A conversation with Rus Belikov and Eduardo Bendek, senior research scientists at NASA’s Ames Research Center, working on next generation technology to directly image planets beyond the solar system.

Transcript

Matthew C. Buffington (Host): You are listening to episode 6 of NASA in Silicon Valley. Today we have a special episode with both Rus Belikov and Eduardo Bendek, Senior Research Scientists here at NASA Ames who specialize in hunting for exoplanets. We discuss the recent announcement from the European Southern Observatory on the existence of Proxima b, an earth-size exoplanet orbiting in the “just-right” habitable zone of our closest neighboring star. We also go into future NASA projects and missions to find exoplanets and how the various methods lead our journey of discovery through the solar system and beyond. Here are Rus Belikov and Eduardo Bendek.

[Music]

Host:Eduardo, what brought you here?

Eduardo Bendek: So I was born in Chile, and I did my undergrad location in Chile, but always dreaming about aerospace, with like rockets and telescopes. And I continue my studies in astronomy and in engineering, both at the same time. Then I joined an observatory, the VLT, the Very Large Telescope in Chile. And I work in the desert. And it’s like I’m enlisted for five years.

Host: The driest place on Earth.

Eduardo: Yes.

Host: As I’ve learned from these conversations.

Eduardo: It’s actually super dry. There is like no vegetation. Because you go to the desert in Tucson, and there are like some kind of little bushes and —

Host: Cactuses, stuff like that.

Eduardo: Yeah. Over there, it’s like nothing.

Host: Wow.

Eduardo: So it’s pretty impressive. It really looks like Mars. I’ve never been to Mars, but from the images, it really looks —

Host: Yet, we haven’t been there yet.

Eduardo: Exactly. Really looks similar. Yeah, so I spend there five years looking at the sky. And then I moved to the U.S. to do my PhD in optics.

Host: Okay.

Eduardo: Because then I realized that there were a lot of astronomers, there were a lot of engineers, but there were few people understanding the main tool, which is optics.

Host: The mirrors and lenses and all that.

Eduardo: Exactly. Which is a very complex discipline by itself.

Host: I imagine.

Eduardo: And it’s kind of a borderline between science and engineering, so it’s kind of a really physics with a little bit of applied physics and engineering. So normally, traditionally, it’s not a discipline by itself. And then I started to do my dissertation work with Olivier Guyon, which is an astronomer and very famous instrumentalist — a person that designed many instruments. And then the opportunity joined to join NASA as a postdoctoral fellow.

Host: Okay, so you were doing your doctorate and then just came on over to work at the same time.

Eduardo: Yeah. So what happened is my research somehow was connected to exoplanet detection, and I was working on a grant for NASA as a student, and then when I graduate and defended, then the opportunity to join as a postdoc with Rus Belikov came up. And then Rus and Olivier helped me to get here as a postdoctoral fellow for two years.

Host: Nice. So you guys met each other like in the process of being doctoral students? Or were you already here, Rus? Were you already at NASA?

Rus Belikov: I was already here, although I think Eduardo and I may have met even before I joined Ames. So I joined Ames in 2008. And the exoplanets community is — most people know almost everybody else, so I had known of Eduardo’s research —

Host: So you knew of his work —

Rus: Yeah, and held it in high esteem, before we actually started working together. Unlike Eduardo, I grew up in a completely opposite hemisphere, so the northern hemisphere as opposed to the south and the eastern hemisphere as opposed to western.

Host: Okay. So you grew up looking at different stars.

Rus: Yeah. Looking at different stars. So I spent the first 12 years of my life in the Ukraine, which was the Soviet Union at the time. And then my family immigrated to the U.S. and ever since I was a kid, just like Eduardo, I was fascinated by space, I was fascinated by astronomy — the whole space race, which was a big thing, of course, during the Cold War, always fascinated me.

My whole childhood, I thought I’d be either an astronaut or some kind of astronomer, just like most kids. Then when I went to college, I felt that those dreams may be childish and may die, or at least that’s what people have been telling me.

Host: Yes. Real life gets to you.

