Remembering Voyager's mastermind, and lizard clean-up crews

Plus, proof of community care in Neanderthals...
28 June 2024
Presented by Chris Smith
Production by Rhys James.


In this episode of The Naked Scientists: Edward Stone, the man who led the Voyager probe missions, which are still working half a century on, has died at the age of 88. We reflect on his legacy. Also, scientists discover what they think is the first Neanderthal with Down’s Syndrome, clearly cared for by his community. And what should be in your first aid kit if you’re heading to a major music festival?

In this episode

NASA photograph of one of the two identical Voyager space probes Voyager 1 and Voyager 2 launched in 1977.

Voyager's Edward Stone remembered
Martin Rees

First this week, tributes have been paid to Edward Stone, the man who oversaw the remarkable Voyager missions. He’s died. He was 88. Stone - who was originally from Knoxville in Iowa - attended the California Institute of Technology before joining the NASA Jet Propulsion Laboratory. It was there that he became project scientist for the Voyager space missions - which would define his career. To find out about Edward Stone and his remarkable achievements, I went to meet someone who knew him, and knows a lot about the cosmos, our Astronomer Royal, Martin Rees…

Martin - Yes, I'm privileged to know him because I went to Caltech for academic reasons quite often. And he was an important presence around there. And of course I was aware of his great achievements, the Voyager Project in particular. But the value of his leadership was very important because he was very genial and engaging, a very good team leader. And of course, it's remarkable that he was in charge of these Voyager projects for 50 years, more or less.

Chris - It was NASA's kind of golden decade, wasn't it? The seventies. But why did they do Voyager when they did in 1977?

Martin - Well, as Ed in particular realised, and others did, there was at that time an interest in a possible grand tour. This is the idea that the alignment of the outer planets was such that by bouncing off them, by going close to them, it might be possible to give an extra push to a spacecraft headed to the edge of the solar system and get to the edge rather quicker. And so this alignment, which happened every 170 years or thereabouts, was a good opportunity and it would be sad if there weren't efforts made to send some probes to the outer planets at that time. And Ed was one of the people who actually implemented this.

Chris - Why two Voyager probes, though?

Martin - They went on slightly different orbits and one of them overtook the other. And I think one was concentrating more on Saturn and Uranus and one hoped to get further.

Chris - What did they teach us?

Martin - Well, of course we got some pictures of those outer planets. And of course there have been some other probes that have given us later pictures, the outer planets and Pluto. But of course, what's been really special about Voyager is that it is still going after nearly 50 years. It's way beyond Pluto. And it's sending back data. And the particular thing which is important for a very remote probe is that it gets out of the inference of the solar system. The solar system, obviously we regard as the planets and the asteroids and Kuiper belt and all that. But there is a region where the solar wind pushes out the interstellar medium. And so we're not really in interstellar space until we get to the edge of this region. And it was generally thought that you had to get further away than Pluto before you would encounter the transition between seeing the wind of the sun still going out and genuine, pristine interstellar matter. And it's clear that the voyagers did get across this barrier and found changes in the density, the temperature, and the magnetic field at that time. So that was the distinctive achievement to actually be the first human based objects that got outside the influence of the solar system.

Chris - I had a look at NASA's website this morning because you can chart the progress of the Voyagers and it says they're 24 billion kilometres away, so that's roughly four times the Earth to Pluto distance at closest. It's a long way <laugh>.

Martin - Yeah, that's right. And it takes more than a day to get a signal to them. And what's been remarkable, and that's been in the news in the last few months, is that the signal from Voyager went dead. Something went wrong. But amazingly they seem to have managed to revive it. And if you just think of what's involved sending a signal to something that far away from a radio transmitter, some dish here, and getting back a signal from that enormous distance from something where the battery gives just a few watts of power. It is amazing really. And of course, the other inference I draw is if we think of the worthwhileness of what can be done even with the technology of the 1970s, think how much better we could do if we were able to launch a whole flotilla of probes with the kind of material that we have in our mobile phones. Much more sophisticated, much more compact.

