NASA had planned to land the Volatiles Investigating Polar Exploration Rover (VIPER) at the Moon’s south pole in late 2025 to probe water abundance and distribution. But, citing ballooning costs, the agency canceled the mission in July 2024. The decision came as a shock to many researchers in the lunar science community who believe that VIPER is essential for NASA’s future Artemis missions, which are intended to establish a long-term human presence on the Moon. What’s more, the rover is ready for launch. VIPER will be stripped for parts unless NASA makes a last-minute save. After receiving researchers’ appeals to reconsider and questions from Congress, the agency plans to make a decision in early 2025 about what will happen to the rover.
VIPER was to be NASA’s first mobile robotic mission to the Moon. The rover would have drilled through permanently shadowed craters near the lunar poles to analyze the distribution and composition of water ice and volatiles such as hydrogen, ammonia, and carbon dioxide. The data were to be used to create a resource map to inform upcoming Artemis missions. Adrienne Dove, a planetary scientist at the University of Central Florida, says that VIPER is essential because it would pinpoint where resources are located before NASA sends crewed flights. Additionally, the rover would explore the shadowed regions of the Moon to better characterize the lunar poles.
The mission experienced multiple delays before being canceled. NASA first scheduled the launch for late 2023 but then moved it to late 2024 to conduct more testing on the lander that would shuttle the rover to the Moon from a SpaceX Falcon Heavy rocket. The agency then pushed VIPER’s launch to September 2025 because of supply chain issues and inflation.
NASA has spent about $450 million building the rover, some $200 million more than projected. And overall funding is tight in 2024: Congress cut NASA’s budget to $24.875 billion, a 2% cut from 2023. In a July press release, NASA said that continuing VIPER would result in delays to or cancellations of other projects.
NASA will save $84 million because it no longer needs to conduct final testing of the rover. The agency has historically pushed ahead with missions that are this far along, Dove says, but lately, the agency “has been coming down harder on missions going over budget.”
Astrobotic Technology, a space robotics company, has a separate $323 million contract with NASA to construct the lander. The agency will still launch that lander as a technology demonstration even without VIPER on board.
Community pushback
Amy Fagan, a lunar geologist at Western Carolina University, says she found NASA’s decision to cancel the mission confusing because multiple decadal surveys have prioritized studying volatiles on the Moon.
“Frustrated is an understatement,” says Clive Neal, a lunar scientist at the University of Notre Dame. He recently met with Capitol Hill staffers to advocate for VIPER, which he says is a key step toward scouting for volatiles before sending humans to Mars. “If we can’t get it right at the Moon, we can’t get to Mars.”
VIPER scientist Benjamin Fernando, a postdoc at Johns Hopkins University, also went to Washington, DC, to discuss keeping the mission alive. Fernando worked on VIPER’s drill instrumentation. “My career is tied to this project,” says Fernando, who came to the US from the UK to work on the rover. He helped organize an open letter to Congress asking members to reinstate VIPER; almost 5000 scientists signed it. The House Committee on Science, Space, and Technology also sent a letter to NASA questioning the decision.
A lifeline?
After receiving the letter from Congress, NASA is considering proposals from US companies to fly the mission with the agency. A NASA spokesperson tells Physics Today in an email that the agency is reviewing 11 responses. Any partner would have to carry out the mission with little to no additional cost to NASA.
The agency will fly other lunar missions, the spokesperson says, including Moon-orbiting spacecraft and experiments on international robotic spacecraft. One such mission is the Polar Resources Ice Mining Experiment-1 (PRIME-1), scheduled to launch in January 2025. But PRIME-1 will drill at only one location and so “will not have the capability to replace VIPER’s science,” says Laura Forczyk, the founder of Astralytical, a space industry consulting firm.
The China National Space Administration plans to conduct similar research in the coming years. The country’s Chang’e 7 and Chang’e 8 rovers are scheduled to explore the Moon’s south pole in 2026 and 2028, respectively. They follow Chang’e 6, which last June delivered the first samples to Earth from the far side of the Moon. China also plans to set up a lunar research station.
NASA has not said when it will make a final decision on VIPER’s fate, although it is expected to propose next steps early in 2025. If a partner is not chosen, the mission will close out in the spring, including disbanding the team and decommissioning the hardware.
