Caltech alumni at JPL have starring roles in the dramatic three-act play of the Mars 2020 mission: Send a rover to the surface of the Red Planet, collect samples, and bring them back to Earth. Success could advance our understanding of the planet’s history—and its potential for future human exploration.
It’s a warm autumn day in Southern California, but inside a pair of buildings on the campus of the Jet Propulsion Laboratory, liquid nitrogen floods the walls and conditions are distinctly chillier—hovering around –80° Celsius. The air pressure is a fraction of Earth’s, and the atmosphere is mostly carbon dioxide.
These are exactly the conditions that the Mars 2020 rover will find at its ultimate destination. It’s the most ambitious Mars mission yet, and JPL—which is managed by Caltech for NASA—is running the show.
Today is the last day of testing for the rover. “We’re putting the vehicle through some day-in-the-life stuff,” says Adam Steltzner (MS ’91), chief engineer for the mission. “We’re way in the thick of it now.”
For the project engineers and scientists, the pressure is considerable. By February, the rover will ship to Cape Canaveral. Meanwhile, two anomalies have been discovered: one in the battery control board, and the other in the robot-powered sampling system designed to collect dozens of Martian samples that will be brought back by another craft on a future mission.
In Building 248, where that sampling system is being put through its paces, Steltzner watches as a couple of engineers send commands to the robots to take another swing at moving the drill bit into the round clamp that holds it while it does its work. That sampling system is ambitiously complex, comprising three or—depending on whom you ask—four robots. On Mars, no humans will be able to tinker with it hands-on, so that’s not allowed during testing, either. The first time around, the drill bit didn’t slide in as easily as expected. “As the first sampling tube was put into the bit, the forces were about 10 times higher than we anticipated,” Steltzner says.
The rover’s drills and sample tubes also have to be hyperclean to avoid contamination from Earth. And that hyperclean requirement poses challenges. First, expose a perfectly clean titanium tube to air, and within seconds particles will begin to accumulate on its surface. Second, almost everything we know about friction is based on how materials behave in Earth’s atmosphere. So what was the problem with the bit? “We don’t know whether to attribute it to dust or to changes in the friction coefficients between the various hardware elements,” Steltzner says as he hoofs it down the hill from Building 248 to a meeting to figure out next moves for the drill. “Testing is an act of humility.”
Steltzner has spent 28 years at JPL. He grew up in Marin County, California, kicking up dirt and breaking bones on mountain bikes. Meet him on the street and you might peg him for a rockabilly guitarist: slicked-back pompadour, cuffed jeans, scuffed black boots, and a black T-shirt that says “Derby Dolls”—as in roller derby—in gothic script. But he’s not performing rockabilly: Instead, he and his team developed the sky crane that landed the Curiosity rover on Mars in 2012.
An hour after the meeting, walking across campus to meet a group of visiting VIPs, Steltzner runs into his friend, JPL engineering fellow Miguel San Martin, whose team took a closer look at that battery control board anomaly. A flyby conversation here, with a tentative conclusion: It might be time for the equivalent of open-heart surgery to fix the board.
The Mars 2020 launch is slated for July 2020, with landing in February 2021. The rover is a near-twin to Curiosity but carries some new tech, including a fully automated sampling system. A future mission will pick up the samples and send them into orbit. A third mission will bring them back to Earth.
Curiosity also is collecting samples, but testing them as it explores. It cooks those samples in its microwave-sized Sample Analysis of Mars instrument that, among other things, can heat rocks to 1,800° Fahrenheit and measure the results. All of that analysis takes time. “Humans check every piece,” Steltzner says. “If we asked humans to okay each decision on Mars 2020, it would take three weeks to go through the process that would cook the sample.” With the process scientists and engineers are planning, Steltzner explains, weeks become hours. “We collect each sample autonomously in 200 minutes, seal it up, and move on. The new system is 100 percent autonomous—and I can assure you I’m questioning the brilliance of that right now, as we stare at these anomalies up the hill.”
The sky crane also returns, with a sophisticated addition: terrain-relative navigation, which allows the rover to set down in a tighter, trickier spot than was available for Curiosity. During descent, cameras will take pictures and match them to images in the rover’s memory, then use the images to determine where the rover should divert to as it sheds the parachute. Here on Earth, we’ll be able to see it all in high-definition video.
We can thank Matt Wallace (MS ’91)—and his daughter’s love of gymnastics—for the rover’s array of cameras. When she was about 9 years old, she saw videos of gymnasts doing flips wearing GoPro-style cameras. “She said, ‘Dad, I want one of those!’” Wallace says. He saw her in action with it and thought, “We really need one of those on the spacecraft!”
Wallace is deputy project manager for Mars 2020. The EDL cameras (for entry, descent, and landing) are dispersed all over the spacecraft, to look up as the parachutes deploy and the propulsion system fires, and down as the rover descends. “For the first time ever, we’re going to have high-definition video of a spacecraft landing on another planet,” Wallace says.
In addition to the cool factor, there is of course some valuable engineering knowledge to be gained. Mars 2020 is meant to be a precursor to human travel. Spacesuit material will go along for the ride to test for radiation exposure. Additionally, the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) will employ electrolysis to convert CO2 into oxygen, which could be used for both rocket fuel and breathing.