Rus: Exactly. So I went into engineering and kind of away from astronomy because I felt that was kind of the more serious discipline. And, also, for grad school, I went to Stanford, and at the time, there was the dot-com bubble, and actually it was — a little bit after that, there was a telecom bubble. And I had considered pursuing astronomy, but the whole telecom bubble in Silicon Valley, you know, promises of riches and entrepreneurship — all that stuff seduced me.

Host: Yes, a modern-day gold rush.

Rus: Exactly. And so I did my grad school in engineering, as well, although it was optics, so it touched upon astronomy. Specifically, I was working with deformal mirrors. And by the time I finished my grad school, the telecom bubble had burst and a lot of people were disillusioned.

And that was right about the time — it was 2004, 2005 — that I found out about the projects that astronomers and NASA, in particular, were developing to detect Earthlike planets. And that completely blew me away because I felt that — I had known that people were detecting exoplanets, but I had no idea that we were so close to being able to detect potentially habitable planets. And that —

Host: And you could just have a job in it.

Rus: Yeah. And I think the critical point for me was when I went to my college reunion, Jeremy Kasdin, who is a professor of engineering at Princeton, and a few others, had given a talk on what was known at the time as TPF — terrestrial planet finder — it was a mission study to detect earthlike planets around other stars. And I was just completely blown away by that. I thought this is it, I am stopping what I’m doing. I am following that path. And I never looked back.

Host: Is there a big optics team at NASA Ames or is it… you know… How does that work?

Eduardo: I think that people sometimes overlook the role of engineering on astronomy. So to be able to do all these observations, you need an extremely sensitive instrument that — we’re constantly pushing the edge of science and technology to make those instrument happen. So every research center in Europe or in the U.S., NASA, they have big teams of engineers working on that.

Now, in our case, it’s very interesting because we’re both hybrids of engineering and astronomy. So I did my main career on mechanical engineering with a minor in astrophysics and then I did optics. In the case of Rus, he did electrical engineering. But what happens is when you understand the fundamental physics, you can always flow down to the application.

So I think that’s the key. And that’s actually what a PhD is about. That’s the reason why it’s called doctor of philosophy, because you start from the philosophy. So Rus leads the group of instrumentation, and probably he could tell you more about how the group started and all that.

Host: Cool, yeah. I was going to say, even before we go really into the exoplanet thing, part of the cool reason of us talking now is the big announcement from ESO — the European Space Observatory? Did I get that right?

Eduardo: No.

Host: No?

Eduardo: Southern European Observatory.

Host: Awesome.

Eduardo: Not European. I know it’s confusing. Sorry, I say it wrong. That’s ESO — European Southern Observatory.

Host: Okay. So there was — Proxima b was the announcement. What exactly happened? Or what exactly did they announce there?

Eduardo: They confirmed that there is a planet around this star, a planet like the Earth — the size of the Earth — approximately the size of the Earth —

Rus: 1.3…

Eduardo: In the habitable zone of the star. Now, they have been looking at this star for many years, and there was —

Host: Being the closest star or within the cluster there —

Eduardo: Yes. And also because it’s a very good candidate. But the samples were not good enough to really confirm the planet. But they have a signal. They have an indication. So now they confirm with a very high likelihood that the planet is there. So that’s the discovery.

Host: And what was the difference — because I know there’s several different methods to identify and confirm exoplanets. So what method were they using, and how is that different from some of the stuff that you guys are working on?

Eduardo: They were using a technique called radial velocity. So there are three main techniques to detect planets that are indirect. So basically you don’t see the planet, you see the star. And the planet perturbs the star. And you see that perturbation. Because actually seeing the planet is really hard, yeah? And there are three ways in which the planet can perturb the star.

One is if the planet goes in front of the star and, therefore, blocks a little tiny bit of the star. And that’s transit photometry. That’s what Kepler does. The Kepler mission. Then there is another option which is radial velocity. So as a planet orbits the star, it creates gravitational tug. So it’s the same way that when you play with a kid and you move the kid around and then you’re kind of flying the kid around, then you wobble around the…

Host: Kind of a wobble, it kind of moves.

