GLENWOOD SPRINGS - For about three months this fall, Joseph Carsten lived on "Mars time."
A Martian day is 24 hours and 40 minutes long, so Carsten, 32, arrived at work each day 40 minutes later than he had the day before, entering a lab in Pasadena, Calif., where the windows had been blacked out to block the sun.
It took 36 days for Carsten to round the clock, starting his shift at 9 a.m., then 9:40, then 10:20, and on into the night.
When he slept, it was in an apartment in Pasadena. During the day, though, he may as well have lived on Mars.
"You very quickly lose track of what day of the week it is," he said. "It's not so bad if you don't have to deal with anyone who is on Earth time."
Carsten, a 1998 graduate of Glenwood Springs High School, is a robotics and software engineer who works on NASA's Mars Rover Curiosity Mission.
On Aug. 5, he helped land a 1,982-pound robot on the red planet and since then he has been part of a team that pilots the device dedicated to continuing NASA's search for life on Mars.
It's a high stakes job: the Rover cost $2.5 billion to build and deliver to Mars, and is equipped with cameras, a scooping arm for collecting samples, weather monitoring gear, and a laser that can determine the mineral content of rocks by analyzing the spark they produce when shot.
Yet Carsten is hardly new to the trade. Before Curiosity, he worked on two previous Rover missions - Spirit and Opportunity - and in total has seven years of experience operating robots on Mars.
Carsten's passion for his work is palpable. To a layman reporter, he can sound like a Martian as he excitedly describes the intimate details of the Mars Rover.
"This is where we scooped," he said, gesturing on his computer screen at a recently photographed self portrait of the Rover Curiosity on the Martian surface. "This is where we had to dump a sample, and this is where we skimmed the samples to level them off."
Growing up, Carsten said, he always loved math and science.
"I had some really good teachers," he said.
After high school he studied engineering at the Colorado School of Mines, then earned a master's degree in robotics from Carnegie Mellon University, one of a few schools in the world that offer such a major.
His graduate school thesis project involved building an algorithm for "path planning" in three dimensions - essentially an equation that determines how robots move and react to obstacles on land, underwater, and in midair.
That focus was a precisely what NASA's Jet Propulsion Laboratory (JPL) was seeking in 2005 as it worked to update the navigation software on two Rovers - Spirit and Opportunity - that were already exploring the surface of Mars.
"I think that was a big reason that they hired me," Carsten said. "They don't usually put people fresh out of college doing flight software upgrades."
These days, the Rover Curiosity mission is back on Earth time and Carsten generally works a daily shift processing data from the Rover and programming its next day of activity.
"It's less efficient, but they realized they can't make people live on Mars time forever," he said.
The mission is comprised of a science team and an engineering team, and Carsten is a member of the latter. At a daily meeting at the Jet Propulsion Lab, he said, the science team lays out what it hopes to explore that day on Mars, and the engineering team is tasked with carrying that out.
"They drive what we do each day," he said.
As the Rover navigates the Martian surface, scooping samples, blasting rocks, and taking photos, its movements are largely those that were programmed by Carsten and his colleagues at the Jet Propulsion Laboratory hours before.
Transmissions between the programmers in Pasadena and the Mars Rover are channeled through four deep space network stations located around the globe, then to satellites orbiting the Earth, and finally to the Rovers themselves.
Sending a transmission directly to Mars and receiving a response from the Rover can take up to 50 minutes, since Mars can be as far as 250 million miles from Earth, depending on its location in orbit.
So far, Carsten said, all three of the Rover missions he has worked on have yielded strong evidence that life could have once existed on Mars. Geology, mineralogy, and ice found at the planet's north pole suggest that Mars was once much wetter than it is today, and life requires water to exist.
These days, the daily work of scientists on the Rover Curiosity mission is dedicated to finding carbon-containing, organic compounds that are another building block of life.
The task is complicated, though, by the possibility that some organic matter may have stowed away in the body of the Rover and arrived on Mars, where it could contaminate samples collected there.
It's a factor that haunts Carsten almost daily.
"We recently found a little white fleck in a sample we collected," he said. His team spent days trying to identify it, only to realize that "it was a small piece of something that had fallen off the Rover."
Though clearly consumed with his job, Carsten said he enjoys making trips back to Glenwood Springs, where his parents still live and where he is now spending the Thanksgiving holiday.
Just as staring at pictures of Mars for months can make Earth seem like a hospitable place, Carsten said living in the Los Angeles area has made him realize the value of the Roaring Fork Valley, and he enjoys coming home.
"I like to hike when I'm at home," he said. "You get a perspective on how nice this place is when you move away."