The unexpected longevity of the Mars rovers has been excellent news for Sarah Stewart Johnson, a member of NASA’s Mars Exploration Rover Team. Johnson, a Kentucky native who got hooked on the magic of Mars and other remote environments as an undergraduate at Washington University, earned degrees in biology and politics as a Rhodes Scholar at the University of Oxford before heading to MIT for a PhD in planetary science. At the Institute, she studied the early climate of Mars and began work on a life-detection instrument that’s headed, with luck, for an upcoming mission. That work continues as rover photos fuel interest in Mars research–and as she spends a year in Washington as a White House Fellow.

On her fellowship, Johnson is working with President Obama’s science advisor, John Holdren ‘65, SM ‘66, on climate, science diplomacy, and global affairs. She served on the U.S. delegation to the Intergovernmental Panel on Climate Change held in Indonesia last October and works on monitoring global greenhouse-gas emissions. She is also working on the impact of mountaintop mining in the coalfields of Appalachia and investigating how to change the way crime labs do DNA testing. A personal highlight of her fellowship so far was stargazing on the South Lawn with the Obamas, astronaut Buzz Aldrin, PhD ‘63, and a bevy of excited middle-school students.

She has also kept a hand in her research. In January, she led an expedition to test her NASA instrument, about the size of a couple of shoeboxes, in an Argentine volcano’s acidic streams, which mirror early Mars environments. “We’re using this as an opportunity to gauge how well the instrument can detect life in harsh conditions and to study a fascinating ecosystem,” she says. “This same remote-sensing technology may transform the way we understand remote parts of the earth, from glaciers to the depths of the ocean.”

When the fellowship ends this summer, Johnson will return to complete her three-year term as a Junior Fellow at Harvard University, where she will continue her research and her work with Common Hope for Health, a nonprofit she cofounded to support grassroots health organizations in Kenya. After MIT and the White House, that may seem almost relaxing.

“I thought I’d never work harder than I did before general exams at MIT,” Johnson says, “but the White House is giving that a run for its money!”