Chris - I'm in awe just of the engineering. 50 years later, well 46 years to be precise, in the worst imaginable environment really in terms of radiation temperature and so on. This stuff is still working. Mostly they've had to shut down some of the systems. There's even a tape recorder on Voyager, one magnetic tape that records things and then sends it back at the princely rate of two kilobits, I think <laugh>. And it sends it back. But that's amazing. It still works.

Martin - The constraint is the weight limit, which means you can't be as robust as you'd like to be with these instruments because of the weight limit. And incidentally, that's going to be a problem that's going to be much eased when we have the new SpaceX rocket, which can launch up to a hundred tonnes into space. So at the moment, we are looking forward to much bigger projects where we can launch heavier things, but this was a very small object, which had to be simple and use technology that's 50 years out of date.

Chris - What I found amazing about Ed Stone was that he was still going through a time where many scientists have hung their test tube rack up. He was still going, still leading a mission at the age of 88. Or thereabouts. That's pretty good.

Martin - Well, that's right. And of course, very few of us have the privilege of having work. We started when we were young, still going and still being fruitful and still being deemed interesting when we were as old as he was. But he was a great guy. He continued in fairly good health.And he was a very good leader. And over his career, he was the director of the big lab at Pasadena, and he was involved in more than a dozen different projects over his time. So he made a great contribution to space exploration in general.

A portrait of a neanderthal in a museum.

Did Neanderthals care for child with Down's syndrome?
Emma Pomeroy, University of Cambridge

A new study has found that fossilised fragments from a Neanderthal child’s skull bear structural changes compellingly consistent with that individual having Downs Syndrome. It is believed the child lived beyond the age of six, which suggests communal caregiving within the palaeolithic community. This has been seen before in anatomically modern human ancestors, but not before in Neanderthals. Emma Pomeroy - who is an archaeologist and Neanderthal specialist at the University of Cambridge - has been taking a look at the study for us...

Emma - The paper is about a fragment from the skull that they found at a site called Cova Negra in Spain. And one of the questions to start out with was, what species did this skull fragment come from? It was in a mixed collection of bones and they weren't sure whether it might be neanderthal or modern human. And then also there were some changes in the bone itself. So it's a fragment from near the ear and it contains a sort of semicircular canals, the various bits of the ear canals involved in hearing and balance. And they also found that there were some, a lot of differences there from the typical anatomy. So they were able to establish that it was a fragment indeed from a Neanderthal individual. And by taking lots of measurements and assessing the ear canals, essentially they were able to show that there was a wide range of anomalies in the way it had grown and linked those to, most likely, down syndrome.

Chris - They haven't got DNA at this stage then?

Emma - No, they haven't. And I think a diagnosis such as down syndrome might be actually quite complicated from the ancient DNA because it's to do with multiple numbers of chromosomes or extra bits of chromosomes. And that's kind of tricky to do with very fragmented DNA.

Chris - So why is this a breakthrough, or a landmark discovery?

Emma - Well, it's very interesting because I don't think we've actually got any identified cases of Down's syndrome in the archaeological or the paleo anthropological record. We know that other great apes can have Down's syndrome. We've got examples of chimpanzees, but this is perhaps the first example that we have from human ancestors. It's also really interesting because they've suggested that it's from an individual who was still a child, perhaps older than 6-year-old, but still pretty young. And that has various implications because the nature of these changes in the bone meant that the child probably would've had quite severe symptoms in terms of real trouble with their balance, problems with vertigo, things like that. So really they wouldn't have been able to do normal everyday activities very well. And the implication of that is that they would've needed substantial care from the mother. But probably, the authors argue, that the care they would've needed would've gone beyond what the mother alone could have offered. So in that sense, there must have been care from a wider group or assistance for the mother enabling this child to actually survive to a fairly good age. For someone with this syndrome at a time when there wasn't really any treatment and medical support.

Chris - Does that surprise you? Based on what we know about the likely community structure, the social structure of these individuals and also anatomically modern humans who overlapped with them, we've learned quite a lot from them. Does that surprise you that they should be looking out for one another?

