Three days before NASA’s moon-orbiting Ebb and Flow spacecraft were purposefully slammed into the side of a lunar mountain, ending the successful GRAIL mission to create a gravity map of the moon, mission controllers activated the camera aboard one of the craft to take some final photos from lunar orbit. One result was this breathtaking video, as Ebb and Flow made their final lunar orbits. The craft were only six miles (10 kilometers) above the lunar surface when this video was acquired on December 14, 2012.
The GRAIL mission’s MoonKAM (Moon Knowledge Acquired by Middle School Students) acquired the video footage. That project used the GRAIL mission to send back images of the moon to U.S. schools as part of an outreach project. The first clip in the video was taken by Ebb’s forward-facing camera and is made up of 931 individual frames. The second was taken from its rear camera and is comprised of 1498 frames.
GRAIL stands for Gravity Recovery and Interior Laboratory. The two craft launched in September 2011 and arrived in lunar orbit about three months later. The two probes flew in formation above the lunar surface, one following the other, mapping the moon’s gravity in unprecedented detail, until they were set on a course to collide with an unnamed moon mountain (between Philolaus and Mouchez at 75.62°N 26.63°W) on December 17.
At the end of GRAIL’s mission, the spacecraft was powered down and decommissioned over a five-day period. Ebb, the lead spacecraft in formation, impacted first. Flow impacted moments later. Each spacecraft was traveling at 3,760 miles per hour (6,050 kilometers/hour). NASA has announced that the crash site will be named after GRAIL collaborator and first American woman in space, Sally Ride.
You can see the object of GRAIL’s mission – a map showing the moon’s gravity – below. The map shows areas of concentrated mass including basin rings and volcanic structures. Because of the GRAIL spacecraft, we now know that the bulk density of the moon’s highland crust is much less than previously believed. As you look at this map, remember, it’s a map of the moon’s gravity. Looking at it is like seeing tiny variations in how strongly the moon can pull across its surface.
There have been more than 100 missions to the moon since the space age began. NASA says space scientists will be studying GRAIL’s gravity maps of the moon for decades to come.
Bottom line: Three days before the twin GRAIL spacecraft were crashed into the side of a lunar mountain, they acquired dramatic footage from only six miles (10 kilometers) above the moon. Watch it here.
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.