Black Holes in Sight

Down to Earth takes a look at tech intended for space which has since found a new home down here on Earth. And this week physicist Stuart Higgins is wrapped up in a Space Blanket...

Stuart - What happens when the science and technology of space come down to Earth?

This is Down to Earth from the Naked Scientists. I’m Dr Stuart Higgins and in this mini series I explore how technology developed for space is used in other applications here on Earth.

This episode: how a space station in critical danger led to the development of the shiny metal blankets that help stop marathon runners and hikers from getting hyperthermia here on Earth…

Before the International Space Station there was Skylab. Launched by the United States in 1973 as a space base laboratory, Skylabs deployment didn’t go quite to plan. During takeoff, part of the space stations meteorite and heat shield tore away and, without shielding, temperatures inside the spacecraft quickly rose threatening the mission.

NASA needed a quick solution that could be put in place easily by astronauts who were about to travel up to Skylab on the next rocket. They needed a material that could reflect heat over a large area and also be folded up neatly in order to get it into space.
After much consideration, they settled on a floppy fabric-like heat shield made up of aluminium coated plastic supported by sheets of nylon.The shield was transported to space folded, pushed through the side of the space station, and opened up like a giant umbrella. The metal side of the plastic reflected the infrared radiation from the Sun back into space successfully keeping the damaged part of Skylab cool… they’d made a space blanket

Metal coated plastics weren’t new to NASA, they’d previously developed them during Project Echo where giant metal covered balloons were placed into space to act as reflectors for radio signals sent from Earth. While the process of metallisation had been around long before that, it was the stringent requirements for manufacturing these materials for use in space that led to the development of a much wider industry.

That ultimately led to the creation of thin, thermally reflective sheets, sometimes referred to as space blankets or emergency blankets. You’ll see marathon runners around the world using them to keep warm at the end of races, or on people stuck up mountains trying to maintain their body temperature while they wait for help. By placing the metal side towards the body, the infrared radiation is reflected back towards the person rather than the other way round as it was used in skylab.

Metallised plastic films are also used in a huge plethora of ways including food packaging, clothing, and continue to be used by space agencies to help protect current spacecraft. So that’s how the development of metal coated plastic for space led to emergency blankets and much more here on Earth.

That was Down to Earth from the Naked Scientists. And join me again soon to learn more about space technology that’s changing lives back on Earth.

If you’ve got a goldfish pond then maybe you’ve worried in the past that, come winter, the water might freeze, seal in the fish below and block off the supply of oxygen. But, it turns out that, you don’t need to worry because the fish have a genetic trick that enables them to operate for months without any oxygen. They do it by burning sugars to produce a small amount of energy and a lot of the waste product lactic acid; this would normally be toxic, but then the fish use a specialised set of tailor-made enzymes to convert the lactic acid into alcohol, which they release into the surrounding water. Michael Berenbrink is the one who fathomed it out...

Michael - We looked at goldfish and Prussian carp, a wild relative of them and I’ve always been fascinated by their ability to overwinter in ice covered ponds in the absence of oxygen. When the ice covers the lake, the animals underneath are closed off and they just consume all the oxygen and then they have to deal with oxygen free situations, which is very unusual and not many animals can do that.

When we are without oxygen, humans and other animals - we produce lactic acid. It’s not so efficient but it just gets us a little bit of energy out of our foodstuff. But there’s a problem there that production of this acid is actually bad for you and cannot be tolerated very well.

Chris - This is the same stuff that when you’re taking a vigorous amount of exercise or doing weightlifting or something your muscles begin to burn, and that’s the build-up of lactic acid in the muscle? Because the muscle’s working harder than the amount of oxygen that’s available to it at that time, so it produces lactic acid as a by-product?

Michael - That’s right; this is just in the muscles. The whole animal is without oxygen then every tissue needs to do that, and soon the amount of lactic acid will overwhelm the body and it can no longer function.

Chris - And that would obviously lead to death, which does lead to death in some human patients doesn’t it?

Michael - It does, exactly. These animals can survive this because they’ve found a trick to convert this lactic acid into alcohol ethanol, which is what you have in beverages like beer and wine, and this can diffuse out of the animal via their gills to the environment of water. This is positive because they can survive for a time as long as they have enough foodstuffs to produce lactic acid and convert it to ethanol, but it’s not very energy efficient. What these animals do actually before they overwinter they accumulate foodstuffs in their liver - it’s called glycogen - it’s just carbohydrate, and they can use this when they are under the ice for three months.

