Brian Cox The order of The Solar SySTem
All About Space speaks to the physicist about our unique place in the universe ahead of his new show The Planets and reveals what he believes will be the future in the colonisation of the Red Planet
It was back in 2010 when you released Wonders
of the Solar System. That was a landmark series.
What is new about The Planets? I think what's been remarkable over the last decade is the amount of detail that we’ve been able to put into the story of the Solar System, mainly proven by new missions. If you go back to 2009, when we were making Wonders of the Solar System, Cassini had only just arrived at Saturn.
Then this grand tack model, as it’s called, which seems fantastical and contrived, is only a recent development based both on observations from space probes and an increased sophistication in computer modelling of the Solar System. Thirdly, the increasing number of observations of other solar systems. It’s critically important for our understanding of the Solar System today that we’ve now seen well over 3,000 planets around distant stars, and what we’ve seen is that the geography and the layout of other solar systems are not like ours in general.
So it’s a combination of a lot of data from a lot of spacecraft. What’s quite exciting from a scientific perspective is that [NASA’s spacecraft] Juno, which is providing magnificent images – very strange images of Jupiter and its poles with its different colours and swirling clouds – that spacecraft has not really had an impact yet on our pitch of the development of Jupiter in the Solar System, as the data is just coming back.
The aim of that spacecraft is to really try and take a cross section through Jupiter so we can see what the planet is made up of. A 3D description of Jupiter straight through, which will allow us to understand more about how it formed. In a way it’s a much bolder series intellectually in that sense because things like the grand tack model have only been around for a couple of years, and it’s unusual to put those kinds of cutting-edge theories into landmark television. It tends to be much more conservative.
The difference is that there’s an underlying philosophy to the series – it’s why I like the Jupiter episode in particular for this reason – and the philosophy is that the Solar System is a system. I think that’s what is surprising and an important point, because it’s quite natural for us to focus our eyes on the Earth alone and think we’re isolated from the goings on in the rest of the universe. This is not the case. There are very practical reasons as to why we need to pay attention.
Was there anything you learned from filming
The Planets that you didn't know before?
Absolutely! So the grand tack model that I just spoke about is one of them. In the context of those models, we see that the evolution of the
Solar System is extremely complicated. That’s the first thing. Secondly, when we were dealing with the planet Mercury – and it comes partly from these computer models again – the idea that Mercury almost certainly formed much further away from the Sun. This is a very new idea. It’s based on a spacecraft that went there and observed the chemical composition of the surface and returned these tremendous surprises, particularly about elements called sulphurous and phosphorus
“It’s quite natural for us to focus our eyes on the Earth alone and think we’re isolated from the rest of the universe”
“There will be Martians if we’re to have a future. At some point we will be the Martians. That's clear to me”
on the surface, which were not present close to the Sun when the planets were forming. They only existed in large quantities further out in the Solar System.
Observations like that, when you begin to piece them together with the modelling, tell you that our Solar System is significantly more dynamic in terms of the geometry of the Solar System today – it was not the same geometry when it began.
I think we tend to think of our Solar System as a fossilised remnant of the initial dust cloud that collapsed. So the initial structure around the Sun 4.6 billion years ago or so is echoed in the distribution of planets today around the Sun. What we’ve learnt recently, and what was surprising to me, is that it is not the case. The Solar System was very dynamic and planets were moving around all over the place in the early years.
Do you think there’s a greater threat to Earth from humans, with climate change, or outside of Earth, for example an asteroid collision?
Ultimately, we feel small when we watch films about the Solar System and beyond. I think there’s a sense in which we feel detached from nature, and that would be a mistake. Science is an attempt to understand nature, of which we’re a part, and that’s vital for our survival. So you mentioned one, which is the legitimate question we could ask: how do planetary atmospheres evolve? What we’ve found is that planetary atmospheres are rather fragile things in a sense, and they can evolve in response to quite small changes. We’ve seen that not only by measuring the Earth’s atmosphere, and modelling it, but also trying to model Venus’ atmosphere, in particular where we also deploy our climate models, and also Mars’ atmosphere and how it lost its atmosphere, which is also a target for our climate models. Investigating the Solar System allows us to test our understanding of the Earth; that’s the point, because we have different laboratories. So that’s number one.
But number two, as you say, the threat of an asteroid strike, for example, is very real. It does happen. Carl Sagan – this is one of my favourite quotes… I always quote it – he said: “If the dinosaurs had a space programme, they’d still be around.”
But he was making a serious point that we do live in a challenging environment, and the more we understand about it, and the more we develop our technologies, it may allow us to mitigate some of these threats. This makes it more likely we are able to survive. So I think that’s also important. That’s not science fiction, it’s a real issue.
