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GRAIL Primary Mission Gravity Maps (AGU 2012)

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.

If the Moon 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, the Moon 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 separation of the two spacecraft.

The free-air gravity map shows these variations directly. (Free-air is a historical term; there is, of course, no air on the Moon.) The Bouguer gravity map subtracts the effect of the bumpy surface to show the lumpiness underneath. The elevation maps from the laser altimeter on Lunar Reconnaissance Orbiter (LRO) were used to create a model of what the gravity would be if the Moon were bumpy but not lumpy. This model was then subtracted from the free-air map to produce the Bouguer map. (Note: The Bouguer map shown here was filtered to emphasize smaller features; harmonic degrees 1 to 6 were excluded.)

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.

While aiding navigation for future lunar missions, GRAIL's gravity measurements reveal information about the internal structure of the Moon, improving our understanding of the origin and development of not just the Moon, but also the Earth and the rest of the inner solar system.
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More information on this topic available at:
http://www.nasa.gov/home/hqnews/2012/dec/HQ_12-417_GRAIL.html

Side-by-side rotating Moon globes showing LOLA elevation and GRAIL free-air gravity.    Side-by-side rotating Moon globes showing LOLA elevation and GRAIL free-air gravity.
Duration: 20.0 seconds
Available formats:
  1920x1080 QT         47 MB
  1280x720   QT         32 MB
  640x360     QT         12 MB
  1920x1080 TIFF (title plate) 126 KB
  320x180     PNG           79 KB
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Side-by-side rotating Moon globes showing Bouguer gravity and crustal thickness. The Bouguer map is filtered to emphasize smaller features.    Side-by-side rotating Moon globes showing Bouguer gravity and crustal thickness. The Bouguer map is filtered to emphasize smaller features.
Duration: 20.0 seconds
Available formats:
  1920x1080 QT         28 MB
  1280x720   QT         17 MB
  640x360     QT         6 MB
  1920x1080 TIFF (title plate) 126 KB
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Rotating Moon globe showing free-air gravity as measured by GRAIL.    Rotating Moon globe showing free-air gravity as measured by GRAIL.
Duration: 20.0 seconds
Available formats:
  1920x1080 QT         38 MB
  1280x720   QT         27 MB
  640x360     QT         11 MB
  1920x1080 Frames (Free air)
  1920x1080 TIFF (title plate) 100 KB
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Rotating Moon globe showing Bouguer gravity. The data is high-pass filtered to emphasize smaller features.    Rotating Moon globe showing Bouguer gravity. The data is high-pass filtered to emphasize smaller features.
Duration: 20.0 seconds
Available formats:
  1920x1080 QT         21 MB
  1280x720   QT         12 MB
  640x360     QT         4 MB
  1920x1080 Frames (Bouguer)
  1920x1080 TIFF (title plate) 102 KB
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Rotating Moon globe showing crustal thickness.    Rotating Moon globe showing crustal thickness.
Duration: 20.0 seconds
Available formats:
  1920x1080 QT         20 MB
  1280x720   QT         11 MB
  640x360     QT         4 MB
  1920x1080 Frames (Thickness)
  1920x1080 TIFF (title plate) 102 KB
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Rotating Moon globe showing topography as measured by LOLA on LRO.    Rotating Moon globe showing topography as measured by LOLA on LRO.
Duration: 20.0 seconds
Available formats:
  1920x1080 QT         26 MB
  1280x720   QT         17 MB
  640x360     QT         5 MB
  1920x1080 Frames (Topo)
  1920x1080 TIFF (title plate) 104 KB
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Print-res still of the free-air lunar gravity globe, centered on 120 degrees west longitude. Includes an alpha mask.    Print-res still of the free-air lunar gravity globe, centered on 120 degrees west longitude. Includes an alpha mask.

Available formats:
  2400 x 2400     TIFF     10 MB


Print-res still of the Bouguer lunary gravity globe, centered on 120 degrees west longitude. The data is high-pass filtered to emphasize smaller features. Includes an alpha mask.    Print-res still of the Bouguer lunary gravity globe, centered on 120 degrees west longitude. The data is high-pass filtered to emphasize smaller features. Includes an alpha mask.

Available formats:
  2400 x 2400     TIFF       8 MB


Print-res still of the lunar crustal thickness globe, centered on 120 degrees west longitude. Includes an alpha mask.    Print-res still of the lunar crustal thickness globe, centered on 120 degrees west longitude. Includes an alpha mask.

Available formats:
  2400 x 2400     TIFF       8 MB


Print-res still of the LOLA lunar topography globe, centered on 120 degrees west longitude. Includes an alpha mask.    Print-res still of the LOLA lunar topography globe, centered on 120 degrees west longitude. Includes an alpha mask.

Available formats:
  2400 x 2400     TIFF     10 MB

Short URL to This Page:http://svs.gsfc.nasa.gov/goto?4014
Animation Number:4014
Completed:2012-11-28
Animator:Ernie Wright (USRA) (Lead)
Scientists:Maria Zuber (Massachusetts Institute of Technology)
 Erwan M. Mazarico (Massachusetts Institute of Technology)
Platforms/Sensors/Data Sets:GRAIL/Lunar Gravity Ranging System/Crustal Thickness
 GRAIL/Lunar Gravity Ranging System/Bouguer Gravity
 GRAIL/Lunar Gravity Ranging System/Free-Air Gravity
 LRO/LOLA/Digital Elevation Map
Series:The Moon
Please give credit for this item to:
NASA's Goddard Space Flight Center Scientific Visualization Studio
 
Keywords:
SVS >> Gravity
SVS >> HDTV
SVS >> Laser Altimeter
SVS >> Lunar
SVS >> Moon
SVS >> LRO
SVS >> Lunar Reconnaissance Orbiter
SVS >> Lunar Topography
SVS >> Lunar Elevation Map
SVS >> Free-Air Gravity
SVS >> Bouguer Gravity
SVS >> Crustal Thickness
SVS >> GRAIL
SVS >> Gravity Recovery and Interior Laboratory
Science paper:M. T. Zuber et al., Gravity field of the Moon from the Gravity Recovery and Interior Laboratory (GRAIL), Science 10.1126/science.1231507 (Dec. 5, 2012)
 
 


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Many of our multimedia items use the GCMD keywords. These keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 8.0.0.0.0

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