Eduardo: Exactly. So that creates a Doppler shift on the light of the star as the star is getting closer to you or going farther away when the planet is orbiting. That creates a signal that we can see. We can see how the spectrum of the star is changing. Now, this is really hard because, to detect Proxima b, you need to measure the speed of the star at 1.4 meter per second — 1.4 meter per second is a velocity of a person walking when you’re shopping on a mall. So imagine that you’re able to measure the speed of the star at that precision.

Host: They’ve discovered using that radial velocity method before, but for stars that are much further away. Is it almost easier to find stars — not easier — being not the right word — because we’ve used that method to discover exoplanets further away. You’d think that for stars that are closer to us, that that might be easier to see that, or is that not the case?

Rus: It is the case given that everything else is the same. But —

Host: Yeah, really far.

Rus: Yeah. So, I mean, the thing about radial velocity is that it’s easier to detect closer-in planets and larger planets. So if you have like a Jupiter that’s on a, let’s say, three-day orbit around a star, then something like that is pretty easy to detect even when it’s way out there. But this planet is very small. It’s 1.3 Earth masses or, to be more precise, it’s 1.3 what’s called m sin i, which is like a minimum mass.

Host: Okay.

Rus: And its orbit is pretty short, you know, 11 days. But, I mean, plenty of planets that have even shorter orbits than that. Also, the star is somewhat —

Host: So you’re saying it’s different from our star. It’s not the same as like the sun —

Rus: That’s right. It’s much fainter than our sun, but it actually — I mean, it also helps because the smaller the star is, the easier it is for the planet to wobble it. Even though there’s less photons from the star for our telescopes to actually measure the wobble.

Host: Okay, because it’s smaller.

Rus: Yeah.

Host: Yeah, okay.

Eduardo: But you touch on a very interesting point. Radial velocity and transit photometry are almost insensitive to the distance. So basically it doesn’t really matter how far the star is — and, actually, if you — because what the matter is if you’re blocking 10 percent of the light of the star, it doesn’t matter if the star is really far or really close as long as your telescope can get the light.

Host: Oh, okay.

Eduardo: With radial velocity, it’s the same. The Doppler shift won’t change whether the star is really close or really far. Now, there are other two techniques that are very sensitive to the distance of the star. One is direct imaging. So if you really want to see the planet, then you’re getting photos reflected from the planet —

Host: Back to Earth —

Eduardo: And then the distance matters because if the planet — if the star is farther out, the distance between the planet and the star gets smaller and smaller.

Host: Have we seen any exoplanets from direct imaging?

Rus: Yeah. Yes, we have.

Host: Wow.

Rus: But not earthlike.

Host: Not earthlike, though.

Rus: Not even close.

Host: Like a big, Jupiter — Jupiter, big-sized planets.

Rus: Yeah. Even more weird than that. The only planets we’ve actually seen by taking pictures of them are planets that are very, very far from the star, like we’re talking farther than the orbit of Pluto, and they’re shining by their own light.

Meaning that they have just formed, and when planets are very young, they just formed, they are very hot because all the rocks, you know, bumping together are heating themselves up to like melting point, and so they glow. And we can detect this infrared glow from them even when they are so far away from the star that the amount of light that they reflect from the star is very small.

So these are the easiest kind of planets that exist to directly image, and those are the ones that have been directly imaged so far. To directly image an earthlike planet is quite challenging.

Host: Yeah, it’s very small, very far away.

Rus: But technology is steadily advancing to where it’s possible.

Host: Yeah. I remember hearing — it was an example of somebody was saying like a spotlight in like, you know, a far-off city, then you see a fly — analogies like that.

Rus: Yes, exactly.

Host: Understanding how hard this really is. Cool. And then, Eduardo, you had mentioned there was another two methods. You talked about the direct imaging. What was — were you going to say another one.

Eduardo: So there are four mainstream methods. There are more alternative methods. There’s always —

Host: We’re not like cutting out any options here.

Eduardo: Exactly.

Host: The more methods, we’ll take it.

Eduardo: But the more mainstreams are four. One is direct imaging, which is the only that is actually seeing the planet. And there are the other three that are not direct.

Host: You’re inferring.

Eduardo: Exactly.

Host: The transit and also the wobble.