Emma - Me personally, no. But this has been a really controversial question in terms of human evolution and when we started to care for one another. So if we look across modern human societies, including living hunter gatherer societies, we do see a great deal of care not only for the young, which obviously children need care for, they can't fend for themselves for a long time in our species, but also for individuals who are unwell or elderly. We know that other human ancestors, like Neanderthals, were living in social groups. We've got evidence that they were collaborating with each other, so for hunting, for example. And we do know that Neanderthals took a long time to grow up just like modern humans do. So they would've needed, as children and as infants, quite substantial care for a number of years based on the elderly Neanderthals as well. And in fact, other earlier human ancestors, we do find evidence of individuals who also must have required substantial care. So with major injuries, major health problems, infections, bone fractures, even perhaps amputations and paralysis. So given we have those findings, I think perhaps it's probably not entirely surprising. The context in which the authors are putting this particular finding is in trying to understand why this kind of social care and when this social care might have evolved. Is it to do with expected reciprocity? So the idea that, if I get an injury now and you help me out, in the future you might get an injury and I can help you out. And so it benefits us both long term. Or is it more to do with sort of evolution of true compassion for fellow members of our group and they are arguing because this particular child would never really have been able to reciprocate, that perhaps helps us to understand how this caring behaviour might have come about in our evolution.

Music festival

How to make a Glastonbury first aid kit
Adam Staten

Glastonbury - which is one of the world’s most famous music festivals - is getting underway near Pilton in Somerset. Our colleague James Tytko is currently there and we thought it might be an idea for him to ask GP and author Adam Staten what he should be taking with him to Worthy Farm…

Adam - I suppose we don't often cope with um, hot weather and sunny weather much in this country. So people are often not very well prepared for it. Dehydration is a big factor, especially when you're active all day and out in the sunshine, out in the heat. You know, I suppose the waste dealt with, it's pretty straightforward. It's just to make sure you're keeping a good intake of fluid up. We'd normally say drink about three litres of fluid or a day like that, but if you're going to be outside all day and gonna be particularly active, even four or five litres, it's probably a good idea. The other thing to bear in mind, obviously that goes hand in hand with these sort of music festivals, is alcohol intake and obviously the alcohol can add to dehydration. So it's a good idea to try to intersperse any alcoholic drinks with non-alcoholic drinks to keep your fluid levels up.

James - I will do my best. I can't promise that I won't be enjoying a few beers though over the course of the weekend, so be good to up my water intake, no doubt. Another thing, I have quite pasty white skin.

Adam - I think most of us have probably experienced sunburn at some time or another. I mean, obviously it ranges from being fairly mild to pretty severe. It's fairly easily avoided if you pay attention and think about what you're doing. Simple things to do is wear things like a hat. Obviously use a high factor sun cream and just try and stay in the shade, particularly in those hottest parts of the day from about 11 in the morning till three in the afternoon when the sun's really out high and strong.

James - The final prong of this triple threat of sunny weather for someone like me is pollen count.

Adam - Anybody that suffers with hay fever, it's worth just making sure you're taking antihistamine every day. Ideally a sort of once daily non-drowsy one. Just take that each day in anticipation. It would also help defend you a little bit against the nasty reactions you might get from any insect bites. If you're unlucky enough to get bitten, it will stop those flaring up so badly. And obviously you might want to think about things like nasal sprays and eye drops if those are particularly troublesome symptoms for yourself.

James - Long days out in the sun, I'll be on my feet for the majority of it dancing a lot too. Hopefully. A problem that I've experienced in the past is my feet getting really sore, especially when you're compounding this over a few days.

Adam - Best thing is to wear some sort of comfortable, well-fitted footwear that's not going to rub and not going to put unusual pressure points on your feet. If you are unlucky enough to get things like blisters, then there are some good blister plasters you can get over the counter from most pharmacies probably in the evening. If you're sat down somewhere for a while, it might be worth taking shoes and socks off and getting some air so they're not sort of sweaty and damp throughout the evening.

James - Yeah, I mean, I can't think of a much easier way to ruin my weekend than a severe bout of athlete's foot. Another inevitability will be loud music being sound systems potentially at points you might find yourself quite close to big speakers.

