Red zone touchdown
On Thursday, Matt Heverly kept tabs on a robot as it fell from outer space through the skies of Mars to the planet’s rust-tinged surface, hoping every step of the way it would land gently.
The nervousness of the former Medford resident and Kennedy Elementary alumnus over something happening 129 million miles away stemmed from the fact that he had helped design the robot, a $2.4 billion rover named Perseverance.
For four years, Heverly, 44, worked as a technical group supervisor for the NASA Jet Propulsion Laboratory’s mechanisms and mobility group — the engineers who designed the rover’s wheels, suspension system, motors and gear boxes — components necessary for Perseverance to move on the planet’s surface while it conducts its primary mission: “Seek signs of ancient life and collect samples of rock and regolith for possible return to Earth,” according to the NASA website.
“Heads are down, hands are on your head, hoping that this thing goes right,” Heverly said Friday.
Everything went just fine.
Falling to Mars
Perseverance left Earth July 30, 2020, and Heverly watched it land Thursday during a small, socially distanced, outdoor get-together in his California neighborhood, where a NASA JPL stream was displayed by a projector in a neighbor’s yard.
Heverly was at the wheel, in a sense, on two other rovers: Opportunity, one of two rovers that touched down in 2004, and Curiosity, which landed in 2012.
Curiosity is still rolling. Ashwin Vasavada, the project scientist for that mission, said in January that the rover was investigating the terrain on Mount Sharp, with evidence that could point to a major climate change event hidden among the terrain’s geological layers. In a strange twist, the parents of both Vasavada and Heverly live at Rogue Valley Manor.
Curiosity’s Mars landing sequence was quite similar to Perseverance’s. It’s called “entry, descent and landing,” or EDL, “the shortest and most intense phase of the Mars 2020 mission,” the NASA website says.
“It’s cool, because when you talk to people about, ‘Here’s the big picture of what we’re trying to do,’ people get excited about it,” Heverly said.
“I feel like we are doing something big and cool and special. And then you reveal the engineering that has to happen to make that work, how the parachute has to work, and the separation has to work, and the landing engines have to work, and the vision system has to work to find the safe place to land, and then it’s like, ‘Oh, my gosh, there are a lot of things that have to go right.’ And the robot has to do it all on its own.”
The leadup to touchdown was a master class in suspense. After seven months in space, Perseverance could see the finish line mere kilometers above the planet’s landing zone: the Jezero Crater, a depression that’s about 45 kilometers wide, yawning below it, an invisible bullseye on the auburn sands.
During its descent through the thin Martian atmosphere, the capsule slowed to a speed of about one kilometer per second. A parachute deployed, slowing its speed even further as its heat shield separated and fell away.
The capsule’s back shell and chute separated from the rover and the rockets, called the “descent stage,” attached to it. The rockets fired, guiding Perseverance the rest of the way down. Imagine a robot with a jetpack, and you’ve got the idea. A system called terrain relative navigation, intended to give an accurate picture of the rover’s position and avoid hazards, guided the descent epilogue until only 20 meters remained between sky and Mars. There, cables lowered Perseverance to the ground, and the descent stage flew off to crash land elsewhere.
NASA referred to this stage as “seven minutes of terror.”
The projector Heverly used to keep tabs on Perseverance didn’t work too well, but he was able to at least get all the streaming audio as it came in.
Heverly’s wife had a camera trained on him in the final moments. He sat ramrod straight, leaning in to listen. Then the pivotal words came through.
“Touchdown confirmed,” Perseverance rover guidance and controls operations lead Swati Mohan announced. “Perseverance is safely on the surface of Mars.”
The first image, a shot of the terrain, brought the reality of the success all the way home. Heverly recalled a similar experience during the 2012 Curiosity landing. Despite its success, his nervousness remained. Then the first photo displayed.
“To see the image, I mean, that’s the thing that makes it real. Like ‘Oh, yeah, there are wheels on the ground on Mars,” he said, breathing a sigh of relief. “OK, now I feel it. That’s kind of, for me, where I get that sense of relief.”
More photos followed. For Heverly, they were reminders of other systems on the rover that worked, of his colleagues’ successes in other JPL departments.
“Each one of these, you know the people behind each of these little things,” Heverly said. “The road that they took over several years to design and build and test and integrate it.”
Perseverance’s main mission will be to drill into the planet and extract chalk-sized rock cores, depositing them into small tubes that will later be picked up by another rover named “Fetch.” A robotic arm on a lander craft will load Fetch’s samples onto a rocket, which will put the samples into orbit before their eventual return to Earth.
Heverly’s latest work has been as “surface phase lead” for that mission, coordinating different objectives as it unfolds.
NASA is collaborating with the European Space Agency on the return mission. The ESA will design the Fetch rover and the robotic arm that will load the samples aboard the rocket, Heverly said. NASA’s Marshall Space Flight Center in Huntsville, Alabama, will design the rocket.
“It’s this collaborative effort across multiple NASA centers, but also across international borders,” Heverly said.
Heverly’s neighbor made a banner celebrating the samples’ eventual return. On Friday, it hung in Heverly’s home.
“Mars Rover, Mars Rover, send samples right over,” the banner reads.
The adventure begins
Perseverance has plenty of work to do until then. First up is testing the drone helicopter named Ingenuity strapped to the rover’s belly, the craft along for the ride to conduct the first powered test flight on the red planet.
Perseverance will use additional tools during its mission, including multiple imaging cameras, spectrometers and sensors for analyzing the composition of Martian surface materials. The rover also carries ground-penetrating radar, and the Mars Oxygen In-Situ Resource Utilization Equipment (MOXIE) is intended to produce oxygen from the Martian atmosphere’s carbon dioxide.
Heverly is counting on something to go wrong. Past missions have shown this. Spirit, which joined Opportunity in the 2004 landing, lost a wheel, and operators had to figure out how to drive in reverse. Opportunity lost a robotic arm joint. Curiosity’s wheels endured wear and tear more quickly than expected, prompting operators to figure out how to drive in different terrain.
“Everything’s not going to go perfect,” Heverly said. “But kind of once you have that yes, we’re six wheels down on the surface of Mars, we can figure out a lot of things and do a lot of good science.”
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