Flying on Mars has always sounded almost impossible because, in many ways, it is. The planet’s atmosphere is so thin that aircraft struggle to stay in the air.
Every bit of lift has to be squeezed out of spinning blades that are already operating near their limits.
Now NASA engineers have pushed those limits even further. During recent tests in California, rotor blades designed for future Mars helicopters broke the sound barrier without falling apart.
That matters because NASA wants future aircraft on Mars to do much more than Ingenuity, the tiny helicopter that made history in 2021.
Ingenuity proved powered flight could work on another planet, but it carried no scientific instruments.
The next wave of Mars aircraft is expected to carry cameras, sensors, batteries, and other equipment that could help astronauts and robotic explorers study places rovers cannot easily reach.
Testing helicopters for Mars
The tests happened inside a massive chamber at NASA’s Jet Propulsion Laboratory in Southern California.
Engineers recreated the thin, carbon-dioxide-heavy atmosphere of Mars and spun experimental rotor blades faster and faster while blasting them with artificial Martian winds.
The results gave NASA confidence that future helicopters can generate much more lift than before.
“NASA had a great run with the Ingenuity Mars Helicopter, but we are asking these next-generation aircraft to do even more at the Red Planet,” said Al Chen, Mars Exploration Program manager at JPL.
“That’s not an easy ask. While everything about Mars is hard, flying there is just about the hardest thing you can do. That’s because its atmosphere is so incredibly thin that it is hard to generate lift, and yet Mars has significant gravity.”
The challenge of flying on Mars
Mars has only about one percent of Earth’s atmospheric density. Helicopter blades there cannot rely on thick air to create lift. Engineers have to compensate by spinning the blades incredibly fast or making them larger.
That creates another problem. As rotor tips approach the speed of sound, airflow becomes unstable and unpredictable.
On Earth, pilots and engineers have dealt with these effects for decades, but Mars adds new complications because sound travels differently there.
In the cold Martian atmosphere, the speed of sound is about 540 mph, much slower than Earth’s roughly 760 mph at sea level.
During Ingenuity’s 72 flights, NASA engineers kept the helicopter’s rotor speeds below 2,700 revolutions per minute. They wanted a safety margin in case Martian winds suddenly pushed the rotor tips into supersonic territory.
“If Chuck Yeager were here, he’d tell you things can get squirrely around Mach 1,” said JPL’s Jaakko Karras, the rotor test lead.
“With that in mind, we planned Ingenuity’s flights to keep the rotor blade tips at Mach 0.7 with no wind so that, if we encountered a Martian headwind while in flight, the rotor tips wouldn’t go supersonic.
“But we want more performance from our next-gen Mars aircraft. We needed to know that our rotors could go faster safely.”
Helicopter rotors in Mars-like conditions
The experiments took place inside JPL’s historic 25-Foot Space Simulator, a chamber built to mimic harsh space environments.
Engineers replaced the air inside with carbon dioxide at pressures similar to Mars. Then they mounted prototype rotors built by AeroVironment and started spinning them.
The team even lined parts of the chamber with sheet metal in case the helicopter blades shattered during testing. Nobody wanted fragments flying around at supersonic speed.
Over 137 test runs, engineers gradually pushed the rotors harder. Speeds climbed to 3,750 rpm, with blade tips reaching Mach 0.98 before headwinds were added. Then the team introduced stronger and stronger winds inside the chamber.
Mars helicopter blades hit Mach 1.08
The helicopter blades eventually reached Mach 1.08. That gave the aircraft about 30 percent more lift capability – enough to support heavier scientific equipment and larger batteries for longer flights.
NASA also tested a second rotor design connected to the agency’s planned SkyFall mission concept.
Because those blades were slightly longer, they achieved similar near-supersonic speeds at lower rotational rates.
“The successful testing of these rotors was a major step toward proving the feasibility of flight in more demanding environments, which is key for next-gen vehicles,” said Shannah Withrow-Maser, an aerodynamicist from NASA’s Ames Research Center and a member of the test team.
“We thought we’d be lucky to hit Mach 1.05, and we reached Mach 1.08 on our last runs.”
Mars exploration is about to change
NASA’s proposed SkyFall mission would send three advanced Mars helicopters to the Red Planet in December 2028. The mission design already includes lessons from these new rotor tests.
Scientists see helicopters as one of the best ways to explore terrain that wheeled rovers struggle to cross.
Cliffs, deep craters, rugged lava fields, and steep canyon walls could suddenly become reachable.
Aircraft can also scout routes ahead of astronauts or rovers and collect data from places no spacecraft has ever touched.
Ingenuity was originally expected to fly only a handful of times. Instead, it stayed active for nearly three years and became one of NASA’s most successful technology demonstrations.
The helicopter showed that flight on Mars was possible. These new blade tests suggest the next generation may be capable of far more than short hops across dusty ground.
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