Instant Genius - The James Webb Space Telescope, with Stuart Clark

Episode Date: December 20, 2021

Astronomer and science journalist Stuart Clark tells us everything we need to know about the most important, high-risk space mission of the decade. Once you’ve mastered the basics with Instant Genius, dive deeper with Instant Genius Extra, where you’ll find longer, richer discussions about the most exciting ideas in the world of science and technology. Only available on Apple Podcasts. Produced by the team behind BBC Science Focus Magazine. Visit our website: sciencefocus.com Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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so you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com to learn more. Science Focus magazine, This is Instant Genius, a bite-sized masterclass in podcast form. I'm Daniel Bennett, the magazine's editor. And today we're talking about the James Webb Space Telescope. I'm joined by Stu Clark, an astronomer and journalist who's been writing about the project for newspapers and magazines as well as for the European Space Agency itself for the last decade. Stuart's a long-time contributor to the magazine. And if you enjoy,

this interview, you ought to check out his book, The Unknown Universe, which is on sale now in paperback. So, Stuart, we've been hearing about James Webb a lot over the past year, and it's hopefully going to launch before the years out. What's the big deal? Why are astronomers and scientists are like so excited about this mission? Yes, it's tempting, isn't it, to think of James Webb as just another space telescope or another space mission. Actually, It's a massive, massive deal. If you think about a NASA flagship mission and then sort of multiply it by 10 times.

And the reason it's so big is because it's taken so long to develop, it's taken so much money to develop, but also the science that it is designed to do is really comprehensive, a broad brush investigation of the evolution of the universe itself. And it will do this by investigating specific celestial objects and classes of celestial objects. But everything, all the science goals of the James Webb Space Telescope are built around this idea that we want to understand how the universe as a whole evolves. And so that's why it's got such potential for discovery.

It's kind of like a big, huge general purpose observatory, but in space, and quite a long way away in space. And as such, it will open a window on our universe that we've never truly exploited in this way before. And every time you do that, history tells us that the potential for discovery is in So put all those things together and this really could be one of the greatest turning points in our understanding of the universe. That's very elegantly put because I, you know, I've been following it for a few years now and it is remarkable. And just I just wanted to sort of, I guess, focus on the details a little bit there. So you talk about the cost and the time.

So how long has it actually been in development for? Yes, so decades, the idea of following up the Hubble Space Telescope with a successor, something that would take what we discovered with Hubble and allowed us to formulate new ideas and hypotheses and then inform the next generation of scientific investigation with a space telescope. And so for a long time, James Webb was actually called the NG-EG-Eas. ST, the next generation space telescope. So literally since the 80s people have been talking about this. And the ambition, when people started breaking it down into what they wanted to do and the kind of hardware they would need to do that, it was beyond anything anyone had ever even imagined

building before, really. And so to develop the technology to make. this huge telescope unfold in space and deploy correctly and work and stop this science flowing back has taken decades and about $10 billion to actually get to this point, which is why I think everyone is equally excited and nervous about this. That's literally, you know, $10 billion worth of spacecraft on a single launcher, you know, and that is a gamble by anyone's standards. But I think it's justified because of the potential scientific return that we could get from it. And to put that into it, because 10 billion is astronomical number, to put that into context of other missions, Is that comparable to things like Mars missions or other?

Much more expensive than say Mars missions, for example. Think about some of the big flagship missions like the Rosetta mission to land on a comet. They're sort of running at roughly sort of a billion euros. So automatically this is 10 times more spend than that. So imagine if you could have split up the money that's going into James Webb into 10 truly extraordinary space missions. And that's the gamble part of all of this. So for the same money that the James Webb Space Telescope is costing,

we could have done many more missions, which are at the pinnacle of what we thought of as sort of flagship missions. And as I say, that's where the gamble lies. James Webb has to really positively did. deliver, you know, on its science promise. That sort of leads me quite nicely to my next question, which is one, which is the most searched for thing around this launch, which is what is the current launch window and then, you know, more appropriately, why so many delays?

