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GRAIL
NASA orbiter mission to the Moon (2011–2012) / From Wikipedia, the free encyclopedia
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The Gravity Recovery and Interior Laboratory (GRAIL) was an American lunar science mission in NASA's Discovery Program which used high-quality gravitational field mapping of the Moon to determine its interior structure. The two small spacecraft GRAIL A (Ebb) and GRAIL B (Flow)[6][7] were launched on 10 September 2011 aboard a single launch vehicle: the most-powerful configuration of a Delta II, the 7920H-10.[1][8][9] GRAIL A separated from the rocket about nine minutes after launch, GRAIL B followed about eight minutes later. They arrived at their orbits around the Moon 25 hours apart.[10][11] The first probe entered orbit on 31 December 2011 and the second followed on 1 January 2012.[12] The two spacecraft impacted the Lunar surface on December 17, 2012.[11]
![]() Artist's interpretation of the GRAIL tandem spacecraft above the lunar surface. | |
Names | GRAIL |
---|---|
Mission type | Lunar orbiters |
Operator | NASA / JPL[1][2] |
COSPAR ID | 2011-046A (Ebb) 2011-046B (Flow) |
SATCAT no. | 37801 (Ebb) 37802 (Flow) |
Website | moon |
Mission duration | 1 year, 3 months and 7 days |
Spacecraft properties | |
Bus | XSS-11[3] |
Manufacturer | MIT Lockheed Martin |
Launch mass | 202.4 kg (each)[4] |
Dry mass | 132.6 kg (292 lb) |
Power | (Solar array / Li-ion battery) |
Start of mission | |
Launch date | September 10, 2011, 13:08:52.775 (2011-09-10UTC13:08:52Z) UTC |
Rocket | Delta II 7920H-10 D-356 |
Launch site | Cape Canaveral SLC-17B |
Contractor | United Launch Alliance |
Entered service | December 31, 2011 (Ebb) January 1, 2012 (Flow) |
End of mission | |
Disposal | Deorbited |
Decay date | December 17, 2012 |
Orbital parameters | |
Reference system | Selenocentric |
Regime | Polar orbit[5] |
Semi-major axis | 1,788.0 kilometres (1,111.0 mi) |
Periselene altitude | 25 kilometres (16 mi) |
Aposelene altitude | 86 kilometres (53 mi) |
Period | 113 minutes |
Lunar impactor | |
Spacecraft component | Ebb |
Impact date | December 17, 2012, 22:28:51 UTC |
Impact site | 75.6083°N 33.4043°E / 75.6083; 33.4043 |
Lunar impactor | |
Spacecraft component | Flow |
Impact date | December 17, 2012, 22:29:21 UTC |
Impact site | 75.6504°N 33.1643°E / 75.6504; 33.1643 |
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