Ingenuity vehicle opens a promising future for airborne exploration on other worlds.
On April 19 NASA’s Ingenuity flyer became the first powered vehicle to take to the skies for a controlled flight on an alien world.
Ingenuity climbed 10 feet in the air, maintained a stable hover for about 30 seconds, and landed safely. The whole flight took just short of 40 seconds to complete.
Ingenuity is an $85-million solar-powered helicopter technology demonstrator designed to explore the possibility of airborne exploration of other planets. It’s made up of a combination of customized components and off-the-shelf commercial parts that come mostly from the smartphone industry.
It arrived on Mars in a storage compartment on NASA’s Perseverance rover. At almost 20 inches tall, with a 47-inch rotor span, Ingenuity stands on four 15-inch legs and launches from a small helipad that was also stored on Perseverance.
Onboard, the vehicle carries miniature avionics and communications equipment, a navigation camera, a single solar panel, and rechargeable lithium-ion batteries—as well as heaters to keep the electronics warm through the frigid Martian nights. There are no scientific instruments onboard—just a high-resolution color imager. Ingenuity is powered by six Sony Li-ion batteries, each with a capacity of 2100 mAh. Each flight needs about 350 watts, limiting the helicopter’s flight time to one daily 90-second flight. And with only room enough for one solar panel, it takes a full day to recharge the batteries.
Ingenuity’s flights are achieved via four carbon fiber blades that spin on two counterrotating rotors.
Designing a flyer to operate on another world required a substantial rethinking of every component of the helicopter, from power to aerodynamics to materials to mechanics to heat management—and more. “We had to remove all the boundaries,” said MiMi Aung, Ingenuity’s lead engineer. “We’re used to having our own chassis … and our own computer for each subsystem. Integrating all of that together, and then combining, also, the aero aspect of it, pulling the whole system together in such a light weight … was the first challenge. That’s what also made it really fun and interesting.”
Ingenuity had to be small enough to fit inside Perseverance for transport, light enough to be able to lift off the Martian ground, and have enough power to remain heated during the brutally cold Martian nights (which can drop to minus 130 degrees Fahrenheit).
The vehicle weighs almost four pounds. The lower gravity of Mars (about three eighths of Earth’s gravity), combined with the planet’s thin atmosphere (about 1 percent as dense as Earth’s), presented Ingenuity’s designers with unprecedented challenges. In order to create upward lift in that environment, Ingenuity’s blades had to spin at about 2,400 revolutions per minute to push enough of the incredibly thin air downward. That’s about 10 times the speed of a helicopter rotor on Earth. In addition, even though Ingenuity’s peak altitude is only about 16 feet on Mars, those conditions are comparable to an Earth chopper navigating at an altitude of 100,000 feet—which is more than twice as high as any Earth helicopter has ever flown. In comparison, a commercial airplane flies at about 35,000 feet above the Earth’s surface.
“Those blades are not something off the shelf,” said Aung. “They are really fine-tuned to maximize the lift that we can generate in such a thin atmosphere.”
An additional challenge: Ingenuity needed to be autonomous enough to navigate by itself. It takes far too long for signals to travel between the planets, so the vehicle couldn’t rely on a navigator with a joystick way back on Earth. It needs to be able to make decisions on how to fly to a waypoint, keep itself warm, and react to possible complications.
Ingenuity’s historic first flight, recorded by the Perseverance rover.
The first flight didn’t come without its mishaps. Originally scheduled to occur on April 9—10 days earlier—Ingenuity’s team encountered an unexpected software glitch. During a scheduled high-speed spin-up test of the rotors, Ingenuity ended the test prematurely due to a “watchdog” timer expiration. This timer monitors the command sequence and interrupts it if there’s anything unusual. “The onboard logic did not recognize the flight control computers as healthy and functional, even though it was confirmed they were,” said Dave Lavery, NASA’s program executive for Solar System Exploration.
The Ingenuity team on Earth spent the next few days analyzing the data and developing and testing a software-based solution: a minor change and reinstallation of the command sequence software that would change the boot sequence for the two flight controllers, allowing both hardware and software to transition from preflight status to flight-ready status.
After testing and validating the patch on Earth, NASA transmitted the update to Mars via the Deep Space Network—a collection of giant radio antennas around the world that the agency uses to communicate with its spacecraft. It was then relayed to satellites orbiting Mars, then down to the Perseverance rover, and from there to Ingenuity’s launch pad and “base station.” At that point, Ingenuity installed the software and rebooted.
Ingenuity’s success opens up a wide range of possibilities for exploration. Airborne craft could transport scientific instruments to places that rovers and landers can’t access—and could take much more detailed imagery of the surface than what’s currently possible. The vehicles could also scout and map locations for future exploration.
And the little chopper isn’t finished yet. Ingenuity is scheduled to attempt a second flight no earlier than April 22.
The 40-second flight of Ingenuity was an amazing feat of engineering—and its success is changing the game when it comes to expanding humanity’s footprint on other worlds.
Read more about NASA’s ambitious mission on the red planet at NASA’s Perseverance Rover Officially Lands on Mars.
