Lunar Prospector
Lunar Prospector was NASA's third Discovery mission. Operating in a 100-km circular polar orbit, its neutron spectrometer confirmed large amounts of hydrogen (indicative of water ice) sequestered in permanently shadowed craters at both lunar poles. Its gamma-ray and alpha spectrometers produced global maps of thorium, potassium, iron, and titanium, while tracking data revealed mass concentrations (mascons). On July 31, 1999, it was deliberately impacted into Shoemaker crater at the south pole.
Mission Imagery & Gallery
Primary Achievement
Confirmed significant hydrogen signatures (water ice deposits) at the lunar poles and mapped global mineral composition and gravity.
Mission Objectives
- Detect and quantify polar hydrogen deposits and identify potential water ice reservoirs
- Map global elemental composition (Fe, Ti, Th, K, U) and surface magnetic fields
- Measure localized lunar gravitational anomalies (mascons) with Doppler tracking
Timeline Events
- 1998-01-07 — Launched from Cape Canaveral Spaceport SLC-46 aboard Athena II rocket.
- 1998-01-11 — Captured into polar orbit around the Moon; confirmed polar hydrogen within weeks.
- 1998-12-19 — Lowered orbit to 40 km altitude (later 30 km) for super-high-resolution mapping.
- 1999-07-31 — Deliberately impacted permanently shadowed floor of Shoemaker crater at 09:52 UTC.
Related Missions
- Clementine (DSPSE) (1994) · BMDO / NASA
- LCROSS (2009) · NASA
- Lunar Reconnaissance Orbiter (LRO) (2009) · NASA
Historical & Technical Sources
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