Chris - Biochemically, Michael, how do they do this alcohol creation step, because that’s effectively the same thing that yeast does when it turns the products of fermentation into stuff that we like to drink in a beer bottle or a wine bottle; that’s what yeast is doing so how is a fish able to do that?

Michael - What we found out in our research by looking at close related species who can produce alcohol and overwinter, and also can’t. We found that they have these microscopic machines that chanel the foodstuffs into lactic acid. What these animals do is they have a second set of these microscopic machines due to a genome duplication, so that means the whole genetic material, by some accident of nature, was duplicated. So they have two sets and they have evolved to use one of the sets in the normal way and another set to channel the foodstuffs into alcohol production.

Chris - When you say micro machines, these are effectively enzymes, biochemical pathways, and they happened by a genetic trick to have copied them by mistake, probably, in the first instance, but they’ve hijacked one of those copies and now they’re using it to produce alcohol under these certain situations?

Michael - Exactly.

Chris - Can the fish turn this second set of enzymes on and off when they want it so they’re not producing alcohol in the summer, they’re only producing it in this wasteful way in winter when they have to?

Michael - What we found is that this second set is only switched on, and massively switched on in the absence of oxygen.

Chris - Why does this matter? It’s very interesting that you’ve unpicked the genetics of this and you’ve found how these fish can cope under these extreme environments, but why is this important?

Michael - There’s something called foetal alcohol syndrome, which is - in humans - very important. When the mother drinks alcohol during the pregnancy, foetal development can be severely affected. Our work contributes to this whole body of research by showing that goldfish regularly are exposed to high alcohol levels during their normal life cycles. So these goldfish have evolved ways to deal with alcohol concentrations that are above the drink/drive limit in many countries for months on end. This would severely damage the liver of a human, but we don’t know how Prussian carp and the goldfish are able to sustain this. We think there is something to find out there by looking closer into this mechanism.

Chris - If you do alcohol concentration measure on your average garden pond after a particularly harsh winter, can you detect the alcohol in the water?

Michael - It’s a good question. If you put a goldfish into a glass of water and let it produce alcohol, so if you prevent oxygen to accumulate, even if you have it in that confined compartment it takes about 200 days to get the strength of a glass of beer, so the alcohol that they actually release is minimal. That doesn’t mean that their blood concentration isn’t high, the blood concentration is really above the drink/drive limit

The best way to analyse a gas of course is to sniff it! Which is what, among other things, NASA’s Cassini spacecraft has been doing around Saturn. It was launched from Earth in 1997; it arrived in 2004 and since then it’s been exploring the planet Saturn, as well as it its rings and its moons, sending back breath-taking images from more than a billion kilometres across space. The mission is almost at an end and, on 15th September, Cassini will plunge headlong into Saturn and break up. With us now to discuss some of what’s been discovered during the mission is mission scientist and atmospheric specialist Ingo Mueller-Wodarg.

Ingo - The probe is about the size of a minibus and it simply is a box with large antenna on the front, a big booster rocket on the back and lots of instruments hanging out of it. Initially, it also had a little dish on the side, which was the Huygens probe, which was released into Titan in 2005.

Chris - Titan, of course, is Saturn’s largest moon, isn’t it. Why were you particularly interested in Titan?

Ingo - Titan is actually quite boring if you look at it through the telescope, it’s just a yellow ball. But the first Voyager flybys in the early 80s showed us that Titan has an atmosphere composed of nitrogen - a thick atmosphere. Nitrogen, of course, is also the main gas in the Earth’s atmosphere and, therefore, people were interested to find out more about this planet and its atmosphere.

Chris - So you send this probe onto the surface of Titan - what did it tell you?

Ingo - Huygens landed in 2005. The furthest we’ve ever landed an object from Earth away. It basically entered through the atmosphere, sniffed the atmosphere as it descended and then, most breathtakingly, it gave us the first glimpse through the global layer of haze that we normally just see through the naked eye, this yellow ball I was talking about initially. We managed, for the first time, to look underneath at the cameras on board revealed a breathtaking landscape with mountains and rivers, a smooth surface, and even lakes, but not the liquids we know from Earth. On Earth it’s water, on Titan it’s liquid methane, so it’s not something you would want to swim in.

