A conversation with Pamela Marcum, Project Scientist on the Stratospheric Observatory for Infrared Astronomy project, also known as SOFIA. For more information on SOFIA, visit www.nasa.gov/SOFIA.
Transcript
Matthew C. Buffington (Host): This is NASA in Silicon Valley, episode 13. Today’s guest is Dr. Pamela Marcum, Project Scientist on the Stratospheric Observatory for Infrared Astronomy project, also known as SOFIA. Pamela works with the SOFIA science team to support astronomers worldwide in exploring the solar system and beyond, specifically delving deep in the infrared to better understand the universe. In fact, she is participating in a conference this week focusing on expanding our understanding of how stars form. SOFIA is also in the news this week, the team announced that scientists on board the airborne telescope directly observed the collapse of six clouds becoming stars larger than our sun. You can check out NASA.gov/Ames for a story on the findings. Without any further delay, here is Dr. Pamela Marcum.
[Music]
Host: Pam, how did you get to NASA? Or also, how did you end up in Silicon Valley, of all places?
Pamela Marcum: Right. I’ve had a very nonlinear career path, actually. I started out as a typical astronomer and, you know, went to graduate school in Wisconsin. And then did a two-year postdoc, University of Virginia, where I was involved in my second NASA mission. When I was a graduate student, I had the honor of being able to work with a large team of people on the second-generation camera that was installed on Hubble. So —
Host: Oh, really? So was that over at Langley that you did this or —
Pamela Marcum: A lot of the testing was done on — actually out here in California.
Host: Oh, really? So you’re in Virginia, but you’re working on like the camera stuff —
Pamela Marcum: Well, I wasn’t at Virginia at the time. This was — as a graduate student I was actually involved in that team effort, at a, you know, kind of — not at a deeply integrated level, but just enough to give me insight into the amount of work that goes into putting together just an instrument that goes onto the observatory. Right? This wasn’t, you know, Hubble. It was already —
Host: Hubble was already —
Pamela Marcum: — launched.
Host: Okay.
Pamela Marcum: So this was one of — it was the camera that helped replace the older camera that wasn’t —
Host: That wasn’t working.
Pamela Marcum: — working so well. Right.
Host: That’s right.
Pamela Marcum: So this had the eyeglasses already installed to allow —
Host: Yes. I remember hearing about that. Because when Hubble first went up, it was kind of fuzzy. So they kind of gave Hubble some glasses —
Pamela Marcum: That’s right. So I was involved at very —
Host: Various stages.
Pamela Marcum: — very — yeah — sort of a loose level as a graduate student in some of that work. That was my exposure to NASA.
Host: That’s awesome. Because I’d imagine you’re into NASA. If you’re going into astronomy, you’re already into NASA, I’m guessing.
Pamela Marcum: Absolutely right. Yeah. So then I did a two-year postdoc after my graduate work in — at University of Virginia, which is just, you know, down the road from Goddard.
Host: Okay. Cool.
Pamela Marcum: And it was out of Goddard that this other mission, relatively small mission, was being developed. In fact, I got involved in sort of like the phase 2 of it.
Host: Okay.
Pamela Marcum: It was a little camera that did a UV ultraviolet survey of nearby galaxies from the shuttle. So this was one of the very few, if — maybe only — I’m not sure — like telescope that was put up and operated in a professional sense on the shuttle.
Host: It’s a nice — we will go into more of the SOFIA program, but that’s a very good precursor of like a telescope on the shuttle.
Pamela Marcum: You know, you’re right. There’s some — yeah — interesting —
Host: Some parallels.
Pamela Marcum: — parallels there. So I worked with the data there and got further immersed into NASA and then did a more traditional career path route — got a faculty position.
Host: Okay.
Pamela Marcum: And I was a faculty member for, you know, well over a decade. And then an opportunity came up to become sort of a temporary visiting scientist at NASA headquarters.
Host: Okay.
Pamela Marcum: And I think that was probably the beginning of, I mean —
Host: I’m coming back.
Pamela Marcum: — full immersion into NASA. Right. So I stayed there for three years and was deeply involved in helping with the management of the infrared portfolio where new detectors are being developed, and the various research projects that were being funded out of NASA headquarters through their various, you know, grant programs. And then the opportunity to join SOFIA as project scientist arose. And —
Host: So you came from headquarters over to Ames to work on SOFIA or —
Pamela Marcum: Well, not quite.
Host: Yeah.
