Lunar Prospector

More Detailed Information on the Mission and Spacecraft

Launch Date: 7 January 1998 UT 02:28:44 (6 January 9:28:44 p.m. EST)
Launch Vehicle: Athena II
Launch Site: Kennedy Space Center
Launch Mass 296 kg (fully fueled), 158 kg (dry)
Power System: Body Mounted 202 W Solar Cells and 4.8 amp-hr NiCd Battery

The Lunar Prospector was designed for a low polar orbit investigation of the Moon, including mapping of surface composition and possible polar ice deposits, measurements of magnetic and gravity fields, and study of lunar outgassing events. Data from the 19 month mission will allow construction of a detailed map of the surface composition of the Moon, and will improve our understanding of the origin, evolution, current state, and resources of the Moon. The spacecraft is a graphite-epoxy drum, 1.37 meters in diameter and 1.28 meters high with three radial instrument booms. It is spin-stabilized and controlled by 6 hydrazine monopropellant 22-Newton thrusters. Communications are through two S-band transponders and a slotted, phased-array medium gain antenna and omnidirectional low-gain antenna. There is no on-board computer, ground command is through a 3.6 kbps telemetry link. Total mission cost is about $63 million. After launch, the Lunar Prospector had a 105 hour cruise to the Moon, followed by insertion into a near-circular 100 km altitude lunar polar orbit with a period of 118 minutes. In December 1998 the orbit was lowered to 40 km. The nominal mission ended after one year, at which time the orbit was lowered to 30 km. On 31 July 1999 at 9:52:02 UT (5:52:02 EDT) Lunar Prospector impacted the Moon near the south pole in a controlled crash to look for evidence of water ice - none was observed.

Scientific Investigations

Gamma Ray Spectrometer (GRS) - G. Scott Hubbard, NASA Ames
Neutron Spectrometer (NS) - William Feldman, Los Alamos
The GRS and NS will return global data on elemental abundances, which will be used to help understand the evolution of the lunar highland crust and the duration and extent of basaltic volcanism, and to assess lunar resources. The NS will also locate any significant quantities of water ice which may exist in the permanently shadowed areas near the lunar poles.

Magnetometer (MAG) - Mario Acuna, NASA Goddard; Lon Hood, Univ. of Arizona LPL
Electron Reflectometer (ER) - Robert Lin, UC Berkeley SSL
The MAG/ER experiments will return data on the lunar crustal magnetic field and the lunar induced magnetic dipole. These data will help provide an understanding of the origin of lunar paleomagnetism and the degree to which impacts can produce paleomagnetism, and allow constraints on the size and composition of the (possible) lunar core.

Alpha Particle Spectrometer (APS) - Alan Binder, Lockheed
The APS instrument will be used to find radon outgassing events on the lunar surface by detecting alpha particles from the radon gas itself and its decay product, polonium. Observations of the frequency and locations of the gas release events will help characterize one possible source of the tenuous lunar atmosphere. Determination of the relationship of outgassing sites with crater age and tectonic features may be possible. This may in turn be used to characterize the current level of lunar tectonic activity.

Doppler Gravity Experiment (DGE) - Alex Konopliv, NASA JPL
This investigation will use Doppler tracking of S-Band radio signals to characterize the spacecraft orbit and determine the lunar gravity field. This data will provide information on the lunar interior and, combined with lunar topographic data, will allow modelling of the global crustal asymmetry, crustal structure, and subsurface basin structure. It can also used for planning future lunar missions.