The rover would have searched for ice and other resources on the moon, but without a last-minute rescue by private dollars, is likely to be dismembered for parts, or crated for warehouse storage. This is, in a sense, the second time NASA has canceled VIPER. The mission can trace its lineage to an earlier mission called Resource Prospector, which NASA spent about $100 million on, and which was also eventually terminated. 

VIPER’s cancellation is bad for lunar science, but good for NASA. Especially in a constrained budget environment, NASA should be willing to cancel more missions, sooner. 

In 2019, when then-NASA Administrator Jim Bridenstine announced VIPER at the 70th International Astronautical Congress, its cost was $250 million—a pretty good deal for a moon rover (if you ignore the hundred million already spent). Less than a year later, the agency signed a $200 million contract with Astrobotic to set VIPER on the moon using the company’s Griffin lander. VIPER had not yet finalized its design when NASA signed the paperwork, but that’s OK, because Astrobotic had never landed on the moon. At the time, NASA officials accepted a 50% success rate for such landings. 

This harkened back to the initial promise of NASA’s Faster-Better-Cheaper era in the 1990s, when the agency commenced a series high-risk, high-reward missions intended to ramp up its launch cadence of robotic spacecraft. Its highest profile successes were Mars Pathfinder and the Near-Earth Asteroid Rendezvous mission. Its biggest failures—and what would eventually doom the program—were the Mars 99 missions, one of which made a new crater on Mars, and the other a lovely shooting star in the Martian sky. 

For poor VIPER, right away, there were problems. In 2022, an inspector general report criticized NASA for lacking “full visibility into the risks and their potential costs to the VIPER mission.” Before the rover’s preliminary design review in August 2020, Astrobotic warned NASA about the risk of “excessive vibration” between Griffin and VIPER during launch. This would necessitate either a change in VIPER’s design, or a change in Griffin’s design.

In March 2021, NASA announced a new total price for the mission: $430 million—not including lander. COVID’s contribution to the price at the time was $16.3 million (though it's fair to say the global lockdowns and resultant manufacturing headaches would contribute to many of the subsequent problems the VIPER team later encountered).

In any event, six months later, the VIPER rover was 15 kilograms over its mass margin, necessitating further changes in the Griffin lander. Concurrently, NASA seemed to get a little nervous about Astrobotic’s progress, and installed an overseer at the company’s facility. In all, this cost $9 million, and represented an agency unable to accept a 50-50 success rate on a now-much-pricier moon mission. 

Development continued. The VIPER team faced “vendor delivery issues and supply chain concerns,” according to a report by the GAO. “Key hardware deliverables” were a year and a half late, and some hardware “required remediations” that ate VIPER’s budget.

NASA soon delayed VIPER’s launch to November 2024. A 2024 GAO report explained that the agency wanted Astrobotic to do more testing on the Griffin lander’s propulsion system. But it seems like there’s blame to go all around: if NASA had not requested a delay for further lander testing, it is unclear how VIPER possibly would have been ready for launch in 2023. (It’s still not ready, after all.) Regardless, this added $91 million to the price of the lander, and another $75 million to the rover. 

In that same report, the GAO reported that the project was on track to exhaust its total funding by July 2024. That seems to have come to pass, and NASA announced on July 17 that it had canceled the VIPER mission. According to NASA Headquarters, if not for cancelation, the total anticipated cost of VIPER would have been $609.6 million—not counting the now $323 million lander—for a September 2025 launch at the soonest. (That’s the earliest Astrobotic’s Griffin lander will be ready.) 

The cancelation, says NASA, will save the agency $84 million. (It will continue the testing phase of the rover through thermal vacuum testing in October.) As for Astrobotic, the Griffin lander will now carry dead weight to the moon in place of VIPER, and the lander mission will be considered a technology demonstrator. Earlier this year, its previous lander, called Peregrine, failed to land on the moon.

Response to NASA’s announcement has been largely negative, but also disingenuous (or at least, confused). More than one critic has prefixed the word “only” to the $84 million that NASA will save.

Moreover, it is misleading to say the rover was “completely built,” and only a “few final tests” remain. Those tests aren’t formalities; they can and do turn up real issues with the spacecraft, and in general, a project's highest financial burn rate is during the integration and testing phase. Already, the project had reduced its subsystem tests to maintain its launch schedule. It is unclear if the estimated $84 million accounted for inevitable issues. 

However, if indeed engineers had managed to build a perfect rover, ready to fly, the total mission cost would still be $609.6 million—a $100 million more than anticipated, after its price had already doubled—on a mission promised initially for $250 million, and based on a mission that had already cost $100 million in development. The scandal isn’t that NASA canceled the mission. The scandal is that NASA waited this long. 

Building a moon rover is hard, and COVID dealt VIPER’s engineers some really bad hands. But NASA isn’t sitting on an ocean of money right now, and there has to be a line beyond which another dollar spent is a dollar too much. It is actually promising that NASA has not fallen prey to the sunk-cost fallacy. Earlier this summer, the agency likewise demonstrated some sense of fiscal resolve when it backed off its Mars Sample Return strategy, which was looking suddenly like an $11 billion mission sequence that wouldn’t see results until the 2040s.

The agency is responding to the Fiscal Responsibility Act of 2023, a debt ceiling agreement passed by Congress and signed into law last year by President Biden. Under the act, non-defense agencies saw spending capped in 2024 and 2025. NASA actually fared well compared to other offices of the federal government, but flat budgets mean there is no more money. (One could look holistically at NASA’s overall budget and find a lot of wasteful spending in human spaceflight, but there is an unofficial firewall between it and science; canceling SLS would not yield fortunes for robotic exploration.)

Absent Congress giving NASA additional money to complete the rover (on top of its current appropriation), other missions, and future missions, would have to suffer. Already, budget overruns on approved missions pushed the next competition for the medium-class New Frontiers program to 2026.

VIPER is not the only mission that has gone over budget. Most notably of late, Dragonfly, an $850 million mission to Titan, Saturn’s ocean moon, stands at $3.35 billion and counting. Would it have been approved at that price? Not a chance. The Dragonfly team has a list of excellent reasons why the mission’s price has risen, including COVID and budgetary games by NASA Headquarters, and one can argue that it’s still a bargain. I wouldn’t disagree. We are indebted to the past for its investment in fundamental science; our continued investment is what we owe the future. But I wasn’t on the proposal team for CAESAR, the runner-up for the 2019 New Frontiers selection. Dragonfly’s overruns mean two fewer New Frontiers missions will fly in our lifetime.

There is still hope for VIPER. Intuitive Machines, the Texas-based spaceflight company that successfully landed on the moon earlier this year, has expressed interest in resurrecting the rover. “Our position there is that VIPER science is important to lunar scientists and the future of the Artemis program, and it’s very important in terms of prospecting for volatiles and entrained water ice in the soil,” said Steve Altemus, the company’s CEO, according to SpaceNews. If that is the case, it is proof that NASA’s cancellation of the mission was a good decision. The mission will still fly, without other missions incurring the cost. If Intuitive Machines doesn’t fly the mission, NASA will still have made the right call. Egregious budget overruns hurt space science as much as egregious budget cuts. Let’s hope NASA is just getting started.