Pamela Marcum: Again, not quite a linear path. So I went back to my home institution where I was a professor and worked there for another year, and then transitioned into a full NASA —
Host: Okay. Cool. So then when — I’m guessing — is that just a job that shows up online? Or how do we even find out about this?
Pamela Marcum: Actually, it is. Yes. Absolutely. All of these positions are advertised, and they’re competed. And there’s actually a, you know, couple of various websites you can look at to see what’s coming up.
Host: And we can go more into the origins or — of even explaining what SOFIA is. But I’d imagine at that time — I know SOFIA — it flies out of Armstrong, which is outside of LA. But then a lot of the science is done over here at Ames in Silicon Valley. So were you aiming at coming here? Or where in California were you planning on heading? Was —
Pamela Marcum: Yeah. Well, Ames is where the science center is located. And so that’s where the project scientist is, along with all of my science colleagues here. The greater number of people involved on the team that are, you know, airplane experts, the pilots and the crew — so they are all stationed in Southern California.
Host: Okay. They keep it up and running. But then the science —
Pamela Marcum: Exactly. Well, it’s actually interesting. And it involves a lot of coordination, as you can imagine, across these two NASA field centers. And, you know —
Host: The synergy and —
Pamela Marcum: Yeah. Absolutely. So, you know, the plane is maintained, repaired when it needs to be repaired, which happens every now and then. It’s an old plane, by the way, you know, so it requires, you know, maintenance. And those guys know how to do it.
And they fly it out. The weather there is mostly good. It’s sort of out in the desert more so than here. And so it provides a good environment to — you know, to do the — to execute the science flights. The data’s collected during flight by the various science instruments. And would love to get a chance to kind of describe what some of those instruments are a little bit later. And so the data’s recorded in flight, put on an archiver, and then downloaded and then transported up here to the science center, where they actually do the data processing.
Host: Okay.
Pamela Marcum: Because it’s just raw data.
Host: You have to make sense of it.
Pamela Marcum: And it doesn’t — you know, you have to calibrate it, take out all the —
Host: Noise [there].
Pamela Marcum: — the noise and the artifacts and — yeah.
Host: So maybe stepping back — because I know for me even, somebody who was like super into NASA — but then finding out like the SOFIA program — so SOFIA — what does that stand for? Because of course, it’s NASA, and it’s the government. We’re going to have an awesome acronym. So what does SOFIA stand for?
Pamela Marcum: And it’s an awesome acronym, isn’t it? It stands for Stratospheric Observatory for Infrared Astronomy.
Host: So it’s a telescope on a plane.
Pamela Marcum: It’s a telescope on a plane. And, you know, the name kind of says it all. But it doesn’t say the whys. It tells you what it is, but it really doesn’t tell you the whys.
Host: Well, and it’s also — I mean, you think of, you know, astronomy and telescopes. And, you know, so often it has to be in a place that’s dry or up in a mountain or a place where there’s not a lot of light pollution.
Pamela Marcum: Right.
Host: And so we’re not the first ones to think, you know, hey, if you put a telescope — like you put a telescope on the shuttle. So if you have one on a plane that can get above all that noise, you can get, really, like just a much better view of the universe.
Pamela Marcum: Yeah. And it really has to do with the nature specifically of infrared astronomy. Of course, there’s lots of ground-based observatories. And many of them are on tall mountains. And some of them aren’t. You know, university campuses or whatever — those typically don’t tend to be the professional facilities, however. But those are mostly optical. There are some exceptions. At really long wavelengths, they tend to be ground-based, like radio telescopes and submillimeter telescopes. But there’s something unique about infrared.
Host: Yeah.
Pamela Marcum: And what that is is the following. It’s pretty simple. The molecules, particularly water, that is in the earth’s atmosphere absorbs — like crazy absorbs that infrared radiation coming from some astronomical source that we’d really like to study.
Host: Okay.
Pamela Marcum: Yeah. So —
Host: And so from the ground, you really don’t — like if you put an infrared telescope on the ground, you really wouldn’t get that —
Pamela Marcum: The photons get caught before they can get all the way to the ground.
Host: And they never quite make it to your telescope. So you got to get above all that with that water vapor in the atmosphere.
Pamela Marcum: Absolutely. So what SOFIA does is it gets above most of that absorbing layer and catches the photons before they can get absorbed.
Host: Okay.
Pamela Marcum: Yeah.
Host: And so how often does the plane fly? It just goes — I imagine it goes up, starts taking a lot of data. That data gets sent down to here at Ames. And then they sort through it.