Eduardo: Transit photometry, the wobble, but the wobble has two different flavors. One flavor is called radial velocity, which you’re measuring the Doppler shift, what we just discussed. But there is another flavor of observing the same phenomena, which is actually looking at the star, looking the wobble the star. Instead of observing how the color of the star changes because of the Doppler, you see the motion of the star, and then you can tell there’s a planet tugging the star.

Host: Is it almost like tidal waves or am I not thinking —

Eduardo: No. It’s actually real motion of the star. But that requires extreme precision, and that technique has not been delivering a lot of results because there are no instruments able to do that. Now, the European Space Agency launched a space telescope dedicated to this, and that started operation a couple of years ago, and probably in two or three years, it’s going to yield thousands of planets.

So people hasn’t seen the impact of that because the data hasn’t been processed or delivered. But it will make a difference. Now, the advantage of that technique is tells you the mass of the planet, tells you how heavy is the planet. Because when you see the star wobbling, you can tell how big is the planet.

Host: Yeah, how much it wobbles depends on how big the other one is, yeah.

Eduardo: Exactly. Instead, transit photometry, radial velocity, and direct imaging have a hard time assessing what is the mass. There are ways to infer the mass, but not very precisely.

Host: Okay. So what are we looking at for NASA? I mean, the Kepler telescope is already out there. The K2, using the same telescope and in a slightly different way. And we have other telescopes lined up to go up. I mean, obviously, they’re working on the James Webb telescope, which is a big one over at Goddard that they’re making. Also TESS. Talk a little bit about what do we have to look forward to of, you know, new instruments, new tools that you guys get to play around with?

Rus: Sure. I guess I’ll take that. So you mentioned a lot of missions, and NASA has a wonderful portfolio of exoplanets missions coming up. So TESS, I believe, is the next one in line, which is a mission to do transit detection of exoplanets, like Kepler, but unlike Kepler, it’s going to look across the entire sky.

So Kepler was looking at a narrow field of view and very deeply, for a very long time, so it was able to detect planets up to very long periods, like a year or even longer. Whereas TESS is designed to see planets that are shorter periods, which can still get you planets in the habitable zone, but around dimmer stars.

Like, for example, if Proxima Centauri was transiting, then that would be potentially one of the stars that — kind of star that TESS could do. So the next one that could do a lot of wonderful exoplanet science is the James Webb telescope, as you said. So that’s launching on 2018.

Host: And how is that going to detect more exoplanets? What method is that using, primarily? Or plan to use, I guess?

Rus: So it can do the transit method, and specifically transit spectroscopy. So I think the whole community is looking forward to the transit spectroscopy that JWST could do on planets, but it’s unlikely that it could do that on any earthlike planets or any potentially habitable planets. I think we would have to be very lucky if one exists sufficiently nearby and it’s around a sufficient star that JWST can do it.

Host: I would think, especially with the transiting method, it’s like not only do you have a tool that’s strong enough to see it and detect it, but you’ve got to — I mean, how long does it take for a planet to rotate? It takes us 365 days. I mean, how often are you lucky enough that a planet crosses in front of it?

Rus: Yeah, well, I mean, there are planets that are much shorter. Like Proxima b, for example, is 11 days. And JWST would not be searching for planets. It would be doing transits on planets that are already known, so it would know exactly when to look.

Host: Oh, okay.

Rus: Yeah. Now, JWST also has a couple of instruments called coronagraphs, and that’s a fancy word to describe an instrument that simply blocks the star so you can take a picture of a planet.

Host: Okay. Like an eclipse kind of.

Rus: Yes, exactly. Yeah, you’re eclipsing, if you will, the star inside your telescope.

Host: Oh, okay.

Rus: And that allows you to take a picture. But it’s coronagraphs where, you know, designed and the design was locked many years before some of the more powerful chronographs that are capable of detecting earthlike planets were developed. So it doesn’t have the performance required to do earthlike planets or anywhere close. But it may give us some interesting other planets.

Then, another mission that the community is looking forward to is NASA’s flagship mission in the next decade, which is 2020s, called WFIRST. And it’s primarily a non-exoplanet mission. However, it will have the capability of doing exoplanet science both by direct imaging and another method called microlensing, which probably not going to get into.

