"Our lunar twins may be in the twilight of their operational lives, but one thing is for sure, they are going down swinging," said GRAIL project manager David Lehman of NASA's Jet Propulsion Laboratory in Pasadena, Calif. This will help NASA engineers validate fuel consumption computer models to improve predictions of fuel needs for future missions. They will fire their main engines until their propellant tanks are empty to determine precisely the amount of fuel remaining in their tanks. No imagery of the impact is expected because the region will be in shadow at the time.Įbb and Flow will conduct one final experiment before their mission ends. Flow will follow Ebb about 20 seconds later.īoth spacecraft will hit the surface at 3,760 mph (1.7 kilometers per second). The first probe to reach the moon, Ebb, also will be the first to go down, at 2:28:40 p.m. They were named by elementary school students in Bozeman, Mont., who won a contest. Both spacecraft have been flying in formation around the moon since Jan. The mountain where the two spacecraft will make contact is located near a crater named Goldschmidt. Track for the Ebb and Flow spacecraft during their final half-orbits is Indicated with red diamonds and red squares, respectively. The Soviet Union's Luna and Lunakhod landing sites are The Apollo 11, 12, 14, 16 and 17 landing sitesĪre indicated with green circles. Possibility of either of the two GRAIL spacecraft impacting near any of Navigators on the GRAIL team haveĭesigned an end of mission plan that rules out the extremely remote Highlights locations on the moon NASA considers "lunar heritage sites"Īnd the path NASA's Gravity Recovery and Interior Laboratory spacecraft Lunar Heritage Sites and GRAIL's Final Mile. "Our little robotic twins have been exemplary members of the GRAIL family, and planetary science has advanced in a major way because of their contributions." "It is going to be difficult to say goodbye," said GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. In eastern North America, the Moon will have transited, riding low and west from overhead Only the best equipped observers can hope to observe the actual release of kinetic energy, an extremely fast flash, near the horn of the north-northwest limb. Waxing between New and First Quarter (4.58 days 26.8% illumination), the distance between Earth and Moon will be increasing at roughly 10 km per minute from 372,628 kilometers. Perspective on the Moon at the estimated time of the GRAIL impacts, projected at 2229 UT, 17 December 2012. The duo's successful prime and extended science missions generated the highest-resolution gravity field map of any celestial body, providing a better understanding of how Earth and other rocky planets in the solar system formed and evolved. EST) Monday, December 17.Įbb and Flow, the Gravity Recovery and Interior Laboratory ( GRAIL) mission probes, are being sent purposely into the lunar surface because their low orbit and low fuel levels preclude further scientific operations. Pasadena (JPL) - Twin lunar-orbiting NASA spacecraft that have allowed scientists to learn more about the internal structure and composition of the moon are being prepared for their controlled descent and impact on a mountain near the moon's north pole at about 2028 UT (5:28 p.m.
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