● GRAIL · GRAVITY RECOVERY & INTERIOR LABORATORY
NASA DISCOVERY PROGRAM · 2011–2012
Weighing the Moon · NASA GRAIL

The Moon, measured

Two spacecraft. One micrometer of difference. The most detailed gravity map of another world ever made, on a globe you can spin.
GRAIL gravity map of the Moon
Loading GRAIL gravity data…
What a spacecraft actually feels, dominated by the terrain it is flying over.
Mass excess Basin Gravity low Crater Landmark
Red is a mass excess, blue a mass deficit.
NASA / JPL-Caltech / MIT / GSFC via Goddard SVS · Full credits
Start here

Pick a path

New here? Choose where to start. You can always come back to this page.

MoonKAM image of the lunar far side with Earth beyond
The photos

The recovered archive

18 lost frames became about 5,100. Fly the cameras the way the students did, and browse the images that were missing for 14 years.

See the photos
A MoonKAM image of the lunar surface
The story

Voices from MoonKAM

The kids who named the spacecraft, the teachers who ran the cameras, and Sally Ride, in their own words.

Read the story
A MoonKAM classroom infographic
For teachers

The classroom kit

The Moon lessons the program handed to classrooms, with the original activity guides, preserved and linked.

Open the kit
Artist rendering of the twin GRAIL spacecraft
The mission

The full mission

Launch, twin-spacecraft ranging, the discoveries, and a deliberate crash named for Sally Ride. The story and the numbers.

Read the mission