Pamela Marcum: Yeah. It’s amazing how much effort it takes to choreograph a flight. And I’ll get a little bit into that in a minute. But to answer your question, it flies usually about 10 hours for a given flight. And over 80 percent of that flight is actually taking science. So there is some time to allow the telescope to cool off. Because cold is better for infrared. Yeah. So as we’re climbing up, we actually start opening the cavity door.
Host: Okay.
Pamela Marcum: We haven’t really even talked about that yet.
Host: Yeah. So I’d imagine telescope’s inside the plane. You open up this door for the telescope to actually go —
Pamela Marcum: It’s like fully exposed to the air. The air is just fluttering by. Absolutely. Isn’t that amazing, the engineering feat in allowing this airplane to have this tremendous hole in the back of the aircraft and be able to fly without —
Host: It’s like a 747. Is that right?
Pamela Marcum: It’s a 747-SP. So that’s like a little special designation. It’s a little bit shorter than most 747’s to allow it to have a larger flying range.
Host: And they put a door in it and put a giant telescope — and if it’s exposed to the elements — I mean, I imagine the wind —
Pamela Marcum: Yes. It’s fully exposed.
Host: You know, it’s just got to be —
Pamela Marcum: But the wind is — by the time you get to altitude, the air is so thin that actually there really — the wind isn’t as bad as you might think it would be. And furthermore, you’re working at infrared wavelengths, which allow some of the distortions you would see at visible optical wavelengths that we see with our eyes — it’s not as bad when you’re looking through infrared eyes.
Yeah. You can — so what they really worried about in the beginning was the turbulence that you might see in the air as it’s flowing over that hole. Right? Imagine a whistle. You blow a whistle, and it makes noise. We were afraid that —
Host: The wind that’s coming over the airplane and then like, oh, big hole, door, and a telescope. So it — and yeah, you’d think that there’d be turbulence and like —
Pamela Marcum: Yeah. And maybe it would even whistle. We — you know, we joked that it — yay. It didn’t whistle when we first flew the plane and tested it for the first time. It was one of the jokes. It wasn’t a big whistle as it was going through the sky. But —
Host: Like a flute.
Pamela Marcum: Exactly.
Host: The air is blowing over it.
Pamela Marcum: But the air is very thin by the time you get to the stratosphere. And also, the — again, the engineering design around that cavity is not just like they cut a hole in the airplane. No. They put a little ramp in front of that hole so the air kind of hits that ramp and kind of goes up.
Host: Skips over.
Pamela Marcum: It skips over. Yeah. And then there’s like a little thing on the other side that kind of catches it and just tries to keep that flow as laminar and smooth as possible. So it’s performed extraordinarily well.
Host: Wow. So what is some of the stuff that you get that you can capture from being that high up in infrared? What’s some of the science and things that you guys have learned that you couldn’t have learned from like an optical or a normal telescope on the ground?
Pamela Marcum: Right. What infrared allows astronomers to do is to peer into dense regions of our own galaxy — and other galaxies, as well, but let’s focus on our galaxy for now — where there’s young stars either in the process of being formed or just recently formed, but they are still surrounded by sort of the embryonic material from which they developed. And if you try to look at these regions at optical wavelengths —
Host: With — yeah. Which our normal eyes can see, it’s just bright or —
Pamela Marcum: Well, actually, you’re going to see black. Because —
Host: Oh, you don’t see anything at all. Okay.
Pamela Marcum: Right. The light from deep inside of those cocoons, the infrared light or —
Host: The normal —
Pamela Marcum: Well, sorry. The normal light, the visible light just can’t get out. Right, so you know, so you see these black areas surrounded by brighter areas where you can actually see the photons.
Host: You think, for a normal human, you see — look in the sky, and there’s like a dense black area. You just assume there’s nothing there.
Pamela Marcum: You would assume there was nothing there. Absolutely.
Host: But it’s not — it’s just the light can’t get out.
Pamela Marcum: Right. So if you just — I was looking for some pictures on the wall here of maybe — of the night sky. But if you just look at the Milky Way, even with your — I mean, if you just go out in a relatively dark sight, you know, and just look —
Host: Nice and clear.
Pamela Marcum: — at the — you will actually see these dark patches even in the Milky Way. Doesn’t mean there’s not stars there. They’re behind all of that dust that’s keeping you from seeing it. But then you look at that same patch of dark —
Host: In infrared.
Pamela Marcum: — in the infrared, with SOFIA.
Host: Nice.