So, yes, so those are two different questions there. We'll take the launch window first and then we'll have a look at why so many delays. So a launch window is literally when the celestial objects are aligned so that you can get to where you want to go with the rocket that you have. Now in the case of the James Webb Space Telescope, it's going to a gravitationally stable point sort of behind the Earth, a gravitationally stable point called the L2 position that's created by the interplay of gravity. throughout the solar system. The launch windows are actually, there's a lot of them to get there. It doesn't require a very specific set of conditions and alignments. There's something like 210 days in a year that you can launch the James Webb Space Telescope. When you go into Mars, for example, because you need to launch in a very specific configuration with Mars and the Earth in exactly

the right position. You only tend to get launch windows to Mars every two years. That's why you'll notice Mars launches, you know, go in batches of every two years or so. So the launch window is just when you can launch to reach where you want to go with the rocket that you have. So in this particular instance, because there are so many launch windows for JWST, that's not the reason for the delay or the delays with the Mars missions like exomars for example if you realize you're going to miss your launch window without sort of rushing or cutting corners then you have to delay the launch by two years you know that's right so you go quite a hard deadline yes exactly and that's been that's been a problem in the past about should you stick to those hard deadlines to try and launch on time

or should you play it safe and accept a delay and the additional cost you know, of a two-year delay to go to Mars, but with the added guarantee that you're probably going to be more likely to succeed by giving yourself that extra time. And that does feed in a little bit here with James Webb because right from the beginning, it was clearly a flagship mission for NASA, the successor of the Hubble Space Telescope, the thing that was going to continue the science that was begun by Hubble. There was a lot of the world. There was a lot of of pressure to get it right. Because it was so big and ambitious, the technological development to produce something that stood, you know, a good chance of working was enormous as well.

And then as the time sort of stretched as people were needing more development time, and so the money and the budget that was being spent on this telescope went up and up, It kind of got into a position where it's sort of, you know, that, that cliche of too big to fail, at which point you start getting even more cautious about it. You want to be even more certain that it's going to work because now there's even more money, time and expectation riding on it. And so that's the situation we've been in with JWST. It's just, it's so complicated.

You know, people talk about it being the most complicated machine to ever be launched into space. Just because of how it's got to deploy what it's got to do autonomously to then be able to work and deliver the science. So there has been test after test after test, you know, caution after caution after caution. Even just recently, we had a four-day delay from the 18th of December to the 22nd of December. In this case, it was because the clamp band that holds the spacecraft to the adapter, this piece of machinery, that then bolts it to the rocket. That clamp band unexpectedly came off. And as it fell off, it shook the telescope a little bit. Now, that should be nothing compared to the vibration that telescope is going to suffer at launch, which it's been built to withstand.

But because there's so much riding on it, they immediately put in an investigation team to do more tests, just to be ultra, ultra careful with all this. So there are going to be a lot of nervous people watching that launch on the 22nd. Okay, I suppose I should be a bit more forgiving of these. delays considering considering all that and I was just you know imagining what that launch room will be like yeah this is not a run-of-the-mill mission no no and I mean it's tense enough when we go to Mars but I guess this is of magnitude higher so we'll definitely get to the build and how it works and and and the way that they actually constructed which is constructed the scope which is fascinating itself but I just wanted to get to you know the science it's going to do out there first in very blunt terms

what will James Webb be able to see that we were not able to see before? Yes, certainly. So this is the fascinating aspect of it, because James Webb is an infrared telescope. And the reason it's working in the infrared part of the spectrum, and it's not just a bigger version of the Hubble Space Telescope, which works in the visible part of the spectrum, is because we've seen so much with Hubble that to extend those studies,

we now need to start looking at other wavelengths. And the natural wavelength to look at are the longer ones, the infrared. And the reason for that is twofold. And that is that we want to understand the evolution of celestial objects with James Webb. and they happened to be, or they happened to be in places where infrared is uniquely suited to looking. But visible light is not. So if we take stars, for example, the Hubble Space Telescope was able to look at the amazing nebulae and star-forming regions and infer what was happening inside by looking at the gases on the outside.

