Podcast: Space junk, and a physicist’s perspective on life

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Host: Shamini Bundell

Welcome back to the Nature Podcast. This week, keeping track of the trash floating around our planet.

Host: Adam Levy

Plus, the legacy of a physicist’s perspective on life. I’m Adam Levy.

Host: Shamini Bundell

And I’m Shamini Bundell.

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Interviewer: Shamini Bundell

Our planet is surrounded by human-made objects. Ever since the very first artificial satellite - Sputnik 1 in 1957 - humans have been launching various things into orbit. These days, we rely on satellites for GPS, television, weather forecasts, credit card payments, and of course, a lot of the environmental and astronomical science that we report on in this very podcast. But things aren’t as easy for modern satellites as they were when Sputnik went up. There are now nearly 2,000 active satellites in orbit and they have a major problem to contend with: space junk. Earth’s orbit is full of artificial debris. There’s defunct satellites, abandoned launch vehicle stages, fragments from explosions, and things that have just gotten lost, including a toolkit that an astronaut from the International Space Station misplaced and which ended up floating off by itself to join the growing collection of clutter far above our heads. Carolin Frueh, an aerospace engineer at Purdue University in the US, is working on ways to track space debris. I asked her: how much is actually up there?

Interviewee: Carolin Frueh

There are around 18,000 objects that are currently catalogued, but if we say okay, how many objects are there in total, going down to centimetre size, then we are talking more about 100,000 to 300,000 objects.

Interviewer: Shamini Bundell

Given that these objects are all very small and Earth is quite bit, and there’s, you know, quite a lot of space up there, does that actually pose a practical problem? Is there not sort of plenty of room for our satellites to steer round them?

Interviewee: Carolin Frueh

It is very true that there is a lot of space, so in an earthly perception it’s not packed in that sense. What makes the problem is that these objects are fast at several kilometres per second and they are not all kind of nicely aligned, but they are in different orbits that cross each other and that means things are running into each other with relative velocities that can have several kilometres per second.

Interviewer: Shamini Bundell

So, we’ve got a whole bunch of bits of rubbish or whatever we’ve got floating around up there and it’s all potentially damaging for our active satellites. What’s the main kind of thing we’re doing at the moment to counter this problem?

Interviewee: Carolin Frueh

So, the only way to get independent information on the objects is observation so there are several sensor networks. We try to keep track of all those objects, get a precise orbit, get a good representation of the uncertainty, and make collision warnings. At the moment, collision warnings are put out through the US Air Force and I would say that the orbits are not precise enough to make that very efficient.

Interviewer: Shamini Bundell

So, collision warnings are important because potentially then an active satellite could be manoeuvred out of the way if the predictions are accurate. So, what are you working on to make these predictions more accurate?

Interviewee: Carolin Frueh

So, one part I’m working on is how can we find out more about the object. So, I’m looking at brightness measurements over time, can we use that to find shape, attitude and the characteristic of the object that directly couple back to the orbit through drag or solar radiation pressure.

Interviewer: Shamini Bundell

And you mentioned attitude, which is sort of orientation and how it’s rotating as it orbits, but how easy is it to tell all of that from down here?

Interviewee: Carolin Frueh

So, for most of the objects we’re not getting a resolved image where we see any details of the object, so that means we just get one bright spot like you see the stars in the night sky.

Interviewer: Shamini Bundell

So, how on Earth can you tell from a little dot what it is and what it’s made of?

Interviewee: Carolin Frueh

So, for the materials we can measure in different wavelengths. We measure in different wavebands the reflection, then we know what type of material has been sent up, and then maybe we can do a comparison. Shape, or attitude motion, if you measure brightness over time, if you know one of the parts, if you know shape we can more easily solve for attitude, if we know the attitude we can more easily solve for the shape. But all of this is more like detective work, like you get clues and then maybe if you put all the clues together it gives you an educated guess.

Interviewer: Shamini Bundell

And thinking about all these objects as kind of space junk, like we’ve been littering up our orbit, I think most people’s first reaction would be like: well, we better clean it up then. That’s what we do with rubbish and litter here on Earth, can’t we do that in space?

Interviewee: Carolin Frueh

The idea is out there. There have been studies about bringing up satellites to clean the space. That’s feasible, maybe, for a couple of big objects, but we will not clean up everything. And we also have to think that’s very expensive to do that, we have to have a dedicated mission to clean five objects.

