NASA's two Gravity Recovery And Interior Laboratory (Grail) spacecraft have completed all assembly and testing prior to shipment to Florida.
The Grail mission is scheduled for launch late this summer. The Grail-A and Grail-B spacecraft will fly in tandem orbits around Earth's moon for several months to measure its gravity field in unprecedented detail. The mission will also answer longstanding questions about the moon and provide scientists with a better understanding of how Earth and other rocky planets in the solar system formed.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Grail mission. The Massachusetts Institute of Technology, Cambridge, is home to the mission's principal investigator Maria Zuber. The Grail mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.
In the course of the mission, GRAIL will conduct two important firsts. This will be the first time any space agency has attempted the complex set of maneuvers required to place two robotic spacecraft into the same precise orbit around a planetary body other than Earth so that they can fly in formation. And it will also be the first time a NASA planetary mission has carried an imager specifically for the purpose of education and public outreach: the MoonKAM cameras whose photographic targets will be chosen by middle school students under the auspices of Sally Ride Science.
n 2011, NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission will launch twin spacecraft in tandem orbits around the Moon to measure its gravity in unprecedented detail. The mission will answer key questions about the Moon's internal structure and give scientists a better understanding of how our solar system formed.
GRAIL MoonKAM will allow classrooms to request pictures of the lunar surface from cameras on the twin satellites. As we count down to the GRAIL launch, we will be adding exciting features and resources to this site, including student activities, teacher guides, and more.
Nov. 6, 2006: Near the end of the mission of Apollo 16, on April 24, 1972, just before returning back home to Earth, the three astronauts released one last scientific experiment: a small "subsatellite" called PFS-2 to orbit the Moon about every 2 hours.
The intention? Joining an earlier subsatellite PFS-1, released by Apollo 15 astronauts eight months earlier, PFS-2 was to measure charged particles and magnetic fields all around the Moon as the Moon orbited Earth. The low orbits of both subsatellites were to be similar ellipses, ranging from 55 to 76 miles (89 to 122 km) above the lunar surface.
Instead, something bizarre happened.
The orbit of PFS-2 rapidly changed shape and distance from the Moon. In 2-1/2 weeks the satellite was swooping to within a hair-raising 6 miles (10 km) of the lunar surface at closest approach. As the orbit kept changing, PFS-2 backed off again, until it seemed to be a safe 30 miles away. But not for long: inexorably, the subsatellite's orbit carried it back toward the Moon. And on May 29, 1972—only 35 days and 425 orbits after its release—PFS-2 crashed.
What happened? The Moon itself plunged the subsatellite to its death. That's the conclusion of Alex S. Konopliv, planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena. He and several colleagues have been analyzing the orbits of various Moon-orbiting satellites since PFS-2, notably the 1998–99 mission of Lunar Prospector.
An improved gravity model from Doppler tracking of the Lunar Prospector (LP) spacecraft reveals three new large mass concentrations (mascons) on the nearside of the moon beneath the impact basins Mare Humboltianum, Mendel-Ryberg, and Schiller-Zucchius, where the latter basin has no visible mare fill. Although there is no direct measurement of the lunar farside gravity, LP partially resolves four mascons in the large farside basins of Hertzsprung, Coulomb-Sarton, Freundlich-Sharonov, and Mare Moscoviense. The center of each of these basins contains a gravity maximum relative to the surrounding basin. The improved normalized polar moment of inertia (0.3932 ± 0.0002) is consistent with an iron core with a radius of 220 to 450 kilometers.
Mineralogy records the geologic character and evolution of a planet, and M3 will characterize lunar mineralogy in a spatial context, drawing relationships between visible landforms and their mineral composition. The instrument will provide scientists their first opportunity to study the Moon's surface at high spatial and spectral resolution, making spectroscopic measurements of lunar minerals in the visible and near-infrared regions of the electromagnetic spectrum, while simultaneously mapping the distribution of these materials across the surface. This information will greatly expand our understanding of the Moon and the inner solar system, and will provide a much-needed long-term baseline for future exploration activities.
The Moon Mineralogy Mapper (M3) is one of two instruments contributed by NASA to India's first mission to the Moon, Chandrayaan-1. M3, a state-of-the-art imaging spectrometer, has provided the first mineralogical map of the lunar surface at high spatial and spectral resolution. By analyzing the data, scientists are determining the composition of the surface of the Moon.