GRAIL Primary Mission Gravity Maps (AGU 2012)

This print-resolution still image was created for the cover of the October 28, 2016 issue of Science. It features a free-air gravity map of the Orientale impact basin based on data returned by the Gravity Recovery and Interior Laboratory (GRAIL) mission.Orientale is about 930 kilometers wide and lies on the western limb of the Moon as viewed from Earth. It s just after sunrise at Orientale, about a day past full Moon. The camera is on the western terminator (day/night line) looking north.The colorful part is the gravity anomaly based on measurements by GRAIL. Red indicates areas of higher gravity, or excess mass, and blue indicates lower gravity or areas of mass deficits. The GRAIL data reveals the structure of the basin beneath the surface. The red in the center of the basin, for example, shows that the crust is particularly thin there, and that denser mantle material is closer to the surface. The Orientale impact basin, combining shaded relief with free air gravity.

Goddard Mars Model (GMM) 3 is a global map of the gravity field of Mars. It was created by studying the flight paths of three Mars-orbiting spacecraft Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO).The travel time and Doppler shift of radio signals sent between the spacecraft and the Earth-based dish antennas of the Deep Space Network are used to measure the position and velocity of each spacecraft. Over time, small variations in these orbital parameters allow scientists to build up an accurate and detailed gravity map of the red planet.If Mars were a perfectly smooth sphere of uniform density, the gravity experienced by the spacecraft would be exactly the same everywhere. But like other rocky bodies in the solar system, including the Earth, Mars has both a bumpy surface and a lumpy interior. As the spacecraft fly in their orbits, they experience slight variations in gravity caused by both of these irregularities, variations which show up as small changes in the velocity and altitude of the three spacecraft.The free-air gravity map shows these variations directly. The map is color-coded to display the departure from the mean gravity of Mars, in milligals, a unit of acceleration. Purple and blue mark areas where the acceleration due to gravity is lower than average, while red and white show where it s higher.The Bouguer gravity map subtracts the effect of the bumpy surface to show the lumpiness underneath. The elevation maps from the laser altimeter on MGS were used to create a model of what the gravity would be if Mars were bumpy but not lumpy. This model was then subtracted from the free-air map to produce the Bouguer map.The crustal thickness map is inferred from the Bouguer map: If the density of the crust is assumed to be uniform, then the gravity anomalies visible in the Bouguer gravity map can be explained by variations in the thickness of the crust. Highs in gravity indicate places where the denser mantle is closer to the surface, and hence where the crust is thinner.The orbit analysis accounted for solar radiation pressure and for the mass and the drag of the thin Martian atmosphere. It also detected the seasonal variation in the amount of carbon dioxide locked up in the polar ice caps as they freeze and thaw.While aiding navigation for future Mars missions, GMM-3 reveals information about the internal structure of Mars that provides important clues to the geological history of the red planet.Learn more about the GMM-3 Mars gravity map.Correction: The surface of the natural-color globe was mapped incorrectly in the initial release of this page. The error was corrected on April 1, 2016. Scientists have used small fluctuations in the orbits of three NASA spacecraft to map the gravity field of Mars. Watch this video on the NASA Goddard YouTube channel.Complete transcript available.This video is also available on our YouTube channel. Side-by-side rotating Mars globes showing MOLA elevation, GMM-3 free-air gravity, and crustal thickness. Side-by-side rotating Mars globes showing MOLA elevation and GMM-3 free-air gravity. Side-by-side rotating Mars globes showing GMM-3 Bouguer gravity and crustal thickness. Rotating Mars globe showing GMM-3 free-air gravity. Rotating Mars globe showing GMM-3 Bouguer gravity. Rotating Mars globe showing GMM-3 crustal thickness. Rotating Mars globe showing MOLA elevation. Rotating Mars globe showing natural-color terrain, based on a Mars Global Surveyor camera mosaic. Print-res still of the Mars elevation, free-air gravity, and crustal thickness globes, centered on 90W. Print-res still of the Mars free-air gravity globe, centered at 90W. Includes an alpha channel. Print-res still of the Mars crustal thickness globe, centered at 90W. Includes an alpha channel. Print-res still of the Mars Bouguer gravity globe, centered at 90W. Includes an alpha channel. Print-res still of the Mars MOLA elevations, centered at 90W. Includes an alpha channel. Print-res still of the Mars natural-color globe, centered at 90W. Includes an alpha channel. Mars free-air gravity map in a cylindrical projection suitable for spherical texture mapping. Centered at 0 longitude. Includes versions with and without shaded relief of surface features. Mars crustal thickness map in a cylindrical projection suitable for spherical texture mapping. Centered at 0 longitude. Includes versions with and without shaded relief of surface features. Mars Bouguer gravity map in a cylindrical projection suitable for spherical texture mapping. Centered at 0 longitude. Includes versions with and without shaded relief of surface features. Mars MOLA elevation map in a cylindrical projection suitable for spherical texture mapping. Centered at 0 longitude. Includes shaded relief of surface features. For More InformationSee [NASA.gov](http://www.nasa.gov/feature/goddard/2016/mars-gravity-map)

