At approximately 2:28pm PST (5:28 p.m. EST) on Monday December 17th, after a fruitful year of scientific discovery, the NASA Gravity Recovery and Interior Laboratory (GRAIL) mission probes are going out with a bang. They will careen low over the surface of the moon, in a path set to carefully avoid historic sites, and crash into an unnamed mountain at 3800mph (6115kph.)
The two probes were named Ebb and Flow by contest-winning Bozeman Montana elementary school students. Ebb will hit the mountain first, followed about 20 seconds later by her washer/drier-sized twin Flow. The impact will be taking place on the dark side and impossible to spot from earth, but the aftermath will be spied-on by our Lunar Reconnaissance Orbiter some time afterward.
Scientists will be studying the mountains of data collected by Ebb and Flow long after their demise. By measuring and mapping gravity levels as an indication of mass density, mankind has discovered the moon has a thinner and more beaten-up than previously imagined. We have confirmed there is no evidence that our moon was once two separate moons that collided.
This will also mark the end of the MoonKam project, a student campaign that used the spacecraft’s cameras to image lunar targets of interest. The science education company that spearheaded the project was funded by Sally Ride, the first American woman in space, who died of pancreatic cancer just this July at age 61.
Even in the final seconds of their lives, these two brave probes will be conducting one final scientific experiment. Just like with a new car, we know the needle is on empty, but the exact point at which the tanks will run dry has only been estimated. Ebb and Flow will burn off all of their remaining fuel along the course toward their target mountain. From this experience NASA will be able to calibrate how much they need to fuel-up for future missions, since hauling extra fuel means extra weight, and therefore more fuel required to get into space in the first place.
NASA Ebb & Flow Moon Crash Planned for Monday [Animation]
Twin NASA Probes Set to Crash Into the Moon
After a trip to the moon, there’s nowhere to go but down.
Launched in September 2011, NASA’s twin moon probes, Ebb and Flow of the Gravity Recovery and Interior Laboratory, have been orbiting the moon. Flying in tandem with the trailing Flow measuring the moon’s gravitational tugs on the leading Ebb, the pair have resulted in the most accurate gravitational measurements in the solar system.
Alas, the two probes will end their mission Monday by auguring into the very ground they’ve been studying. Low on fuel and destined to be more man-made moon junk, the two crafts will be sent to the far side of the moon, where they will be intentionally crashed into a mountain in an act of self-disposal.
The choice of their final resting place was made carefully to avoid any chance of the twin crash landings wiping out historic lunar sites, like a moon buggy or an astronaut’s famous footsteps.