Jet Propulsion Lab rovers will conduct autonomous experiments to test viability of mostly independent robotic work in space.

After years of research and development, the National Aeronautics and Space Administration announced that its CADRE mini-rovers will soon arrive on the Moon aboard a lunar lander to test the viability of cooperative robotics in future exploration of celestial bodies.

Developed by NASA's Jet Propulsion Laboratory (JPL) in Southern California, the Cooperative Autonomous Distributed Robotic Exploration or CADRE project will see a network of small rovers working together to explore the Moon in an extraplanetary experiment to determine how functional these devices will be without constant monitoring or input from humans.

"Our mission is to demonstrate that a network of mobile robots can cooperate to accomplish a task without human intervention – autonomously," said CADRE Project Manager at Jet Propulsion Lab, Subha Comandur.

NASA/JPL-Caltech

The first iteration of JPL's autonomous rover, the Autonomous Pop-Up Flat Folding Explorer Robot that eventually evolved into the four-wheeled CADRE edition.

A follow-on from JPL's Autonomous Pop-Up Flat Folding Explorer Robot (A-PUFFER) rovers, which developed an initial version of the multiagent autonomy software that CADRE will be utilizing on the Moon; what was initially the size of a shoebox has grown to roughly the size of a carry-on suitcase, and better aligns with the tasks that NASA hopes it will accomplish.

Slated to arrive aboard a lander sometime in Spring this year, as part of NASA's Commercial Lunar Payload Services (CLPS) initiative, a trio of miniature robots will be lowered onto the Reiner Gamma region of the Moon via tethers.

Upon touchdown, the CADRE rovers will drive to find a place first to soak up the sun, opening their built-in solar panels to charge up. Afterward, they'll spend roughly 14 Earth days – the daylight hours of a single lunar day – conducting experiments to test their capabilities.

"It could change how we do exploration in the future," said Comandur. "The question for future missions will become: 'How many rovers do we send, and what will they do together?'"

Mission controllers back home will send a broad directive to the rovers' base station aboard the 13-foot-tall lander. From these initial instructions, the robots are programmed to elect a "leader," which in turn will distribute work assignments to accomplish the collective goal.

Essentially, each rover will figure out how best to safely complete its assigned task on its own.

"The only instruction is, for example, 'Go explore this region,' and the rovers figure out everything else: when they'll do the driving, what path they'll take, how they'll maneuver around local hazards," said JPL's Jean-Pierre de la Croix, CADRE's principal investigator. "You only tell them the high-level goal, and they have to determine how to accomplish it."

Teamwork makes the dream work

NASA/JPL-Caltech

At NASA's CADRE technology demonstration, three small rovers that will explore the Moon together show off their ability to drive as a team autonomously – without explicit commands from engineers – during a test in a clean room at the agency's Jet Propulsion Lab.

The rovers will face several tests – all within view of a monitoring camera on the base station atop the lander.

The first is to drive in formation and stay on course using ultra-wideband radios to maintain relative positions while relying on sensors to avoid obstacles. In a second experiment, the rovers will each take a path of their own choosing to explore a designated area of about 4,300 square feet, creating a topographic 3D map with stereo cameras.

The project will also assess how well the team would adapt if a rover stopped working for some reason.

Ultimately, success will indicate that multi-robot missions are a good choice for exploring hazardous but scientifically rewarding terrain.

And while CADRE isn't focused on conducting science, the rovers will be packing multistatic ground-penetrating radars.

Driving in formation, each rover will receive the reflection of radio signals sent by the others, creating a 3D image of the structure of the subsurface as much as 33 feet below. Together, they can gather more complete data than current state-of-the-art ground-penetrating radars like the one on NASA's Perseverance Mars rover, RIMFAX (Radar Imager for Mars' Subsurface Experiment).

"We'll see how multiple robots working together – doing multiple measurements in different places at the same time – can record data that would be impossible for a single robot to achieve," Comandur said. "It could be a game-changing way of doing science."

Mineral exploration potential

While there are multitudes of scenarios that will test the full extent of the CADRE rovers' autonomy and teamwork capabilities: surviving the harsh thermal environment near the Moon's equator; monitoring the longevity of its JPL-developed cooperative autonomy software – all while utilizing a combination of commercial off-the-shelf parts and custom-built components – the true test will be whether the rovers are robust enough to make it through its trial period relatively unscathed.

With a swarm of autonomous rovers sweeping over regions, mapping, surveying, and accumulating terrain conditions and states, while this will be beneficial for science, the eventual functionality for mineral exploration needs little explanation.

Asteroids, minor planets, or spent comets, a payload of a fleet of rovers to sweep over potential mineral anomalies, is perhaps the first generation of space mineral exploration that humanity will see.

While the goal now is to show that a group of robots can work together to accomplish tasks and record data as an independent, autonomous team – if the project succeeds, future missions would likely include teams of robots spreading out to take simultaneous, distributed scientific measurements to potentially support astronauts or astro-miners.

"We have been in overdrive getting this tech demo ready for its lunar adventure," added Comandur. "It's been months of nearly round-the-clock testing and sometimes re-testing, but the team's hard work is paying off. Now we know these rovers are ready to show what a team of little space robots can accomplish together."