NASA Lunar Flashlight and RPM: How to Mine the Moon for Water

Lunar Flashlight mission will map the lunar south pole for volatiles.

Credit: Solar System Exploration Research Virtual Institute (SSERVI)

There's a lot of water on the moon, and NASA wants to learn how to mine it.

Space agency scientists are developing two separate mission concepts to assess, and learn how to exploit, stores of water ice on the moon  and other lunar resources.

The projects, called Lunar Flashlight and the Resource Prospector Mission (RPM), are notionally targeted to blast off in 2017 and 2018, respectively, and aim to help humanity extend its footprint out into the solar system.

"If you're going to have humans on the moon and you need water for drinking, breathing, rocket fuel, anything you want, it's much, much cheaper to live off the land than it is to bring everything with you," said Lunar Flashlight principal investigator Barbara Cohen, of NASA's Marshall Space Flight Center in Huntsville, Alabama.

It's therefore important to "understand the inventory of volatiles across the whole moon and their purity, and their accessibility in particular,"

Cohen said in July during a presentation at the NASA Exploration Science Forum 2014, a conference organized by the Solar System Exploration Research Virtual Institute at the agency's Ames Research Center in Moffett Field, California.

Solar sailing to the moon

Lunar Flashlight is working toward a possible launch date in December 2017, when it would blast off on the first test flight of NASA's Space Launch System (SLS) megarocket, along with several other piggybacking payloads.

Lunar Flashlight is a CubeSat mission, meaning the body of the spacecraft is tiny, about the size of a cereal box, Cohen said, but after it's deployed in space, the probe would get much bigger by unfurling an 860-square-foot (80 square meters) solar sail.

The spacecraft would then cruise toward the moon on a circuitous route, propelled along by the photons streaming from the sun.

Lunar Flashlightwould start orbiting the moon about six months after its launch, then spend another year spiraling down to get about 12 miles (20 kilometers) from the lunar surface.

The probe would then make about 80 passes around the moon at this low altitude, measuring and mapping deposits of water ice in permanently shadowed craters near the lunar poles. It would do this science work with the aid of its solar sail.

"We're going to use it as a mirror," Cohen said. "We're going to take the sunlight, bounce it off the solar sail into the permanently shadowed regions, and we're going to use a passive infrared spectrometer to collect the light from the permanently shadowed regions in wavelengths that are indicative of water frost."

Lunar Flashlight aims to find water ice that would be accessible to future explorers, be they human or robotic.

"What we're looking for is water right at the surface," Cohen said. "Could humans or their vehicles go into a permanently shadowed region and just scoop up the regolith and use what's at the surface to be able to extract water ice?"

Such deposits could provide drinking water for potential manned lunar outposts, and moon water could also be split into its constituent hydrogen and oxygen, prime components of rocket fuel, which could then spur and support exploration even farther afield, advocates of moon mining say.

Space mining advocates envision lunar extraction of minerals and ice as near-term objectives.

Credit: NASA

A water-mapping rover

While Lunar Flashlight would eye the moon from above, the Resource Prospector Mission (RPM) plans to send a rover onto the lunar surface to get an up-close look.

This rover would land at a yet-to-be-determined polar site and map surface and subsurface concentrations of hydrogen at two different locations, which would ideally be separated by at least 0.6 miles (1 km).

RPM would use a neutron spectrometer to measure water concentrations up to 3.3 feet (1 m) underground and a near-infrared spectrometer to make its surface measurements.

The solar-powered rover would roll into permananently shadowed regions, relying on batteries to keep working in the dark. It would likely have an operational lifetime of about one week on the lunar surface, mission officials have said.

Like Lunar Flashlight, RPM is geared to help enable future exploitation of water ice on the moon.

"How is the water ice distributed in the soil?" RPM project scientist Tony Colaprete of NASA Ames said at the Exploration Science Forum event.

"That's really what Resource Prospector is fundamentally about, is identifying, locating the 'ore' and understanding how to excavate it, how to get at it, and what does that cost in terms of energy."

The rover would also be equipped with a drill, allowing it to take samples from up to 3.3 feet (1 m) deep, Colaprete said.

