Before we send humans on the first foray to the Moon’s south pole—a mission currently planned for late 2025—scientists are gathering as much information as possible about this mysterious place. Starting in December 2022, a new NASA instrument called ShadowCam – 200 times more sensitive to light than previous lunar cameras and mounted on the Korean Danuri spacecraft – has allowed scientists to see the details of permanently shadowed areas on the Moon for the first time.
“We don’t know about these areas,” says Eunhyeuk Kim, principal investigator of the Danuri probe. Korea Aerospace Research Institute. “This is the first time we’ve… seen what it looks like inside, if it’s different from other normal craters.
At the Moon’s poles, the sun does not rise or set, but rather appears to slowly circle the horizon, occasionally disappearing behind a high peak or crater rim. This phenomenon occurs because the Moon is not tilted on its axis like the Earth, and the low-hanging Sun throws the landscape into a duality of light; some areas are illuminated most of the year, while others have no direct sunlight for eons. In the light we could place solar panels to support the human base and in the dark we can find means of survival.
“If there’s water ice, then that water ice can be extracted and used for consumables for astronauts, it can be used to protect astronauts from harmful cosmic radiation, and the water can be used as rocket propellant,” he says. David Kringa planetary scientist at the Lunar and Planetary Institute in Houston, Texas.
Among the coldest places in the solar system—down to minus 400 degrees Fahrenheit—Permanent Shadow Regions (PSRs) exist at both the moon’s north and south poles, though the south has more impact craters and extreme terrain that creates more pockets of shadow. These craters may contain deposits of materials called volatiles, which are water ices and other compounds such as carbon dioxide that would evaporate into gas at higher temperatures.
“Fifty years ago we had no idea there was ice on the surface of the moon,” he says Jacob Bleacher, a principal research scientist at NASA. These ancient deposits could be studied to create a “storybook,” he says, that tells the history of water in the solar system—and could even be used to usher in the next era of space exploration.
Bird’s eye view
ShadowCam images help NASA plan future surface exploration goals; for example, the brightness of the material in these pockets of darkness can be used to estimate how much ice they contain.
“We can look for frost, and one of the things we might see is changes in frost coverage,” says Mark Robinson, a planetary scientist at Arizona State University and principal investigator of ShadowCam. By tracking the frost throughout the year, scientists hope to learn how the volatiles move around the moon.
Much of what we know about this shadowy material comes from 2009, when part of a rocket was deliberately crashed into the moon’s Cabeus crater and the impact debris was measured. The spacecraft, called LCROSS, or the Lunar Crater Observation and Imaging Satellite, followed close behind the empty rocket stage when it hit the moon.
“We followed it up with the Shepherd spacecraft on a suicide mission to observe the impact up close with all of our instruments, and eventually we flew through the ejecta plume and landed on us,” says NASA. Anthony Colapreteprincipal investigator of the LCROSS mission.
Data transmission up to the last second, the spacecraft found a lot of water ice but also methane, ammonia, carbon dioxide and carbon monoxide ices. LCROSS also measured the flash of light produced when the 5,500-pound rocket stage hit the moon, which can tell scientists about the type of material it hit. The explosion was not as bright as expected, suggesting that the material in the PSR may have been “fluffier” than typical lunar soil.
“We know there are volatiles, but we don’t know if it’s ice dirt or dirty ice,” Bleacher says. Exactly what happens to this lunar material after it has sat in the shadows for billions of years is one of the things scientists want to figure out.
To learn more about what those shadows hold, NASA needs to take a closer look, so the space agency plans to send a new rover to the moon’s south pole — a robotic explorer equipped to tackle the moon’s frigid realms. In 2024, the Volatiles Investigating Polar Exploration Rover, or VIPER, is scheduled to land on the lunar surface.
Riding into the dark
NASA has not landed a spacecraft, either robotic or manned, on the moon since Apollo 17 in 1972. To return to the surface, the space agency relies on private companies to build lunar landers.
Intuitive machines and Astrobotic technology have built two commercially developed landers, named NOVA-C and Peregrine, to be launched later this year—each hoping to achieve America’s first moon landing since the Apollo program. Astrobotic is also building a larger lander that it plans to bring to the surface of NASA’s VIPER rover.
On most parts of the Moon, a two-week period of daylight is followed by 14 days of lunar night, making it difficult for spacecraft to survive. However, near the South Pole, where some areas are illuminated most of the time, solar panels on the sides of VIPER’s body will allow the rover to operate for more than a hundred days.
During this time, VIPER will enter several permanently shadowed areas and use a meter-long drill to obtain material for study using a suite of onboard science instruments.
The rover will first explore the shadows of a 50-mile-wide crater near the landing site. “It’s a very old, degraded crater. Our team estimated its age to be 3.6 to 3.7 billion years old,” says Colaprete, who is also the VIPER project scientist. “It has a beautifully beveled entrance from the north… It’s almost like it was designed for a rover to drive into.
The VIPER team, which operates the rover 24 hours a day, will enter the target shadowed areas twice, in what Colaprete calls a “double dip.” The first way is to map the area and the second way is to drill and examine the excavated material and look for ice. The team must complete both descents within the rover’s nine hours of battery life before taking it to higher ground to recharge using solar panels.
No one knows exactly what VIPER will find, but if the material in the PSR is in fact fluffy, the rover could get into some deep lunar dirt. To avoid getting stuck, VIPER was designed with larger wheels than the Mars rovers, about 1.6 feet wide, and each can spin and move up and down independently.
“He can walk,” says Colaprete. “If we dig in, we bury deep, soft. regolithWe can lift the wheels up like we lift a leg and put it forward and pull ourselves out of quicksand, if you will.”
At various locations near the moon’s south pole, in both sunny and shadowy locations, VIPER will look for clues to determine how much ice is on the moon and where it came from.
Mysteries of Moon Ice
In addition to providing a possible resource for astronauts on the lunar surface, ice deposits in the lunar shadows could contain information about where water ice and other volatiles come from.
“We have at least three, if not more, potential sources of volatiles,” he says Noah Petro, planetary geologist at NASA and science lead for the Artemis III mission. “Hydrogen is produced from the Sun and interacts with the lunar surface.” there are volatiles that come from the deep interior of the Moon, remnants of lunar formation; and then there are the volatiles that deposit meteorites and comets.’
When scientists figure out which of these sources produced lunar ice, they can learn something about how water is produced and distributed in the solar system. Missions like ShadowCam and VIPER will provide clues, but to find out for sure what secrets the moon’s ancient shadows hold, astronauts will need to travel to the moon’s south pole and collect key samples.
“The most impressive science experiment we’ve ever sent anywhere is human eyes paired with a well-trained brain,” says Petro.
Starting with Artemis III, humanity could enter a new era where humans exploring the South Pole of the Moon make transformative scientific discoveries.
“Understanding what’s happening on the moon today gives us an idea of what happened on the moon a billion years ago,” says Petro. “It gives us this guidebook for interpreting our own history, the history of the solar system, and indeed the history of other solar systems in the universe.”