Chris - Still, not a very nice place to go and hang out though. What about the other moons of Saturn, because Saturn has quite a few and Cassini has had the privilege of being in that system for more than a decade and taking multiple passes among them? What has it seen?

Ingo - The other most exciting of the 50 moons that Saturn has is Enceladus, a small icy body that nobody really expected to see anything interesting in. But it turned out that Enceladus had geysers of water coming out of the southern pole and these were discovered by Cassini for the very first time. We have looked at countless other moons, and the rings of Saturn, and Saturn itself.

Chris - Just talking for a minute about Enceladus because that was really a staggering finding, wasn’t it, those jets of water that spray into space; they go enormous distances? Don’t they even, in fact, contribute to one of Saturn’s rings, the material that they’re ejecting?

Ingo - Indeed, they feed one of the rings with material. In fact, this water that is emitted by Enceladus ultimately enters into the atmosphere again so it’s quite an interesting cycle of water transport over huge distances. But, looking at Enceladus as an isolated system, these geysers they come out of the cracks in the southern pole. We managed to fly through these water jets and we found that they contained molecular hydrogen, carbon dioxide, and methane amongst others. The interesting bit is that these are not chemically in equilibrium the way you would expect them to be. There’s basically too much molecular hydrogen and this could be caused by processes we also see on Earth. Basically, it’s hot water in the ocean flowing through cracks on the seafloor and then reacting with iron rich rocks to form molecular hydrogen.

Chris - Could it also be, one of the things people were very excited about, were saying there’s warm water there which is encouraging because we think water is an essential ingredient for life. Could also some of this equilibrium be because there are maybe biological processes which are exploiting that very strange environment that Enceladus is providing?

Ingo - These imbalances are not caused by microbial life, but they could indeed host microbial life because we see exactly the same happening on Earth. Whenever there’s a surplus on the ocean bed of molecular hydrogen, this can be used by microbial life as an energy source. Whether or not this life exists on Enceladus we don’t know, but we can say that the conditions for microbial life to exist are there.

Chris - Cassini has, undoubtedly, been a staggeringly successful mission, hasn’t it? It’s gone on for all these years and returned this huge amount of information and data, and these surprised like what emerged from Enceladus. Why has the decision been made to bring the mission to a close and crash land Cassin - why are you doing that?

Ingo - You’re absolutely right. It’s been a wonderful mission and all of us would love for it to continue another decade, but it’s running out of fuel. This means that there is enough fuel to power the systems, there is enough electricity on board, but there isn’t enough fuel to control the spacecraft anymore because you have to steer it on it’s orbit. We don’t want the spacecraft to get out of control and then we would risk the spacecraft landing on one of these delicate moons, for example, like Enceladus. We don’t want that to happen so that’s why we decided, while there is fuel, to bring it to a controlled end. We call it it the grande finale, because this is a whole mission again on it’s own with exciting new science to be done very close to Saturn, something which has never been done before.

Chris - So it will continue to send back data to you right up until it finally gives up the ghost as it plunges into the atmosphere of Saturn?

Ingo - Yes, indeed. Normally the data is saved onboard and then transmitted later once the high gain antenna points towards Earth but the exception will now be that it sends the data live while it plunges into the atmosphere. Because once it’s in there, it reaches a point where the spacecraft disintigrates and then we would have lost the data if it hadn’t been sent directly. It will be the first ever in-situ exploration of the atmosphere of Saturn. In-situ means that you sniff the atmosphere on location and this has never been done before on Saturn.

Chris - It seems sad to be looking forward to the demise of something but, at the same time, it will be a spectacular demise we hope, won’t it?

When it comes to telescopes, bigger is better! This year marks the beginning of a new era. Radio telescopes dotted across the globe have joined up to create a telescope the size of the Earth. The initiative is called the Event Horizon Telescope and the aim is to capture the first images of a black hole. Luciano Rezzolla, from the Institute of Physics in Frankfurt, is part of the collaboration and joined us. Chris Smith asked him to explain what exactly is a black hole...

Luciano - A black hole is one of the most cherished objects in our imagination nowadays and yet, as a scientist, we don’t have any definitive observation that confirms their existence. A black hole is an object which gravity’s so strong that they posses a surface which is called the event horizon where nothing, not even the lightest particle, can escape, and the lightest particle is, of course, light. So one can think of black holes as objects where gravity has the ultimate word, and where life cannot move out of this very specific surface, the event horizon.

Chris - How do we know then that black holes exist if no-one’s ever seen one?