What gaps do you think there are in our knowledge of the Solar System and where would you like to see visited next by human space probes?
The next big mission from NASA is the Europa Clipper. It’s a Jupiter orbiter, but it’s focused on
[its moon] Europa. I think the big questions now are astrobiology, which we deal with in a couple of the other programmes in the series with the question: is there life, particularly on Mars and on some of the icy moons? That’s what the Europa Clipper mission is designed to answer, and it's also designed to scope out landing sites on Europa and try and understand whether it may be possible to get something into the ocean below the icy surface.
I expect after the Europa Clipper, the next one after that would probably be a Titan mission.
Titan is a planetary-sized moon with a very thick atmosphere. It has a liquid-water ocean below the surface, a long way down, and it has the most complex organic chemistry of another body other than the Earth in the Solar System. There is a plan to put what is essentially, a helicopter onto Titan in the form of a drone. That’s great because the gravity of Titan is a ninth of Earth’s gravity and the atmosphere is denser than Earth’s, so you can fly anything around it.
I think astrobiology is going to be the focus of the next two big NASA missions. Beyond that we’d like to see orbiters around Neptune. There’s a lot of pressure to put an orbiter around Neptune, but it’s very, very difficult to do.
What are the ethical considerations in colonising Mars, a feat that Elon Musk hopes to accomplish?
It’s a superb question. In a sense, if there’s no life on Mars then I don’t think the ethical consideration arises. But if there are microbes, and we think about this very carefully in terms of the places we land on Mars and the way we treat the spacecraft out there, we do not want to contaminate it with Earth microbes.
There’s a scientific reason for that, which is that if there is life there, we’d like to see if there was a second genesis, or whether there was a single genesis on Earth or Mars, because we know organic material can be transferred between planets. So it ruins the science.
In terms of ethics, we can go into quite a deep, philosophical area I think. It’s how important microbes are. Now, they’re important scientifically, of course, but the ‘Muskian view’ – which is actually what’s called the ‘O’Neillian view, going all the way back to a famous author called [Gerard] O’Neill who wrote a great book called The High Frontier – the idea is that intelligent civilisations are extremely rare and valuable and cannot survive for very long on a single planet. So there’s that philosophical trend which has been there since the 1950s, I think, or even before. It’s the idea that we as a species need to see ourselves as a space-faring species that is part of the Solar System that has access to resources beyond the Earth.
I think we have to be very careful from a scientific perspective about damaging potential ecosystems on Mars. We are already extremely careful; it’s called ‘planetary protection’ and we take it very seriously. But, at the same time, I don’t think that can stop us from going to Mars. It is actually the only place we can go beyond
Earth in any plausible scenario.
I say in the Mars episode, I actually make this case, I say that there may not have been Martians and we need to find out, but there will be Martians if we’re to have a future. At some point we will be the Martians. That’s clear to me, because we can’t stay here forever. The point is that O’Neill and a man called Robert Zubrin, who Musk is very heavily influenced on, all make this point that the great challenge on Earth at the moment is to manage an expanding population. To manage a civilisation that requires new frontiers, both intellectually and physically, and is confined to a very small planet with a lot of pressure on the resources that are here. The Solar System contains essentially infinite resources – it's effectively unlimited.
What are your thoughts on exoplanet research and what it can tell us about the past and future of the Solar System?
The great shock when we looked at other solar systems was that they were not arranged like ours. When I was at university, you tended to build theories that said the rocky planets form close to the Sun and the big gas giants form further out, and we had loads of plausible theories why that would be the case until we looked and saw that it was not the case in most other solar systems. And that’s why I think one of the driving factors behind rather convoluted models, like the grand tack model, is because then you start to say, “If it’s not obvious that the rocky planets form close to the star and the gas giants further out, why is our
Solar System the way that it is?” And that’s driven a lot of the modelling. So yes, it has had a profound effect.
Do you think it’s a miracle that our planet exists?
The more we learn, the more remarkable it seems. You can be misled with that line of argument because there are a lot of things that have to happen to get the specifics, and you can go right back to little collisions with grains of dust in the formation of the Solar System, or actually, even the laws of nature themselves. We don’t even know where the laws of nature came from.
So, in a way, it’s empty of information to say we are lucky to be here. Even with each individual, think about the likelihood of you personally being here, what with your parents and grandparents. It’s almost a miracle that each one of us exists as an individual. But what you do learn is that if you are just asking the generic questions about planets that could have an ecosystem that supports evolution by natural selection for billions of years, then you do find something valuable: the story of the Solar System. You look at it and think, “Well, actually, there are a lot of things that had to happen to keep this planet stable.”