Life possible on Pluto – NASA's mission head
More than five years ago, humanity managed to glimpse into the farthest corner of our solar system, Pluto and the Kuiper Belt. We asked Dr. Alan Stern, planetary scientist, astronaut and head of NASA's Pluto mission what wonderful discoveries still lie ahead of us.
Sophie Shevardnadze: Dr. Alan Stern, planetary scientist, astronaut, head of NASA's Pluto mission. Great to have you with us today, Alan.
Alan Stern: Thanks. It's just great to be here.
SS: So you've been the principal investigator of NASA's mission to Pluto and the most widespread conception of Pluto, in the eyes of the public, is the ball of ice floating out there in the dark. So can you call it a scientific wonderland? What makes it so special?
AS: Well, it really is a scientific wonderland. And we have a pretty good idea of that from studies from the Earth, but what New Horizons, the NASA mission that explored Pluto for the first time in 2015 discovered was far beyond our expectations. Pluto, which is a planet with five moons, an atmosphere, highly active geology, and evidence for a liquid water ocean in its interior that could even be a host for biology is just far beyond our wildest imaginations. And I think you add all that up, it easily qualifies as a scientific wonderland.
SS: If I were to set my foot on Pluto, what would I see there?
AS: Well, it depends on where you go because just like the Earth, Pluto is a very diverse planet, with mountain ranges and canyons and glaciers, and other kinds of geology. So depending upon where you go, you would see different terrains. But one thing that you would see everywhere is something that New Horizons discovered, which is that the atmosphere which is blue in color and would look like a faint version of our sky, actually has dozens of haze layers stacked up all the way to orbital altitudes. And that's something unlike anything we had seen anywhere else in the solar system.
SS: New Horizons flyby mission has discovered water ice on Pluto and its moon Charon. Can this point out at the possibility of some sort of some form of life in this icy corner of our solar system?
AS: Well, the water is an important ingredient for all biology on the surface of the Earth. But, you know, the ice on Pluto, water ice and the other ices on Pluto are extremely cold temperatures because Pluto is 30 times farther away from the sun. So the sunlight is about 1000 times weaker, and the temperature is almost absolute zero. So the biologists will tell you that they don't know how to make biology that can operate at those temperatures. But as I was saying a moment ago, deep inside Pluto's interior beneath the crust, as the temperatures get warmer and warmer, as you go down towards greater and greater depths that water ice liquefies and becomes room temperature or at least liquid water, and its global ocean in there. It's a shell, if you will, all around the planet, from what we can tell, beneath the crust of liquid water. And that got our attention from an astrobiological standpoint. Then later, one of the scientists on our team Dr. Dale Cruikshank discovered through compositional spectroscopy, basically chemical fingerprinting done by New Horizons, that there are places on the surface of Pluto, where the water appears to have erupted and flooded out onto the surface. And interestingly, that water is laced with organic compounds. So the story gets more interesting for sure.
SS: Do recent discoveries on Pluto actually give us any hint on how life started here on Earth?
AS: They don't, but it could be that with future missions back to Pluto, that with an orbiter, and then landers, even someday submersibles that could go into an ocean, we could learn about the origin of biology or where biology was stopped for some reason on Pluto, that would illuminate our understanding of how these processes took place long ago on our own planet.
SS: So you and your colleagues called Pluto a ‘forensic clue’ of how our solar system is formed. If you could sum it up for our viewers who aren't like necessarily astronauts or into astrophysics, what exactly does it tell us?
AS: Well, Pluto and the Kuiper Belt, which it orbits in, is kind of the solar system’s “deep freeze.” But by dint of the fact that it's so far away, that temperatures are so low, out there, far from the Sun, the chemical properties and physical properties of these bodies are very well preserved. And that's what makes it so fascinating. It's kind of analogous to an archaeological dig into the history of our solar system. And this is why our National Academy of Sciences here in the United States plays such a high priority on going out to the Kuiper Belt and making this first exploration that our team on New Horizons did.
SS: So is a flyby the only realistic way to explore Pluto nowadays? Will it ever be possible to send, I don't know, a rover, or let's dream wild, a manned mission?
AS: Sure. There are many ways to explore Pluto and a flyby is just the first baby step. Here in the United States in the last year, NASA has funded studies of how to conduct the next step, which will be a Pluto orbiter, which would stay in the system rather than just fly by it and bring much more sophisticated package of instruments to study Pluto and its satellites. And one of the jobs of that orbiter would be to scout for landing sites for future robotic landers or rovers as you're talking about. That's within our technological grasp. Now, sending people all the way out there is not yet something that we can confidently do. You know, it's a big step just to send people to Mars, probably in the 2030s. This is a 100 times farther than Mars is on average. And the technical challenges are great. It took New Horizons almost 10 years and it was the fastest spacecraft ever launched – 10 years to travel out there. If we send people, and we would have to develop a much faster propulsion system, or it would be a 20-year journey just to go out and back. And I'm not sure we get a lot of volunteers for that.
