Gravity Recovery and Interior Laboratory
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GRAIL Artist's Rendition
Using a precision formation-flying technique, the twin GRAIL spacecraft will map the moon's gravity field, as depicted in this artist's rendering.
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GRAIL's Twin Spacecraft fly in Tandem Around the Moon (Artist's Concept)
The Gravity Recovery and Interior Laboratory (GRAIL) mission utilizes the technique of twin spacecraft flying in formation with a known altitude above the lunar surface and known separation distance to investigate the gravity field of the moon.
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GRAIL Flying in Formation (Artist's Concept)
Using a precision formation-flying technique, NASA's twin GRAIL spacecraft will map the moon's gravity field. This is an artist's concept.
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GRAIL's Twin Spacecraft -- Crust to Core (Artist's Concept)
The Gravity Recovery and Interior Laboratory (GRAIL) mission utilizes the technique of twin spacecraft flying in formation with a known altitude above the lunar surface and known separation distance to investigate the gravity field of the moon.
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GRAIL-B Performing its Lunar Insertion Burn
Artist concept of GRAIL-B performing its lunar orbit insertion burn. Image credit: NASA/JPL-Caltech
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GRAIL-A in Orbit Around the Moon
Artist concept of GRAIL-A in orbit around the moon. Image credit: NASA/JPL-Caltech
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GRAIL Twins are Covered
Spacecraft technicians monitor the movement of a section of the clamshell-shaped Delta payload fairing as it encloses NASA's twin Gravity Recovery and Interior Laboratory spacecraft at Cape Canaveral Air Force Station in Florida on Aug. 23, 2011.
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GRAIL Mission Comes Together
NASA's twin Gravity Recovery and Interior Laboratory (GRAIL) spacecraft are lowered onto the second stage of their Delta II launch vehicle. At top is the spacecraft adapter ring which holds the two lunar probes in their side-by-side launch configuration.
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Testing the GRAIL Twins
In this photo, taken April 29, 2011, technicians install lifting brackets prior to hoisting the 200-kilogram (440-pound) GRAIL-A spacecraft out of vacuum chamber after testing.
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Mission Summary
The Gravity Recovery and Interior Laboratory, or GRAIL, mission was designed to create the most accurate gravitational map of the moon to date, which when combined with topographic data, can provide insight into the moon's internal structure, composition and evolution.
Using the technique pioneered by NASA's Grace mission orbiting Earth, GRAIL mapped the moon's gravity by measuring the push and pull between twin spacecraft(Ebb & Flow) flying in tandem around the moon. The spacecraft collected data on the moon's far side by communicating with one another when the signal to Earth is obscured. It was the first time such a technique has ever been attempted on another world.
On December 17, 2012, the twin spacecraft of NASA's GRAIL mission completed their final rocket burns and impacted the moon at 2:28 p.m. PST (5:28 EST). The two probes hit a mountain near the lunar north pole, bringing their successful prime and extended science missions to an end. The two probes were sent purposely into the moon because they no longer have enough altitude or fuel to continue science operations.
NASA has named the site where the twin agency spacecraft impacted the moon in honor of the late astronaut Sally K. Ride, who was America's first woman in space and a member of the probes' mission team.
Scientific Instrument(s)
- Lunar Gravity Ranging System (LGRS)
- MoonKAM
