Why it’s so difficult to fly NASA’s Ingenuity helicopter on Mars

On Earth, humans have spent more than a century working in the art of flying. We have only just started on Mars.

NASA’s four-pound helicopter, Ingenuity, landed on the surface of Mars on April 3 and will begin flight testing in early April. It will be the first time that humans have flown something on another planet.

In a nod to the Wright brothers’ maiden flight, it carries a small piece of the plane that flew at Kitty Hawk. If all goes well, Ingenuity can take up to five 90-second flights over 30 sols, or Mars days, which are slightly longer than Earth days.

For decades, scientists have explored the surfaces of moons and planets from spacecraft high above. Robbers look up close, but are painfully slow. Ingenuity has the advantage of flying low – only 10 to 5 meters in the air – while traveling relatively fast. It is only equipped with a camera. But future drones can carry more tools.

“It represents opening a new avenue of space exploration,” said Josh Ravich, mechanical head of Ingenuity. “It opens up a lot of possibilities, not just for Mars, but for any body with an atmosphere.”

A proposed mission to Saturn’s moon Titan includes a drone called Dragonfly. Data from Ingenuity can help make it happen.

The question remains, can Ingenuity fly?

That is not an easy task.

Different planet, different atmosphere, different rules

If the flight tests begin in April as expected, Mars will be anywhere from Earth. At that distance, it would take up to 15 minutes for a signal from a pilot to reach Ingenuity, a delay that would make it nearly impossible to manually control the drone.

Even if scientists had someone on the surface of Mars with a joystick, NASA Jet Propulsion Lab (JPL) researchers discovered years ago that even the best drone pilots have trouble navigating a Mars-like atmosphere, which is only about 1 percent. as close as that of the earth.

Because there are fewer molecules to push off, Ingenuity’s helicopter blades have to spin between 2,000 and 3,000 times per minute, compared to 300 to 500 on Earth. To account for increased vibration, Ingenuity’s nearly four-foot-long blades are much thicker at the rotor than the tips, affecting the way it works.

The flight model of the Ingenuity helicopter.

Around 2014, a few years before Ravich joined the Mars Helicopter team, he said the researchers were trying to fly an earlier version of the drone into a vacuum chamber.

“They had a really experienced drone pilot, like a private toy drone pilot, try to joystick him by hand,” he said. ‘It doesn’t work the way you think it would. You try to move it one way and it goes the other way. It was a good lesson they quickly learned that, yes, a human couldn’t fly with it. “

Their solution was to equip it with a computer and sensors so that it could control itself and adapt on the fly to changes in speed, direction and altitude.

Solve the Ingenuity puzzle

Given the thin atmosphere, engineers had to thread the needle between providing enough power for the rotors and the computer and making it light enough to fly.

To process data on Ingenuity, NASA turned to Qualcomm, who could provide a Snapdragon 801 processor – the same one you’d find in a Samsung Galaxy S5. The lightweight, efficient processor could handle the rigorous testing NASA threw on it, said Dev Singh, GM of robotics, drones and intelligent machines at Qualcomm.

“Keeping the electronics warm enough to actually work safely is a trick”

“They tested it with radiation,” he said. “While other processors just fell apart, our processor got through all that … It can run the 4K camera. It can run all rotors. It can perform machine learning and avoid obstacles. “

An important ingredient to Snapdragon’s success is its energy efficiency. Since it requires less power than other processors, Ingenuity can have a smaller battery.

“Batteries are very heavy, so if you don’t need them, why take more?” said Ravich of JPL.

Ingenuity’s solar-charged battery powers the rotors, computer, and heating system to keep the whole thing from freezing. Mars is cold, sometimes reaching -110 degrees Fahrenheit or below on cold days.

Qualcomm’s processors are only capable of operating in temperatures ranging from about 255 F to -40 F, Singh said.

Have you ever tried to start your car when it’s -40? It doesn’t always turn on, ”Ravich said, laughing. “Keeping the electronics warm enough to actually work safely is a trick.”

The 90 second flights don’t actually take that much power. Most of the battery’s energy goes to heating.

The future

Plans for a Mars helicopter have been in the works since the late 1990s, Ravich said.

The team “had been playing with it for a while and it wasn’t until the 2014 timeframe that it really gained traction,” he said. In 2018 they tested flights of the current Mars helicopter model.

“We are very excited,” said Ravich of the team. “We put a lot of our heart into this and it is still amazing that we are there and that we got the chance to try to fly.”

The Perseverance rover drops Ingenuity to the ground, a process that takes six sols.

The Perseverance rover drops Ingenuity to the ground, a process that takes six sols.

Image: NASA / JPL-Caltech / MSSS

A successful flight would pave the way for more helicopter missions to Mars and other planets and moons in our solar system. As Qualcomm’s Singh pointed out, drones can cover a lot more ground than a rover. Curiosity took nine years to travel less than 25 kilometers.

“Think about the future of Mars exploration, you could cover 15 miles in an hour, flying and exploring,” said Signh. “If you send in five, you could probably cover Mars within five years and have pictures of different elements.”

Exploration is one thing. Going forward, Ravich said he could envision helicopters on Mars that would help astronauts.

“One of my favorite crazy uses for this is, if you’re an astronaut and you forget your wrench back on your base and you don’t want to go back and get it yourself,” he said with a laugh. “Just send a helicopter to pick it up for you.”

Let’s hope this thing works, for the sake of future forgetful astronauts.