What’s better than one lunar rover? Three lunar rovers! In 2024, NASA plans to send a team of suitcase-sized wheeled robots to the Moon as part of the Commercial Lunar Payload Services (CLPS) program. Collectively called CADRE – Cooperative Autonomous Distributed Robotic Exploration – the rovers will spend one full lunar day (14 Earth days) exploring the Moon and showing off their unique capabilities.
The CADRE rovers are special – they are designed to be able to complete tasks without relying on humans to solve their problems. Mission control will send the rovers tasks, but it is the rovers’ job to figure out how best to carry them out while avoiding obstacles and conserving precious electricity.
“Our mission is to demonstrate that a network of mobile robots can cooperate to accomplish a task without human intervention – autonomously,” says Subha Comandur, the CADRE project manager at NASA’s Jet Propulsion Laboratory. “It could change how we do exploration in the future. The question for future missions will become: ‘How many rovers do we send, and what will they do together?’”
Some of the planned tests for CADRE include driving in formation while maintaining relative positions from each other, all while avoiding potentially dangerous or rough terrain. In another test, they will use stereo cameras to create a 3D topographical map of a 400 square meter area.
They will also test how the rovers would react upon losing one of the trio. Part of the use case for a swarm of rovers like this is that one rover could explore a dangerous but scientifically interesting area, like a lava tube, without endangering the entire mission. One rover could sacrifice itself for important but difficult-to-reach data, which it would beam back to its counterparts, and they would continue on their mission without it.
Engineer Kristopher Sherrill observes a development model rover during a test for NASA’s CADRE technology demonstration in JPL’s Mars Yard in June. Credit: NASA/JPL-Caltech.That is a vision of the future, of course. CADRE is a technology demonstration mission and not, primarily, a mission of exploration. The pack of rovers will remain reasonably close to the lander which carries them to the surface, which will act as a home base and communications center.
But the Moon is a hazardous environment nonetheless, and they will be pushed to their limits keeping their power supply and cooling systems in working order. Part of CADRE’s testing campaign will involve ensuring the cooperative autonomy software on board each rover has enough power to run their processors. Each of the rovers, and the home base, carry a processor already being used in another example of robotic teamwork: the Ingenuity helicopter on Mars, which has been scouting ahead of the Perseverance rover in Jezero Crater.
The lunar environment offers different challenges than Mars does, with its especially high daytime temperatures. The rovers will work in half-hour stints, then ‘sleep’ to recharge, radiating away heat and keeping their processors in good shape. Upon waking, they can share their respective working conditions with each other, choosing a leader to assign the next tasks, and carrying on with the mission.
Assuming all goes well, the rovers are carrying scientific instruments too. In particular, they have ground penetrating radar that can peer as deep as 10 meters below the lunar surface. Working in tandem, they will be able to create a 3D map of the subsurface that a single rover wouldn’t be able to do on its own.
Ultimately, CADRE will be a short mission. After two weeks, lunar night will spell the end of the rovers’ capabilities. Their solar panels will be shadowed and their power supply cut off.
But those two weeks promise to be a flurry of activity and provide a wealth of engineering and scientific data that will shape the future of robotic exploration. Someday, roving packs of robots may support humans in their exploration of the solar system, taking risks for science that a single explorer – human or robot – wouldn’t dare attempt alone.
Learn More:
NASA’s Trio of Mini Rovers Will Team up to Explore the Moon. JPL.
