NASA is about to take to the air on one other planet.
As a part of its subsequent mission to Mars, leaving Earth this summer time, the house company will try to do one thing that has by no means been completed earlier than: fly a helicopter via the rarefied ambiance of Mars.
If it really works, the small helicopter, named Ingenuity, will open a brand new means for future robotic explorers to get a fowl’s-eye view of Mars and different worlds within the photo voltaic system.
“This is very analogous to the Wright brothers moment, but on another planet,” stated MiMi Aung, the mission supervisor of the Mars helicopter at NASA’s Jet Propulsion Laboratory over the previous six years.
Flying on Mars shouldn’t be a trivial endeavor. There may be not a lot air there to push in opposition to to generate elevate. On the floor of Mars, the ambiance is simply 1/100th as dense as Earth’s. The lesser gravity — one-third of what you’re feeling right here — helps with getting airborne. However taking off from the floor of Mars is the equal of flying at an altitude of 100,000 ft on Earth. No terrestrial helicopter has ever flown that top, and that’s greater than twice the altitude that jetliners sometimes fly at.
The copter will hitch a trip to the pink planet with Perseverance, which is to be the fifth robotic rover NASA has despatched there. The mission is scheduled to launch on July 20, one among three missions headed to Mars this 12 months.
At a information convention final week previewing the Perseverance mission, Jim Bridenstine, the NASA administrator, made a degree to spotlight Ingenuity. “I’ll tell you, the thing that has me the most excited as an NASA administrator is getting ready to watch a helicopter fly on another world,” he stated.
Till 1997, the entire spacecraft despatched to the floor of Mars had been stationery landers. However in 1997, the Pathfinder mission included one thing that was revolutionary for NASA: a wheeled robotic. That rover, Sojourner, was roughly the scale of a brief submitting cupboard. That success was adopted by two golf cart-size rovers, Spirit and Alternative, arriving on Mars in 2004 after which Curiosity, in regards to the dimension of a automotive, in 2012.
For a robotic explorer on one other planet, the flexibility to maneuver round gives nice benefits.
Planetary scientists are not caught watching one spot. A rover can drive throughout the panorama, stopping for nearer seems at intriguing rocks. That freedom was key to gaining the present understanding of early Mars, that the planet, now chilly and dry, was as soon as moist and possessed a minimum of some environments that have been probably liveable for all times.
Ingenuity is in essence the aerial counterpart of Sojourner, an illustration of a novel know-how that could be used extra extensively on later missions. The physique of Ingenuity is in regards to the dimension of a softball with 4 spindly legs protruding. Two units of blades, every about four ft from tip to tip, spin in reverse instructions. It weighs simply four kilos and stands about one and a half ft excessive.
Bob Balaram, the chief engineer for the helicopter, began working with some colleagues on the thought again within the 1990s.
“It didn’t really go anywhere,” Dr. Balaram stated. “We did run some small tests, but then it sat on the shelf till about six, seven years back.”
He stated Charles Elachi, then the director of the Jet Propulsion Laboratory, got interested and offered cash for additional examine. “And that got us going,” Dr. Balaram stated.
Doing one thing that had by no means been completed earlier than was an engineering problem that appealed to Ms. Aung, who joined because the mission supervisor in the midst of 2014.
“About 20 years ago, it couldn’t have been possible, really, because of the math,” stated Ms. Aung who was a deputy supervisor of the Jet Propulsion Laboratory’s autonomous programs division earlier than becoming a member of the Mars mission.
However quite a few advances, equivalent to miniaturization of electronics, batteries that saved extra power and supplies that may very well be formed into light-weight blades, had lastly made the dream of Mars flying machines right into a technological risk, Ms. Aung stated.
Turning the chance right into a working helicopter took years of trial and error.
By the tip of 2014, the engineers had constructed a small prototype. The little helicopter was positioned in a chamber the place many of the air was sucked out, replicating the density of the Martian ambiance. As a result of that they had but to put in writing the software program for the helicopter to fly itself, a member of the staff tried to information its movement with a joystick, like a hobbyist flying a drone.
Because the blades spun, the helicopter rose up. It instantly veered uncontrolled.
That they had elevate however no management.