SS: Yeah, I'm not sure either. So Pluto, correct me if I'm wrong, is part of a Kuiper Belt, which is a circle of objects hugging the outer solar system. How many planets or planet-like objects like Pluto could be there inside the Kuiper Belt?
AS: Yeah, the Kuiper Belt, which was named for a Dutch-American astronomer, his name was Kuiper, in the mid-20th century, who postulated it would exist, was discovered in the 1990s. And Pluto turns out to be the brightest but also the largest object in the Kuiper Belt. Our current estimates from studies over the last 25 years tell that the Kuiper Belt has billions of comets in it, objects just a few kilometres across, and it has about a dozen small planets, of which Pluto is the largest. And then there are some intermediate-sized objects that are in between little rocky asteroidal comet-like bodies and full-fledged planets.
SS: So, how important can the study of Kuiper Belt be to our understanding of solar system? I mean, what kind of groundbreaking surprises can the Belt hold for us?
AS: Yes, great questions. In fact, the Kuiper Belt has already revolutionised our knowledge of our solar system. Just studying, as we were saying, ‘forensic clues’ about the distribution of objects there and their properties, we have learned, for example, that when the solar system was first formed, that the giant planets, Jupiter, Saturn, Uranus, and Neptune, underwent changes in their orbit that pushed Uranus and Neptune outward by about a billion miles, about 1.6 billion kilometres, which may have even ejected another giant planet that once orbited with the four that we have now. That's a pretty important discovery even in itself. But then the Kuiper Belt just taught us that dwarf planets, even though they're small, and Pluto's only about roughly the diameter of the continental United States, that those small planets can be as active and as geologically complex as bigger planets like Mars and the Earth, which really almost no one expected. And yet, that's what Pluto is. And then, after we flew by Pluto, New Horizons went on another 1.5 billion kilometres over three years to study a small Kuiper Belt object, one of those building blocks that made planets like Pluto. It's called Arrokoth and from it we learned how these building blocks are formed, something that was never known before, only debated.
SS: New Horizons has the velocity to leave the solar system and go into interstellar space like Voyager. Will it just fly off into space at some point? Or will it stay around the current position until it runs out of juice?
AS: Well, New Horizons is travelling at a speed of about 500 million kilometres per year upward on this escape trajectory from the solar system that you just mentioned. And we can't stop it. We don't want to stop it, but it's coasting and leaving the solar system just like the Voyagers. So every year, it travels farther and farther and farther. Eventually, it'll run out of power, and we won't be able to communicate with it and collect any more data from it. But that's probably almost 20 years away.
SS: So let me ask you this for it. For all these years of astronomical observations, we've only known nine planets in our solar system, to be there for sure. And you're saying that there are hundreds more planets to be potentially found. But you achieve that basically just by changing the definition of what a planet is, right? So it really just becomes semantics, doesn't it?
AS: Actually, I think it's very important science now because science is a reductionist activity where we try to look at a lot of data and then boil down to patterns. And one of the things that that we were limited by till the 1990s was that our telescopes weren't powerful enough to see far out into the solar system. So Pluto looked like kind of a misfit or an odd ball, a small planet, all by itself out there beyond the giant planets. But since the 90s, we've been discovering more and more small planets like this. And the reason we call them ‘planets’ is because they share all of the key properties that worlds like the Earth and Mars and other planets have. They don't look like asteroids, they don't look like comets, they don't look like meteors – they look like planets, with, as I said, mountain ranges, and atmospheres and systems of moons, and active geology, and so forth. And so that's why planetary scientists call them ‘planets’ because they fit well in that category in terms of their characteristics. It's really not semantics. It's about enlarging our view through collecting new data and accepting the fact that the world has changed a little bit, they're just more planets than we thought there were. Something very analogous took place more than 100 years ago, when it was discovered that the number of stars was not the few thousand stars that your eye can see but countless numbers of stars that make up our galaxy and all the galaxies beyond. And this is a similar step for planetary science and a very important one. I think we finally understand that the most populous class of planets in our solar system turns out to be the small ones like Pluto.
SS: But Pluto and Neptune were discovered on paper first using mathematics, and only later were confirmed as existing by astronomers. Do we need the same to happen to establish the existence of many Pluto-like objects in the Kuiper Belt, or will a mission like New Horizons suffice?
AS: Well, we don't search for new bodies, new objects in the Kuiper Belt. It's better done from the Earth with much bigger telescopes. And it's on those ground-based telescopes that we've spotted these other planets out there with names like Haumea, Makemake, Eris, Ixion, Triton and so forth, so these are not theoretical worlds. These are worlds that we photograph and study with ground-based telescopes all around the world.
SS: So private spaceflight is becoming very popular. In 2022, NASA is sending you abroad of Virgin Galactic to run experiments. SpaceX Crew Dragon has this year carried NASA's astronauts to ISS, there's also Jeff Bezos’ Blue Origin. Is it a good thing that space missions are becoming and being outsourced to private companies?
