MIT Professor finds meaning in the search for a new Earth
By Rudi Anna
MASSACHUSETTS– The memory is vivid. She was 16 years old. It was one of the first times she’d been away from home overnight. She walked into an observatory almost by accident and was asked to look up.
What she saw would change her life forever.
Sara Seager recalls that night 30 years ago: “I think that may be one of the best days in my life,” she says in the early spring hours of 2016 with bright eyes radiating a giddy earnest probably matching her teenage self.
From the University of Toronto to Harvard, then to a fully tenured professorship at the Massachusetts Institute of Technology by the time she was 35 years old, Seager has soared on the cutting edge of planetary science studying exoplanets, those strange and unimaginably distant worlds outside our solar system scientists have only just begun to pursue. NASA has repeatedly referred to her as the Indiana Jones of astronomy.
Seager was born in Toronto, Ontario in 1971. Her parents divorced when she was very young. She lived predominately with her mother during the week. Every other weekend, she stayed with her dad, who went to great lengths to arrange memorable excursions with his gifted daughter during their short windows of interaction. It was, she says, her father who had the most prolific influence on her upbringing.
“My father was what I like to think of as a feminist before his time,” said Seager, explaining that her dad had two sisters, one of whom married into an abusive relationship with a man who wasn’t very well off. Seager remembers her aunt being forced to run away from him. Without a formal education, the aunt found she had very limited options. “She was basically screwed. And [my father] saw that himself, and so his message to my sister and me was, you better support yourself,” said Seager.
Seager’s father wanted her to simply have a life of her own, and make a decent living without a dreaded feeling of inescapable dependency. One of his ways of instilling this was to make sure that Seager was as well-rounded with her education as possible. Trips to the art museum were a regular affair. Piano lessons with strict teachers filled many Wednesday nights.
All of it was to make sure that whatever Seager chose to do as an adult would be on her own terms.
When she was 16, she took her burgeoning sense of independence with her to that life-changing experience at the sky-watching open house at the observatory at the University of Toronto.
“I learned that you could be an astronomer as a job. I was so excited,” said Seager. She went home to tell her father, knowing that he’d be just as excited about the discovery as she was.
He wasn’t.
“He was livid,” said Seager, “You can’t do that. You have to be a lawyer or a doctor.” He felt scientists made shabby livings and had to constantly beg for money to fund research and a way of life. Seager recalls the message her father threw down on her was “in the top three of the worst lectures I ever got.”
Not that her father wasn’t to blame for diligently planting the seeds of astrophilia prior. Seager remembers hearing her dad tell stories of the star constellations. She recalls him telling her how different cultures have entirely different names for the same constellations with different stories to go along with them. Then there were the ‘star parties’ she and her father would attend at the Royal Astronomical Society of Canada.
“People would come to these and they’d all bring their telescopes, and you could look through and I saw the moon through a telescope for the first time. I just lost my breath,” said Seager.
These experiences got planted deep inside. As Seager grew, they remained an important part of her—even when she wasn’t thinking about it.
But the maturing young woman raised on the bedrock philosophy of being self-sufficient and independent found herself on a fairly short leash with her aspirations. When she did finally ship off to college, she focused her studies not on the stars, but on vastly general areas like mathematics and physics. She knew, to please her father, she had to keep her options open.
Then at college, another philosophy on how to design one’s life course took root.
“There’s the strategic path to follow in life, or there’s the random walk,” said Seager. “I chose the random walk.”
In physics, a random walk is a common term used, in one sense, to describe how particles interact with light. When light emanates from the sun and enters Earth’s atmosphere, it hits and interacts in some way with Earth’s particles. What the light does next is up to the physical properties of the specific particle. Where it goes next is random occurrence. Typically, if we’re seeing it, the light beam has landed in our eyeballs, but not before pinballing its way randomly from particle to particle across the cosmos and into our awaiting retinas.
Seager sees herself, at least her early twenties self (and maybe a little today), as a well-prepared but wandering flicker of light, waiting for the next particle—the next opportunity—to hit.
Following her graduation from the University of Toronto with a degree in math and physics, Seager wasn’t sure what to do next.
Random nature struck. On a cross-country ski trip, she happened to meet Mike Wevrick, an Ottawan, outdoorsman, and her future husband. He was 30 and she was 22. Their acquaintance would occur on the same fateful day she found out she was accepted to Harvard University for grad school.
Seager and Wevrick were instantly attracted to one another, and their relationship would waste no time undergoing its first major test.
On the same ski trip, Seager invited Wevrick to accompany her on a nine week, bare-knuckled canoeing and camping trip by themselves in the great Canadian wilderness.
“We knew after that trip they’d either never speak again or we’d be hearing church bells,” said Jana Stetson, a long-time friend and one-time college roommate of Seager’s.
Such is the life of the random walk. Intense challenges. No fixed destination in sight. Go on excursions to the Northwest Territories with a virtual stranger. Figure out what happens next afterward.
Needless to say, the trip went very well. Seager moved to Boston for grad school. Wevrick did too.
When Seager finally got to Harvard, still somewhat undecided in a career path, she initially decided she had to study one of the most difficult fields of science available: magneto hydrodynamics.
“Sara came to Harvard very much ahead of the class,” said Dimitar Sasselov, a Harvard astrophysicist and mentor to Seager during her graduate studies. He believes Seager’s studies at prestigious high school and her undergrad achievements provided the right tools for success. “She stood out early on.”
But magneto hydrodynamics wouldn’t be the challenge she was looking for. She found herself a little unhappy and routinely bored. She’s not even sure why she focused on it in the first place.
She found herself on another random walk, and other much more attractive particles were nearby.