Collected samples would be heated up in an oven, and the volatile materials such as water liberated by this process would be identified and quantified.

RPM also plans to extract oxygen from lunar dirt in a demonstration of in-situ resource utilization (ISRU). (This oxygen can be combined with hydrogen carried onboard to create water.)

"We need to take the first steps in demonstrating off of this world utilization of material," Colaprete said.

"There's a lot of technology demonstration in here that's not just applicable to the moon; it's applicable to any mission, to any surface where you want to manipulate materials."

Mars is one such place. Indeed, NASA is also planning to conduct an ISRU experiment on the Red Planet in the coming years.

In July, agency officials announced that its next Mars rover, slated to blast off in 2020, will carry an instrument that will generate oxygen from the carbon-dioxide-rich Martian atmosphere.

NASA LRO: Metamorphosis of moon's water ice explained

Panoramic lunar view taken by the Lunar Reconnaissance Orbiter Camera of the north rim of Cabeus crater. 

The distance from left to right is about 75 kilometers (46 miles). 

Image courtesy of NASA/GSFC/Arizona State Univ.

Using data gathered by NASA's Lunar Reconnaissance Orbiter (LRO) mission, scientists believe they have solved a mystery from one of the solar system's coldest regions—a permanently shadowed crater on the moon.

They have explained how energetic particles penetrating lunar soil can create molecular hydrogen from water ice.

The finding provides insight into how radiation can change the chemistry of water ice throughout the solar system.

Space scientists from the University of New Hampshire and NASA's Goddard Space Flight Center have published their results online in the Journal of Geophysical Research (JGR): Planets.

Lead author of the paper is research scientist Andrew Jordan of the University of New Hampshire's Institute for the Study of Earth, Oceans, and Space (EOS).

Discovering molecular hydrogen on the moon was a surprise result from NASA's Lunar Crater Observation Sensing Satellite (LCROSS) mission, which crash-landed the LCROSS satellite's spent Centaur rocket at 5,600 miles per hour into the Cabeus crater in the permanently shadowed region of the moon. 

These regions have never been exposed to sunlight and have remained at temperatures near absolute zero for billions of years, thus preserving the pristine nature of the lunar soil, or regolith.

Instruments on board LCROSS trained on the resulting immense debris plume detected water vapor and water ice, the mission's hoped-for quarry, while LRO, already in orbit around the moon, saw molecular hydrogen—a surprise.

"LRO's Lyman Alpha Mapping Project (LAMP), detected the signature of molecular hydrogen, which was unexpected and unexplained," says Jordan.

Jordan's JGR paper, "The formation of molecular hydrogen from water ice in the lunar regolith by energetic charged particles," quantifies an explanation of how molecular hydrogen, which is comprised of two hydrogen atoms and denoted chemically as H2, may be created below the moon's surface.

"After the finding, there were a couple of ideas for how molecular hydrogen could be formed but none of them seemed to work for the conditions in the crater or with the rocket impact." Jordan says.

"Our analysis shows that the galactic cosmic rays, which are charged particles energetic enough to penetrate below the lunar surface, can dissociate the water, H2O, into H2 through various potential pathways."

That analysis was based on data gathered by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument aboard the LRO spacecraft.

Jordan is a member of the CRaTER scientific team, which is headed up by principal investigator Nathan Schwadron of EOS.

Schwadron, a co-author on the JGR paper, was the first to suggest energetic particles as the possible mechanism for creating molecular hydrogen.

CRaTER characterises the global lunar radiation environment by measuring radiation dose rates from galactic cosmic rays and solar energetic particles.

Says Jordan, "We used the CRaTER measurements to get a handle on how much molecular hydrogen has been formed from the water ice via charged particles."

Jordan's computer model incorporated the CRaTER data and showed that these energetic particles can form between 10 and 100 percent of the H2 measured by LAMP.

The study notes that narrowing down that percent range requires particle accelerator experiments on water ice to more accurately gauge the number of chemical reactions that result per unit of energy deposited by cosmic rays and solar energetic particles.