Interviewer: Shamini Bundell

So, for the meantime, you’re focusing more on tracking rather than tidying so to minimise the amount of debris that’s added and to keep track of what’s already up there. And do you think that at some point, we could reach a stage where we actually know where everything is at any given point of time, kind of like an air traffic control system but for space?

Interviewee: Carolin Frueh

In order to make that work, we need better sensors and better algorithms. We also would need international agreements. At the moment, it’s pretty much like on the oceans that when you are in the midst of the ocean, whose legal responsibility is it, right? And that’s pretty much how space is. So, even though collision messages are put out - and I think we need a lot more work on those to make them more reliable, to make them better - we’re also lacking a lot of legislation and we have no tool to enforce things.

Interviewer: Shamini Bundell

But right now, the collision warning systems we have in place are doing a pretty good job. We’re avoiding sort of big collisions. There’s still, you know, maybe damage from smaller bits of debris and there’s still costs of sort of having to manoeuvre around the way of stuff. But how urgently do we need to improve our systems?

Interviewee: Carolin Frueh

We are not in a position where we can afford doing business as usual. There are many objects we don’t know about. The collision warning system that we have at the moment is insufficient. The space environment, in terms of how we’re utilising it, is rapidly changing, making the problem worse and we cannot just go on the way that we have.

Interviewer: Shamini Bundell

That was Carolin Frueh of Purdue University. She’s been interviewed, along with other people working on the space junk problem, for a Feature in Nature this week which you can find at nature.com/news.

Host: Adam Levy

Still to come in the News Chat, testing out a powerful mini-accelerator, and a new plan for open access. But now, it’s time for the Research Highlights, read this week by Richard Hodson.

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Interviewer: Richard Hodson

Graphene is a marvellous material. It’s formed of carbon sheets just a single atom thick and has unique conductive and physical properties. Despite its extraordinary qualities, researchers have now found that it can be produced in an ordinary microwave. A tube of silicon and silicon dioxide were heated in a microwave to form a 700-degree Celsius charged gas. Adding methane to the mix led to some of the methane’s carbons forming graphene. These graphene scraps grew into sheets in the same way that snowflakes form. The graphene snow floated down and was collected and used to make a sensor. Read more in Advanced Materials.

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Now, a story with a twist and this one’s a real gut-wrencher. Yes, it’s about how our intestines develop their twisted shape. Researchers looked at the guts of developing chick and mouse embryos. They found that connective tissue gets decorated with amino-acid chains, only on the right-hand side of the gut. This causes the right-hand side to expand substantially compared to the left, leading to the gut’s crucial counterclockwise turn. For a long time, a protein on the left side was thought to be the key player. Turn to that study in Developmental Cell.

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Host: Adam Levy

Shamini, if I say the name Schrödinger to you, what is the first thing that pops into your head?

Host: Shamini Bundell

A dead cat. Oh, or an alive cat. One of the two.

Interviewer: Adam Levy

Yeah, well, either way that is the answer that I’m looking for. This dead/alive cat is in fact a famous thought experiment Erwin Schrödinger used to draw attention to the bizarre implications of quantum mechanics. But this thought experiment was just the tip of the Schrödinger quantum iceberg. There’s also the Schrödinger equation which describes the fundamental behaviour of quantum systems, and in 1933, Schrödinger received a Nobel prize for his work on quantum mechanics. But Schrödinger was also interested in life, and no, not just the life of cats. Ten years after winning the Nobel prize, and 75 years ago this year, Schrödinger delivered a lecture series that brought physics and biology a bit closer together. Writer Phil Ball has been discussing this series in Nature’s Books and Arts section, and explains that the story started in Dublin in Ireland.

Interviewee: Phil Ball

Well, Schrödinger himself ended up in Dublin because he was essentially an exile fleeing from the Nazi occupation of Austria, his home country. So, there he was in 1943, and he was required to give some public lectures and he chose, probably to the surprise of some, to talk not about quantum physics but about biology.

Interviewer: Adam Levy

These biology lectures from a physicist were very well-attended. The following year, they were published as a book. The title of both was What Is Life?. Safe to say then that Schrödinger wasn’t interested in tackling easy questions. Schrödinger used the series to cast a physicist’s eye over some of the core concepts of modern biology.

