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NASA’s Ingenuity helicopter is gearing up for its 14th flight to the Red Planet, but the thinning Martian air makes such sorties increasingly difficult.
The upcoming release, which could take place any day now, is a simple jump from some of the more daring reconnaissance flights that Ingenuity did to help NASA’s Perseverance rover, mission team members said in a recent update. There’s a good reason for the simplicity: The 1.8 kg (4 pound) chopper will test higher rotor spin speeds to see if it can continue to fly in rapidly changing seasonal atmospheric conditions on Mars.
The flight plan foresees Ingenuity to take off, climb up to 16 feet (5 meters) and perform a lateral maneuver before landing. The flight was originally scheduled to take place no earlier than September 17, but that depended on the mission team’s readiness on occasion. Updates will be released on The official Twitter feed of Perserverance as further developments can be reported.
Related: Watch NASA’s Ingenuity helicopter explore the intriguing elevated ridges of Mars
The short test flight, whenever it occurs, should include a rotor speed of approximately 2,700 revolutions per minute (RPM), assuming a scheduled ground test of a rotation of 2,800 RPM is going as planned. (By comparison, before March the experiment had allowed Ingenuity to fly at around 2,537 rpm.) The higher rotation rate, the engineers hope, will allow the drone to fly despite diminishing atmospheric density.
“It’s actually more and more difficult [to fly] every day: I’m talking about atmospheric density, which was already extremely low and continues to decline due to seasonal variations on Mars, “wrote Ingenuity chief pilot Håvard Grip of NASA’s Jet Propulsion Laboratory in Southern California, in the update.
Grip explained that Ingenuity’s flight campaign was designed to last just a few months after the Perseverance mission landed inside Jezero de Mars crater in February. Ingenuity has far exceeded expectations and continues to fly, testing how rotorcraft could act as scouts for rovers or perhaps even human missions.
But Ingenuity was not designed for changing seasonal conditions. Originally, the atmospheric density in Jezero Crater was equivalent to about 1.2% to 1.5% of that on Earth. But now the densities are approaching 1% during the preferred afternoon hours for flight, when currents on the ground cause less instability for the low-flying drone.
“The [atmospheric] The difference may seem small, but it has a significant impact on Ingenuity’s ability to fly, ”explained Grip. Martian atmosphere thins. If the atmospheric density drops too much, Ingenuity could perhaps be approaching a stall in the air.
“Fortunately, there is a way to solve this problem, but it involves spinning the rotors even faster than we have done so far,” continued Grip. “In fact, they’ll have to spin faster than we’ve ever attempted with Ingenuity or any of our test helicopters on Earth. It’s not something we take lightly, it’s why our next Mars operations will focus on careful testing of higher rotor speeds for future flights. “
The Ingenuity team will look for a few potential issues. The first is that the higher rpm, coupled with the movements of the wind and helicopters, could cause the rotor blades to strike the atmosphere at around 0.8 Mach, or 80% of the speed of sound. (The speed of sound on Mars is only three-quarters of that on Earth, due to the red planet’s much lower atmospheric density.)
“If the blade tips get close enough to the speed of sound, they will experience a very large increase in aerodynamic drag which would be prohibitive for flight,” said Grip. “For Ingenuity’s rotor, we don’t expect to encounter this phenomenon until even higher Mach numbers, but this has never been confirmed in tests on Earth.”
Engineers will also monitor for potential resonances that could cause the helicopter to vibrate at particular frequencies, which, at worst, could “damage hardware and lead to deterioration of the sensor readings needed by the flight control system,” Grip said. . Other considerations will include more power required from the electrical system and higher loads required by the rotor system.
“All of this presents a significant challenge, but by approaching the problem slowly and methodically, we hope to fully test the system at higher rotor speeds and allow Ingenuity to continue flying in the months to come,” Grip said. “Stay tuned for updates.”
Follow Elizabeth Howell on Twitter @howellspace. Follow us on twitter @Spacedotcom or Facebook.
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