The Volatiles Investigating Polar Exploration Rover dubbed VIPER is headed to the moonâ€™s south pole in late 2023 to search for resources that could sustain future human settlements in space. The NASA rover will travel to areas of the lunar surface that have never seen sunlight to map and analyze concentrations of water ice in near real-time. The distribution and availability of water could have big implications for NASAâ€™s Artemis program, which has the goal of returning humans to the moon by 2024.
â€œIt’s kind of mind-blowing when you think about the fact that we’ve got rovers going all over Mars and we have never sent a rover to the moon,â€ says Tracy Gregg, a planetary volcanologist at University at Buffalo College. â€œWe sort of skipped over that partâ€”we sent landers and then we sent astronauts with a dune buggy.â€
In September, NASA announced that VIPER will touch down just west of Nobile, a crater near the moon’s south pole chosen for its terrain and potential for hosting water. To prepare for that occasion, here are five things you should know about NASAâ€™s first lunar rover:
VIPERâ€™s Main Purpose Is to Search for Water
Scientists already know that frozen water is trapped at the moonâ€™s south pole from remote sensing data. The Lunar Crater Observation and Sensing Satellite confirmed the presence of water ice at the moonâ€™s south pole in 2009. But exactly where that water is and how it got there remain a mystery. The roverâ€™s meter-long drill will offer an in-depth look at lunar soil that scientists have been limited to assessing remotely. â€œTo really get at the heart of some of these questions, we need to get to the surface,â€ says Anthony Colaprete, VIPERâ€™s project scientist at NASAâ€™s Ames Research Center. â€œThat’s where the VIPER rover comes in.â€
Water is a critical resource not just for human consumption, but for space exploration. Water can buffer humans from radiation and can be used to make rocket fuel and breathable oxygen. â€œIf there’s a way to avoid shipping water through the solar system, and instead find water where you are, suddenly space travel and having humans on the moon for extended periods of time becomes feasible,â€ says Gregg. She notes that launching a Mars-bound rocket from the moon rather than from Earth is potentially cheaper because the effort would require a fraction of the fuel, but it would only be possible if the moon had enough water.
Based on remote sensing data, NASA suspects the moonâ€™s soils could contain hundreds of millions of gallons of frozen water. Scientists think itâ€™s unlikely the rover will find water ice in large chunks or sheets like those found on Earth. Instead, water will likely be in small fragments within the lunar dust. â€œIf the water is literally frozen onto the outside of these lunar dust particles, that’s fairly accessible,â€ says Gregg. â€œYou shovel it into a heater, and the water melts and you collect the water and the and the dirt is left behind. What’s harder would be if the water is more chemically bound to the lunar materials, and then it’s not just a matter of an oven, then you’ve actually got to do chemistry.â€ That doesnâ€™t mean water will be impossible to accessâ€”it will just be more costly and time consuming to obtain.
VIPERâ€™s primary goal is to assess what resources the moon can provide for future missions, but the characteristics of the moonâ€™s polar water could even provide insight into the presence of the water on Earth and elsewhere in the inner solar system. The roverâ€™s samples could help identify the origin of the moonâ€™s water, which may have arrived on an asteroid or comet before getting trapped in icy shadows.
â€œI don’t know what we’re going to find yet,â€ says Colaprete. â€œWe go into these things as best we can with our eyes wide open because we will learn things we did not anticipate.â€
VIPER Can Endure in Some of the Coldest Places in the Universe
The rover will look for frozen water ice in the only place the substance could survive on the moon: places where the sun never shines. The moonâ€™s axis has only a slight tilt compared to Earthâ€™s, which means the sun doesnâ€™t rise as high on the horizon and leaves basins of craters in a permanent shadow. Because the moon lacks the Earthâ€™s insulating atmosphere, surface temperatures reach a sweltering 225 degrees Fahrenheit during the day. At night and in permanently shadowed areas, the lunar surface drops to -400 degrees Fahrenheit, making the moonâ€™s polar craters some of the coldest places in the universe.
