NASA is pulling the plug on its only planned robotic mission to the Moon’s surface. The space agency has reportedly canceled its Resource Prospector — a small rover that was designed to excavate materials such as hydrogen, oxygen, and water from the lunar poles. The move has angered many lunar scientists, and now they’re calling on NASA’s new administrator to keep the program alive, claiming it’s a crucial mission to help return humans back to the Moon.

The main goal of Resource Prospector was to help NASA better understand what kind of materials are lurking at the Moon’s poles. Multiple lunar spacecraft have proven that water exists there in the form of ice, but we don’t know much about what this ice is like. Most of the data we have comes from NASA’s Lunar Reconnaissance Orbiter, which is in the Moon’s orbit, and a couple of spacecraft that purposefully crashed into the Moon to get quick measurements of the surface’s composition. The Resource Prospector would examine this water ice up-close for an extended period of time, learning more about its consistency and how much of it is out there.

“There are no other [NASA] missions being planned to go to the surface of the Moon.”

That vital information could drastically change how we plan future lunar missions. Scientists have proposed the idea of mining the water ice at the poles, to turn it into drinking water or rocket fuel. But we won’t know if we can even access this precious resource unless we send a robot up there to check out the area first, and now NASA has canceled its quickest way to find that out. “There are no other [NASA] missions being planned to go to the surface of the Moon,” Phil Metzger, a planetary physicist at University of Central Florida who is part of the science team for Resource Prospector, tells The Verge.

NASA released a statement after this story’s initial publication, saying that some of the instruments from the Resource Prospector mission would be used in other missions that would land on the moon later. The response was oddly vague about the fate of the rover. “We’re committed to lunar exploration,” said Jim Bridenstein, NASA’s recently sworn-in administrator. “Resource Prospector instruments will go forward in an expanded lunar surface campaign.” The tweet, like the statement, made no reference to the rover itself.

The cancellation seems at odds with the current administration’s plans for NASA. In November, President Donald Trump directed the space agency to return humans back to the Moon as part of Space Policy Directive 1. That’s why a group of scientists with the Lunar Exploration Analysis Group, or LEAG, which advises NASA on lunar exploration, wrote a letter to Bridenstine, urging him to reverse the decision on Resource Prospector. “We wanted to make him aware so he could do his own investigation as to why Space Policy Directive 1 is being ignored,” Clive Neal, an engineering professor at the University of Notre Dame and LEAG Emeritus Chair, tells The Verge.

“We wanted to make him aware so he could do his own investigation as to why Space Policy Directive 1 is being ignored.”

The Resource Prospector has two main components: a lunar lander and a rover with a drill, which would roam the Moon’s surface digging up materials for analysis. The mission was not fully funded yet, but NASA has been working on it for four years. Engineers have been perfecting the designs for the hardware, as well as figuring out what kind of instruments they want to use. They even tested out a prototype rover here on Earth in 2015 and 2016.

The concept was ready to go through a major design review by the end of the year, with the aim of launching in 2022, according to Neal. “It’s far enough along that it’s a real mission,” he says. But on April 23rd, NASA told the Resource Prospector team to cease all operations by the end of May, according to the LEAG letter.

Metzger, who confirmed the cancellation to The Verge, speculates the trouble started when the mission was transferred to a different directorate within NASA. Originally, Resource Prospector was being funded with money set aside for human exploration. Then it got moved to the directorate that funds science missions instead. But Resource Prospector is not doing straight science; it’s doing economic science, Metzger says. Even though it’s a robotic mission, it doesn’t quite fit within the science directorate’s priorities or budget, which is why it was likely canceled.

Metzger can only speculate as to why the mission was moved. “I don’t really know what the motive was, but I’m guessing it was probably budget related,” he says. NASA’s human exploration program is currently working on a giant new rocket, the Space Launch System, which takes up a sizable portion of the annual human exploration budget. It’s also behind schedule, so it’s possible Resource Prospector was moved to the science directorate to free up funds to prevent further delays.

The mission should have stayed within the human exploration program all along, says Metzger. Resource Prospector would ultimately inform what NASA astronauts will do on the Moon when they get there. Astronauts will be spending a lot of time studying the geology of the region, but also developing new technologies to utilize the Moon’s resources, like the water-ice deposits.

Those deposits may be used in a lot of different ways. Water can be split apart and made into rocket propellant, which could then be used to launch spacecraft to and from the lunar surface. That way NASA wouldn’t need to carry all of its fuel from Earth for a Moon mission, which can be both heavy and costly. Additionally, there are indications that carbon is lurking in this water ice. That could be used to make plastics to shield habitats against radiation. “If we can demonstrate that we can access the water on the Moon, then we can start to design the equipment that will mine it and deliver it to the outpost,” says Metzger.

“If we can demonstrate that we can access the water on the Moon, then we can start to design the equipment that will mine it.”

And Resource Prospector could help jumpstart a vibrant lunar economy. Numerous private space companies are interested in mining the Moon for water and minerals. And if the industry is able to make enough propellant with this water, they could fill up multiple “space depots” — which could be used to refuel spacecraft in orbit around Earth and the Moon. Such depots could help lower the cost of sending satellites to space, and even make going to Mars a more affordable endeavor. A Mars rocket could fuel up at one of these depots before making the long journey to the Red Planet.

Of course, it could turn out that the water isn’t easily accessible at all, and that could change a lot of plans within the industry. “Right now, we don’t know whether those business cases will close,” says Neal.

Either way, Resource Prospector would tell us a lot about what’s lurking on the Moon, and it seems to fit with what the current administration wants. After the election, Trump’s NASA transition team asked the space agency for its plans to excavate the Moon, and NASA touted the Resource Prospector as a vital mission for that purpose, according to Motherboard. And Administrator Bridenstine tweeted yesterday that he’s looking forward to returning to the Moon, starting with “an aggressive robotic program.” But without Resource Prospector, NASA doesn’t have a fleshed out program to send robots to the Moon’s surface. The space agency plans to start funding small and medium-sized landers in the near future, but no robotic surface mission is as far along as Resource Prospector.

The Trump administration has also said that it wants to increase NASA’s partnerships with the commercial space industry. Resource Prospector did just that: it’d help inform companies that want to mine the Moon, and NASA planned to use a commercial lander to get the rover to the lunar surface, Metzger claims.

Canceling Resource Prospector means starting from scratch when it comes to sending astronauts back to the Moon. “People have been talking about, How can we do Moon missions as fast as possible? Well, this is the only mission we’ve been developing to go to the Moon,” says Metzger. “It’s actually a super important mission and I can’t think of anything more important to do on the Moon than this.”

Updated 5:45PM ET: Adds NASA’s oddly vague statement.