June 18, 2021

glassmerchantsbalaclava

Skillful education crafters

NASA’s Ingenuity helicopter made history by flying on Mars

7 min read

Editor’s note: This story will be updated periodically.


A helicopter just flew on Mars. NASA’s Ingenuity hovered for about 40 seconds above the Red Planet’s surface, marking the first flight of a spacecraft on another planet.

In the wee hours on April 19, the helicopter spun its carbon fiber rotor blades and lifted itself into the thin Martian air. It rose about three meters above the ground, pivoted to look at NASA’s Perseverance rover, took a picture, and settled back down to the ground.

“Goosebumps. It looks just the way we had tested it in our test chambers,” Ingenuity project manager MiMi Aung said in a news briefing after the flight. “Absolutely beautiful flight. I don’t think I can ever stop watching it over and over again.”

As data from the flight started coming in to Ingenuity’s mission control room at NASA’s Jet Propulsion Lab in Pasadena, Calif., at about 6:35 a.m. EDT, a hush fell. And then cheers erupted as Håvard Grip, Ingenuity’s guidance, navigation and control lead, announced: “Confirmed that Ingenuity has performed its first flight, the first flight of a powered aircraft on another planet.”

image of the Ingenuity helicopter's shadow during its first flight
NASA’s Ingenuity helicopter took this photo of its own shadow while hovering about three meters in the Martian air on April 19.JPL-Caltech/NASA

“It’s amazing, brilliant. Everyone is super excited,” said mechanical engineer and team member Taryn Bailey. “I would say it’s a success.”

The flight, originally scheduled for April 11, was delayed to update the helicopter’s software after a test of the rotor blades showed problems switching from preflight to flight mode. After the reboot, a high-speed spin test April 16 suggested the shift was likely to work, setting the stage for the April 19 flight.

“I never let you celebrate fully. Every time we hit a major milestone I’m like, not yet, not yet,” Aung told the team moments after the flight was confirmed. Now is the moment to celebrate, she said. “Take that moment and after that, let’s get back to work and more flights. Congratulations.”

Ingenuity lifted into the thin Martian atmosphere for the first time on April 19, proving that flight is possible on another planet. This video was taken by the Perseverance rover, which watched from a safe distance away.

This first-ever flight was a test of the technology; Ingenuity won’t do any science during its mission, set to last 30 Martian days from the moment it separated from the rover, the equivalent of 31 days on Earth. But its success proves that powered flight is possible in Mars’ thin atmosphere. Future aerial vehicles on Mars could help rovers or human astronauts scout safe paths through unfamiliar landscapes, or reach tricky terrain that a rover can’t traverse.

“Technology demonstrations are really important for all of us,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “It’s taking a tool we haven’t been able to use and putting it in the box of tools we have available for all of our missions at Mars.”

Ingenuity’s flight was the culmination of more than seven years of imagining, building, testing and hoping for the flight team.

“That is what building first-of-a-kind systems and flight experiments are all about: design, test, learn from the design, adjust the design, test, repeat until success,” Aung said in a news briefing on April 9.

Aung and her team began testing early prototypes of a Mars helicopter in a 7.62-meter-wide test chamber at JPL in 2014. It wasn’t a given that flying on Mars would even be possible, Aung said. “It’s challenging for many different reasons.”

Before it hitched a ride to Mars on the rover Perseverance, Ingenuity underwent extensive testing in a Mars simulator on Earth. Its engineers experimented with early prototypes and later with Ingenuity itself. These tests convinced the team that the craft could fly in Mars’ thin atmosphere.

Even though Mars’ gravity is only about one-third of Earth’s, the air’s density is about 1 percent that at sea level on Earth. It’s difficult for the helicopter’s blades to push against that thin air hard enough to get off the ground.

Another way to think about it is that the air is thinner on Mars than it is at three times the height of Mount Everest, Ingenuity engineer Amelia Quon of JPL said in the news briefing. “We don’t generally fly things that high,” Quon said. “There were some people who doubted we could generate enough lift to fly in that thin Martian atmosphere.”