Harvard also features the Smithsonian Center for Astrophysics where hundreds of gifted physicists and researchers work every day. They also hold daily lectures and talks on new breakthroughs in research. These events would soon consume much of Seager’s time.
“One of my favorite things about [Harvard] was that if you were really interested in something and wanted to study it or incorporate it into your studies, they’re so open to you doing that, to take that risk” said Seager when she pivoted course to steer solely toward astronomy.
After pouring over the accumulated literature and grounding herself in the required understanding, Seager was ready to make the dramatic shift from one field of science to a completely different one.
“She has an eye for a great problem—a solvable problem,” said Sasselov. “This helped set her on a successful path, despite the daunting task of having to master a new discipline.”
To essentially get her feet wet, Sasselov directed Seager to an obscure but important problem in cosmology: Modeling how radiation ricocheted off hot gas in the aftermath of the Big Bang. “Believe it or not,” Seager says, “that remains my most highly cited work.”
But while Seager was focused on the edge of the universe, a quiet revolution was breaking out closer to home. In 1995, researchers found the first known planet orbiting another Sun-like star, called an exoplanet. Dubbed 51 Pegasi b, it was about as massive as Jupiter but circled so close to its star that it must have baked at a temperature of almost 2,000 degrees Fahrenheit.
Over the following year, an astronomer at the University of California, Berkeley discovered six more exoplanets, three of which were also big and broiling. Humanity finally had hard proof that the universe is full of other solar systems, something that until then had been the stuff of sci-fi.
Sasselov realized the models he and Seager were applying to hot gas in the early universe could be used to study the hot gas in the atmospheres of these overcooked alien planets, if only someone could get a clear look at them. At the time, all the known exoplanets hadn’t even been seen. They were merely detected indirectly by their gravitational tug on their stars.
That detection’s hard enough. Seeing starlight streaming through the air of an alien planet? Far more difficult. If it were possible, though, it could reveal all of a planet’s key details: temperature, composition, even the local weather.
Sasselov and Seager huddled, and together they made a fateful decision. “That was when I figured out she was a special student. She was so very bold,” says Sasselov. Together, they plunged into the infinite, unproven field of exoplanets.
From here on, Seager’s random walk starts to assume some predetermination.
“Prior to that moment, I wasn’t even sure I wanted to be a scientist,” said Seager with a wink. “But after getting into exoplanets, I was pretty sure I knew what I wanted to be when I grew up.”
The year was 1997. Seager modeled the appearance of starlight reflecting off the atmosphere of an exoplanet, showing other astronomers what to look for. In 1999, she predicted that the element sodium should leave a prominent fingerprint in light shining through the atmosphere as a planet transits in front of its star, a finding soon confirmed by several other astrophysicists.
With her finding, the whole paradigm of solar-system understanding was shaken up, and Seager became an instant superstar in the field. “People were very impressed,” she says.
With that triumph, she snagged a postdoctoral appointment at the Institute for Advanced Study in Princeton. Another new challenge, another mystery as to where it would lead her to. “I showed up and got to be the resident expert on exoplanets. I was the only one. There were no barriers,” she says. “That’s how I got into the Earth stuff.”
Small, Earth-like planets are even more challenging to observe directly than are giant gas balls like 51 Pegasi b. Nobody had cracked the problem then, and still nobody has cracked it now. But the scientific stakes could hardly be higher. Finding water vapor in the atmosphere of an Earth twin could indicate that a planet has the potential for life. Detecting molecules like oxygen and methane, which are associated with known biological processes, would be even more stunning. It would show that life really is out there, on another world, trillions of miles away.
A discovery like that would be, perhaps, one of the greatest of all time.
In 2007, married and a mother of two sons, Seager landed a tenured job at MIT. Her office is on the 17th floor of the Green Building. She has an incredible view of the Charles River. On her bookshelf is a copy of her book Exoplanet Atmospheres. She wrote the book on the new field. On the top shelf are Champagne bottles from when her PhD students graduated. A placard on the wall has Seager’s name engraved on it. This is the 2013 MacArthur fellowship—better known as the “genius” award. She’s definitely become the success her father, who died just before her move back to Massachusetts, had molded her into becoming.
But random walks still occur, good and bad.
It was about three years after starting MIT that Wevrick started experiencing intense stomach pains. Seager’s father had described similar symptoms before dying of pancreatic cancer, so she nervously coaxed Wevrick to the doctor. After an agonizing series of medical visits, he was diagnosed with Stage 3 cancer of the small intestine. He died in July 2011, two days after her 40th birthday.
She went through the gusts of rage and muddy slog of depression, but she’s slowly been rebuilding her life. Her sons, hurting through their own emotional journeys, helped her get by.
Today, Seager talks about Wevrick’s death as a tragedy but also a salvation. “Before he died, I told him, ‘Your death has meaning. I’m going to go on, and I’m going to do great things.’ All he said was, ‘You would have done it anyway.’”
With two young boys at home and her husband gone, Seager had to flip her life course around. Her greatest thrills previously came from wilderness adventures, the more dangerous, the better. Now, she directs her energies into her research with a new sense of purpose. “I’m dedicated to finding another Earth,” she says, “because what else can I do?
That’s what she hopes to do in her lifetime, and not just “another Earth”. She wants to find at least 500 of them, maybe even a few hundred that show life-friendly biosignatures.
And so the random walk continues. When asked what motivates her to do what she does every day, Seager doesn’t seem to have a concrete reason. It’s probably why she likes it so much.
After getting pressed, she finally answers: “I think I do it because I was a born explorer. If I was born in the past, I probably would have been one of those guys who made it to Antarctica. I start a project, and I get really excited about it, the heart beats faster. I just love what I do.”