Pamela Marcum: Right. And you’re going to suddenly see light. You’re going to see stars. You’re going to see nebulosity. And, you know, astronomers, for many, many decades or perhaps centuries, have really wanted to understand more about how stars are formed. Our sun is a star. You know, so how did we get here? It really comes down to origins. Right? So what is the physical process involved, especially when you consider all of the factors that would disrupt star formation?
Star formation, in its essence, is a blob of gas that, by its own gravity —
Host: Starts —
Pamela Marcum: — starts —
Host: — condensing.
Pamela Marcum: — to condense, compress to the point where a star is formed.
Nuclear reactions begin.
Host: Yeah. It’s — all of it just coalesces, spins around, gets so tight that the electrons just can’t take it.
Pamela Marcum: Exactly. Right. But there are so many other forces when you consider that this process is not happening in isolation. It’s happening inside of a galaxy where there are differential forces trying to tear it apart. There might have been some recent star formation causing solar winds that’s disrupting it. Right. There’s a lot of —
Host: It’s not just gravity pulling on itself to form — there’s all kinds of other noise and other stuff messing with it.
Pamela Marcum: Yeah. So there’s a lot of — so one of the things that astronomers are really interested in learning more about is what are those factors that either make or break a star from being born in a given cloud condition. Right? So by looking at lots of different star formation regions that are subject to different kinds of external influences or environments, and looking at different stages of star formation, you can really then start putting together a complete picture of how we, our own star, came to be —
Host: Of how it all came together.
Pamela Marcum: — and the planets, as well.
Host: Oh, wow. And so talk a little bit about — so you get all this incredible data from this telescope. But I imagine there’s also like other telescopes that are getting their own data. And it’s like — is there interesting stuff that you find when that data’s all like put together?
Pamela Marcum: Absolutely. Yeah. Absolutely. Synergy is what — and cross-wavelength studies, you know, multi-wavelength studies is really what the modern astronomer does. There really isn’t —
Host: You don’t have to live on your own with your own telescope. You can like capitalize on all the other work the other people are doing.
Pamela Marcum: Absolutely. So let me tell you one really cool example that happened. It was a really neat science result from a couple of years ago now. And it really shows that kind of synergy. SOFIA was used to observe one particular line of this molecular species. And then a ground-based observatory was able to observe a submillimeter line at a longer — much longer wavelength.
Host: Okay. In the optical — or is it also infrared —
Pamela Marcum: Oh, it’s like — it’s beyond infrared. So if you imagine in your mind’s eye, like the really high-energy stuff would be like ultraviolet. And then you get to visible, where we can see with our eye.
Host: And then on the other side —
Pamela Marcum: The reddest color you can possibly imagine just to the red of that would be the infrared. And then that goes on for a long time.
Host: And then some.
Pamela Marcum: Yeah. There’s a lot of infrared — right? — in the infrared spectrum. And then on the end of that is when we start entering what we call the submillimeter and then the radio, radio just like —
Host: Radio.
Pamela Marcum: Radio, just like the signals that you pick up every morning when you’re getting ready for work. Yeah.
Host: And so had one telescope looking at that submillimeter thing and then SOFIA looking at the infrared.
Pamela Marcum: Well — so yeah. So what happened was, you know, this one particular molecular species produced this one line that SOFIA could detect.
Host: Molecular species. You — this is like a cluster of stars, or is this like a nebula or something? Or what is it?
Pamela Marcum: Well, it was looking at a nebula where some recent stars had just been formed. And what was interesting is this nebula had just produced some stars that were similar to our own sun.
Host: Oh, cool.
Pamela Marcum: So that was kind of cool.
Host: Excellent.
Pamela Marcum: Call it solar mass stars. But this one particular — it was sort of like a molecule — right? — a little cluster of atoms bound together that produced a line, an emission feature. Let me go into that a little bit. So I can’t talk about spectra without really kind of explaining.
Host: Well, like one question, like, “Explain that.” And we just keep getting deeper and deeper.
Pamela Marcum: So don’t let me forget to —
Host: I guess that’s science.
Pamela Marcum: Yeah. Exactly. Don’t let me forget to come back to the story, though, because it’s a really interesting synergy story.
Host: I’ll hold you to it.
Pamela Marcum: Okay. Good deal. The spectrum is really just a rainbow. When you see a rainbow, a real rainbow, what you’re seeing is a tiny — you’re seeing a small slice of the bigger rainbow that’s really the — you know, the electromagnetic radiation/spectrum that we talk about. When you look at a rainbow just on the purple side, that would be where the ultraviolet would start. And the red side would be where the infrared — and then further on would be the radio would start. A spectrum is simply taking light from an object and smearing that light out across its — for — across color.