Oceanus Procellarum, or the Ocean of Storms, is the largest of the dark maria visible to the naked eye on the near side of the Moon. Its relatively flat surface of basaltic lava covers most of the northwest quadrant of the Moon s near side, flooding low-lying areas with lava.The rectangular shape differs from the circular shape expected for an impact basin. It more closely resembles the pattern of cracks that form in materials subjected to thermal stress. In fact, the paper compares the shape of the Procellarum gravity anomaly with a feature spanning the south pole of Enceladus, the ice-covered moon of Saturn. Gravity anomalies (red) bordering the Procellarum region are overlaid on a global elevation map.

This print-resolution still image was created for the cover of the May 28, 2014 issue of Geophysical Research Letters. It features a free-air gravity map of the Moon s southern latitudes developed by S. Goossens et al. from data returned by the Gravity Recovery and Interior Laboratory (GRAIL) mission.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 gravity that a cueball Moon would have. The deviations are measured in milliGals, a unit of acceleration. On the map, 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.The map shown here extends from the south pole of the Moon up to 50dinger basin in the center of the frame. The terrain in the image is based on Lunar Reconnaissance Orbiter (LRO) altimeter and camera data. A high-resolution free-air gravity map based on GRAIL data, overlaid on terrain based on LRO altimeter (LOLA) and camera (LROC) data. The view is south-up, with the south pole near the horizon in the upper left and the crescent Earth in the distance. The terminator crosses the eastern rim of the Schrdinger basin. Gravity is painted onto the areas that are in or near the night side. Red corresponds to mass excesses and blue to mass deficits.

A mission to map the moon s crust. The different colors indicate variations in thickness.

These print-resolution stills were created for the cover of the February 8, 2013 issue of Science. They show the free-air gravity map developed by the Gravity Recovery and Interior Laboratory (GRAIL) mission.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 , a point near the eastern edge of the constellation Cetus. The four bright stars in the upper left quarter of the image are (clockwise from the top left) epsilon, rho, sigma, and pi Ceti.

The Gravity Recovery and Interior Laboratory (GRAIL) mission comprises a pair of satellites launched in September, 2011 and placed in orbit around the Moon in January, 2012. The two satellites, named Ebb and Flow, used radio signals to precisely measure their separation as they flew in formation, one following the other in the same nearly circular polar orbit. These measurements allowed mission scientists to build up an accurate and detailed gravity map of the Moon.GRAIL ends its successful mission by impacting the Moon on December 17, 2012 at approximately 5:27 p.m. EST (22:27 UT). The two spacecraft were placed in an orbit that takes them within a kilometer of the surface, so low that they will hit the side of an unnamed mountain that lies between Mouchez and Philolaus craters, near the north pole at 7511 s last orbits across the night side of a waxing crescent Moon. On their penultimate orbit, Ebb and Flow just miss the mountain they will hit on their next pass. A more distant view of the impact site, just seconds before the impact of Ebb.