 12:03 AM EST.


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