(PLANETQUEST) -- Webster Cash's passion for space began when he saw his first planetarium show as a child. Now, as the principal investigator for one of NASA's future exoplanet mission proposals, Cash is on the cutting edge of ideas that could help change our perception of the universe.
PlanetQuest: How exactly are you involved in the hunt for exoplanets?
Webster Cash: I'm the principal investigator of the New Worlds Observer mission concept, something we're really excited about because of its potential to capture images of extrasolar planetary systems.
PQ: How does this concept work and how did you get involved?
Cash: Well, the idea is actually an old concept - we use a starshade, which is basically a black sheet of material a lot like an umbrella, to block the light of a star before it enters a separate telescope. I took inspiration from my previous work in X-ray instrumentation to develop a better way to suppress diffraction (the bending or scattering of light) at the edge of the star shade, so that we could obtain better images.
PQ: So you haven't always been an astronomer?
Cash: Not quite. When I was eight years old, I wanted to be a medieval historian, but then I saw a planetarium show at the University of North Carolina about Project Ozma -Frank Drake's early attempt to search for radio signals from nearby stars. From that day forward I wanted to be an astronomer. I got my BS in physics from MIT and my doctorate from UC Berkeley. I've had a long love affair with black holes and supernovae before returning to the search for planets and life.
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Visualization of the New Worlds Observer mission proposal. The inset is a simulation of the exoplanet images the mission would be able to produce. |
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PQ: When did you start to apply your x-ray astronomy to planet-finding and how has it helped you develop the New Worlds Observer concept?
Cash: I took a look and started playing around with ideas in 2003. X-ray wavelengths are very short and you need to be very careful and precise in dealing with them. The technical experience gained there helped in figuring ways to observe the faint light of exoplanets lost in the glare of their parent stars.
PQ: What potential does New Worlds Observer have for studying exoplanets and how is it different from other instruments that block light from stars, like a coronagraph?
Cash: With a coronagraph, all the light from both the stars and the planets enters the telescope at the same time. You then have to be extremely careful because the starlight causes a lot of issues with diffraction and scatter inside the telescope. With New Worlds Observer, the light either misses the edge of the "umbrella" or it doesn't - starlight never enters the telescope and all you see is the planet. We'll be able to see lots of exoplanets and their colors and brightness range, and also be able to classify and understand them more independently of the context of our own solar system.
PQ: So this instrument could give us pictures of extrasolar planets?
Cash: Yeah, it actually works best in visible light. For example, if you were using it from far away to look at our solar system, you would just be able to pick 'em off - the blue dot would be Earth, the white one Venus, and so on, all the way out to Neptune.
PQ: Besides planet hunting, what do you like to do in your spare time?
Cash: Well, living in Colorado (Cash is the chair of the Department of Astrophysical and Planetary Sciences at the University of Colorado at Boulder) I do a lot of hiking and, of course, skiing at places like Winter Park, Keystone and Copper�the list goes on. I love traveling, too, especially to Italy, where some of my wife's family is from. I really like their culture, history, art, food and scientists.
PQ: What do you foresee as the impact of finding habitable exoplanets or even signs of life elsewhere?
Cash: I think that if we find a habitable planet, it will affect our "spaceship Earth" mentality and motivate us to push out into the universe - it's easier to think about crossing the gulf of interstellar space when you have somewhere attractive to land your ship. And finding life -that's something just about everyone wants to know, isn't it? I think that an answer either way will greatly change mankind's understanding of the universe.
Written by Joshua Rodriguez/PlanetQuest
