Is there water on the moon? This lunar flashlight may find out.

Fifty years have passed since the Apollo 17 mission first put humans on the moon. While people haven’t been back since, a new satellite launched in December 2022 could confirm for the first time what many suspect is lurking on the South Pole of the moon: water.

On Earth, we take water for granted, but it’s one of the most valuable resources to space exploration. Water is heavy, expensive and inefficient to transport because it takes up space. If it exists on the moon, perhaps astronauts could drink it on future missions, minimizing the need to transport it from Earth. Water could also be used for watering plants in the event astronauts do an extended stay on the moon and want to grow crops. Water can also be split into hydrogen and oxygen, allowing oxygen to be used for breathing and hydrogen as rocket fuel.

NASA’s satellite is the size of a briefcase (and referred to as a CubeSat—short for Cube Satellite). Known as Lunar Flashlight, its goal is to search for surface ice on the South Pole of the moon by beaming four lasers of near-infrared light that can only be absorbed by water ice. If less light is reflected back to the spacecraft than expected, that means there’s water lurking in the craters.

“The South Pole is a much nicer place for water resources than the North, because the South has a lot of craters that are permanently shaded,” says Jud Ready, who is involved in the mission as Lunar Flashlight’s principal investigator.

This mission is the first attempt to look for ice using a laser reflectometer, although Ready says that previous NASA missions have suggested that the moon may have frozen water at the South Pole. Lunar Flashlight plans to map out some of these areas at spatial resolutions of 1-2 kilometers (around a mile) to provide more detail.

“We think from various different indirect measurements that it’s an area roughly the size of the state of Virginia covered with water,” says Ready, also a principal research engineer at Georgia Tech Research Institute. But what in form is the water? Frost? Snow? A glacier? “That’s what we’re aiming to find out.”

How Lunar Flashlight was built and tested

The Lunar Flashlight mission was conceived by NASA’s Jet Propulsion Laboratory and built by researchers at Georgia Tech who won a proposal to put the 30-pound CubeSat together. Ready says that around 40 people at the university worked on the project, including undergraduate and graduate students.

Beginning in August 2021, many different pieces of the CubeSat (such as solar panels, lasers and tiny rocket thrusters) arrived from all over the country and were put together in a “nicely renovated attic of one of our oldest buildings on campus.”

Lunar Flashlight has plenty of high-tech attributes. For one, it’s completely solar powered. Its lasers run on a large lithium-ion battery that is charged by solar panels on the satellite. Another battery operates a radio and a computer. Lunar Flashlight is also the first planetary CubeSat mission to use an eco-friendly propellant called ASCENT, which was developed by the Air Force Research Lab. ASCENT is less toxic and safer than another common spacecraft propellant called hydrazine.

After assembling the spacecraft, the Georgia Tech team tested Lunar Flashlight to make sure it could survive strong vibrations created from the launch, withstand extreme temperature changes and operate its communication system and lasers. The team even came up with a way to test the lasers by firing them at a mirror at the other end of the lab so that they would bounce back, convincing the team that “we had a reasonable chance of the light hitting the detector in the right spot,” Ready says.

A small aircraft with big advantages

Ready says there are plenty of perks to using a small spacecraft for missions once reserved for larger spacecraft. CubeSats are cheaper and faster to develop and are great ways to experiment. “This is a way to demonstrate different technologies in space,” he says. Whether it’s lasers or a propulsion system, “future missions can say, ‘Hey, that’s not a risky technology. Let’s bolt it on. We’ll just do it.’ And that lowers the risk profile of the overall mission.”

The other advantage of a small satellite is that “it’s very easy to get a ride to orbit.” “There’s always a few extra kilograms to have a CubeSat or two as a secondary payload on whatever big school bus-size satellite is getting launched,” Ready says.

This is a way to demonstrate different technologies in space, and that lowers the risk profile of [future missions].

—Jud Ready, principal investigator, Lunar Flashlight mission

Lunar Flashlight, for example, launched on a SpaceX rocket, sharing a ride with the HAKUTO-R Mission 1, run by Japanese company ispace. Although the moon is “only” about 250,000 miles from Earth, Lunar Flashlight had to travel farther than that because it doesn’t have enough thruster power to stop, given its small size. Now, Lunar Flashlight is being re-positioned into a “high Earth orbit” so that it can accomplish periodic flybys of the lunar South Pole to collect data.

Mission control, a delicate operation

Georgia Tech also functions as the mission operations center, with graduate and undergraduate students monitoring signals to make sure everything is going as intended.

Lunar Flashlight requires regular adjustments to align the solar panels with the sun. It’s essential that the battery is fully charged when the time comes to start firing lasers over the South Pole because every time a laser fires, the battery is sucked “all the way down to zero,” Ready says.

In addition, when researchers want to communicate with Lunar Flashlight, they need to make sure its antennas are pointed at Earth. Communication between mission control and the CubeSat is made possible through NASA’s Deep Space Network. For example, when Georgia Tech sends out a command to Lunar Flashlight, such as “fire a thruster for five seconds,” Lunar Flashlight responds to the long-distance call on the Deep Space Network via giant antennas at three facilities around the world, a strategic placement that allows constant communication with spacecraft as the Earth rotates.

Lasers scheduled to fire in May

Ready says that Lunar Flashlight should be ready to begin firing its lasers in May 2023. The plan is for Lunar Flashlight to do at least 10 orbits around the North and South Poles, firing lasers once a month. It will swoop over the South Pole, shine its lasers, charge solar panels using the sun, then point toward the Earth to transmit the data. The team has already fired the laser several times into space to ensure it works.

If water is found, maybe one day it will be used for gardening or consumed by astronauts. But the information it could provide about the universe is priceless. “There’s a scientific usefulness to it because that water is primordial water,” Ready says. “It’s been there for 4 or 5 billion years, since the moon and the Earth became, and nothing’s changed it. Any microbes found in the water were deposited there by comets.” Examining the ice, in that case, “would answer the question, ‘Where did life come from?'”

The information gathered will inform a future expedition to the South Pole, known as the Artemis III expedition. It is currently planned for 2025 and will involve humans visiting the region for the first time.

Ready says that Lunar Flashlight might be small, but it’s reliable—an important quality in spacecraft. For Cube Satellites, “you want them to operate for as long as intended or even longer. That’s the type of spacecraft we put together, and we’re really proud of it,” Ready says.

View where Lunar Flashlight is in real-time on NASA’s 3D interactive Eyes on the Solar System website.

Lead image of the Lunar Flashlight’s lasers scanning a shaded lunar crater for the presence of ice courtesy of NASA/JPL-Caltech.