“It did kind of what we had to do at that point, which was say we can actually get off the ground,” stated Havard Grip, the engineer who led work on aerodynamics and attaining managed flight. “So in that way, it was a success. But it also was clear that there was a lot more work to be done here on understanding how this thing behaves.”
Dr. Balaram and Dr. Grip stated one downside was that the blades bounced up and down as they spun at 2,000 to three,000 revolutions a minute. On Earth, the strain of the air pushing in opposition to the blades minimizes the bouncing. However within the skinny Martian ambiance, the bouncing created an instability that made it arduous to manage the movement of the helicopter.
The answer turned out to be making the blades barely stiffer, however that added some weight.
“Arriving at a suitable design for that was, I think, one of the biggest issues early on,” Dr. Grip stated. Finally, they discovered an answer.
“It’s quite astounding when you lift one of these blades, if you hold it in your hand, you think you’re going to lift something substantial, and it’s as light as air and, at the same time, extremely stiff.”
The engineering concerned a sequence of compromises wanted to suit throughout the constraints of dimension, weight and battery energy.
Dr. Grip on the identical time spearheaded the event of laptop algorithms that might have the ability to steer and modify the flight of the helicopter rapidly sufficient to robotically reply to shifting atmospheric circumstances on Mars.
In Might 2016, the following prototype was prepared. In the identical chamber simulating the diaphanous Martian ambiance, the helicopter rose, then hovered steadily and softly landed. For the primary time, a helicopter prototype had flown beneath management in circumstances that simulated the Martian ambiance, though it was nonetheless linked to an exterior energy supply and laptop.
The whole design, with the batteries, a Qualcomm Snapdragon processor that’s the identical as these in cellphones, communication programs and sensors all built-in, was prepared in January 2018. To imitate the weaker gravitational pull of Mars, a pulley pulled upward to counteract a part of Earth’s gravity. The density of air within the chamber was pumped down once more. However this time, as a substitute of leaving wisps of Earth air, a little bit of carbon dioxide — the primary constituent of Martian air — was pumped in.
The helicopter rose and flew.
Half a 12 months later, NASA gave the go-ahead for including the helicopter to NASA’s subsequent Mars rover mission, Perseverance.
Ingenuity is now connected to the stomach of Perseverance, which is present process last preparations for launch from Cape Canaveral, Fla.
Within the meantime, Ms. Aung and her staff are rehearsing what they are going to be doing as soon as Ingenuity is on Mars. With the Jet Propulsion Laboratory largely shutdown due to the coronavirus pandemic, all that work has been completed by way of teleconferences, with the entire staff members working at dwelling.
About two months after Perseverance lands on Mars in February, the exams of Ingenuity will start. The rover will discover a suitably flat spot, drop the helicopter onto the bottom, then drive away a minimum of 100 yards away. “The helicopter never returns to the rover,” Ms. Aung stated.
Over 30 days, the helicopter will make as much as 5 flights. A lot of the time shall be sitting round ready for photo voltaic panels to recharge the batteries.
The primary is to go up about just a few ft and hover for as much as 30 seconds, then land. Subsequent flights shall be longer, increased, farther. On the fifth flight, if every thing works, Ingenuity will go up about 15 ft, fly out 500 ft after which return again to the place it began. It has two cameras: a downward-facing, black-and-white one for conserving monitor of the place it’s; and a colour one for indirect views of the panorama. The flight will final a minute and a half.
As soon as the flights are completed, Ingenuity shall be left at its last touchdown web site, and Perseverance will drive off for the remainder of its mission.
Mr. Aung stated that the know-how may very well be tailored to an even bigger craft, as much as about 30 kilos in weight as a substitute of 4. That could be massive sufficient to hold a few kilos of cameras and different devices.
Already, NASA has plans for sending Dragonfly, a nuclear-powered rotorcraft to Titan, the most important moon of Saturn. However Titan has a thick ambiance, so flying there doesn’t pose the identical technological challenges as Mars.
Even when future helicopters are headed to Mars, they’ll nearly actually by no means be a viable mode of transportation for astronauts there.
“You wouldn’t envision extending it to where you can fly humans like you can on Earth,” Ms. Aung stated. “There just isn’t enough atmosphere.”