From the first Artemis mission to deliver astronauts to the moon, currently scheduled for 2025, to later efforts to establish a sustained lunar presence, “there’s a vast array of uses for robots on the moon,” said Joshua Mehling, NASA principal technologist for robotics.
In addition to moving people and equipment, robots are being developed to help NASA identify lunar resources and construct lunar landing pads.
Dull, dirty and dangerous
Terrestrial robots tend to perform jobs deemed too dull, dirty or dangerous for people. The same will be true on the moon.
Astronauts traveling to the lunar surface could rely on robots to perform routine inspections, sift through the lunar regolith and travel into craters or lava tubes.
“We have scenarios in which we would rather a robot do something than the crew because the crew’s time is more valuable spent elsewhere,” Mehling said. “The robots free up the crew for their top priorities.”
When crews leave the moon to travel to the lunar Gateway space station or back to Earth, robots can continue to survey the lunar landscape and maintain lunar infrastructure.
“There are a lot of opportunities to use robots both when the crew is there and when they’re not, because they’re a valuable extension of that human presence,” Mehling said.
Remote or autonomous?
Communications challenges loom large for lunar robotics.
“The remote nature of the lunar surface makes it difficult for direct control of robots by human operators on Earth,” Mehling said. “But at the same time, the nature of the tasks to be performed on the surface will require a high cadence of operation. That will necessitate new control paradigms and greater autonomy for our robots.”
NASA centers are developing hardware and software for lunar robotics including remote control and autonomy features.
“It’s not an either-or equation, where you have direct remote control or something is entirely autonomous,” Mehling said. “In fact, the sweet spot for lunar operations, certainly at the outset, is going to be a shared control or supervised autonomy.”
Mehling likens it to driver assistance technologies for cars. The vehicles are not fully autonomous, but they include features like lane assistance and adaptive cruise control that make the driver’s job easier.
At the same time, NASA centers are developing highly autonomous robots for future lunar missions. For instance, the Cooperative Autonomous Distributed Robotic Exploration (CADRE) project includes three shoebox-size rovers, a multistatic ground-penetrating radar and a base station slated to travel to the moon on the third Intuitive Machines mission in 2024.
“CADRE is a demonstration of multiple autonomous rovers and a base station working together as a team,” said Jean-Pierre de la Croix, Cadre principal investigator. “On every single experiment, we’re going to provide from the ground a high-level goal such as explore this area or do a distributed measurement along this path. Then, the robots will coordinate amongst themselves to do the individual tasks to achieve the high-level goal.”
Subha Comandur, JPL CADRE project manager, said CADRE will “show for the first time that rovers can work as a team cooperatively and autonomously” while performing experiments on the moon. “It will change the way we do exploration,” Comandur added.
In the future, instead of sending one large rover to explore the moon, “the question will become how many robots we send and what will they do together,” Comandur said. “The ground-penetrating radar is just one science instrument. You could have many more such applications. And these sorts of robots can take on hazardous or tedious tasks like drilling, collecting samples, processing them and searching for water and minerals.”
Prospecting for water
Another demonstration of autonomy has been developed by NASA’s Kennedy Space Center and the Biological Computation Lab at the University of New Mexico. Robots, known as Swarmies, are equipped with webcams, GPS, Wi-Fi antennas and sensors to search for water. Like ants that cover a large area to look for food and water, Swarmies communicate their paths to the other Swarmies.
“It’s difficult to manually control a large swarm of robots obviously,” Kurt Leucht, senior software engineer at the NASA Kennedy Space Center Swamp Works, said May 15 at the Space Tech Expo in Long Beach, California. “The system is designed to be fully autonomous. It requires no operator inputs once it’s started.”
When water or other valuable in-situ resources are discovered, robotic excavators could collect it.
Terrestrial mining equipment is far too heavy for spaceflight. As a result, NASA engineers are developing lightweight lunar excavators about the size of a go-kart. The wheeled excavators are equipped with hollow cylinders and scoops on both ends for collecting regolith. To dump the regolith, the excavators reverse the rotation of the cylinders.
“It’s a simple yet very innovative design and it works well even in low gravity environments,” Leucht said.
Withstanding the cold
Temperature extremes pose another challenge for lunar robotics.
To cope with the lunar night, which lasts about 14 Earth days and dips to minus 130 degrees Celsius, Jet Propulsion Laboratory engineers developed the Cold Operable Lunar Deployable Arm. ColdArm is a 3D-printed titanium scoop equipped with features to measure soil properties.
While it looks like robotic arms on Mars rovers, ColdArm functions at cryogenic temperatures without heaters. In contrast to the Mars missions which expend time and energy warming up robotic arms before they function, “we can operate ColdArm at any time of the day,” said Ryan McCormick, ColdArm principal investigator. “The moon gets a lot colder than even Mars. Especially in the polar regions or permanently shadowed regions, this technology can be very enabling.”
ColdArm has been tested in a thermal vacuum chamber, where it functioned at a temperature of minus 173 Celsius. Next up is ColdArm vibration testing.
“We’re looking for opportunities to fly to the moon potentially as part of the Commercial Lunar Payload Services program,” McCormick said.
In spite of the environmental challenges inherent in lunar operations, NASA sees promising applications for terrestrial robotics technology.
“You can find a lot of analogies to manufacturing robots or exploration robots or warehousing robots here on Earth to the types of tasks we’ll be doing on the moon,” Mehling said. “NASA wants to provide an onramp for those types of technologies to their analogous tasks on the lunar surface. We think that partnership between robotic applications here on Earth and robotic applications on the moon will lead to faster development for the types of things we want to see long term.”
This article originally appeared in the June 2023 issue of SpaceNews magazine.