Sara Seager: Exoplanets

Sara Seager is a dynamic researcher who has pioneered the detection of atmospheres around exoplanets and been instrumental in bringing new ideas to the field.  She is currently a participating scientist on the Kepler mission to detect exoplanets; a Co-Investigator on EPOXI, the new science mission for the Deep Impact spacecraft; and the Ellen Swallow Richards Professor of Planetary Science and Professor of Physics at the Massachusetts Institute of Technology.

Her ten 2010 peer-reviewed publications (to date) include:

• Beatty, Thomas G. and Seager, Sara. (2010) Transit Probabilities for Stars with Stellar Inclination Constraints. ApJ 712:1433.
• Rogers, L. A., Seager, S. (2010) Three Possible Origins for the Gas Layer on GJ 1214b.  ApJ 716(2):1208.
• Seager, S., Deming, D. (2010) Exoplanet Atmospheres.  Annual Reviews of Astronomy and Astrophysics, in press.

Seager frequently gives talks about exoplanets, both for technical audiences and the general public.  I caught up with her in December 2009, between her Smithsonian Institution Bahcall Lecture and a Kepler briefing at NASA Headquarters.  Excerpts from our interview, done as part of the Discovery Program Oral History Project, follow:

Niebur:  Could you just tell us a little bit about your background, about how you first got interested in space science, and what you did about it?

Seager:  I first got interested in space as a small child.  I think just seeing the moon through a telescope and seeing all the bright stars in a dark sky was just extremely amazing.  And I don’t know why, I always latched onto that as something very fascinating. Then, later I was pressured by my father to just try to do something more practical.  But I went into university aiming to study all of the sciences, whereas my father wanted me to be a doctor because he wanted me to have a job where I could support myself…. I didn’t even know you could be an astronomer for a career until I was 15 or 16.  It was more of a random thing.  Eventually, I decided how much I loved astronomy and I knew if it was a potential career I should just try it. 

Niebur:  How did you choose where you wanted to apply [for your first postdoc]? 

Seager:  …I went to visit the Institute for Advanced Study (IAS) at Princeton after they invited me… I couldn’t believe a place like that existed…. People really are seeking–it sounds so corny, but are seeking the truth.  It’s a kind of unique place, because you live on campus and you work there.  At the Institute, they did whatever they could to make your job easy….  One example with some of the post docs, shows the priority John [Bahcall] put in enabling his postdocs to work without problems…  There’s a daycare at the institute and they take children from the town.  But, they wouldn’t take infants because, you know, infants are really hard to deal with — you’re a mother, right?  So, for the daycare–and we weren’t talking newborns, but maybe, you know, six month or three month old babies.  Well, even that’s hard, and they wouldn’t take any.  People had lobbied and tried to get this to happen.  But, when John heard about this, he made a phone call, and then the daycare instantly took infants.  That’s the kind of power that John had and how he used it….  Even just to get a place to take an infant part-time, John appreciated that that would be a big difference…. The goal was he wanted to support his post docs.  And if it meant making the daycare take a baby, he would do that. 

He did other things.  He loved PowerPoint and he made his postdocs use it.  This was in the early days when not everyone did PowerPoint, and he’d say, “This is the last talk you’re giving without PowerPoint.”  Well, he was also very strict.  But, what John did was, when PowerPoint wasn’t that common, he purchased projectors as small as possible, which in those days were not very small, so that the post docs could take them around to their job talks.  John would just do whatever was possible. 

Niebur:  What made you believe so strongly that [the successful search for exoplanets] was going to happen, in a timeframe that would have worked with your job search, for example?

Seager:  Oh, but it didn’t, because remember I said I wasn’t planning strategically?  I plan strategically now, but at the time, actually, in grad school, I wasn’t committed to a job in astronomy and I had nothing to lose.  When my thesis advisor suggested that new planets had been discovered, it was a chance to work on something new, I thought it sounded really great….  A lot of people don’t give a student such a risky project because it might not work out and then the student doesn’t have anything to show for a job application. At that time, a few people at Harvard believed and that’s why it worked.  They knew what they were doing.  But, most astronomers–a lot of them didn’t even believe they were planets.  They thought there was some other phenomenon going on with variability in the star.

Now, I know you were on a ton of different working groups over the last decade. That’s a large number of working groups for somebody so early in their career.

Seager: Well, I’ll tell you how it happened, because it’s such an unusual time in astronomy and most people don’t have this opportunity. But, it was Margaret Geller who said if you’re going to plan strategically, you want to be in a field that matures 10 years after you get your Ph.D., because then you’re sort of growing up with the field, and then you’re the most senior person. And so, even though now at my age, I’m basically one of the most senior people in exoplanets. And that is now.  This is 10 years after my Ph.D.

Niebur: That was very wise.

