Following a series of reconnaissance missions that found hydrogen and then water on the Moon, NASA is laying the groundwork for a lunar rover that would scout for subsurface volatiles and extract them for processing.

The heart of the proposed Resource Prospector Mission (RPM) is the Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE) payload, a technology development initiative that predates its official start two years ago in NASA’s Human Exploration and Operations Mission Directorate’s Advanced Exploration Systems Division.

Notionally targeted for launch in 2018, RPM would be NASA’s first attempt to demonstrate in-situ resource utilization (ISRU) beyond Earth. The agency has spent just north of $20 million on the project to date, but expects its investment to top out around a quarter of a billion dollars.

“The concept of RPM came up out of the need to fly RESOLVE and the near-term, close way to test that would be on the Moon,” said Jason Crusan, director of Advanced Exploration Systems at NASA headquarters in Washington.

“A lot of the technologies have broader use than just lunar, so RPM is not about a lunar mission per se. It’s just a convenient location to be testing the ISRU technology,” he said.

All NASA’s planning for eventual human missions to Mars depends on tapping the indigenous resources to make propellant for launching the return ship back to Earth.

RESOLVE, as well as a second ISRU payload slated to fly on NASA’s 2020 Mars rover, is intended to pave the way toward incorporating use of space resources into mission architectures.

“Even though [RESOLVE] is a lunar mission to look at water ice on the poles, it has ties to what we might also want to do on Mars,” said Bill Larson, the former head of NASA’s ISRU program at the Kennedy Space Center.

“This is a cheap way to do a precursor mission. It’s a way to not only learn a little bit more about the resources on the Moon, but test the technologies that we might need to go to Mars and try to assess in a similar fashion,” he said.

Resource Prospector is among a handful of NASA lunar initiatives, including an ongoing solicitation for companies interested in tapping agency personnel, equipment, facilities and software to develop landers. NASA expects to select one or more partners for unfunded Space Act Agreements in April for its so-called Lunar CATALYST program.

While NASA intends to partner with international space agencies for Resource Prospector’s rover and lander, if those plans fall through the agency might consider a commercial alternative, Crusan added.

NASA intends to cap RPM costs at $250 million, including the launch vehicle, which has not yet been selected. Additional contributions are expected from international partners and potentially commercial firms as well. Discussions with Canada for a rover are underway, Crusan said.

Other potential partners are the Japan Aerospace Exploration Agency, which is considering providing a lander, and the Korean space agency, which has discussed a lunar orbiting communications satellite and science instruments.

Partnership agreements are expected to be finalized this year, Crusan said.

NASA expects to spend about $16.8 million for the program for the fiscal year that began Oct. 1, including costs of 68 full-time employees. In 2012 and 2013 , the agency spent a combined $18 million. NASA’s Ames Research Center in Mountain View, Calif., is overseeing the mission.

The idea is to have the rover scout for areas with high concentrations of subsurface hydrogen and then drill out samples for heating and analysis. The big payoff would be water, although RESOLVE also will be equipped to extract oxygen from the lunar regolith and process it with hydrogen to make water.

“Water is just huge in anything. It’s life support, but it’s also propulsion, and propulsion is the big bang for the buck for ISRU,” Larson said.

“If we had water on the Moon that was easily accessible, you could start to set up fuel depots based on lunar propellant. It’s a lot easier to bring water up out of the one-sixth gravity well of the Moon than it is to bring it up out of the one gravity well of Earth,” he said.

If the concentration of water in a soil sample is as much as even 1 percent by mass, project managers plan to recondense the vapor to form a droplet for public relations and educational purposes.

If the samples come up dry, an alternative ISRU demonstration is planned.

“The Moon is 42 percent oxygen by mass in the regolith itself. In the minerals, there is oxygen,” said Jacqueline Quinn, RESOLVE project manager at the Kennedy Space Center.

“We can take the sample, heat it to over 900 degrees Celsius and pass hydrogen over it in a reducing environment. Then we liberate the oxygen from the granular material and it joins with hydrogen and creates water,” she said.

In an operational mission, water molecules could be further processed by electrolysis to produce oxygen for breathing or for propellant, while the hydrogen is recirculated back into the system.

“While that doesn’t give us all the fuel we would need, when you look at a launch vehicle sitting on the launch pad, two-thirds of the mass is usually liquid oxygen. We can buy down most of the propellant mass fraction for any vehicle by simply making oxygen on the lunar surface,” Larson said.

“The holy grail, of course, is water and the ability to make methane or liquid hydrogen, but it’s not a bust if you must make oxygen on the lunar surface,” he added.

RESOLVE engineers will not have much time for their demonstration. The lunar polar regions targeted for study spend long periods in darkness, a showstopper for the solar-powered rover. Without heaters to keep its electronics warm, once the rover shuts down it is not likely to revive. RESOLVE, which will be remotely operated by control teams on Earth, is expected to run for six to 10 days.

“We can get a lot of information in that time,” Quinn said.

Engineers plan to get the rover off the lander as quickly as possible and drive it at least 1 kilometer to search for regions with high hydrogen signals. Instruments on lunar orbiters already have identified potential hydrogen-rich areas, though the maps show detail only to about 60 kilometers. RESOLVE’s instruments will be able to fine-tune that measurement down to 1 meter.

“This is just that first prospecting step that you have to take before you begin to seriously consider, ‘Is there enough water there to go mine?’” Larson said. “It’s very analogous to the Earth mining process.”

A review to assess if the mission is ready to move forward is planned for this spring.

“We’ve demonstrated in field tests to advance our readiness and learn how to do this,” Quinn said. “It’s obvious that we’re ready to move to the next step to flight.”