So it is not expected or not designed, I should say, to detect earthlike exoplanets, but there is some possibility that it may. And so either with a chronograph, if the chronograph outperforms — if we’re lucky and it outperforms the design requirements, or if some ingenious person figures out how to process the data to squeeze out potentially habitable planets out of it.

There’s also a study going on to see if you can fly something called a star shade with this telescopes, which is a big shield — it’s kind of a funny-shaped shield that you fly tens of thousands of kilometers away from your telescope to block the star.

Host: Oh, interesting.

Eduardo: So that’s still kind of speculative for WFIRST, but it’s a very interesting idea. And if that happens, it would be absolutely amazing because then that would enable us to do earthlike planets.

Host: And so for both of you — from the optics point of view — does that like really fold into your work in terms of like how these get designed? Or is it also just kind of understanding what kind of information you get form these telescopes and then deciphering it?

Rus: Yeah, so our work is primarily on designing instruments, but, I mean, to design an instrument, you also have to do a lot of simulations on what science you get and what kind of performance you get. So what I’ve just described are kind of missions that are officially on NASA’s roadmap. And a lot of the work that we’re doing is actually supporting those mission and designing things for those missions.

However, another aspect of what we’re doing, and I think Eduardo and I are particularly excited about that, is the possibility of launching small, low-cost missions that allow us both to demonstrate technology and potentially directly image a potentially habitable planet a lot sooner than some of these larger missions we do. Now, we wouldn’t be like upstaging those missions. We would be helping those missions.

But the bigger missions would give us hopefully a large survey of many different stars and find planets around many different stars. But it isn’t impossible to launch a very small, low-cost space telescope to target at the Alpha Centauri system to directly image potentially habitable planets around it, as early as this decade.

Host: Oh, wow. And so, looking at the different instrumentations and, you know, because the Spitzer telescope, we have Hubble, you know, Kepler that’s out there, the new ones that are going up, not to mention the land-based telescopes, I’d imagine like each of these telescopes kind of, using the different methods, is kind of getting a little piece of that puzzle, a little bit of that mosaic. And so I’d imagine, within the community, of combining some of that data, you find stuff that probably wouldn’t find on their own.

Eduardo: Yeah, that’s exactly the most common way to confirm planets. For example, Kepler measures the presence of a planet, and then a radial velocity instrument on the ground can confirm —

Host: Can confirm it, so you’re using two methods —

Eduardo: Exactly, with a separate technique, so you remove false positive. Also, I think it is important to mention, on the landscape of missions, turns out that we are observing an anomaly on the number of missions devoted to exoplanet. Because if you look at it, you have GAIA, which is this European Astrometry mission. Then you have Kepler, TESS, then the Europeans will have CHEOPS and PLATO.

So in a timescale of 15 years, you have more than five space missions dedicated to this subject, which is completely unseen on astrophysics, that you have five space missions devoted to this subject. That shows you a little bit how this field is growing. But not only that. If you look at those missions, four of them — which is Kepler, TESS, CHEOPS, and PLATO — are transit photometry.

So the same technique of, say, how the planet goes in front of the star. Now, that technique can only get about 1 percent of the total planets because it’s very unlikely that the system is aligned in such a way that the planet can block part of the light of the star. That also shows you something else, that it is necessary to start to dive into the systems in particular, because those missions are survey.

They will tell you demographics, they will tell you probabilities of planets, but they won’t tell you specific details of an interesting system. So for Rus and I, our focus on Alpha Centauri is because we really think that is a very, very nice system to look at, that is suitable to do direct imaging in.

Therefore, we are taking all that heritage, all that knowledge, and from that, we’re inferring that this system is the best system to dive in and look in, in detail.

Host: Excellent. For anybody who’s listening, if you have questions for Eduardo, questions for Rus, we are on Twitter, @NASAAmes. We’re using the #NASASiliconValley. You can also hit up @NASAKepler, as well, as I’m sure you guys pay a lot of attention to what’s going through over there. So thank you so much for coming.

Rus: My pleasure. Always love speaking about these things.

Eduardo: Thank you for the opportunity.

[End of recorded material.]