AS: Well, I think so. Because the national space agencies, like the Russian Space Agency, and NASA here in the United States, JAXA in Japan, etc. and even the European Space Agency can only do so many things with the budgets that they have. And just like at sea, there are many commercial activities and in the air there are many commercial activities, many more than just what the government agencies do, the explosion of applications of commercial space, and not just space tourism and space research, but also expanded communications, expanded Earth monitoring, reusable rockets and lower launch costs, are all the result of this commercial innovation. And it's really, in my view, the way that we begin the journey to the ‘Star Trek’ era in the 23rd century.
SS: I wonder, is this what space exploration could be like in the future? What I mean is like government space agencies sort of laying down the theory and private companies putting the theory to practice, or at least bringing scientists into space to do it?
AS: I think very much so. And, you know, there's an analogy in my country that the first explorations as the United States started to expand across the continent to the West were government funded explorers like Lewis and Clark. And then the military came to make forts to protect the settlers who then followed in much larger numbers, and then the industrialists came with the railroads, and the mills and the mines and so forth. And I think we'll see a similar development in commercial space as humans proliferate into a real spacefaring species with industry in Earth orbit, and then on the moon, and then on to the planets when we become a multi-planet species.
SS: Surely, these days, data could be collected just by robots, it's safer, possibly cheaper. Why is it always better to send humans into space to conduct experiments? And is it really? I don't know.
AS: Well, it's a good question. Humans have many uses besides just doing research. Many uses in space, besides doing research. But just speaking as a researcher, the experiment that I'm doing on Virgin Galactic in 2022, is very likely to cost about a third what it would have cost if we tried to automate it. So by putting a person in the experiment to conduct it, we make it much simpler, much faster to carry out and much more reliable. And as a demonstration of that, you know, if you think automation is so great, why isn’t every university laboratory automated? Why isn't every research ship the robot ship? Why isn't every geological expedition done by robots? It's because in all those other fields they know that having the scientists there is simpler, more reliable and less expensive than automation. Now, in spaceflight, we can join the club with all the other sciences where our researchers actually go to space and do the research and improve on it over what robots can do in many cases.
SS: You know, is cooperation like this going to be like the actual bread and butter of commercial spacecraft? I mean, perhaps tourism was what Virgin has in mind, but realistically, isn't the price tag going to be too much for space tourism to be viable business anytime soon?
AS: You know, it's very expensive for an individual. If you want to buy a ticket to the International Space Station flying Soyuz, I believe it's about 70 million US dollars. If you want to fly in a Virgin Galactic, it's much less expensive to go suborbital, but it's still hundreds of thousands of dollars, and that's too expensive for most people. But it's the beginning. In the 1920s, a century ago, air travel was extremely expensive and only a few people could afford to do it. But by scaling, and getting economies to scale, the prices were able to drop to where all of us can afford to travel in the air when we have a need to, and I think the same will happen in space as well. But we're in the very early days of that. I expect the prices will come down across the 20s, 30s, 40s to much lower numbers than we're seeing now.
SS: A mission to Mars, let's talk about it, which is right now pretty much discussed by flamboyant billionaires on Earth, could end up costing billions of dollars. A mission like New Horizons is cheaper in comparison, several hundred million. But do you think private initiative in space could result in sponsoring a probe mission, like, for instance, sending an orbiter to Pluto or another probe to Saturn etc.? Or will commercial space exploration revolve around, you know, headline-making, like ‘send a man to Mars’, sensational ideas only?
AS: It’s a great question. We know that in Earth orbit private companies are sending robotic missions in very large numbers to do space science and to study the Earth. And we already have companies in the United States, in Europe, and in China for that matter, that are already beginning to offer services to fly experiments to Venus and Mars and to the asteroids. And I think this is just the leading edge of what will become an increasingly commercial venture alongside of the space and science agencies like RSA and NASA and ESA.
SS: I read that the costs of flagship missions like going to Mars are actually so high, they might end up underfunding other NASA projects, like facilitating one breakthrough perhaps but slowing down others. Is the pace of discovery in NASA only basically decided by budget? I mean, do you see a scenario where a private space enterprise steps in to help with that somehow? Or is it too big of a pride blow to an independent agency like NASA?
AS: No, not at all. We're not limited just by budget, because through innovation, we can learn to do more with the budgets that we have. And a good example is NASA's now using SpaceX rockets that are much lower-priced for many of their launches. And as a result, every dollar it saved and it's actually tens or hundreds of millions of dollars per mission it saved can go into making more missions. And then in addition, we have the leverage that private companies will be doing the exploration as well. So we'll get more done than we used to be able to, because we've innovated into a better future. And it's very reminiscent of the computer revolution. When computers were enormous machines that filled rooms and they were very rare, and they were very expensive, and not very powerful certainly, by today's standards, and now a generation later, computers are not rare but routine, their prices have dropped dramatically and yet they're more powerful. And we're seeing the same revolution in spaceflight. And I think that by the 2050s we’ll be living in a completely different world in terms of spaceflight because of these innovations.
SS: Well, me and you are still going be around to see that thank God, hopefully. Alan, it's been great talking to you. Thank you very much for this wonderful insight. And all the best of luck to you.
AS: Thank you.
SS: All right. Bye. Take care.