NASA built a Moon rover but can’t afford to get it to the launch pad

NASA has spent $450 million designing and building a first-of-its-kind robot to drive into eternally dark craters at the Moon's south pole, but the agency announced Wednesday it will cancel the rover due to delays and cost overruns.

"NASA intends to discontinue the VIPER mission," said Nicky Fox, head of the agency's science mission directorate. "Decisions like this are never easy, and we haven’t made this one, in any way, lightly. In this case, the projected remaining expenses for VIPER would have resulted in either having to cancel or disrupt many other missions in our Commercial Lunar Payload Services (CLPS) line."

NASA has terminated science missions after development delays and cost overruns before, but it's rare to cancel a mission with a spacecraft that is already built.

The Volatiles Investigating Polar Exploration Rover (VIPER) mission was supposed to be a robotic scout for NASA's Artemis program, which aims to return astronauts to the lunar surface in the next few years. VIPER was originally planned to launch in late 2023 and was slated to fly to the Moon aboard a commercial lander provided by Pittsburgh-based Astrobotic, which won a contract from NASA in 2020 to deliver the VIPER rover to the lunar surface. Astrobotic is one of 14 companies in the pool of contractors for NASA's CLPS program, with the goal of transporting government-sponsored science payloads to the Moon.

But VIPER has been delayed at least two years—the most recent schedule projected a launch in September 2025—causing its cost to grow from $433 million to more than $609 million. The ballooning costs automatically triggered a NASA review to determine whether to proceed with the mission or cancel it. Ultimately, officials said they determined NASA couldn't pay the extra costs for VIPER without affecting other Moon missions.

"Therefore, we’ve made the decision to forego this particular mission, the VIPER mission, in order to be able to sustain the entire program," Fox said.

“We're disappointed," said John Thornton, CEO of Astrobotic. "It's certainly difficult news... VIPER has been a great team to work with, and we're disappointed we won't get the chance to fly them to the Moon."

NASA said it will consider "expressions of interest" submitted by US industry and international partners by August 1 for use of the existing VIPER rover at no cost to the government. If NASA can't find anyone to take over VIPER who can pay to get it to the Moon, the agency plans to disassemble the rover and harvest instruments and components for future lunar missions.

Scientists were dismayed by VIPER's cancellation.

“It's absurd, to be honest with you," said Clive Neal, a planetary geologist at the University of Notre Dame. "It made no sense to me in terms of the economics. You’re canceling a mission that is complete, built, ready to go. It's in the middle of testing."

"This is a bad mistake," wrote Phil Metzger, a planetary physicist at the University of Central Florida, in a post on X. "This was the premier mission to measure lateral and vertical variations of lunar ice in the soil. It would have been revolutionary. Other missions don’t replace what is lost here."

Built with nowhere to go

Engineers at NASA's Johnson Space Center in Houston finished assembling the VIPER rover last month, and managers gave approval to put the craft through environmental testing to make sure VIPER could withstand the acoustics and vibrations of launch and the extreme temperature swings it would encounter in space.

Instead, NASA has canceled the mission after spending $450 million to get it to this point. "This is a very tough decision, but it is a decision based on budgetary concerns in a very constrained budget environment," Fox told reporters Wednesday.

VIPER is about the size of a golf cart, with four wheels, headlights, a drill, and three science instruments to search for water ice in depressions near the Moon's south pole that have been shaded from sunlight for billions of years. This has allowed these so-called permanently shadowed regions to become cold traps, allowing water ice to accumulate at or near the surface, where it could be accessible for future astronauts to use as drinking water or an oxygen source or to convert into electricity and rocket fuel.

But first, scientists need to know exactly where the water is located and how easy it is to reach. VIPER was supposed to be the next step in mapping resources on the Moon, providing ground truth measurements to corroborate remote sensing data from satellites in lunar orbit.

