At 9:28 p.m. (EST) on January 6, 1998, Lunar Prospector (LP) blasted off to the Moon aboard a Lockheed Martin solid-fuel, three-stage rocket called Athena II. It was successfully on its way to the Moon for a one-year, polar orbit, primary mission dedicated to globally mapping lunar resources, gravity, and magnetic fields, and even outgassing events. About 13 minutes after launch, the Athena II placed the Lunar Prospector payload into a "parking orbit" 115 miles above the Earth. Following a 42-minute coast in the parking orbit, Prospectorís Trans Lunar Injection (TLI) stage successfully completed a 64-second burn, releasing the spacecraft from Earth orbit and setting it on course to the Moon, a 105-hour coast. The official mission timeline began when the spacecraft switched on 56 minutes, 30 seconds after liftoff. Shortly after turning the vehicle on, mission controllers deployed the spacecraftís three extendible masts, or booms. Finally, the spacecraftís five instruments -- the gamma-ray spectrometer, alpha particle spectrometer, neutron spectrometer, magnetometer and electron reflectometer -- were turned on. On Sunday, January 11, at 7:20 a.m. (EST), Lunar Prospector was successfully captured into lunar orbit, and a few days later began its mission to globally map the Moon.

Lunar Prospector's identified critical science objectives are:

• "Prospect" the lunar crust and atmosphere for potential resources, including minerals, water ice and certain gases,
• Map the Moonís gravitational and magnetic fields
• Learn more about the size and content of the Moonís core.

• Neutron Spectrometer (NS) --Map hydrogen at several signature energies and thereby infer the presence or absence of water.
• Gamma Ray Spectrometer (GRS) -- Map 10 key elemental abundances, several of which offer clues to lunar formation and evolution.
• Magnetometer/Electron Reflectometer (Mag/ER) -- These two experiments combine to measure lunar magnetic field strength at the surface and at the altitude of the spacecraft and thereby greatly enhance understanding of lunar magnetic anomalies.
• Doppler Gravity Experiment (DGE) -- Make an operational gravity map of the Moon for use by future missions as well as LP by mapping gravity field measurements from changes in the spacecraftís orbital speed and position.
• Alpha Particle Spectrometer (APS) -- Map out-gassing events by detecting Radon gas (current outgassing events) and Polonium (tracer of recent, i.e. 50 years).

References
http://lunar.arc.nasa.gov/index.html