JPL came to recruit at his school in fall 1993, and he remembers telling the recruiter how he was fascinated by NASA's Voyager mission -- twin spacecraft that had photographed Jupiter in unprecedented detail. His excitement apparently made an impression: He landed an interview at JPL in January 1994, and started his job that June.
Today, he lives on a quiet Pasadena street, in a cozy house that boasts some of his nerdy treasures, including an extensive collection of science fiction books. "But then my life became science fiction," he said, explaining why he's reading more Shakespeare and Dickens these days. As he shows off his collection, his cat Molly purrs, demanding his attention. The brown and black marbling on her otherwise white fur looks somewhat like the Martian landscape, although that's not why he adopted her.
A glass-paneled cabinet hosts metallic "Star Wars" and Mars rover lunch boxes. There's a vial of a substance he calls KimSim, a material his girlfriend helped create to figure out how to rescue the Spirit rover after it got stuck in a "sand trap" of alien soil on Mars in 2009.
And there are stones from the Cotswolds, an area in England he bubbles with excitement over. He says, "Wait, wait," like a child about to demonstrate a new toy, and runs to get a book filled with images of the region. He likes the views from the ground better than the aerial shots -- ground-level is more like what a rover would see, he explains.
The wider, well-manicured street perpendicular to his own, with larger houses and roses growing on front lawns, is the sort of place where he'd always wanted to live, but he says the houses are "wicked, ridiculous, crazy expensive." Still, he loves the house he bought, with the added bonus of a lemon tree growing at its side.
It's a bit like how he loves his job driving a vehicle on Mars, even though he dreamed of becoming an astronaut.
"Things in my life aren't quite how I pictured them," he said, "but they rhyme."
At NASA, not just a sojourner
It's been 18 years, but Maxwell still occasionally interrupts himself to say things like "I can't get over that I work at a place called the Spacecraft Assembly Facility" when he mentions that building at JPL.
For the first couple of months there, Maxwell felt like he was in a foreign country where he didn't speak the language. He says it was fun to be clueless about the acronyms his colleagues were throwing around. "Now, I'll use 10 acronyms in a sentence and won't think twice about it," he says, "but you kind of have to pick up the culture."
He started out working on software to decode data from spacecraft. He also wrote software to help coordinate various teams working around the world to get commands to spacecraft.
In the mid-1990s, Maxwell was asked if he wanted to work on a mission called Mars Pathfinder. Maxwell had no idea what that was, and working on the team didn't appeal to him.
What he didn't know was that Mars Pathfinder would mark the first time NASA had sent an untethered robotic device to another planet. The 90-day mission was carried out by a rover named Sojourner.
"I just thought that was super cool, that really just captured my imagination, that you could go for a walk on another planet," he says. "Not with your squishy, frail, human body, but you could design a robot body that would go to Mars for you."
Although he passed up that opportunity, another chance came in 1999 when Brian Cooper, who'd driven Sojourner, approached Maxwell about developing rover-driving software for the next Mars mission.
"More or less before the words were out of his mouth -- like, 'Do you want to come work on this project?' -- I was like, "YES! Yes! I'd like to come work on this project, that'd be the coolest thing in the world, yes!"
That mission was eventually scrapped, but their efforts were put toward a different endeavor that did take off: Spirit and Opportunity, the twin Mars exploration rovers that launched in the summer of 2003.
Maxwell helped write the software that rover drivers would use for the pair, as well as for Curiosity. He would soon move from writing software to using it to command -- and ultimately drive -- the rovers.
His first time commanding a rover was on his 33rd birthday, in 2004. Spirit hadn't started moving across the Mars surface yet, but Maxwell and his colleague were checking out the instruments. Maxwell told the rover to ignore the state of a switch on one of the instruments -- not exactly driving, he said, "but by golly, I commanded a Mars rover that day."
The real drama came about three weeks later when he got behind the wheel, so to speak. He remembers obsessing over what he had to do, checking everything multiple times, before sending the driving instructions.