Okay. So a color is like a wavelength. So you’re just saying, you know, how much is this thing emitting at this color? How much is this thing emitting at this other color? You’re building up a spectrum when you do that.
Host: And that helps you understand what that thing is.
Pamela Marcum: Absolutely. It tells you —
Host: Because different colors or different atoms or different molecules or different, you know —
Pamela Marcum: Or temperatures.
Host: Oh, wow. Okay.
Pamela Marcum: Yeah. The whole shape of the spectrum tells you about the temperature.
Host: So you can infer like that’s what we’re looking at. We know what it is. We know it’s — or it’s a molecular, you know, organic thing.
Pamela Marcum: Right. Well, so let me get to that. That’s — because it’s a little nuance on this. So I kind of described what the spectrum looks like kind of overall. But on top of this overall sort of spectrum is our discrete little blips. Sometimes they’re above this continuum, spectrum. And sometimes they dip below as an absorption feature. Each atom and molecule in the universe produces its own special fingerprint signature of lines. So if you see a series of lines, you might say, “Ah, I know those lines were produced by hydrogen.”
Host: Exactly. Yeah.
Pamela Marcum: And you might see another bunch of lines.
Host: Like some college science classes are coming back to me — the fingerprints.
Pamela Marcum: There you go. Fingerprints. Think of them as fingerprints. And so —
Host: You know what it is.
Pamela Marcum: Yeah. So the point is by looking at the — a spectrum, data that SOFIA produces by many of its instruments, you can instantly recognize, ah, there must have been carbon monoxide in that cloud that I was looking at, and measure how much there was. Right? So it provides the ability — isn’t it amazing?
Host: That’s insane.
Pamela Marcum: You’re looking at this thing that —
Host: Like light years away.
Pamela Marcum: Inconceivably far away.
Host: And you can see what it is.
Pamela Marcum: And you’re able to say how much of each kind of chemistry it has.
Host: How much oxygen, how much hydrogen. Yeah. And then — so you — I want to bring you back to the original story.
Pamela Marcum: Thank you. Okay. So this particular molecule produced a line that SOFIA could see, so an emission feature, a blip.
Host: A fingerprint.
Pamela Marcum: A fingerprint. And then it also produced a line at longer wavelengths at the submillimeter that this ground-based observatory was able to measure. By taking a ratio of the strength of those two lines, it could tell the scientists who were studying this cloud how long this cloud had been in the process of making these solar mass stars. And it turned out that the answer was a lot longer than just simple physics would have —
Host: Have you think.
Pamela Marcum: — predicted. So it was kind of — it opened up a mystery rather than confirming something we already knew. So the implication was that maybe the — so the collapse was going slower than it should have.
Host: Than you thought. Yeah.
Pamela Marcum: And so one thought is maybe magnetic field lines, another of those factors that sort of mess with star formation, was helping to oppose the gravitational collapse. So what’s cool is SOFIA now has an instrument — it’s a brand-new instrument — that can measure magnetic field.
Host: Really. Okay. So that gives you one more piece of that puzzle.
Pamela Marcum: Absolutely. So hopefully, you know, in a year or so from now, we’ll be able to go back —
Host: We’ll have you right back, and we’ll start talking —
Pamela Marcum: — and say, “Aha. That was the answer.” Or maybe there will be another mystery that’s open.
Host: Or maybe it opens another door further on. Cool. So if somebody wanted to get more information on SOFIA, read more up on it, where do they need to go?
Pamela Marcum: Well, probably the first place would be our science center webpage, which is at www.sofia.usra.edu. And there’s also a tab off of the NASA.gov website, as well.
Host: For the mission.
Pamela Marcum: So if you just go to NASA.gov and go under the missions and then SOFIA, you’ll be able to find that, as well.
Host: Excellent. This is a reminder for everybody. If you have any questions — more questions that we want to relay over to Pam, you can tweet at us @NASAAmes. And also, there’s @SOFIAtelescope. And of course, we use the hashtag NASA Silicon Valley. Excellent. So thank you so much for coming over, Pam.
Pamela Marcum: It was my pleasure, Matt.
Host: Excellent. I’m sure we’ll have more content in the future and have you back as our returning Jeopardy champion.
Pamela Marcum: I’ll look forward to it. Thank you very much.
[End]