Lunar Prospector was the third mission selected by NASA for full development and construction as part of the Discovery Program. At a cost of $62.8 million, the 19-month mission was designed for a low polar orbit investigation of the Moon, including mapping of surface composition including Lunar hydrogen deposits, measurements of magnetic and gravity fields, and study of lunar outgassing events. The mission ended July 31, 1999, when the orbiter was deliberately crashed into a crater near the lunar south pole, after the presence of hydrogen was successfully detected.Data from the mission allowed the construction of a detailed map of the surface composition of the Moon, and helped to improve understanding of the origin, evolution, current state, and resources of the Moon. Several articles on the scientific results were published in the journal Science.Lunar Prospector was managed by NASA Ames Research Center with the prime contractor Lockheed Martin. The Principal Investigator for the mission was Alan Binder. His personal account of the mission, Lunar Prospector: Against all Odds, is highly critical of the bureaucracy of NASA overall, and of its contractors.In 2013 an unidentified object was discovered in an unstable orbit around the Earth, and assigned the provisional number WT1190F. After it crashed into the Indian Ocean it was identified as probably the translunar injector of Lunar Prospector.

The Discovery Program is a series of solar system exploration missions funded by the US National Aeronautics and Space Administration (NASA) through its Planetary Missions Program Office. The cost of each mission is capped at a lower level than missions from NASA's New Frontiers or Flagship Programs. As a result, Discovery missions tend to be more focused on a specific scientific goal rather than serving a general purpose.

The Discovery Program was founded in 1990 to implement the policy of the then-NASA administrator Daniel S. Goldin of "faster, better, cheaper" planetary science missions. Existing NASA programs had specified mission targets and objectives in advance, then sought bidders to construct and operate them. In contrast, Discovery missions are solicited through a call for proposals on any science topic and assessed through peer review. Selected missions are led by a scientist called the principal investigator (PI) and may include contributions from industry, universities or government laboratories.

The Discovery Program also includes Missions of Opportunity, which fund US participation in spacecraft operated by other space agencies, for example by contributing a single scientific instrument. It can also be used to re-purpose an existing NASA spacecraft for a new mission.

As of June 2021, the most recently selected Discovery missions were VERITAS and DAVINCI+, the fifteenth and sixteenth missions in the program.