Kepler's Exoplanets: A Personal Quest

Kepler has returned the first results from NASA's extra-solar planet hunting mission and some of these newly discovered worlds are like nothing we've seen before. The space telescope is quite literally on the frontier of exoplanet studies and there's hope that the discovery of an Earth-like world will happen soon.

Steele Wotkyns, Lowell Observatory's Public Relations Manager, caught a moment with Kepler co-investigator Ted Dunham to find out what goes into this exoplanet hunt and how he became involved with the mission that could potentially change our perspective on the cosmos forever...

Steele Wotkyns: Tell us a little about your background, particularly some of the highlights and how you got into your particular niche in astronomy?

Ted Dunham: I became interested in astronomy in middle school. I had some earlier interest, but it didn't blossom until middle school. I wanted to make a telescope and was frustrated because I didn't have the skills. I think that's how I ended up working on astronomical instrumentation -- by degrees I've learned how to build a telescope, among other things.

By the time I was in high school I was deep into astronomy. I was a physics major at Carleton College, attended graduate school at Cornell, and joined Jim Elliot's group that later moved to MIT. The main thing that caused me to choose Cornell for graduate school was that I wanted to do planetary astronomy -- both observing and instrumentation -- and Cornell was one of the rare places where that could be done.

Steele: What are some of the highlights of your career so far?

Ted: Well, there was the Kuiper Airborne Observatory (KAO) -- that first happened for me while I was still a graduate student. It all started because of being weathered out too many times. Jim Elliot got interested in the KAO and thought we could get good data using it. On our first try we ended up with a successful observation of an occultation of Epsilon Geminorum by Mars. The "central flash" was discovered on that mission. Nobody expected it -- we flew right through the middle of the shadow, and there it was. Dick French figured out what caused the central flash.

I was part of Jim Elliot's team when he proposed to observe an occultation by Uranus in 1977, and that proposal was successful. Larry Wasserman from Lowell Observatory did the astrometry for it.

We ended up having to fly the KAO all the way to Perth (Australia) to observe that event. This was the occultation where the rings of Uranus turned up.

That's how I got sucked into airborne astronomy and now it's kind of in my blood. I became the project scientist for the KAO later on.

Later when MIT was looking for a faculty member Jim Elliot got the job and took our whole group with him. I ended up being at MIT for 11 years. We had wanted to build a CCD (charge-coupled device) camera for occultations. We really needed a way to image to subtract background light properly, but didn't have any success getting funds through NASA.

In 1983 the Army turned out to have a project -- the Airborne Optical Adjunct -- that was part of Reagan's Star Wars program. It was designed to target ICBMs popping up over the horizon. They desperately needed to know about image quality for airborne telescopes. With their funding we built and flew a test camera and used it for a wind tunnel test too. We used that instrument for the Pluto occultation in 1988. That was the event when Pluto's atmosphere was discovered.

The KAO airborne testing was the high point of what I did at MIT. It feeds right into how I ended up at NASA Ames for SOFIA (the Stratospheric Observatory for Infrared Astronomy) and for that matter into my work on the Discovery Channel Telescope here at Lowell.

In 1990 I was offered a job at NASA Ames mainly to work on SOFIA. Before long I was Deputy Project Scientist for SOFIA and Project Scientist for the KAO. I continued working on occultations and occultation predictions and in 1992 I also started working on what later became the Kepler Mission. In 1996 I came to Lowell Observatory because NASA privatized SOFIA. Our team here designed and built a special instrument for SOFIA called HIPO.

HowStuffWorks: How do occultations work? How are they used by astronomers?

Steele: Tell us about your involvement in Kepler and your take on the first results of discovering five new exoplanets?

Ted: I'm a co-Investigator on Kepler, NASA's Search for Habitable Planets. Brian Taylor and I at Lowell built the software and electronics for the camera for a critical Kepler lab test. This was something really good that Lowell Observatory did for Kepler -- it was crucial for getting the mission selected to fly.

I'm much more than pleased with the first results from Kepler. The data are just super! We were really worried about possible variability of the stars, but there are a lot of stable ones.

In this first data we found the planets just announced, and a lot more objects that look like planets but still need follow up observations. The first five all have spectroscopic orbits. As we go on we're going to have many hundreds of these things and it will be impossible to do the same level of work on all of them.

So what we have to do is to figure out what our success rate in weeding out false positives is without getting a spectroscopic orbit for every one. It's like doing a poll: you don't talk to everybody; you look at a sample and figure out the behavior in a statistical sense. In the end we will be able to publish a catalog of probable planets together with an estimate of the number of false positives in it.

The first proposal for Kepler was called Frequency of Earth Sized Inner Planets (FRESIP). Are planets like Earth common or not? Fundamentally, that's a statistical question. What we're measuring is the number of planets the size of the Earth in the habitable zones of other stars.

Steele: When you first started in astronomy did you ever imagine you would be involved in something like this?

Ted: No, there's no way I would have ever imagined this.