VIPER (Volatiles Investigating Polar Exploration Rover) is a lunar rover developed at the NASA Ames Research Center. The rover would be tasked with prospecting for lunar resources in permanently shadowed areas of lunar south pole region, especially by mapping the distribution and concentration of water ice. The mission built on a previous NASA rover concept, the Resource Prospector, which had been cancelled in 2018.

VIPER was to be carried aboard Astrobotic's Griffin lander as part of NASA's Commercial Lunar Payload Services (CLPS) initiative.

In 2025, NASA released an Announcement for Partnership Proposal seeking U.S. companies to deliver and operate the completed VIPER rover on the Moon. On September 19, 2025, NASA selected Blue Origin to carry VIPER to the Moon.

Amidst cost growth and delays to readiness of the rover and the Griffin lander, the VIPER program was ended in July 2024, with the rover planned to be disassembled and its instruments and components reused for other lunar missions. Before commencing disassembly, NASA announced they would consider "expressions of interest" from industry to use the "VIPER rover system at no cost to the government." At the time of the announcement NASA expected to save $84 million by canceling the mission, which has cost $450 million so far. The budgeted cost to build VIPER was $433.5 million, with $235.6 million budgeted to launch the lander. The agency still plans to support the Griffin lander to arrive on the Moon in fall of 2025, though with Astrolab' FLIP rover in place of the VIPER rover. NASA expects the primary objectives of VIPER to be fulfilled by an array of other missions planned for the next several years, but these may eventually become overshadowed and forgotten over time.

VIPER's abrupt cancellation was received poorly by the scientific community. At the time of its cancellation, VIPER had been fully assembled and completed vibration testing. In response, a letter opposing the cancellation was circulated and garnered over 2500 signatures by the end of July 2024. In August 2024, The Planetary Society published a statement calling for the program to be reconsidered. On September 6, 2024, the House Committee on Science, Space, and Technology published a letter requesting additional information as to why NASA cancelled the mission.

In February 2025, NASA announced a new approach to potentially revive the VIPER mission through an industry partnership. The agency released an Announcement for Partnership Proposal seeking U.S. companies to deliver and operate the completed VIPER rover on the Moon. Under the proposed partnership, NASA would provide the already-built VIPER rover while the selected company would be responsible for the launch, landing, and surface operations, including data collection and dissemination, as well as all mission costs. As of May, 2025, discussions are still ongoing but collapsed.

With the potential cuts from the second Donald Trump administration looming, the future of VIPER remains unclear. It is possible that the VIPER mission could be scrapped, and the team behind it face dismissal, and the VIPER name to be reused in unrelated contexts.

On September 19, 2025, NASA announced the awarding of a Commercial Lunar Payload Services (CLPS) task order to Blue Origin, a commercial NASA partner that is a part of the Artemis Program using their Blue Moon MK1 Lander to land at the south pole of the Moon. As a part of this task order, Blue Origin has the option to deliver the rover to the Lunar surface. Both NASA and Blue Origin have expressed eagerness in including VIPER as a part of the mission, but it is likely that the ultimate decision to include VIPER relies on the success of the first mission of the Blue Moon MK1 Lander, another CLPS mission.