Luciano - The idea is to use the indirect evidence. For instance, in the case of the supermassive black hole at the centre of our galaxy, you can convince yourself there’s a black hole because you see stars that are moving around an object which doesn’t emit any light, which is extremely massive - 4 million solar masses and yet you don’t see it. So the motion of stars near a supermassive black hole is a way of telling that there is a black hole. What we would like to see is “a smoking gun” for presence of black hole and that is the presence of an event horizon. That’s what we’re trying to do with this project - the event horizon telescope.

Chris - I suppose it’s complicated this, because astronomy is largely based on looking at things using light and, if you’re trying to see something that doesn’t let light escape, that must be tricky?

Luciano - It’s actually quite frustrating. But we do have an option here and that is given by the fact that if a black hole is immersed in a bath of radiation, of light, then there’s going to be a region out of this bath which will be darker because some of the light will not be able to reach us. This is actually what we are trying to measure and take a picture of, this region which is less luminous. It is what we call the shadow of a black hole, so through radio telescopes we’re trying to reproduce the shape of this shadow.

Chris - Right, so in other words by looking out how the light that you can see behaves you can infer what must be influencing the light in that way and, therefore, work out what must be there to do that and then you can see whether your observation is a theory?

Luciano - That’s right, that’s correct. And the shape can be telling a lot of information because different black holes have different theories of different properties will give you a different shadow. So, by measuring the properties of the shadow we will know a lot about the properties of the black hole.

Chris - Now why has the Event Horizon Telescope been convened to do this? We’ve got lots of telescopes on Earth - why do this with them?

Luciano - The problem is that light in wavelengths that are not radio tend to be absorbed, so what you want to have is radio telescopes measuring this shadow. Radio telescopes are actually ideal for this, not only because they can get the only radiation that reaches us, but also allows us to have the highest resolution. In order to have an idea of the high resolution that you need, it is like taking a picture of an orange which is placed on the surface of the moon. It’s a humongous resolution and the best telescope to give us this resolution is radio telescopes because there is a very simple rule in the resolution and that is that given a certain wavelength, you want to have the largest possible telescope to see this wavelength. In the case of the radio telescope you can get very large dishes, hundreds of metres. As a matter of fact even 100 metres would not be enough. What you really would like to have is a radio telescope which is as big as the whole planet. You may think this is just impossible. Actually it is possible and people have pioneered this technique which is called very large baseline interferometry decades ago. So the principle is you can’t have a single telescope, why don’t you have two telescopes as far apart as possible, and you just make sure they record exactly the same radio wave front. That’s what you do by synchronising these two telescopes with atomic clocks. In this case the larger is the better and if you can have more than two telescopes picking up the same wavefront the better because even the detail of this wavefront would be more precise. That’s what the Event Horizon Telescope collaboration has done this spring. It has set up a very large campaign where all the biggest telescopes scattered across the planet have recorded data, and this data we are now analysing.

Chris - You’ve even got the telescope in Antarctica which has made some recordings, but you haven’t got the data from that yet because you haven’t got the hard disks back from Antarctica have you?

Luciano - This is the most advanced technology to do this type of job. At the end what you really need is an aeroplane getting this data that is stored in these discs. But that’s it - you can’t win with the solar winter so we have to wait for planes to be able to land at the south pole telescope and pick up the data. Which actually is very important because the south pole telescope is the one that can always look at the galactic centre. While other telescopes would be as the Earth rotates they would not be seeing the galactic centre during some time of the day. But the most important piece of the puzzle is actually still missing and that’s why we hope that once we have that data we will have the most accurate measurements ever made of the galactic centre.

Chris - So you merge the data from all of these individual telescopes, which have all looked at the same event at the same time so you know that they’re all seeing it from a slightly different viewpoint and that should, therefore, give you this very deep detailed picture. But what will the picture that ultimately emerges when you put this sort of montage or this mosaic together, what will this look like?

Luciano - This will depend a lot on the quality of the data. This is data that is taken over several days, but we hope we will see some evidence of this shadow. So an evidence of a region where there’s going to be a lack of luminosity, while nearby there’s going to be a lot of emission. This is what our numerical simulations are telling us we should see.

In practice, I’m not able to tell you the quality of the data up until we have processed it. We might be very lucky and see something which is very suggestive of the presence of a horizon, or we might have to try again and remove some of the uncertainties to do, for instance, with the fact that the light would be scattered and so the image would be blurry.