Seager: But, the thing is I didn’t plan, really. That was just–it unfolded that way. I didn’t plan, “Okay, I’m going to start in exoplanets. It’s going to be big.” Maybe it would have gone nowhere. For example, if hot Jupiters were rare but easy to find — If we didn’t have the pool of exoplanets we have today, we wouldn’t be so successful because a lot of the results, all the stuff I work on, is sort of hinged on having a pool of planets that we could follow up.

Seager: There are some key people who look out for younger people, who I didn’t know at the time, like Chas Beichman. I don’t know if you know Chas. He read one of my papers, and he took me aside specifically and said, “This is a really great paper. It’s really excellent. Congratulations.” And that was before the paper had actually been recognized as so foundational– At this time when you look back, it was foundational. But, he recognized it at the time.  And I think people like Chas — it’s true I had expertise to bring, but I had so much to learn. I’m grateful for Chas and others like him for bringing me on the teams. In the first couple years on the TPF [Terrestrial Planet Finder] team, I couldn’t even help with anything. I was just sort of figuring out what the teams were. Then, later I was able to help more and more…. They needed people who really were working on exoplanet science. But, the fact that they gave opportunities to such young people, it was really great, because then I was able to contribute more effectively later.

Niebur: In 2007, Discovery put out a participating scientist call for Kepler. And clearly, this was very relevant to your field. What did you think? Did you immediately say, “Oh, that’s something I’d like to get involved in?”

Seager: Well, initially I thought I wouldn’t, because, this may sound a little on the negative side, but I saw it happening that I would just have to attend tons and tons of more meetings, and I’m already traveling constantly. Kepler has four meetings a year. I wasn’t sure what it was really going to enable me to do. Initially, I wasn’t sure that the benefit would be a big enough payoff for me. But, actually, this is one of the cases where having a mentor really pays off…. My former thesis advisor [Dimitar Sasselov] who was on the Kepler team, said, “You need to do this. I don’t care what you think.” … He said, “Look, this is a really important problem. It’s your expertise. You propose to do it and then the Kepler team can do it.” … He really encouraged me.

Seager: So, I did, and there you go. I got it. And afterwards, I was the only woman on the Participating Scientist team, and I was kind of irritated…. I was glad my advisor had pushed me. Maybe there were other women who just thought it was going to be too much effort for very little return. But, in the end–so, then I got on the team and I was pretty excited.

Niebur: That’s wonderful. And so, what was your introduction to the team?

Seager: Hmm. Well, I already knew Bill pretty well because in the early days of exoplanets, he had to go to every meeting to promote his idea. I was at every meeting because I was young and I had time. I didn’t have kids or anything at the time, and I traveled. And he’d often be just having dinner by himself, when we’d be in New York or something. So, actually I got to know him. And I knew him pretty well. I mean, everyone knew all about Kepler because he had been going to meetings for so long. He had to propose many times before Discovery selected it.

Seager: Kepler’s going to have 28 papers in January…based on the 10 days of commissioning data. Kepler is going to change exoplanets and astronomy as we know it.

Niebur: Wow.  Can you talk a little bit about the advantages or the disadvantages of being a PSP?

Seager:  Well, first I just want to say the PSP program is so great because it gives people like me an opportunity to join the team.  When Kepler was forming, I was either in high school or undergrad or–you know, I wasn’t on the playing field.  And that’s really great.  So, the advantage is that it gives people a chance to join the team who actually weren’t already on it.  Another advantage that we were already talking about was it gives Kepler extra money because there’s a separate pool of money that supports the PSP efforts…. One advantage is not having to suffer through all the stress of getting the mission launched…. I think a disadvantage is there’s still definitely a hierarchy on the team. Co-I’s, perhaps rightly so, because they’ve been there for so long…. there’s definitely a hierarchy, but I think we’re sorting through those issues on the team.  And once the data is flooding [in], I think those barriers will go away.

Niebur: Some of the people reading excerpts from this interview will be reading it from the Women in Planetary Science column, and some will be undergraduates or graduate students that maybe haven’t been exposed to [professional] women in planetary science, as sad as that is.  So, my question is, if you had an undergraduate come and talk to you and say, “I want to be on a mission.”  You know, she’s the kind that plans ahead.  She wants to be on a mission one day.  What would you say that most important things to do to prepare would be?

Seager:  Well, that’s a great question.  I think you need to prepare, to have some skills.  You have to have something to offer to the mission….  There are a lot of politics involved, but, I think having the skills to offer is key.  Being able to communicate well is important.  And, you know, being willing to do a tough or tedious job initially, I think, will count for a lot. 

Niebur:  A lot of people get on missions through instrument building experience, but that clearly wasn’t the way you did it.  Would you recommend somebody trying the PSP program, once they’re at the postdoc or, you know, junior professor level?

Seager:  I think the PSP is a great way to get involved.

Thank you, Sara!

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