NASA’s Perseverance rover is currently collecting rock and soil samples in Jezero Crater on Mars, which will one day be returned to Earth. Under the current plan, in 2030 the rover itself will deliver the sample tubes to a Mars lander for transport back home. But if anything goes wrong, a pair of small helicopters will be ready to swoop in, as NASA’s Mars sample return team announced in late July.
If this happens, the Sample Recovery Helicopters will be the second and third rotorcraft ever to fly to another planet. And their inclusion in the Mars Sample Return mission, a joint effort between NASA and the European Space Agency, could signal the start of a new chapter in Mars exploration—one in which small, lightweight helicopters regularly orbit the Red Planet.
The news of adding helicopters to the Mars Sample Return mission comes just over a year after the first aircraft in history to take powered flight to another planet, when NASA’s Ingenuity helicopter took to the Martian skies in April 2021. Since then, the experimental rotorcraft has taken 28 more fields far exceeding expectations.
“The whole point of Ingenuity was to be that Wright Brothers moment that leads to some future in the way of further aerial exploration of Mars,” said Teddy Tzanetos, Ingenuity Mars Helicopter team leader at NASA’s Jet Propulsion Laboratory. “Ingenuity’s goal was to make flying boring… Now we can just keep making boring flights and doing exciting things with boring flights.”
Initially, the Mars Sample Return mission concept involved a so-called fetch rover: a robot capable of collecting the samples already stored in tubes from the Perseverance rover. The retrieval rover would carry them several hundred yards across the Martian surface to a lander near Jezero Crater, where the sample tubes would be transferred to the Mars Ascent Vehicle. The rocket-powered ascent vehicle will then launch the container containing the sample tubes into orbit, where it will await a spacecraft destined to return to Earth.
But, says Anne Devereaux, who is deputy manager of the Mars sample return program, “getting a rover that’s big enough and capable enough to go and do a reasonable job of collecting samples has been problematic.” . It would be expensive to design and send such a rover along with the Mars Ascent Vehicle.
The team was exploring other concepts just as Ingenuity made its first test flights. After the rotorcraft proved successful, engineers began investigating whether helicopters might be the best option for retrieving the samples cached by Perseverance.
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Helicopters are smaller, lighter and more agile than rovers in many situations, Devereaux says. Although the plane needs a safe place to land, it doesn’t have to worry about crossing dunes on heavy tires.
The designs for the example return helicopters will not differ much from the Ingenuity. “When you’re talking about robots in space, legacy is extremely important,” Tsanetos says. “We want to stick as close as possible to the Ingenuity design because we know it’s reliable, we know it’s robust.”
Because Martian air is so thin — about 1 percent of the density of Earth’s — any plane on Mars would have to be extremely light and have large, fast-spinning rotor blades to provide enough lift, he explains. Ingenuity’s repeated flights have confirmed that NASA’s aerodynamic simulations are accurate—so much so that the models will guide how engineers build the new pair of flying robots.
However, the trial recovery helicopters will not be an exact replica of the Ingenuity. The team will have to make some changes, Tsanetos says, because these two rotorcraft will have to do more than just fly. They would have to walk about 2,300 feet from the lander to the storage site, pick up a tube, fly back to the lander and drop it off at a designated drop location — and then repeat that cycle 15 times, he says.
And that means the choppers will have to support more weight than the 4-pound Ingenuity. The current conceptual design of the sampling helicopters requires additional tools, such as sampling arms and wheels for maneuvering in the cache dump and disposal sites, which could add another kilogram to the robots, according to Tzanetos.
“We did the math and realized there were certain changes we could make to the rotor system to make it lift more mass,” he says. Now that Mars Sample Return mission managers have decided to move forward with the retrieval helicopter concept, Tzanetos and his team are focusing on making those changes.
One of their first steps is to determine how much further they can push Ingenuity’s original rotor system. Just in case the Martian environment was more challenging than predicted by the team’s models, engineers designed the test helicopter to have more lift than they thought was necessary.
“We’re starting to work to figure out what the optimal point is to exchange all these different mainstream applications,” he says. “We can turn the blades a little faster, we can demand more of the rotor system, for example, and we can carry a heavier aircraft that allows us to accomplish the mission.”
However, helicopters may not be needed at all. They will be sent to Mars only in case the Perseverance rover is unable to deliver samples or the robot meets its demise before the retrieval is complete.
But the future of helicopters on Mars may already be foreshadowed by Ingenuity’s success.
“That helicopter was phenomenal,” says Devereaux, describing how Ingenuity proved it could fly ahead of the Perseverance rover and scout ahead for the rover’s ground reconnaissance. She adds that helicopters offer us an additional perspective on our neighboring planet. Perhaps one day a drone-like rotorcraft could traverse canyons like those that make up the Valles Marineris, revealing the Red Planet’s geological layers up close where rovers can’t go.
“Rovers are now commonplace” for Mars exploration, Tsanetos says. “We understand how to build rovers, we understand how to fly rovers. I hope we’ll be saying the same thing about helicopters for decades to come. Perhaps fleets of aircraft, he says, with wings like airplanes or blades like helicopters, will one day fill the Martian sky.