â€œIf the ice is there, and it’s there in any quantity, that’s the likely place you’re going to find it,â€ says Thomas Watters, senior scientist at the Smithsonian National Air and Space Museum. Any water deposited on the moon by an asteroid impact, for example, would have immediately evaporated in the sunlight. Only water that settled in sunless crater basins would survive in these cold traps. VIPERâ€™s components are designed to withstand extreme temperatures, but the rover must run heaters to stay warm enough to function in shadowed areas. Unlike Perseverance and other nuclear-powered robots, VIPER will have to stay warm using energy generated from solar panels alone.
â€œGoing into the unknown for the first time, so many unknown questions will be answered,â€ says Colaprete. â€œThat moment that we go into that dark crater that’s never seen the light of day 3 billion years or so…thatâ€™s what I’m most excited for.â€
VIPER Has Custom-Made Tools for the Moon
VIPER will spend part of its time soaking up the energy from its three solar panels, and part of its time using headlights to navigate the craters of the south pole. The rover must maintain enough power to venture into dark craters and to make it back to sunlight before it dies.
Because VIPER is â€œgoing to a place that is unlike anything we’ve explored before,â€ says Colaprete, â€œthe rover is quite distinct.â€ The moonâ€™s crater-pocked landscape poses a challenge to the golf-cart-sized rover, which can comfortably cruise a slope of up to 15 degrees and handle a slope of 25 or 30 degrees when necessary. VIPERâ€™s onboard cameras will help rover operators avoid rocks and other hazards, in addition to capturing images of the lunar surface. The mobile robot has four independently controlled wheels, those solar panels and that meter-long drill that will cut samples of lunar soil to be analyzed by onboard spectrometers.
The neutron spectrometer is â€œkind of like the bloodhoundâ€ of the rover, explains Colaprete. It can sense neutrons leaking out of the soil as the robot cruises the landscapeâ€”and can pick up on hydrogen atoms as deep as one meter, which could be an indication of water. The near-infrared spectrometer assesses minute changes in the color of lights from the lunar surface, which could also reveal the presence of water or other volatile compounds. VIPERâ€™s mass spectrometer measures gases released from the moonâ€™s surface, which could be kicked up by the rover as it agitates the moonâ€™s top layer of soil.
VIPER Will Hibernate to Survive
Because no satellites that could be used to relay communications to Earth orbit the Moon, VIPER needs a direct-to-Earth radio link. That means the rover needs to avoid large landscape features like high mountains or steep crater rims which would block the communication signal. And when the moonâ€™s south pole rotates away from view, which happens for two weeks of every month, the rover must wait out in an identified â€œsafe havenâ€ location until communication can resume.
These safe havens are particularly secure, sunny spots so that the rover can glean enough energy to survive stretches of darkness. VIPER needs regular access to sunlight, as it canâ€™t survive more than 72 hours of continuous darkness. Often, the safe havens are elevated areas where slices of sunlight can reach the rover for the maximum time possible. While parked in such a location, â€œmost of the time the rover is just sitting there in the sun, basking, just relaxing,â€ says Colaprete. When darkness descends and temperatures drop, the rover shifts into hibernation, using just enough power to keep warm and stay alive.
The mission is scheduled during the summer season on the moonâ€™s south pole to maximize periods of life-giving daylight. NASA hopes to get 100 days out of the mission, which will span November 2023 through March of 2024. As the summer draws to a close on the moon, periods of darkness will grow longer and longer until VIPER can no longer generate enough power to survive.
VIPER Will Rove in Near Real-Time
Unlike rovers on Mars missions, VIPER will operate close to Earth, allowing quicker communication. Rovers on Mars took up to 20 minutes to send commands to Earth, while VIPERâ€™s latency will be a mere 6 to 10 seconds.Â
â€œThe travel time between issuing commands from Earth and the rover receiving that command is just a couple of secondsâ€”think about a laggy cell phone call,â€ says Gregg. â€œIt’s going to be like a video game, almost, being able to drive this thing and react almost immediately to the data and to what you see on the surface.â€
Mars rovers carry out a series of pre-planned commands alone on the planetary surface, while VIPER operators stop, move and reorient the rover every 15 feet depending on what they see via the roverâ€™s cameras. As soon as the lunar rover samples are analyzed in an area, NASA scientists can decide within minutes about where to drill next. â€œIt allows us to react and plan and optimize our observations in ways that we wouldn’t learn much usually done over a much longer period of time for example with Mars rovers,â€ says Colaprete. â€œThat’s a really unique and exciting aspect of this mission.â€