It even had an infrared camera that could just see into the near infrared region, so it could peer into the clouds a little bit. If we want to see deeper into those clouds, so to even younger stars, then we need to look at even longer wavelengths, because they can penetrate dusty, gaseous regions more easily than visible light. It's the reason why we generally tend to have orange street lamps rather than white ones is because the blue in the white light gets scattered very easily from the mist and just sort of blinds you. Whereas the more penetrating rays from the orange sodium lamps, they're longer, they don't scatter as easily.

and so they give you more visibility through the mist. Same thing is happening here with James Webb, is just looking deeper into these star-forming clouds so we can see more of what's actually happening in that process of star and even planet formation there. If we look at galaxies, then those galaxies, they formed very long time ago, 10 billion years or more ago.

And so because of the way the universe expands, we need to be looking incredibly far away to see the light from those very young objects, which has taken 10 billion years or more to reach us. Because the universe is expanding, however, what's set out from those galaxies as visible light being given off by stars has been stretched. And when you stretch the wavelengths of light, you shift it towards the red end of the spectrum. This is what we call the cosmological redshift. And at the extreme distances that we want to look so that James Webb can see the very first galaxies to form, then what was once visible light in those galaxies has been stretched into the infrared region. And so by looking there,

again, at these longer infrared wavelengths, astronomers will actually be able to directly compare those early galaxies that James Webb has seen, with the galaxies that Hubble has seen in the visible, because the light is effectively the same thing coming from stars and was once all at that same visible wavelengths. And so there's a one-to-one correlation that we can do there to chart this sort of evolution of these celestial objects. So James Webb will be able to see further away than we've sort of effectively ever been able to see and therefore further back in time because of the way, you know,

the amount of time that that light takes to travel to us. So I guess the next sort of obvious question is, why is that of interest? Why is it so interesting? It's interesting in and of itself, but what do we want to know about the sort of early universe? Yes, there's another aspect to the James Webb Space Telescope that folds into that,

as well. And that is that molecules in the universe, they tend to be most active when interacting with infrared light. So molecules give out and absorb infrared light. And so another key reason for James Webb being an infrared telescope is so that it can do these kinds of molecular studies. And the reason that's important is because ultimately, of course, we do want to understand how life began in the universe, how we're here. And in order to trace that process, you have to start at the very beginning, the origins of the universe and the celestial objects within it, because that starts the process, the first stars, they start the process of chemically changing hydrogen and helium into the heavier life-giving elements like carbon, oxygen, nitrogen,

all the things that make up the calcium in our bones, the iron in our blood. All of those things are forged in stars. And so the universe itself is rather like one big sort of molecular factory or big chemical factory that first takes the fundamental particles of physics that are created at the origin of the universe. And it then processes those into the very first atoms, hydrogen and helium. And those are then processed inside stars to become the diverse chemical elements of the periodic table, which then are processed inside the big giant molecular clouds in the universe into more and more complex molecules, which somehow, when they find the right planetary environment become life.

And so James Webb is uniquely suited to looking at this chain of events, at all the different steps in the process. And that's what drives the very science, the top-level objectives of this telescope, is looking at the origins of all the celestial objects in order to try and take us kind of. closer to an understanding of the origin of ourselves. So are you saying that James Webber will be able to look back and forgive me for borrowing a biblical turn?

But effectively, something like Genesis, you're looking at the sort of dawn of creation. And we will be able to look over at these nebula where stars are sort of forming and we'll be able to understand the sort of the molecules that are around in that. nebula, you know, from our distant, lowly position here on Earth. We'll be able to see that level of detail. Yes, there'll be an awful lot of sort of chemical studies that take place with James Webb. It's a real attempt at moving the boundaries of astrochemistry outwards, you know, further into the... Yes, further into the universe than we've ever seen before. And that, once you get to chemistry, that's your bridge between physics and biology.

