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Speaking with Jared Males
Astronomy Ph.D. student at Steward Observatory, University of Arizona

One day, we will photograph 
habitable planets around near-by stars

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Claude Lafleur, April 26, 2013
Jared R. Males is an astronomy Ph.D. student at Steward Observatory, University of Arizona.  He is studying adaptive optics (AO) and extrasolar planets with Professor Laird Close, in the Center for Astronomical Adaptive Optics (CAAO).  He is the instrument scientist for the VisAO camera, the world's first visible-wavelength camera for large telescopes. 

“The goal of my research, he says, is to, one day, take a picture of a habitable planet around a star like our sun - a place where humans could live.  We have some work to do, and some problems to solve, but we will take that picture in my lifetime.”

Astronomer Jared Males at work.

In April 2013, he published a paper titled Direct Imaging in the Habitable Zone and the Problem of Orbital Motion in which he highlights plans and problems of using AO systems on future 30-meter telescopes to probe the habitable zone of nearby stars.  The main problem his team has identified is that the motion of planets, while orbiting their star, is not negligible when using large telescopes over 10-20-hour long-exposure times.  “We show that this motion will limit our achievable signal-to-noise ratio and degrade observational completeness,” he reports.

Below is the interview he gave us by phone on April 26, 2013.

Q.:  How and why did you choose to become a scientist, and than an astronomer?

          My dad is a scientist, he’s an animal scientist, and my mom is a math teacher, so I grew up in a house where my dad does lab experiments and wrote papers.  I thus always thought that was all people does.  So, I was sort of set up to think that science is what you do in life. 
          Somehow alone the way, I start getting into astronomy and physics.  Maybe it’s a sort of a cliché but I saw Carl Sagan’s Cosmos series and that definitely sent me into the path that studying stars and the Universe will be pretty interesting.  So, I’d study physics in college, and I really like doing technically challenging things (software and hardware).  So, for me, astronomy is a perfect combination of that: It’s having to deal with the natural world - you go out on mountain top, fight with high winds and having to worry about clouds - but, at the same time, you’re doing this high-tech cutting-edge science.  This is really a nice combination of stuff!
Q.:  You are more an engineer than an astrophysicists, isn’t?

          In some sense, yes.  As astronomer, we divided ourselves into sort of three broad groups of people: there are the theorists, the observers and the instrument builders.  I’m an instrument builder.  That’s really what I do: develop new technologies, take it to the telescope and make it works.
Q.:  How did you become interested in exoplanets?

          I think the single most compelling question in science is whether or not life exist elsewhere in the Universe.  This is the driving question for a lot of astrophysicists today and one of the top philosophical question: are we alone and what it all means if there is someone else in the Universe? 
          Right now, we’re looking on how it works; life needs a planet which needs to be about 1 AU from a G-star, so it can have liquid water on it.  I’m not ruling out other ways to have life, but it seems a pretty good guess that life like we have here on Earth is going to exist on planets like Earth around stars like our Sun.  So, If we’re going to find life, I think we first need to find planets and characterized them and understand what they’re like.  And it’s why I’m interested in exoplanet.
Q.:  And so, your goal, as a researcher, is to photograph an exoplanet in its habitable zone?

          That’s right. 
Q.:  Why did you choose this goal?

          Well, basically, it’s the same logic: we will have to take picture of planets if we are going to understand whether or not they had life. 
          Most of the exoplanets we know of today are from radial velocity (RV) and transit surveys.  They gave us fantastic results that tell us that planets are really common, but the limitation of these techniques is that they only tell us that a planet is there and they give us a hint of it’s mass and its radius.  So, we’re kind of having an idea of how big is the planet.  But these techniques don’t actually let us take any measurements of their atmosphere, we can’t understand whether they have oxygen or nitrogen or water.  For this, we’ll have to collect photons of light from the planet itself and these techniques (RV and transit) are working with photons of light coming from the stars and watching the effect of the planet on its star.  They are not taking measurements of the planet itself.  With imaging, what we do is we collect photons from the atmosphere of the planets themselves and try to understand what the planets are like.
Q.:  What are you doing right now?  Where are we in term of photographying exoplanets?