So Quon and her team put the helicopter through a battery of tests over the course of five years. “My job … was to make Mars on Earth, and enough of it that we could actually fly our helicopter in it,” Quon said. The Mars simulation chamber could be emptied of Earth air and pumped full of carbon dioxide at Mars-like densities. Some versions of the helicopter were suspended from the ceiling to simulate Mars’ lower gravity. And wind speeds up to 30 meters per second were simulated by a bank of about 900 computer fans blowing at the helicopter.

The final version of Ingenuity is light, about 1.8 kilograms. Its blades are longer (about 1.2 meters wingspan) and rotate faster (about 2,400 rotations per minute) than a similar vehicle would need to be able to fly on Earth. By the time the helicopter hitched a ride to Mars with the Perseverance rover in July 2020, the engineers were confident the helicopter could fly and remain in control at Mars (SN: 7/30/20).

Perseverance landed in a region called Jezero crater on February 18 (SN: 2/22/21). The helicopter was folded up beneath Perseverance’s belly under a protective shield until March 21.

Over  the next few weeks, Perseverance drove around to find a flat spot for Ingenuity to launch. Then Ingenuity slowly unfolded itself and was finally lowered gently to the ground beneath Perseverance on April 3. The rover drove away quickly to get Ingenuity out of its shadow and allow the helicopter to charge its batteries with its solar panel, giving it enough power to survive the freezing Martian night. 

Perseverance unpacking the Ingenuity helicoper
Ingenuity arrived on Mars folded up under the Perseverance rover in a protective shield the size of a pizza box. After landing, Perseverance dropped the shield and slowly lowered Ingenuity to the ground, then drove away.JPL-Caltech/NASA

On April 8 and 9, Ingenuity unfolded its rotor blades and tested their ability to spin in preparation to take to the air. After trouble-shooting the software problem and retesting the rotor blades April 16, the flight got a green light for April 19. It was scheduled for roughly 3:30 a.m. Eastern Daylight Time on April 19, which corresponds to 12:30 p.m. Mars time, in the early afternoon. That gave the craft’s solar panel enough time to charge up its batteries for the flight. It was also a time when Perseverance’s weather sensors, called MEDA, suggested the average wind speed would be about six meters per second.

Ingenuity testing its rotors on Mars
NASA’s Ingenuity helicopter tested its spinning rotor blades on April 8, a week and a half before taking flight in the thin Martian air for the first time.JPL-Caltech/NASA

Ingenuity had to pilot itself through the flight. That’s partly because of the communication delay — Mars is far enough from Earth that light signals take about 15 minutes to travel between the two planets. But it’s also because Mars’ thin air makes the helicopter difficult to steer. “Things happen too quickly for a human pilot to react to it,” Quon said.

Perseverance filmed the flight from about 65 meters away, at a spot named Van Zyl Overlook. Ingenuity also filmed the flight from its own perspective, with two sets of cameras: Its downward facing navigation cameras capturing the view below it in black and white, and its color cameras scanning the horizon.

selfie image of Perseverance rover with Ingenuity helicopter in the background
Over several days, NASA’s Perseverance rover gently lowered the Ingenuity helicopter to the ground and then took this selfie with it on April 6 from about four meters away. The rover then drove off to a safe distance of 65 meters to get ready to watch Ingenuity’s first flight.MSSS/JPL-Caltech/NASA

Now that this first flight went well, the team hopes to take up to four more flights over the course of Ingenuity’s mission, possibly starting as soon as April 22. Each will be a little bit more daring and riskier, Aung said. “We are going to continually push all the way to the limit of this rotorcraft.” And each one will be a nail-biter: Just one bad landing could end things immediately. Ingenuity has no way to right itself after a fall.

That may be the way the mission ends, Aung admitted in the April 19 news briefing. “Ultimately, we expect the helicopter will meet its limit,” she said. Even if it eventually  wipes out in a crash, the engineering team will learn valuable information from how the helicopter eventually fails.

At the end of Ingenuity’s mission, Perseverance will drive off, leaving the little helicopter that could behind, and continue its own mission: to search for signs of past life in Jezero crater, and to store rocks for a future mission to return to Earth.