So this is an essential step in understanding how life emerges in the universe. That's not to say, however, that we understand all the physics of these early celestial objects. that's another key goal of the James Webb Space Telescope. So we know, for example, that it appears as if all galaxies essentially have a supermassive black hole at their center. And that supermassive black hole, that could contain perhaps 1% of the entire mass of the galaxy, which when you think that you've got hundreds of billions of stars in a galaxy, you know, to have a single object that contains 1% of the mass is pretty staggering. And it could be, in fact, it seems highly likely that those supermassive black holes are the seeds around which galaxies form,

sort of the gravitational centres around which galaxies form. But we don't know how the supermassive black holes form in the first place. we may have that completely backwards that it's the galaxy and the stars that forms first and the supermassive black hole in the centre is a result of that process or as I say it may be that the black holes are the gravitational seeds around which the gas that then becomes the stars in the galaxy accumulates. So that's a key thing for James Webb to try and look at there is to try and find the emission from gas close to these black holes

and see if we can discriminate whether the black holes come first or the galaxies come first. And again, I suppose it'll be trying to understand the sort of chemistry or certainly the molecules that are forming in the midst of these supermassive black holes. Yeah, so in that particular instance,

in that far back, you probably don't have very many molecules at all because you've just literally got hydrogen, helium, a little bit of lithium and brilliant. You've just got those simplest atoms that were formed in the Big Bang, the origin of the universe itself. Then, once you start getting the black holes and the first stars, then you can start looking from doing, if you could possibly do spectra of those stars or spectra of those early galaxies. You can start seeing the chemical constituents of those early stars and galaxies.

And so you can start to see how the elements are built up, whether they're built up quickly or more sedately. And then as we get to closer environments to us, James Webb would be able to really start to pull apart the molecular structure of things. So I'm going to ask you a very tough question now, which is one. My last boss once asked me this, and he was confounded by the idea that you could have a telescope in space like James Webb, looking at the infrared spectrum as you've described.

And so how does it actually see these things and make these inferences? And I had a fair idea having worked on a magazine for a while and explained. spectroscopy, Tim, and those sorts of things. But why does that work? Why does that work? It was one of these things. And I realized, you know, how is James Webb able to take infrared light from so far away and make these kinds of deductions?

Yes, it's a very simple answer, in fact. It's because the laws of physics are the same everywhere. The laws of physics do not change if you're located here on Earth or in the most distant possible galaxy. So that is the root level foundation that all science is based on. And the reason why we can have confidence in that is because if the laws of physics were different in different parts of the universe, nothing would make sense to us. You know, there is always debate over the interpretation of results. But if you were to even change the laws of physics very slightly, you know, you can't build stars anymore.

Or they'd have radically different lifetimes. Or they'd burn at different temperatures and things like this. And we see none of these things, and these would stick out like sore thumbs. They would stick out like huge anomalies that we just simply couldn't understand. which is not to say that we understand everything about the universe, but that is the key to all of this, the universality of the laws of physics. They're hardwritten into this universe in all parts of it.

And that means that we can look at molecules in the laboratory on Earth, see how they interact with infrared light, and then we can go and look for those signatures in even the most distant celestial object. And if we see a correlation between what we see in the lab and what we're seeing in those distant objects, then we can have a level of confidence that we're seeing those kinds of molecules in there. And so that's really, that's how it works. This, you know, science is not some imaginative social construct.

You know, it's based on things that we measure, that we extract out of nature. you know, whatever reality is, measurement takes us closer to it. And then through the laws of science mathematics, we can interpret what we see in ways that are meaningful to us. So that's how we do it. Science by its very nature taps into something that is truly universal. That was Stu Clark there, explaining how James Webb can see deep into the early moments of the universe. If you'd like to hear Stuart and I dig a little deeper into the technical side of the James Webb Telescope launch, how to work and how it's been built, check out Instant Genius Extra, a bonus podcast available via subscription on Apple's podcast app.

Thanks for listening. The Instant Genius podcast is brought to you by the team. behind BBC Science Focus magazine, which you can find on sale now in supermarkets and news agents, as well as on your preferred app store. Alternatively, do come find us online at sciencefocus.com. See you next time. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name audio believes you can have digital precision with analog warmth. Alongside French acoustic specialist vocal,

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