But late parts deliveries delayed construction of the VIPER rover, and in 2022, NASA ordered additional testing of Astrobotic's Griffin lunar lander to improve the chances of a successful landing with VIPER. This delayed VIPER's launch from late 2023 until late 2024, and at the beginning of this year, more supply chain issues with the VIPER rover and the Griffin lander pushed back the launch until September 2025.

This most recent delay raised the projected cost of VIPER more than 30 percent over the original cost of the mission, prompting a NASA termination review. While the rover is now fully assembled, NASA still needed to put it through a lengthy series of tests, complete development of the ground systems to control VIPER on the Moon, and deliver the craft to Astrobotic for integration onto the Griffin lander.

The remaining work to complete VIPER and operate it for 100 days on the lunar surface would have cost around $84 million, according to Kearns.

A rendering of NASA's VIPER rover.

Credit: NASA

Kearns said it was possible the $84 million figure could grow if the VIPER mission faced another delay. If it didn't launch by November 2025, the mission's next launch opportunity would not come until the second half of 2026, when the solar-powered rover would have the proper lighting conditions at its polar landing site.

"So we were taking into account the cost it would take to continue VIPER, and also the risk that it would still be possible that either VIPER or Griffin would not be ready at the launch date that was desired in 2025," Kearns said.

NASA officials said they worried they would have to scavenge funding from other missions to pay for more VIPER cost overruns. The agency's science mission directorate is facing budget cuts, with its funding level this year nearly $500 million less than last year's budget, and $900 million below the White House's request.

"We cancel a half-billion dollar rover, that is built, to save $84 million, plus the mission costs," Neal said. "It still doesn't add up to me, but NASA is reacting to the situation they find themselves in because of Congress."

NASA's contract with Astrobotic for the Griffin lander mission remains in effect. The value of NASA's contract with Astrobotic increased from $200 million to $323 million since the initial award in 2020, partially to cover NASA's desire for additional testing on the Griffin lander to gain confidence the unproven craft could safely deliver VIPER to the Moon. Combining VIPER's development cost with Astrobotic's transportation and delivery contract brings the anticipated total mission cost to $932 million.

A disappointment

Astrobotic's first lunar lander, named Peregrine, failed to reach the Moon after launching in January. John Thornton, Astrobotic's CEO, told Ars on Wednesday that engineers have completed the investigation into what happened on the Peregrine mission. The inquiry confirmed what Astrobotic first thought—a helium valve in the spacecraft's propulsion system didn't reseat properly, causing pressure to rise in a propellant tank until it ruptured.

The Griffin lander is significantly larger and more complex than Peregrine. Kearns said NASA would like to see Astrobotic demonstrate a successful landing with the Griffin spacecraft, which could be used to deliver heavier cargo to the Moon than the landers available from other CLPS companies.

"The mission is still a go," Thornton said. "We have an opportunity to put some other payloads on this manifest, and we're excited about that. We've got some interesting ideas around that. One of the ones that we're looking at is an idea of putting our LunaGrid program on that lander."

Astrobotic's LunaGrid program involves deploying vertical solar arrays to generate electricity, an architecture that is particularly useful at the Moon's poles, where some high-elevation points receive near-continuous sunlight. The power generated from these locations could be distributed to landers and rovers in darkness nearby, allowing them to survive the two-week-long lunar night. Some elements of LunaGrid could now be demonstrated on the Griffin lander.

"It's a possibility of creating the first infrastructure on the moon with a pop-up deployable solar array, and the possibility of power infrastructure on the Moon," Thornton said in an interview with Ars. "We're basically trying to turn these lemons into lemonade, and I think we have that opportunity here. The business development side of me is interested and excited about that, but certainly it's been challenging news. We would rather be in a position to fly VIPER, but we're going to do the best with what we’ve got here."

Artist's illustration of Astrobotic's LunaGrid system, which would use vertical pop-up solar arrays to generate electrical power at the Moon's poles.