Interviewee: Phil Ball

His key question was: what is it about life that makes it seem to be able to evade the second law the second law of thermodynamics, this notion that things eventually end up in chaos and dissolution and randomness. So, that was his key theme and there were two aspects of that question that emerge in his lectures, and the first one that he spent most time on is how it is that organisms are able to stably inherit traits from the parent organisms, how they’re passed down from generation to generation because if those traits are encoded in genes at the molecular level, physics tells you that they ought to be kind of submerged by the randomness, the chaotic motions that exist at that level. But then he asked: well, even if we understand that process of inheritance, how do those instructions that are encoded in the genes act out to guide the development of an organism. And there he really didn’t make much progress, but he made a very clear statement of that problem and I think, you know, often that’s a more valuable thing to do in science: to clearly articulate the problem.

Interviewer: Adam Levy

In What Is Life?, Schrödinger has a lot of thoughts about genes and gene-encoding molecules, but this was back in 1943 when it was still unclear what a gene actually was. At the time, Schrödinger and others thought that these molecules would probably be proteins. Of course, we now know genes are encoded in DNA, but while Schrödinger wasn’t right on this one, he honed thoughts on how these molecules could be used to pass information from generation to generation.

Interviewee: Phil Ball

What he said was that there must be something about these molecules that encode genes that remains stable. And he talked of the genes as being something like what he called an aperiodic crystal, and what he meant by that was it has a particular arrangement of atoms so it’s non-random but it remains fixed, and somehow it encodes the information that genes carry and pass between generations.

Interviewer: Adam Levy

It wasn’t until 10 years later that Watson and Crick published their description of the double helical structure of DNA. But Schrödinger’s description of a non-random code capable of storing information was inspiring to many, including Watson and Crick who both said that What Is Life? motivated their work on genetics. But Schrödinger’s What Is Life? wasn’t without its critics.

Interviewee: Phil Ball

There was some grumbling and some said the biology in the book was actually a little bit out of date. And also, that his ideas about there being some kind of code that was somehow inscripted in molecules, there had been one or two biologists that had made similar suggestions and one or two of whom were a little bit miffed that they or their colleagues weren’t recognised. There was also grumbling later on in the 1980s. Max Perutz, who was one of the key people for understanding the structure of proteins, he rather dismissively said about the book that what was original in it wasn’t particularly valuable and what was particularly valuable in it wasn’t particularly original.

Interviewer: Adam Levy

But this is the response from some of the biologists at the time. 75 years on we have a wealth of additional understanding of life and its interplay with physics. So, what is the legacy of What Is Life? today? Here’s Phil’s take.

Interviewee: Phil Ball

In retrospect, its value wasn’t so much what Schrödinger said but the way he said it. He was able to bring disciplines together. He really highlighted the value of different disciplines talking to one another. I also think that in where Schrödinger was going, it’s possible to see a foreshadowing of some important themes that have emerged today, even if Schrödinger himself didn’t recognise them. This question of information and what role information plays in biology is absolutely central, and it isn’t as simple as saying well, all the information is in the genes because it clearly isn’t. For example, in terms of how genes are turned on and off - the science of epigenetics - by their environment and by what cells tell each other to do, you know, this is really one of the themes at the forefront of understanding biology today. So, you know, I think I can see that as one of his key legacies, that we need to understand living organisms as self-organised systems that involve an interaction between the information they contain and information that they receive from the environment.

Interviewer: Adam Levy

That was writer Phil Ball. You can read his retrospective of What Is Life? over at nature.com/books-culture. Thanks to Benjamin Thompson for producing that interview.

Interviewer: Shamini Bundell

Now, it’s time for the News Chat and I’m joined in the studio by Flora Graham. Hi Flora.

Interviewee: Flora Graham

Hello.

Interviewer: Shamini Bundell

So, Flora is editor of the Nature Briefing and we’ve got some interesting stories mentioned in the Briefing that we’re going to chat about, and the first one is all about the move towards open access science.

Interviewee: Flora Graham

That’s right. This is a very big move from European funding agencies. These are 11 funding agencies from all across Europe including France, the United Kingdom, the Netherlands and others, and they have come up with a pledge which means that all scientists that receive funding from any of these agencies must publish their work in an open access model. That means those papers are freely available to read immediately upon publication and released under a very liberal open license.

Interviewer: Shamini Bundell

So, if a scientist wants the money, they have to sign up to this open access plan.

Interviewee: Flora Graham

Exactly. If they want money from these particular funding agencies, and the news is that there probably will be more funding agencies signing up to it in the future as well.

Interviewer: Shamini Bundell

So, we’ve already got open access journals and we do hear about it a lot and there are funders that require science that they’ve funded to be published in open access journals. What makes this particular announcement different?