Some tech used in 2012 turned out not to be as plug-and-play as expected. The heat shield cracked early in testing; a new one had to be built. The supersonic parachutes turned out to need an upgrade; they’re the same size as Curiosity’s—21.5 meters in diameter—but with a stronger canopy, and they slow the rover’s descent from 1,000 mph to around 200 mph before the sky crane takes over. As for the anomalies: “Always looking around the corner, constantly questioning whether you’re making a good decision, whether you have the right people doing that work, or whether you’ve done enough testing in this domain—that comes with the territory,” Wallace says. “If you’re not doing that, then you’re probably not doing it right.”
When the rover lands, the engineering team will hand over the keys to the science team. The landing site is Jezero Crater, an ancient lakebed about 40 kilometers across, where a once-flowing river formed a delta rich with sediment. From Jezero, the rover may head into highland terrain known as Northeast Syrtis, which has its own distinctive geology. For project scientist and Caltech’s W. M. Keck Foundation Professor of Geochemistry Ken Farley, it’s an unprecedented opportunity to learn about the history and geology of the Red Planet. Here on Earth, deltas are good places to find fossilized evidence of past life.
Farley headed Caltech’s Division of Geological and Planetary Sciences for a decade. It was in his lab that a now widely practiced technique was developed to use helium isotopes and other noble gases to establish the cooling and exhumation history of rocks. Farley describes his groundbreaking work in deceptively simple terms. “I do things like geochronology,” he says. “I date rocks.” One key instrument for that is a mass spectrometer that uses a 1,000-pound magnet. The spectrometer can’t go to Mars, so Mars is coming to the magnet in the Mars 2020 sample tubes—where they’ll be investigated by the full arsenal of a terrestrial lab and its experts.
We know a couple of things already, Farley says. “Mars had a traumatic climate change event. There were rivers, lakes, glaciers, all sorts of features that certainly don’t exist today.” What happened? To try to answer that question—and others scientists don’t yet even know to ask—the rover will take samples from about 35 locations and rock types.
NASA is presently considering a plan that could have samples back on Earth as early as 2031. Then, Farley says, we’ll face a deeper question: “How do you look for life as you don’t know it?”
Kathryn Stack Morgan (MS ’11, PhD ’15) is deputy project scientist on Mars 2020. She’s also part of the scientific team for Curiosity. In her graduate work at Caltech, she used orbital and rover data to study the geology of Mars. At JPL, she’s one of a handful of people fluent in moving between orbital and rover data sets.
Gearing up for Mars 2020, she and other scientists have been collaborating with engineers to ensure that the rover has the instruments it needs to get the job done—determining which capabilities are critical and which can go because of cost or schedule delays. Morgan also is shaping the process scientists will use to make day-to-day science decisions about where the rover will travel and for how long. A central task is compressing the turnaround time between when new data are downloaded and when new commands need to be uplinked. That’s essential to gathering a cache of samples in just one Mars year—slightly under two Earth years. “It’s a pace of sampling no other mission has come close to accomplishing,” Morgan says.
Morgan also has designed a process to make new data available to scientists more broadly right away. “That’s really important for this mission,” she says, especially given how ambitious the goals are—both on the surface of Mars and, someday, back on Earth.
Meanwhile, Sarah Milkovich (BS ’00) and her team, who are working on the rover’s instruments, are digesting what they’ve learned from the system thermal test—the Mars-environment testing of everything from the weather instruments to the ground-penetrating radar. As science systems engineer, she’s in some sense the glue between teams of scientists and engineers. This means both ensuring that lessons learned from the testing data are applied and looking for efficiencies in how tactical planning will happen on the Martian surface. It also means things don’t slow down once the rocket launches. “We haven’t hit the peak of the roller coaster yet,” she says.
Milkovich, who has a doctorate in planetary geology, points out that the ambitious goal of sample gathering also entails documenting context in detail. “These rocks are going to represent Mars to us,” she says. Apollo astronauts brought back rocks from the moon and revolutionized how we understood the formation of not just the moon but also Earth, she says. With Mars we’ll go from two data points to three.
At the end of the day, over the hills above JPL, a couple of canary-yellow Canadian Super Scooper planes fly by, carrying water to dump on wildfires burning to the west. Adam Steltzner hustles to pick up his four-year-old son from the JPL early childhood education center. (Steltzner is a father of three, with two older daughters.) He has his rover: a mud-spattered SUV, mid-’90s vintage, with off-road tires and jerry cans on the back. U2’s “Beautiful Day” is playing on the radio.
“When we start a mission, we have a pretty good idea of the thing that needs to be done, but it’s imperfect,” Steltzner says. “As the mission progresses, our understanding of exactly what we need to accomplish and how to do it evolves and improves.”
The fact that the samples from Mars 2020 will come back to Earth gives this mission a whole new dimension. “We don’t have to chisel out the questions we need to ask,” he says. New questions can be posed as scientists test the samples here. “We can have the full ingenuity of this nation to answer them. People who look at the sampling system think it’s far too ambitious. I agree. We have a standing invitation to the universe to teach us how to do this more simply.”
That word—ambitious—seems to crop up time and again.
“I personally think that’s our job—the Jet Propulsion Laboratory’s job, and Caltech’s job: to ride the sharp edge of ambitious. We are doing a performance in the art of the possible. And if we’re not ambitious, it’s a boring piece of art.”