The rotor blades that will carry NASA’s next-generation helicopters to new Martian heights broke the sound barrier during March tests at NASA’s Jet Propulsion Laboratory (JPL) in Southern California. Data from the tests, which took place in a special chamber capable of simulating environmental conditions on the Red Planet, indicate that the fastest-traveling parts of the rotor blades — the tips — can be accelerated beyond Mach 1 without breaking apart. Data gathered from 137 test runs will enable engineers to design aircraft capable of carrying heavier payloads, including science instruments.
Al Chen, Mars Exploration Program Manager at JPL, stated:
“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. That is not an easy ask. While everything about Mars is hard, flying there is just about the hardest thing you can do. That is because its atmosphere is so incredibly thin that it is difficult to generate lift, and yet Mars has significant gravity.”
Ingenuity, which performed the first powered, controlled flight on another world just over five years ago on April 19, 2021, was a trailblazing technology demonstration that did not carry science instruments. NASA’s recently announced SkyFall project and other potential future Mars aircraft will be capable of carrying payloads — including science instruments and sensors — to collect data in support of future human and robotic missions.
Need for Speed
In the fast-moving world of rotors, more thrust comes from quicker spin or larger diameter. Because the Martian atmosphere is only 1 percent as dense as Earth’s, maximizing thrust requires pushing blade tips toward the speed of sound to achieve significant lift. While Mach 1 on Earth at sea level is approximately 760 mph, the speed of sound on Mars is significantly slower — roughly 540 mph — due to the planet’s thin, cold, carbon-dioxide-rich atmosphere.
Blade-Proof Chamber
To evaluate the rotors, the team mounted a three-bladed rotor inside JPL’s historic 25-Foot Space Simulator, evacuated the air, replaced it with carbon dioxide to match the Martian atmosphere, and blasted the rotor with wind as it spun at increasing speeds. The team pushed rotor tip speeds to Mach 1.08, boosting the Mars vehicle’s lift capability by 30 percent. This breakthrough allows future missions to support heavier scientific payloads, including advanced sensors and larger batteries for extended flight.
Jaakko Karras, JPL Rotor Test Lead, commented:
“If Chuck Yeager were here, he would tell you things can get squirrely around Mach 1. We planned Ingenuity’s flights to keep rotor blade tips at Mach 0.7, but we want more performance from our next-gen Mars aircraft. We needed to know that our rotors could go faster safely.”
Shannah Withrow-Maser, Aerodynamicist at NASA Ames Research Center, added:
“The successful testing of these rotors was a major step toward proving the feasibility of flight in more demanding environments. We thought we would be lucky to hit Mach 1.05, and we reached Mach 1.08. We are still digging into the data, and there may be even more thrust on the table. These next-gen helicopters are going to be amazing.”
The SkyFall mission design team has incorporated the test team’s findings into performance specifications. Inspired by Ingenuity, SkyFall is designed to carry three next-gen Mars helicopters to the Red Planet in December 2028.
