VIPER

Mission objectives

NASA defines VIPER as a lunar volatiles detection and measurement mission focused on the south polar region. Its core science objectives are to map the distribution and concentration of water ice and other volatiles — including CO₂, NH₃, and CH₄ — at and below the surface; characterize whether water exists as ice crystals, molecules bound in minerals, or hydroxyl; and investigate multiple ice stability regions (ISRs) across a range of illumination and thermal environments, including permanently shadowed regions (PSRs).

From an exploration standpoint, VIPER is intended to create resource maps showing where water and other volatiles are located and in what abundance, assess the accessibility and extractability of those volatiles for future ISRU systems, and provide the engineering-relevant data needed to design equipment capable of producing breathable oxygen and rocket propellant from lunar ice. NASA describes it as "the first resource-mapping mission on another world."

Operationally, the rover is designed to traverse roughly 20 km over approximately 100 Earth days — spanning about three cycles of lunar day and night — visiting at least six locations within the Nobile/Mons Mouton area where orbital data and prospectivity modeling indicate ice may be present. Mission operations end when the rover encounters a prolonged period of darkness and cold it cannot survive.

Science strategy and operational concept

VIPER's four instruments function as an integrated prospecting system. As the rover drives, the NSS continuously scans the subsurface for elevated hydrogen signatures down to approximately one meter. When a promising area is identified, VIPER slows or stops and the TRIDENT drill is deployed to retrieve cuttings from multiple depths at that site.

NIRVSS then examines the exposed cuttings and nearby surface, determining the physical and chemical state of volatiles — distinguishing water ice from hydroxyl and characterizing associated minerals. Simultaneously, MSolo samples gases released from the disturbed regolith, identifying volatile species and their isotopic compositions. These isotopic ratios are critical for understanding the origin and evolution of polar volatile deposits.

VIPER is designed to sample four main soil environments with distinct illumination and temperature regimes — both inside and outside PSRs — to understand how volatile deposits vary with environment. Data from all four instruments are synthesized into regional water resource maps, with particular focus on the Nobile crater area, to inform future human landing site selection and ISRU system design.

Landing site: Mons Mouton and the Nobile region

NASA selected Mons Mouton, on the western edge of Nobile crater near the lunar south pole, as VIPER's landing site. The choice was driven by four criteria applied simultaneously: sufficient Earth visibility for two-way X-band communications; available sunlight for solar power and thermal regulation; high predicted potential for near-surface water ice based on remote-sensing data and prospectivity modeling; and terrain traversable by the rover.

The area west of Nobile crater satisfies all four conditions. It includes a mix of sunlit terrain and nearby permanently shadowed regions — among the coldest locations in the Solar System, where ice may have been preserved for billions of years. Orbital data from missions including Lunar Prospector, the Lunar Reconnaissance Orbiter, Chandrayaan-1, and LCROSS had already indicated polar water ice, particularly in south polar PSRs.

A dedicated prospectivity model for the Mons Mouton landing site was developed to predict where water ice is most likely within the top ~1 m of regolith, using neutron spectroscopy, thermal models, illumination and temperature history, and other orbital data. This model guides both the exact landing zone and the planned traverse and drill locations, focusing on zones with maximum predicted ice abundance while respecting VIPER's engineering constraints.

During operations at this site, VIPER is planned to move in and out of PSRs, entering dark, ultracold craters to investigate ice and then returning to sunlit areas to recharge. Its headlights and infrared lamp (part of NIRVSS) enable scientific work and navigation inside permanently shadowed terrain where the Sun never reaches.

Delivery and CLPS partnership

VIPER was originally contracted for delivery under NASA's Commercial Lunar Payload Services (CLPS) program as Task Order TO 20A, awarded to Astrobotic Technology of Pittsburgh. Under CLPS, NASA purchases landing services rather than owning the lander; Astrobotic would build and operate the Griffin lander — a roughly 5,900 kg-class vehicle — and carry VIPER to the lunar south pole, with launch planned on a SpaceX Falcon Heavy. The CLPS delivery contract with Astrobotic was valued at approximately $320–323 million, making it the most expensive CLPS delivery to that point.

To reduce risk for the large Griffin lander, NASA requested a one-year delay and paid an additional $67.8 million for extra testing of the vehicle's guidance, navigation, and control systems. Despite this, the VIPER project's cost estimate rose above $609.6 million — more than 30% above its formal cost commitment — triggering an automatic cancellation review. The mission also slipped from an original target of 2023 to a planned launch in late 2024, then to 2025.

After VIPER's cancellation, NASA decided it would still pay Astrobotic the full approximately $323 million for Griffin landing services, reasoning that the vehicle's eventual flight to the Moon — even without NASA payloads — would benefit broader commercial lunar capability. Astrobotic subsequently reported receiving approximately 60 expressions of interest from other parties for payload space on Griffin.

Cancellation and revival

On 17 July 2024, NASA formally announced its intent to discontinue VIPER after an internal review. Science Mission Directorate leadership stated that continuation of the project — whose cost estimate had grown to approximately $609.6 million, more than 30% above its formal cost commitment — would threaten funding for other CLPS missions within a constrained science budget. By that point NASA had spent roughly $450 million on the rover itself, not including the approximately $323 million CLPS contract with Astrobotic for delivery services.

The cancellation drew strong opposition. House Science Committee leaders wrote to NASA Administrator Bill Nelson seeking detailed cost and schedule justification, and approximately 1,000 scientists and engineers signed a letter urging Congress to refuse to authorize the cancellation, calling the decision to end VIPER after such large sunk costs "unprecedented and indefensible." NASA acknowledged that Congress holds the final authority over the termination.

Despite this pushback, NASA proceeded with project close-out through spring 2025. Plans called for disassembling the rover — which had been fully assembled and had just entered environmental testing at the time of cancellation — and reusing its instruments and components on future lunar missions. Three VIPER instruments were explicitly expected to fly on other lunar robotic missions. NASA also invited industry expressions of interest for use of the complete rover system at no cost to the government, but no public announcement followed indicating a successful external partnership.

In September 2025, NASA selected Blue Origin to deliver VIPER to the Moon's south pole in late 2027 aboard a Blue Moon MK1 lander, reviving the mission under a new commercial delivery arrangement. NASA separately confirmed that Astrobotic's Griffin Mission One CLPS flight would still proceed without VIPER as a lander and engine demonstration, targeted no earlier than fall 2025.