Adam - Prolonged loud noises can damage your hearing. In the context of a festival. The damage you're likely to be hearing is going to be short term really. You might be left with some ringing ears and slightly muffled hearing for a few days, but that should recover. Obviously if it's something that happens really regularly or it's happening on a prolonged basis, then that can lead to long-term hearing problems. If you're someone that's gonna go to a lot of music festivals and a lot of gigs and things, then some kind of ear defence is probably not a bad idea.

James - The last thing I wanted to get your opinion on going to festivals, the toilets are infamous and some people may decide, you know what, I just don't want to go through that experience. It's too arrowing. I know there are drug treatments out there to kind of b yourself up for the duration of a festival to wait till you get home to do your business. Are those advisable in that context?

Adam - Yeah, you're right. There are brands like Imodium, which is generically called loperamide and Anti-diarrhoea Medicine, and it'll slow you down and tend to constipate you. I mean, it's a bit of a personal choice really, but the downside to it is you take away the diarrhoea, it can make you quite constipated, which then might give you the other problem when you get home with pain and difficulty getting going. So, I would have to leave that in your hands, James, to decide if you feel that's worth it. But I suppose it is an option.

James - On that note Adam, thank you so much for all your advice. I'm going to go to the pharmacy now, armed with the knowledge and I think I'll probably be leaving Imodium on the shelf in that instance. Thank you so much for speaking with me.

A heath goanna

Goanna lizards could save Australian farms millions
Tom Jameson, University of Cambridge

Scientists at the University of Cambridge have found that giant lizards called heath goannas could save Australian sheep farmers a lot of money each year by keeping blowfly numbers down. The goannas act as natural clean-up crews by clearing maggot-ridden animal carcasses from the landscape. To explain more is Tom Jameson from the University of Cambridge’s Department of Zoology…

Tom - So rewilding projects are this form of landscape restoration where we're looking to reintroduce locally extinct species in order to restore the functions and services they provide to ecosystems. And what I've been really interested in studying is the role that reptiles might play in these sorts of projects, as they've been massively overlooked. So we wanted to study the role of reptiles when it comes to rewilding projects.

Chris - Which reptiles? I can imagine, given the geography you've referenced, South Australia, I can imagine what you're going to say, but what sort of reptiles specifically?

Tom - So I've been working on looking at monitor lizards as a bit of a case study for this project. So these are monitor lizards or goannas. This is the group that includes the Komodo dragon and its relatives. And they have a really high diversity in Australia of the 80 species worldwide. There's around 30 or so in Australia. And so we've really focused in to see how they could be managed and included in rewilding projects.

Chris - Some of them are really big. You say Komodo Dragons? Some of the ones I've come across in Australia are massive.

Tom - Absolutely. Yeah. So we've got species like the perentie that live right in the centre. And these are beautiful. They're the second largest lizard in the world after the Komodo dragon. They can get over two metres long. And I've been looking at another relative of the Komodo dragon, the heath goanna. So these are a lovely, very pretty species. They sort of range from a glossy black to an olive brown covered in these, these beautiful yellow spots and stripes. And they live down on the south coast and they grow to about 1.5 metres long.

Chris - Have you gone about it?

Tom - We worked down with the Marna Banggara project. So this is a Rewilding project down on the south coast of Australia, right in the centre of the south coast of Australia on a place called the Yorke Peninsula. This project aims to restore 170,000 hectares of landscape. So this is roughly the footprint of the size of London. So it's a really, really massive area. And from this area most of the native mammals have been lost. Most of the native species have been lost. So 90% of the native mammal fauna is gone from this huge region, mainly as a result of predation by invasive foxes and cats. And so the wider project, what they seek to do is to reintroduce these native species in order to try and restore that landscape. So the project was very focused on mammals and what we wanted to focus on was what the role of reptiles might be in this project, particularly these heath goanna, as I've mentioned, these 1.5 metre long lizards, how they might be able to contribute to restoring this landscape to these ecosystem services.

