The National Aeronautics and Space Administration (NASA) has begun testing drones for Mars exploration. In a desert with an environment similar to Mars, it flew drones with both rotors and fixed wings to test navigation instruments and software. A four-legged robot for Mars exploration is also training in the desert. After proving themselves on battlefields and industrial sites, drones and quadruped robots are now expanding their stage of activity beyond Earth.
In 2021, NASA landed the Perseverance rover, which moves on four wheels, and the ultra-small unmanned helicopter Ingenuity on Mars. There had been Mars rovers transfer, but it was the first helicopter to fly in the Martian sky. The rover is still operating, but the helicopter crashed last Jan., ending its mission. NASA said it will deploy drones for aerial exploration on Mars instead of helicopters going forward.
◇ Successor to the first helicopter to fly beyond Earth
The Jet Propulsion Laboratory (JPL) said on Dec. 2 that it is testing drones and robots in desert regions for exploration of the Martian surface and by air. Early this year, the research team took three research drones to Death Valley National Park and the Mojave Desert in California. Sand dunes were necessary to ensure trouble-free flight in the Martian sky. Ingenuity, which crashed during its 72nd flight mission on Mars on Jan. 18 last year and broke a rotor, was also flying over sand dunes at the time.
Until now, lunar or Martian exploration had been conducted only on the ground. Stationary unmanned probes or wheeled rovers carried out the missions. Ingenuity expanded the horizon of extraterrestrial exploration to the sky. Ingenuity arrived on Mars on Feb. 18, 2021, attached beneath Perseverance's belly. In its first flight on Apr. 19, two months later, it ascended to a height of 3 meters and came back down.
With Ingenuity's success, humanity set a record for powered flight in the sky not only on Earth but also on another celestial body for the first time in a century. Earlier, to wish for Ingenuity's flight success, NASA attached to the craft a stamp-sized piece of fabric taken from Flyer 1, the airplane in which the Wright brothers achieved the first powered flight in 1903.
Ingenuity flew 72 times, traveling more than 17 kilometers for a total of 128.8 minutes. Because the atmospheric density on Mars is only 1% that of Earth, it was thought to be difficult to generate enough lift to raise the fuselage by spinning rotors. NASA researchers overcame this limitation with two ultra-high-speed rotors spinning 2,400 times per minute. Because real-time remote control from Earth is impossible, they applied autonomous flight technology.
NASA suspected that Ingenuity crashed because it was flying over irregular sand dunes rather than flat terrain. Roland Brockers, a JPL researcher and drone pilot, said, "Ingenuity estimates motion by observing visual features of the ground and is designed to fly in areas where the terrain is distinct," and added, "We hope future exploration aircraft won't have to worry even when flying in challenging areas like sand dunes."
The Mars drone tests can also help with exploration of other celestial bodies. NASA is developing "Dragonfly," an exploration aircraft that will go to Saturn's moon Titan. It flies with eight 1-meter-diameter horizontal rotors. NASA plans to launch Dragonfly in 2027 and land it on Titan in 2034.
◇ Tests also underway for long-range drones and robot dogs
NASA researchers have been visiting Death Valley National Park since the 1970s. At the time, NASA was preparing to land the twin Viking spacecraft on Mars for the first time. Death Valley was an ideal place to test Mars exploration. One area was so strewn with volcanic rocks on a barren slope like Mars that it earned the name "Mars Hill."
Half a century later, Death Valley is still a go-to test site for Mars explorers. Earlier, JPL researchers validated Perseverance rover's precision landing system with a remotely piloted helicopter over Death Valley. NASA researchers visited Mars Hill and the Mesquite Flats sand dunes in Death Valley in late Apr. and early Sep. They tested how various camera filters aid drone observations of the ground and whether new algorithms can safely land drones in complex terrain like Mars Hill.
Three days later, the team headed to the Dumont Dunes in California's Mojave Desert for additional tests. It is where they tested Curiosity, the rover that landed on Mars in 2012. With its wave-shaped dunes, Dumont was ideal for testing the ability to fly over irregular terrain similar to where Ingenuity crashed.
NASA is also developing a large Mars exploration aircraft. NASA's Langley Research Center is developing the Mars Electric Reusable Flyer (MERF). About the size of a small school bus, it has twin propellers on fixed wings, enabling vertical takeoff and landing and hovering. As the aircraft streaks across the sky at high speed, instruments mounted on its belly can map the surface.
◇ Robot dogs to carry out combined ground-air operations
NASA researchers also developed new technology to explore the Martian surface: a four-legged robot dog. In Aug., a team from NASA's Johnson Space Center tested a dog-shaped robot named LASSIE-M in White Sands National Park, a desert region of New Mexico. LASSIE is an acronym for "Legged Autonomous Surface Science In Analogue Environments for Mars." The researchers are testing whether LASSIE-M can walk even in desert sand where legs sink.
Robot dogs like LASSIE-M can carry out combined operations with new aircraft. Marco Hutter, a professor at ETH Zurich, said in Nature in Aug., "Just as human experts form teams and mobilize diverse technologies, robots can complement one another to carry out Mars exploration missions." Hutter took first place with the quadruped robot ANYmal in the subterranean exploration robot competition hosted by the Defense Advanced Research Projects Agency (DARPA) in 2021.
NASA is already training robots in Earth's lava caves in preparation for building crewed bases on the moon and Mars. At the American Geophysical Union annual meeting in 2021, JPL unveiled a robot dog to explore the moon and Mars' rugged terrain and caves in place of wheeled rovers. It modified Spot, a quadruped robot developed by Boston Dynamics, a subsidiary of Hyundai Motor in the United States, for Mars exploration. Because it can walk autonomously, it was named "Au-Spot."
Until now, Mars exploration has been handled by rovers like Opportunity and Curiosity. But wheeled rovers could travel only on flat ground. Most of the terrain scientists want to explore is rugged and beneath the surface. NASA scientists said Spot can walk down into the subsurface and stand back up after a fall, making it ideal for exploring Mars' rugged terrain.
References
NASA (2025), https://www.nasa.gov/solar-system/planets/mars/nasa-tests-drones-in-death-valley-preps-for-martian-sands-and-skies/
NASA (2024), https://science.nasa.gov/resource/supercams-rmi-spots-ingenuitys-broken-rotor/