GRAIL Free-Air Gravity Map for the Cover of Science
- Visualizations by:
- Ernie Wright
- View full credits
If the Moon were a perfectly smooth sphere of uniform density, the gravity map would be a single, featureless color, indicating that the force of gravity at a given elevation was the same everywhere. But like other rocky bodies in the solar system, including Earth, the Moon has both a bumpy surface and a lumpy interior. Spacecraft in orbit around the Moon experience slight variations in gravity caused by both of these irregularities.
The free-air gravity map shows deviations from the mean, the gravity that a cueball Moon would have. The deviations are measured in milliGals, a unit of acceleration. On the map, dark purple is at the low end of the range, at around -400 mGals, and red is at the high end near +400 mGals. Yellow denotes the mean.
These views show a part of the Moon's surface that's never visible from Earth. They are centered on lunar coordinates 29°N 142°E. The large, multi-ringed impact feature near the center is Mare Moscoviense. The crater Mendeleev is south of this. The digital elevation model for the terrain is from the Lunar Reconnaissance Orbiter laser altimeter (LOLA). Merely for plausibility, the sun angle and starry background are accurate for specific dates (December 21, 2012, 0:00 UT and January 8, 2013, 14:00 UT, respectively).

The GRAIL free-air gravity map of the Moon, rendered on the Moon's surface as it floats in front of a starry backdrop (the constellation Hydra). About 75% of the visible disk is illuminated from the left, lighting longitudes roughly between 75° and 180° east. The view is centered on Mare Moscoviense, a feature on the far side.

The GRAIL free-air gravity map of the Moon, rendered on the Moon's surface as it floats in front of a starry backdrop (the constellation Cetus). About 60% of the visible disk is illuminated from the right, lighting longitudes roughly between 130°E and 130°W. The view is centered on Mare Moscoviense, a feature on the far side.

The GRAIL free-air gravity map of the Moon, rendered on the Moon's surface, with no background (the image includes an alpha channel). About 75% of the visible disk is illuminated from the left, lighting longitudes roughly between 75° and 180° east. The view is centered on Mare Moscoviense, a feature on the far side.

The GRAIL free-air gravity map of the Moon, rendered on the Moon's surface, with no background (the image includes an alpha channel). About 60% of the visible disk is illuminated from the right, lighting longitudes roughly between 130°E and 130°W. The view is centered on Mare Moscoviense, a feature on the far side.
Credits
Please give credit for this item to:
NASA's Goddard Space Flight Center Scientific Visualization Studio
Animator
- Ernie Wright (USRA) [Lead]
Scientists
- David E. Smith (NASA/GSFC)
- Erwan M. Mazarico (NASA/GSFC)
- Gregory A. Neumann (NASA/GSFC)
- Maria Zuber (Massachusetts Institute of Technology)
Papers
This visualization is based on the following papers:Missions
This visualization is related to the following missions:Series
This visualization can be found in the following series:Datasets used in this visualization
U.S. Naval Observatory UCAC3 (A.K.A. Catalog) (Collected with the Third CCD Astrograph sensor)
GRAIL GRAIL Free-Air Gravity (A.K.A. Free-Air Gravity) (Collected with the Lunar Gravity Ranging System sensor)
Hipparcos Tycho Catalogue (A.K.A. Tycho 2 Catalogue) (Collected with the Telescope sensor)
Dataset can be found at: http://archive.eso.org/ASTROM/
See more visualizations using this data setBright Star Catalogue (A.K.A. Yale Bright Star Catalogue)
Dataset can be found at: http://tdc-www.harvard.edu/catalogs/bsc5.html
See more visualizations using this data setNote: While we identify the data sets used in these visualizations, we do not store any further details nor the data sets themselves on our site.