After an eight-day delay due to a software glitch, NASA’s Ingenuity Mars helicopter has had its Wright Brothers moment.
At about noon Mars time, yesterday, it lifted off the Martian surface, hovered about 3 metres above the ground, rotated 90 degrees and set back down. In the process, it even managed to take selfies of its shadow on the ground below it.
Video of the flight taken from the Perseverance rover, which was standing off at a safe distance, looks so ordinary it almost seems banal… until you realise that this helicopter is flying on Mars, where the atmosphere is comparable to that high in the Earth’s stratosphere.
The flight itself occurred at about 12:30am Pacific Time in the US (4:30pm Monday AEST), but due to complexities in the downlink to Earth, NASA’s mission crew wasn’t able to learn what had happened until several hours later. (The data had to be transferred from the helicopter to a base unit, then to the Perseverance rover, then to an orbiting satellite, and then to Earth – a slow process.)
But when it came, the scientists and mission controllers crew were waiting in a conference room at NASA’s Jet Propulsion Laboratory. Who cared if for them, it was the middle of the night?
“It was around 3:30am this morning, but it sure didn’t feel like early in the morning,” said MiMi Aung, Ingenuity’s project manager. “It just felt like a very normal middle of the day, very exciting.”
And while Aung and others had repeatedly expressed confidence in the helicopter’s design, the tension was palpable, even through masks and social distancing.
At about 3:40am, information started to come in.
First, it was simply confirmation that data had arrived. Then, at 3:51, the data was handed over to the technical team for analysis.
At that point, things started happening quickly, and when telemetry, altimeter readings, still photos, and even snippets of video proved that the helicopter had truly flown, there were arms raised in victory and exclamations of “Wow!” and “This is real! This is real!”
Aung stood and ripped up a couple of sheets of paper. “[That was] the contingency speech!” she said.
The mission, she said a few hours later, has now achieved all three of its objectives.
The first was to demonstrate that controlled flight was possible in the thin Martian gravity.
That much, she and mechanical engineer Amiee Quon had said at a prior press conference, had already been demonstrated in a vacuum chamber containing a Mars-like atmosphere. Though not, they discovered the first time they attempted it, possible for a human pilot.
The thin air, they found, made the first prototype very touchy to control, even for an experienced pilot. It did get off the ground, demonstrating that liftoff was possible, but the flight was simply a couple of badly controlled hops followed by what Quon, with dry, engineering humor, described as “rapid, unscheduled disassembly.”
“Think of it as if you were driving your car and turned the steering wheel just a little bit, and suddenly you were doing donuts,” she said.
That was sobering, but given the distance to Mars and the time lag with radio signals, nobody had ever planned to try to fly the real helicopter with a joystick. So, they equipped it with a high-speed processor, a camera that can take pictures of the ground 30 times a second to track its position, and the ability to make instantaneous adjustments.
It worked on Earth, and yesterday it worked on Mars. Goal number two completed.
As an extra benefit, the navigation camera is the one that returned the shadow-selfies when the helicopter completed the third of its three goals: not only flying on Mars, but returning telemetry that could facilitate the design of even better Mars helicopters in the future.
Thankfully the software glitch that delayed the mission didn’t affect either the telemetry or the navigation system. It was basically a hitch in turning the whole thing on, or as the Ingenuity team put it, getting it into “flight mode.”
The patch took about a week to develop and test, and even then, Aung said, in tests it only worked about 85 percent of the time. But if it didn’t work, nothing dangerous happened. “If it fails, the helicopter just stays there, and we try again,” she said before the flight.
It turned on first try, however, and everything else worked beautifully. “It did exactly [what we’d told it to] and it did it perfectly,” said Håvard Grip, Ingenuity’s chief pilot. “And it stuck the landing, right in the place where it was supposed to go.”
Grip’s team was even able to take the telemetry and construct a 3D animation of the flight to compliment the images taken from the Perseverance rover. “What we see is it’s just really steady,” he said. “It’s a beautiful flight.”
Not that anyone is ready to say “mission complete.”
There’s still a lot of work to do, Aung says, and the delay chopped eight days out of the month of mission time the helicopter crew had been allotted before the rover needs to abandon Ingenuity and set out on its primary mission, the exploration of Jezero Crater and collection of samples for eventual return to Earth.
Still, Aung says, there appears to be time for four more flights. “We have two weeks left,” she says.
Next up, probably on Thursday, she says, is to lift to 5m (2m higher than today), fly 2m laterally, then come back and land.
That will be followed a few days later by again rising to 5m, but this time moving 50m out and 50m back.
After that, she’s not sure. But Aung says she’s like to stretch the range to 600–700m. The goal, she says is to push the helicopter’s limits by going faster and further on each flight. If it crashes, so be it. “Ultimately, we expect the helicopter will reach its limits,” she says. “But we really want to know what the limits are.”
“We want to be sure that, when all is done, we know the full scope of what is possible with that machine,” adds Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate.
Meanwhile (other than the remaining risk that any given flight could be postponed if the helicopter fails to switch into flight mode), the helicopter is healthy, says Bob Balaram, the project’s chief engineer.
In fact, he says, “it’s even healthier than before.” During yesterday’s flight, he says, “she shook off some of the dust that had been covering her solar panels.”
And, he adds, “the batteries are looking good. The communications system is fantastic.”