Bad Astronomy

GRAIL’s Stunning Parting Shots

One of the last images from the lunar GRAIL spacecraft.
One of the last images from NASA’s lunar GRAIL spacecraft, taken from a height of about 10 km. Note the edge of the Moon at the upper right.

Image credit: NASA/JPL-Caltech/MIT/SRS

At the very end of 2011, NASA put two space probes into lunar orbit. Together they were called GRAIL, for Gravity Recovery and Interior Laboratory. Individually named Ebb and Flow, they made very sensitive measurements of the Moon’s gravity, which was used to probe the interior composition and density of our nearest cosmic neighbor. To do this, they had to fly in formation very close to the lunar surface.

After the successful completion of both prime and extended missions, there wasn’t enough fuel left to raise their altitude to a safe, stable orbit. So, instead, the probes’ orbits were lowered to crash land them on the lunar surface. On Dec. 17, 2012, both spacecraft slammed into the northern regions of the Moon…and the folks at NASA JPL created this amazing movie comprised of images taken by Ebb on Dec. 14, just a few days before it and its partner met their dusty demise.

[You seriously want to make that hi-res and full screen.]

Note the animation is displayed at 6x normal speed. The spacecraft were over the far side of the Moon, near Jackson crater, and about 10 kilometers (six miles) above the surface when these shots were taken.

The impact site was eventually named after Sally Ride, the first American woman in space, and true pioneer. That was a nice touch by NASA.

Tip o’ the Cavorite sphere to my friend and NASA scientist Michelle Thaller on Facebook.