NASA's autonomous rovers are ready to roll on lunar terrain

As part of NASA's CADRE technology demonstration, three small rovers exploring the Moon will demonstrate their ability to drive as a team autonomously — without explicit commands from engineers — during tests in a clean room at the agency's Jet Propulsion Laboratory in December 2023. Credit: NASA/JPL-Caltech

Construction and testing has been completed on the CADRE rovers, which will map the lunar surface as a technology demo to show the promise of multirobot missions.

A trio of small rovers that explore the moon in sync with each other are headed for launch. Engineers NASAThe Jet Propulsion Laboratory in Southern California recently finished assembling the robots, which were then subjected to a punishing series of tests to ensure they could survive their jarring rocket ride into space and their journeys in the unforgiving lunar environment.

Part of the technical description called CADRECooperative Autonomous Distributed Robotic Exploration), the size of the suitcase each solar-powered rover carries. The rovers and associated hardware will be installed on the lander heading to the Moon's Reiner Gamma region. They will spend the daylight hours of one lunar day — the equivalent of about 14 days on Earth — autonomously exploring, mapping and conducting experiments using ground-penetrating radar that peers below the moon's surface.

Members of the CADRE assembly, test, launch and operations team pose with the finished hardware in a clean room at JPL in late January. Behind the three rovers are the situational awareness camera assembly, one of the deployers that land the rovers on the lunar surface, and the base station. Credit: NASA/JPL-Caltech

The goal is to show that a crew of robotic spacecraft can work together to accomplish tasks and record data as a team without explicit commands from mission controllers on Earth. If the project is successful, future missions could include teams of dispersing robots to take simultaneous, distributed scientific measurements to support astronauts.

Engineers have put in long hours of test driving rovers, building bugs to finalize the hardware, get it through testing, and prepare it for integration with the lander.

During a test in November 2023, one of NASA's CADRE rovers was shaken tightly on a shaker table. The vibration test was designed to show that the rover could withstand a rocket trip to the Moon on a lunar lander. Credit: NASA/JPL-Caltech

„We are very excited to prepare this tech demo for its lunar adventure,” said Suba Komandur, JPL's CADRE program manager. „Almost 2-2-4 hours of testing and sometimes re-testing is ongoing, but the team's hard work is paying off. We now know these rovers are ready to show what a team of small space robots can achieve together.

Shake and bake

While the list of tests is extensive, the most grueling include extreme environmental conditions to ensure the rovers can withstand the rigors of the road ahead. That includes having a bootie Thermal vacuum chamber It simulates the airless conditions of space and its extreme hot and cold temperatures. The hardware is strapped to a special „shaker table” that vibrates vigorously to ensure it survives the trip out of Earth's atmosphere.

A CADRE rover is being prepared for electromagnetic interference and compatibility testing in a special chamber at JPL in November 2023. Such testing ensures that the operation of electronic subsystems does not interfere with each other or with those on the lander. Credit: NASA/JPL-Caltech

This is what we submit, to 'shake' to simulate a rocket launch and 'bake' to simulate the extreme temperatures of space. Witnessing it in person is mind-blowing,” said JPL's Guy Zohar, the program's flight systems manager. “We use a number of carefully selected commercial areas in our program. We expect them to work, but we're always a little worried when we go to test. Happily, each test was ultimately successful.

Engineers also conducted environmental testing of three hardware components mounted on the lander: a base station that the rovers communicate with via mesh network radios, a camera that watches the rovers' activities, and deployer systems (see video below) that lower the rovers to the lunar surface via a fiber tether that is slowly ejected from a motorized spool.

Engineers tested a system that would land three small rovers on the lunar surface while NASA's CADRE (Cooperative Autonomous Distributed Robotic Exploration) technology arrived at the moon on the lunar lander. The test took place in a clean room at NASA's Jet Propulsion Laboratory in Southern California in December 2023. Three deployment systems will be installed on the lander – one for each rover. Credit: NASA/JPL-Caltech

Even putting the code to the test

Meanwhile, engineers working on CADRE's cooperative autonomous software have spent days on JPL's rocky, sandy soil. Mars yard with full-scale versions of the so-called rovers Development models. With flight software and autonomous capabilities, these test rovers showed they could achieve key goals for the program. They drove together in formation. Faced with unexpected obstacles, they adjusted their plans as a team by sharing updated maps and replanning combined routes. When one rover's battery charge was low, the entire team paused so they could continue together later.

Two full-scale development model rovers were tested at JPL's Mars Yard in August 2023 as part of NASA's CADRE tech demo. These tests ensured that the project's hardware and software worked together to achieve key goals. Credit: NASA/JPL-Caltech

The project conducted several drives at night under large floodlights so the rovers could experience the intense shadows and lights that approximate what they would encounter during lunar daylight.

After that, the team performed similar drive tests with flight models (the lunar rovers) in the JBL clean room. When the pristine surface there proved a bit slippery — a texture different from the lunar surface — the robots dropped out of formation. But they halted, adjusted, and advanced on their planned course.

„Handling curves — that's key to autonomy. The key is that robots respond to things that go off plan, then they re-plan and are still successful,” said JBL's Jean-Pierre de la Croix, CADRE principal investigator and head of autonomy. „We're unique on the moon. Going into context, of course, there will be some unknowns. We have done our best to prepare them by testing the software and hardware together in various scenarios.

Next, the hardware will be sent to Intuitive Engines for installation on a Nova-C lander. SpaceX A Falcon 9 rocket from NASA's Kennedy Space Center in Florida.