Interview with Sarah Stewart Johnson

Sarah Stewart Johnson photo

By Catherine Hsu

A fascinating exploration of the bounds of human existence, The Sirens of Mars: Searching for Life on Another World by Sarah Stewart Johnson is the recipient of the 2021 Phi Beta Kappa Award in Science. This award recognizes superior contributions by scientists to the literature of science. First offered in 1959, the award encourages literate and scholarly interpretations of the physical and biological sciences and mathematics. Past winners include political statistician Nate Silver and conservation biologist Thor Hanson.

Currently an assistant professor of planetary science at Georgetown University, Sarah Stewart Johnson holds a bachelor’s degree from Washington University in St. Louis, degrees in PPE (Philosophy, politics and economics) and biology from the University of Oxford, and a Ph.D. from the Massachusetts Institute of Technology. At Georgetown, she leads the Johnson Biosignatures Lab, which focuses on implementing planetary exploration, analyzing current spacecraft data, and devising techniques for future missions.

Now a visiting scientist at NASA’s Goddard Space Flight Center, Johnson has also worked on NASA’s Spirit, Opportunity, and Curiosity Rovers. A former Goldwater, Truman, and Rhodes Scholar, Johnson has also worked with former U.S. President Obama’s science advisor in the White House. 

Combining a coming-of-age memoir and scientific history, The Sirens of Mars reveals how Johnson’s fascination with Mars began as a child, looking at the night sky with her father. Now, she works as a female scientist conducting fieldwork in Earth’s most hostile environments to develop new life-detection methods. By weaving her personal journey into those of other seekers such as Galileo and Carl Sagan, Johnson tells the story of Mars and highlights how it works as a reflection of the story of Earth. 

This book also won the 2021 Whiting Writers’ Award in Nonfiction.


Can you tell us more about your experiences with your father — his fascination with the Mariner 4 mission, the trip to the Vega-Bray Observatory — and how they shaped your interest in planetary sciences?

JOHNSON: My father has been an amateur astronomer all his life, and I think that has had a profound effect on me. In some ways, our lives are really different, but it’s been this wonderful thing we can share. Some of my favorite memories have been looking up at the sky with him — like at the Vega-Bray — and also more recently with my young son and daughter, who experience the same joy I do when he points out the space station arcing overhead or shows them the craters on the moon.

What has been your favorite location to conduct fieldwork in? What makes this place especially important?

JOHNSON: They’re all compelling in different ways, but Antarctica does stand out. Arriving there feels like arriving on a different planet, and the terrain is impossibly vast. As a polar desert, it’s also one of the most Mars-like places on Earth.

In the book, you write about how Mars reflects the story of Earth, untouched and yet marked by human history because of how we see it as a utopia. What is it about space and Mars in particular that captivates us? And what can we learn about ourselves and our Earth through exploration of Mars?

JOHNSON: Different people have seen Mars as different things over the years — a utopia, yes, but also wilderness, a refuge, a hellhole, the past, the future. I think Mars can encompass so many divergent imaginings because it has been a blank slate, particularly before we had data and still to this day, since there’s so much we don’t know. I also think Mars invites us to project ourselves onto it because it seems so similar to Earth in some crucial and relatable ways, most obviously that it’s next door, and it’s also a planet where very similar conditions existed right around the time life was getting started here on Earth. So it’s only natural to wonder if life started there, too, and what that life might be like. And even if there’s no life on Mars, that’s also interesting. Why not, and what can we learn about our own history from studying Mars, a planet with a nearly perfectly preserved past (unlike our own)? It’s really tantalizing in that way. As for what captivates us about space generally, I think it’s just inherent to being human, to being part of being a species that cares and wonders about what came before and what will come after us, to ask fundamental questions about being alive: Where did we come from, are we alone, and what might our future hold? From my perspective, space is a natural place to turn with such questions.

The Mars quest has gone on for generations. Where are we, and where do we go from here?

JOHNSON: The big thing that is happening next is the return of samples from Mars — carefully selected samples that could contain traces of ancient life. Once we have those back in our labs, we can hit them with everything we’ve got, no longer limited by the instruments we are able to ship to Mars and operate remotely. That will be a huge boon for the science. I think astronauts will travel to Mars, too. There are immense challenges in doing that safely. At the same time, it took only twelve 12 for us to figure out how to go from nothing, before Sputnik, to the Apollo moon landings. There were tremendous investments being made at that time, of course, and whether there will be another space race remains to be seen. Still, I think the technological leap from the moon to Mars is smaller, and the stage is set for rapid progress if we decide to do it. We can and should also expand our scientific efforts beyond Mars, to places like the moons of the outer solar system. But I still believe Mars remains one of our best scientific targets and one of our best hopes for finding extraterrestrial life.

What does it mean to you and to your work to have The Siren of Mars selected for the Phi Beta Kappa Award in Science?

JOHNSON: It was a tremendous honor. I’ve been scribbling in notebooks all my life, but it’s only recently that I’ve started sharing my writing with others. This is my first book, and I really had no idea what to expect. It means the world to me to have it recognized by a community of scholars like ΦBK, and to see it join a group of past ΦBK award-winning books that have been hugely formative in my life. I still can’t believe it!

Catherine Hsu is a recent graduate of the University of California,Berkeley where she majored in political science and art practice. She was inducted into Phi Beta Kappa there in May 2021. UC Berkeley is home to the Alpha of California chapter of Phi Beta Kappa.