          We already have taken photos of exoplanets.  There is the HR 8799 system and beta Pictoris b planets, as well as the Fomalhaut b planet (but this last one may not be a planet; people are working on this).  The way these planets were found had been using adaptive optics (AO), a technique for correcting the turbulence in our atmosphere. 
          As everybody knows, stars twinkle when we look at them.  That twinkling is due to the turbulence in our atmosphere.  And that twinkling corrupts images; no matter how big is your telescope, it limits your resolution to about 1 arcsecond on the sky.  This really limits the things you could look at (at least, for the bright things).  With adaptive optics, we measure that turbulence in the order of a thousand time a second and deformed a piece of glasses (called a deformable mirror) a thousand time a second to correct that turbulence - basically ‘de-twinkling’ the stars. 
          And so, the kind of instrumentation I’m working on is all AO and my current project over the last five years – I’m just finishing my Ph.D. at Arizona - has been working on a new camera for an AO system that works in the visible range.  As of now, on large telescopes, adaptive optics has only work really well in infrared.  But for the first time, we took picture with AO at wavelengths that we could see with our own eyes.  The camera has done its ‘first light’ six months ago.  It’s call VisAO and if you got to, you’ll see a lot of pictures and information about this system.
          Direct imaging that had been done so far are always been on light-separation of planets that are even further away than Saturn is from the Sun; we’re talking about orbits of a hundred years.  (That is: these planets take a hundred years to circle around their star.)  They are far away and they are also bright because they are very massive and young (they are still radiating their heat following their formation).  So, they are bright and far away from their star and they don’t move very much.  It only takes an hour to photograph them, and they don’t move. 
          In our study, we realized there will be a problem for our current-generation VisAO camera if we tried to do this around, for example, Alpha Centauri A.  The problem is that we need long-time exposure  – 10 to 20 hours – if we were to detect a planet.  And because we will search for planets in the habitable zone, with orbit of roughly one year, the projected orbital motion is high enough that it smears out on our detector.  On our photos, they won’t look anymore like planets but more like smear blobs.  That makes them hard to identify and hard to detect. 
          We also realized that this will be a general problem when you scale it up with the next-generation of giant telescopes.  And since we expect that AO camera will be one of the premier science instrument for these telescopes, we realized that we need to think this thorough and understand how this phenomena is going to affect these giant telescopes. 
Q.:  And what could we do to tackle this problem? 

          There is two ways to look at it.  One on which we had spend a lot of time in analyzing: if we look at a star and we have no idea whether there is a planet or not – what we call a blind search -, we can look at our images and find hints if there is a planet there and then, post-processing with software the orbit in those images.  So, we could take a bunch of shorter exposures and digitally moving them around along possible orbit of these planets and see if we can make the planet pop out of the noise by doing that. 
          But the more likely way to solve the problem is to use other techniques - radial velocity or transit or most likely astrometry - to tell you that there is already a planet, so we’ll have some idea what the orbit of the planet we’re looking for is on.  You thus use this information to chew your analysis, which makes your problem a lot easier.  So, while you’re doing your 10-to-20-hour exposure, you know where the planet is during each step of that exposure.
          But it’s still messy because in science, we always have error bars [error margins] - there are always uncertainties - and so you have to take them into account.  In other words, you’ll never know the orbit of the planet perfectly.  So, it’s still messy but it is solvable, it is something that we can deal with and start finding some planets. 
Q.:  Are we talking about a new method to find planets or simply a method to study planets that we already know? 

          I think the problem of signal-to-noise ratio of the planet moving around its star will limit our ability to do large surveys.  But I’m guessing, since there could be other solutions other than the ones we’d considered and I think that people will really thought a lot about it and find a way to figure out how to solve this problem.  But I think most likely the way 30-meter giant telescopes are gonna work, they’re going to be looking at stars where we already know there is a planet.  I think we’re gonna find that it will be the most efficient way to do these long-exposures.  It’s probably not a way to find new exoplanets with giant telescopes, but it’s a way to characterize those planets we know that are there.
Q.:  Why not just look around a star just to see if there is a planet or not?

          Well, in general, we do that with adaptive optics in direct imaging and such surveys are planned in space using space-based chronographs.  It’s a good way to find planets, especially since radial velocity and transit methods can only find planets that are align with our line of sight.  So, direct imaging has been finding planets.  The system HR 8799 is in fact a system of planets that is nearly face on, so RV would never had found these planets.  So, it will have a place as a way to find planets.  But, as we’re moving in this regime of habitable zone and into fainter moving planets close to their star, we expect to have this issue of really long-exposure times and using very specialized instruments.  My guess is that it’s not going to be a very efficient way to find new planets because it is very, very hard to spatially resolved the light from planets since, as yon know, a planet like Earth is over a billion time fainter than a star like the Sun.  And that’s a really, really hard technical challenge!
Q.:  What could we expect to see on these long-exposure photos?  Could we hope to distinguish some planet’s features?

          Yes, but probably not in the way you’re thinking!  We won’t have pictures of clouds or oceans.  In other words, we won’t see spatially-resolved features: we won’t see a hurricane on the surface of a planet.  What we will do is to photometrically observe these planets, we will take measurements of the spectrum (their spectra) at various point and using that to diagnose things like water clouds and oceans, or whether or not there is oxygen.  There are many different things we called biomarkers and that you could look for and that are hints that there is some chemical process on that planet.  That’s what we will do.
Q.:  On these pictures, we will only see a blob of light?

          Yes.  And with a spectrometer, we will see what’s going on in the atmosphere of that planet.
Q.:  When could we expect to see some results with the kind of camera you’re working on and placed on a giant telescope?

          For these giant telescopes. I think it is roughly a decade from now. That’s a round number; it could be 8 or it could be 12 years.
          But right now, we’re building our instrument and putting them to telescope, we sort of laying the ground work for the new telescopes.  And we are already achieving some results.  For example, there is the large binocular telescope here at Arizona that is constantly producing results.  And so, while we are getting ready for these giant telescopes, our current generation of 8-meter telescopes are doing great work. 
          And I’ve just received a NASA’s Sagan Fellowship which mean that, during the next two years, I will be working for NASA, just continuing this work, continuing our effort to push our instrumentation to the point where we could start taking pictures or stars with planets around them.  It’s pretty exciting to keep working on this!
Q.:  And we will follow your works!  Thanks Jared.

© Claude Lafleur, 2013 Mes sites web: