This week DARPA kicks off a competition called the Subterranean Challenge, where hordes of robots are unleashed into caves and tunnels to test how well they can autonomously navigate these environments. One team, headed up by NASA's Jet Propulsion Lab (JPL), is entering a crew of bots that could inform future designs of spacefaring robots that explore caves and lava tubes on other planets and moons.

The DARPA Subterranean Challenge was designed to help plug an apparent gap in the ability of robots and autonomous systems to navigate underground environments. That includes natural cave networks, which have irregular terrain and both constrained and large caverns; artificial tunnel systems with long passages, vertical shafts and multiple levels; and urban underground environments like subway systems, which can have complex layouts over multiple stories.

To help stimulate innovation in this area, DARPA is putting out the call to teams of engineers and scientists at institutions and companies all over the world. There's over US$5 million in prize money up for grabs for the teams that can successfully map these environments, avoid the hazards and retrieve hidden items as proof.

The first test, running this week, is the Tunnel Circuit. In this, teams must map old mining tunnels and find certain objects hidden inside, such as phones and heated mannequins. No humans are allowed in the tunnels of course – teams have to send in robots of their own design to do the dirty work for them. The winner is the team that marks the locations of the most objects, accurate to within 5 m (16.4 ft).

Of course with DARPA at the helm, the most promising technologies from the competition will most likely be put to work in defense scenarios, but the organization also says that first responders could benefit, sending robots into potentially hazardous underground environments to, for example, search for survivors of disasters or locate gas leaks.

But not all the robots will have applications here on Earth. Made up of 60 members from JPL, Caltech, MIT and KAIST, the Collaborative SubTerranean Autonomous Resilient Robots Systems (CoSTAR) team is entering the contest in order to get some practice for a fleet of robots that could one day search for signs of life underground on other worlds.

The CoSTAR team is entering a fleet of robots with different strengths into the Challenge. In the Tunnel Circuit, wheeled rovers and robots with tank-like treads designed to handle the rugged terrain will crawl across the ground. The tank-like robot can even rotate its flipper-shaped treads to stand upright. These will be assisted by drones flying overhead, encased in protective shells to withstand bumping into walls.

The robots will be equipped with a suite of sensors including cameras, lidar and inertial measurement units (IMU), and will communicate with each other to map out the environments as completely as possible.

For future tests in this ongoing challenge, the CoSTAR team plans to use a robot called Drivocopter, which can both drive along the ground and fly up along cave walls and through gaps in the ceiling.

The ultimate goal for the team is to apply the lessons learnt in this challenge to robots designed to explore similar environments on the Moon, Mars and other worlds. These underground environments are among the most promising places to look for traces of extraterrestrial life, either still living or long dead.

"The big question for NASA is: Is there life beyond Earth?" says Ali Agha, principal investigator of the CoSTAR team. "One of the main places to find answers to that question is subsurface environments because they are some of the most pristine locations, shielded from ultraviolet radiation and cosmic rays. If there is life in the solar system, these are the most likely places to harbor it."

The Tunnel Circuit of the DARPA Subterranean Challenge will run from August 15 to 22, and involve 11 teams. After that, the Urban Circuit will follow in February 2020, then the Cave Circuit in August 2020 and the Systems Final a full year after that.

Check out the CoSTAR team's robots in action in the video below.

Sources: JPL, DARPA, Team CoSTAR