Chris - Do you mean as in, in terms of, as you restore the landscape, their numbers change and the landscape responds to their numbers changing, so it's like a domino effect. Is that what you mean by what they do? Or is it that they're already there and as the landscape rewilds, they make a contribution to that process or both?

Tom - A little bit of both. The idea is that what we want to study is if we're looking to boost their numbers, so by either reintroducing individuals to help grow the population or by doing specific conservation measures to help those populations grow the knock-on effects that they will then have as their populations grow by the different things they do in the landscape. And so in this case, we wanted to look at specifically how as those populations grow through conservation measures, how they're contributing to scavenging and what benefits that might have for the wider ecosystem

Chris - And what do they contribute?

Tom - So what we found is that they are really, really effective scavengers. They remove large amounts of carcasses from the landscape and that reduces a lot of the problematic things that might breed in these carcasses. So things like blow flies, animals that cause disease, we find the presence of these heath goannas removes this from the landscapes. They're providing a really, really important service.

Chris - And presumably, I mean, there’s enormous number of flies around us here, probably preying on us here in Grantchester. But presumably if you remove those flies, because one of the other big Australian industries is going to be things like sheep and cattle. Does that have a knock on benefit for those industries?

Tom - Absolutely. Yeah. So I mean, one of the reasons we were interested in looking at the effects that these heath goannas might have on blowfly populations is because in this wider landscape we're working in, there's a lot of sheep farms. And a big problem for these sheep farms is these blowflies. They cause a disease called fly strike, a really horrible disease. The blowflies will lay their eggs on the wool of sheep. Those eggs hatch into maggots and they borrow into the sheep's flesh, start to eat them alive. It's a very costly disease as well. This costs the Australian sheep farming industry $280 million a year. And so any role of a native species that might be to reduce these numbers of blowflies, reduce the incident incidences of this disease could have really positive effects, quite big financial effects. And so that's what we find, we find these goannas, they reduce the numbers of these blowflies and that potentially reduces incidences of this disease that might have some big positive effects for the agricultural industry too.

Solar flares on the sun's surface.

Can stars exist outside a galaxy?

Thanks to Matt Bothwell for the answer!

James - Galaxies are systems of stars, gas and dust orbiting around a centre of mass. In the case of large galaxies, like our own Milky Way, more than a hundred billion stars circle the supermassive black hole at its centre, but can stars exist outside of this orbit? Here's Matt Bothwell, public astronomer at the University of Cambridge.

Matt - This is a great question. The very short answer is yes. The interesting bit is how they get out there. All stars form inside galaxies. You need a dent cloud of molecular gas to form a star, and these dense clouds only exist inside galaxies. As a side note, when astronomers talk about a dense cloud of gas, this isn't what most people would think of as dense. A dense cloud of gas in space has far fewer atoms per cubic metre than the best vacuum on earth. So while stars always form inside galaxies, sometimes they are unlucky enough to be thrown out. Now, there's a concept in physics known as escape velocity. Basically the speed you need to travel in order to escape the gravitational pull of an object. Earth's escape velocity is around 40,000 kilometres per hour. So if you want to escape Earth's gravity, this is how fast you have to launch yourself. You need to go really, really fast to escape a galaxy. The Milky Way's gravitational pull is a lot bigger than Earth's, and so you need to travel at around 2 million kilometres per hour. We do, in fact, see rogue stars in intergalactic space, and so the big question is what could possibly fling them out at this absurd speed? We think there are two things that could do it. Firstly, when two galaxies collide, the gravitational forces of the collision could fling millions of stars out into intergalactic space. And secondly, super massive black holes can slingshot things at very ridiculous speeds and throw things out of a galaxy. In 2012, a team of astronomers noticed around 700 stars beyond the edge of the Milky Way, heading off into the intergalactic darkness. All of these stars showed signs of originating in the very heart of the Milky Way in the super massive black hole's back garden. In other words, before they were thrown out. It's not all doom and gloom though for these stars. Any planet orbiting one of these rogue stars ejected would have one of the most spectacular views in the universe standing on one of these planets, you'd be able to look up and see an entire galaxy covering the sky. I think that would be worth the journey.


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