Interviewee: Flora Graham

Absolutely. Well this is taking it to the next level. This represents €7.6 billion in funding across Europe and the idea is that this will be initial step of what possibly could become a European Union wide initiative although we’re not at that point yet.

Interviewer: Shamini Bundell

But people have been trying to push open access. Has it not been progressing as fast as people would like?

Interviewee: Flora Graham

That’s exactly what people are saying. Robert-Jan Smits, who’s the European Commission’s special envoy who’s really pushed this forward, he feels that this is just not happening fast enough. And the consensus among a lot of people in the open access community is that things like hybrid journals, which are a mix of paywalled and un-paywalled, and things like that are moving things forward but this - considering how quickly it’s going to come into effect - is going to be a massive step change.

Interviewer: Shamini Bundell

And just to go over the basics again, so if the journal isn’t charging people to view the papers, who is paying for these papers to be published?

Interviewee: Flora Graham

Good question. So, the researchers, or the funding body, or the tax payer, depending on how the research is being funded, would be the one who pays. So, that raises the question: what does this mean for the business model of publishers? How much are these funding bodies actually willing to pay to get their papers published? According to the plan, there will be a cap on the amount that the agencies are willing to pay, but they haven’t disclosed what that cap is going to be. Some publishers, who unsurprisingly have not reacted well to this plan, have brought up the issue that if this type of thing goes global and science is a global endeavour, how will people in developing nations, for example, pay the kinds of fees that people in the developed nations are able to pay in order to get into the top journals.

Interviewer: Shamini Bundell

And so, is there a divide in the scientific community in terms of who thinks this is a great idea - open access for all - and people who are more sceptical?

Interviewee: Flora Graham

This plan would prevent these funded researchers from publishing in Science and Nature, for example, so some of the highest impact journals, some of the most prestigious journals will no longer be open to people who take funding from these agencies. I think there is, broadly speaking, a lot of support for open access publication, but of course, that doesn’t necessarily speak to every single reason why someone might choose one journal over another.

Interviewer: Shamini Bundell

But is the alternative not that maybe the journals will be forced to change their policies?

Interviewee: Flora Graham

Well, it’s no doubt that this will affect journals. The question is: how will the journals respond and how will the companies respond because this plan does not lay out any business model for publishers to follow. The argument is that publishers can charge for the services they provide in a different way so they’re actually asking the funders to pay rather than the readers, but there’s really a big question mark over whether that will support scientific publishing as we know it.

Interviewer: Shamini Bundell

And when is this plan from these funders who’ve signed up to this agreement, when is it being implemented?

Interviewee: Flora Graham

Well it should come into force in 2020, so not long now.

Interviewer: Shamini Bundell

And so, we could be seeing big changes just within a couple of years?

Interviewee: Flora Graham

Absolutely. This is right around the corner and I think everything in publishing right now is definitely changing and this will cause even more changes to come even more quickly, especially in Europe.

Interviewer: Shamini Bundell

Well, we’ll be interested to see how that goes. The next topic is a new experiment at CERN, famous for being a giant circular particle accelerator, but this is a slightly different and new kind of particle accelerator.

Interviewee: Flora Graham

Exactly. So, the problem with a giant particle accelerator is that it’s huge and expensive. So, what researchers at CERN are trying to do is prove that a new type of electronic accelerator, which can be much smaller and cheaper, actually works. And they have successfully proven that they can accelerate electrons by kind of surfing them on the wake of protons and this could mean that you need a lot less energy, and of course a lot less money, to do some high energy particle physics experiments.

Interviewer: Shamini Bundell

It sounds kind of good to be true. It’s cheaper, it’s easier - why has no one thought of this before?

Interviewee: Flora Graham

Well, actually this idea has been around for a while but of course, I say cheaper and easier but that doesn’t mean that you can knock this out of cereal boxes and tape. It’s still a major experiment, and just showing that the theory and the concept and the engineering pans out in the real world is a big step forward. Now, this doesn’t mean they have a working accelerator that they can start using for experiments tomorrow. What this means is they successfully created a coherent beam of electrons, so it works in principal successfully, but we’re still far from running day-to-day experiments on this type of equipment.

Interviewer: Shamini Bundell

Thank you, Flora. To read all the latest news from the world of science, head over to nature.com/news. And for a daily update from Flora in your inbox, make sure to sign up to the Nature Briefing.

Host: Adam Levy

That’s all for this week, but tune in next time for even more of the latest science news. Until then, I’m Adam Levy.

Host: Shamini Bundell

And I’m Shamini Bundell. Thanks for listening. [Jingle]