Credit: Astrobotic

NASA doesn't plan to add any of its own science instruments to the Griffin lander. Thornton said Astrobotic is open to ideas for commercial payloads that could fly on the Griffin mission, but with a launch potentially next year, there's little time to search for customers. "We will need to make a decision very quickly if we're going to be trying to make a push for another payload, or if we're going to be flying the lander as is," he said.

Last month, NASA's inspector general released a report on the CLPS program that highlighted rising costs and delays in the program. The CLPS contract with the largest cost growth was Astrobotic's delivery of the VIPER rover. The value of that contract rose by 62 percent after NASA asked Astrobotic to perform extra tests to mitigate the risks of using a new lander design to deliver a half-billion-dollar rover to the Moon.

NASA established the CLPS program in 2018 with the goal of fostering the nascent industry for commercial lunar missions, and to provide a cost-effective way to transport science payloads to the Moon. The first CLPS missions launched in January and February of this year, several years later than originally planned. Astrobotic's lander didn't make it, but a robotic lander from a Texas-based company named Intuitive Machines became the first US spacecraft to land on the Moon since 1972.

The first two CLPS missions were relatively modest, well short of the capability required to land a mission like VIPER.

“We and the companies have not yet accrued enough experience to properly understand how to smoothly deliver such a large and sophisticated payload as VIPER to the lunar surface," Kearns said.

Ceding leadership

NASA approved development of the VIPER rover after the agency canceled a similar mission named Resource Prospector in 2018, hours before former NASA Administrator Jim Bridenstine officially took the helm of the space agency. NASA changed its strategy to pursue commercial missions to the Moon, and the CLPS program was born.

VIPER was designed to answer some of the same questions as Resource Prospector: Where is the water ice? How much of it is there? How accessible is it?

"Everybody agrees that a serious prospecting campaign is crucial, and VIPER is the best start," Metzger wrote. "So now, if it is cancelled again (after Resource Prospector), we will get several more years of delay or longer. This will be harmful to sustainability in space exploration, to geopolitical challenges in space, and to the most important science. Congress needs to find the money to continue VIPER."

China plans to land astronauts on the Moon by 2030 and establish a lunar base called the International Lunar Research Station. An end goal of NASA's Artemis program is to support a sustained human presence on the Moon. "Part of making that happen is understanding where the resources are to properly locate the base, and yet, we've canceled the only mission that is doing that," Neal said.

"There is also geopolitical concern about nations competing over lunar resources," Metzger wrote. "We believe it is crucial for nations that support the international rules-based order to be leading in lunar exploration to influence and help establish fair and just policy. So it is vital for democratic nations to operate missions like VIPER as quickly as possible. Another couple years' delay could be disproportionately harmful to the world’s future in space."

"China has already stated that Chang’e 7 and 8, to be launched in ’26 and ’28 respectively, are going to the south pole to prospect for volatiles in order to inform China where to correctly site their International Lunar Research Station," Neal told Ars. "So we're ceding leadership. 'Hey, China, go for it.'"

This image shows the distribution of surface ice at the Moon’s south pole (left) and north pole (right), detected by NASA’s Moon Mineralogy Mapper instrument.

Credit: NASA

Kearns said some future CLPS missions, and eventually NASA astronauts, could go after similar goals as Resource Prospector and VIPER. But there's no one-for-one replacement on the books at NASA—no mission that combines VIPER's scientific instrumentation and ability to go into dark craters for up to two days at a time.

"The science that VIPER would get would far exceed the other CLPS missions that we have in line," Neal said.

NASA eventually plans to include lunar rovers for astronauts to drive on Artemis missions, and these could allow for human exploration of permanently shadowed craters harboring water ice. But the first rover won't fly until NASA's third Artemis landing, slated for 2030 or later.

If Congress doesn't save the VIPER mission, perhaps another international space agency or a commercial company could take over. But it would be expensive, and NASA hasn't allowed much time for outside entities to express interest. Thornton said Astrobotic probably doesn't have the money to pay for the rest of VIPER's testing and mission operations on its own. "That's a pretty tall order for us and anyone else," he said.