And now we reach the third part of our trilogy on the human exploration and colonization of Mars. Humans will inevitably tire of living underground, and will want to stretch their legs, and fill their lungs with fresh air. One day, we’ll contemplate the possibility of reshaping Mars to suit human life. Is it even possible? What technologies would be used, and what’s the best we can hope for?
All About Mars:
Back to Mars:
Terraforming Other Places in the Solar System:
Pamela, we talked about last week about how Mars is very hostile to life. The temperatures can be 150 degrees below zero at the poles. Even on your best hottest summer day you’re not going to get but a few degrees above freezing. The pressure is one percent of what we experience here on Earth. There’s radiation, essentially a long-term lethal dose of radiation. It’s cancer for everyone living out on the surface of Mars.
So, we’ve talked about people living underground in essentially pressurized space suits or in pressurized chambers where you can keep the pressure, the temperature, and protect them from radiation. That’s a really hard way to live. So inevitably the question is: Could we change Mars? How possible is it with the laws of physics to change Mars?
Dr. Pamela Gay: Well with the laws of physics, you can do it. The question is can you afford to and if you can’t afford to, should you? There are a lot of ethical questions to consider when you start thinking about completely changing the nature of another planet that just might harbor fossil life or actual life somewhere within its soils.
Fraser: Why don’t we deal with the ethical issues later? Imagine that you were some superpower human being and some advanced civilization with tremendous access to power and all of that and you want to sorta quickly modify Mars to make it more appropriate for human life. What are the things that you could do with a snap of your finger?
Pamela: [Laughter] If you want to do it quicklyâ€¦..
Fraser: No, I don’t want to say do it quickly, but the point is if we could change Mars to be more appropriate for human life, what are the things that need to change on the planet?
Pamela: Well, there are basically three issues. First of all you have to give it a thicker atmosphere. Then you have to give it warmer temperatures. These two are actually coupled to one another. Third, you need to find a way to deal with the whole lack of a magnetic field and that one gets much trickier to deal with. Dealing with the first two, the low temperatures and the very thin atmosphere, can be dealt with by first releasing a lot of greenhouse gases into the atmosphere of Mars. Either by perhaps crash-landing rockets filled with chloro-flora carbons onto the surface of Mars or use some other mechanism that some chemical engineer still needs to imagine.
By releasing all of these greenhouse gases onto the planet you can systematically increase the planet’s ability to retain its heat. Right now, sunlight hits Mars, it reflects off and a lot of this heat is lost back into Space as infra-red light.
You can imagine being able to essentially wrap an atmospheric blanket around Mars such that sunlight hits the planet, starts to reflect off the soil, hits the atmosphere and then reflects back down. This heat stays with Mars and continues to build up and warm the planet over time. Sorta like heat that’s released by the coils in your oven is kept in by the walls of your oven allowing the temperature in your oven to continually increase.
Fraser: You could really see that when on your car. When you keep the windows up, even on a not very hot day, it’s amazing how hot the car will get inside. If you even crack the window just a little bit to let that heat escape, then the car will cool down quite a bit.
Pamela: And right now Mars’ atmosphere is so thin that it is essentially a convertible with the top completely removed. By simply dumping a bunch of chloroflorocarbons on to the planet, we can raise the roof of that convertible. That small change will allow more of the water ice on Mars to melt and add water vapor to the atmosphere of Mars. Water vapor itself is a greenhouse gas so here we’re starting to roll up the windows of our convertible.
Over time as you build up more and more gases that have been previously trapped as various ices within the soils and at the north and south poles of Mars, you can convert these ices into atmospheric gases which will continue to heat the planet. Pretty soon we might be able to get something that at least in terms of temperature is suitable for human life.
Fraser: Right, so you would be able to put on a jacket, head outside, and the temperature wouldn’t be really awful. But, you’ve still got the atmospheric pressure so you’re saying that you really can’t thicken the atmosphere really too much?
Pamela: Well, you can thicken it but getting it thick enough that it is comfortable for a human being used to living at ground level here on the planet Earth is unclear. We don’t know if there are enough gases trapped within ices on Mars that you can, using just what is there, get that thick of an atmosphere on a useful time scale. The problem is these gases are continually escaping from Mars.
It is a little planet with very little gravity, light elements that are released into the atmosphere just through normal particle to particle collisions they are accelerated to escape velocities. Then you have the Sun blasting the atmosphere of the planet and in turn blasting away bits and pieces of the atmosphere. So, you have to be able to release these gases quickly. Even then, they might only hang around for a thousand to a few thousand years without being restocked. You have to start asking where do you restock the gases from?
You start considering ways to capture comets and otherwise bring oxygen, carbon dioxide, and nitrogen all to the atmosphere. There is also no natural buffer gas. Here on Earth we have an atmosphere rich in nitrogen that doesn’t totally get involved in building molecules on a regular basis.
The types of gases that the Martian atmosphere would be rich in are things that like to form molecules. Thus, you need this buffer gas as well to make a nice happy atmosphere.
Fraser: So, the problem you’re getting here is that Mars has no magnetic field, right? The Earth’s magnetic field forms a protective bubble that buffets away the Solar Wind and keeps it from really interacting with our atmosphere. If we didn’t have our magnetic field, the Solar Wind would be blasting away our atmosphere just like it did to Mars.
You would need some way to constantly replenish the atmosphere on Mars or you might have it incredibly thick in the beginning and then over time it would just be eroded again. You would no longer have reserves on the planet you could be using to rebuild it. Without that magnetic field it’s a lost cause. And also with a lower gravity, that sounds like a pretty big problem.
Pamela: Yeah. But it’s not something that if you throw enough energy at the problem isn’t unsolvable. As I said, you could conceivably go out and start capturing comets. Comets are rich in things like water that you can tear apart and turn into atmospheres.
It’s not exactly a trivial problem to go out to the Quaker belt and capture yourself a whole bunch of large icy objects and tote them back to Mars. While we’re wandering out in the dreamland of terraforming, it’s possible to conceive that on the thousand year time scales things like this might be possible.
Fraser: But it almost sounds like with that problem and the lack of a magnetic field is going to come back to haunt us for another part as well. It might make sense to just get more mass on the planet, right? [Laughter] Smash Mars and you know all the Asteroid Belts gather. Crash that intoâ€¦.you know? [Laughter]
Pamela: There is actually an even more interesting solution that I read about. There weren’t any real descriptions of how you do this but one of the ideas I saw kicking around on the internet was you find a way to build a giant magnifying lens. The biggest magnifying lens ever and place it in an orbit such that it focuses the light of the Sun on Mars and melts Mars until it has a liquid core again. You wait for the planet to cool off enough that you can stand on the surface again.
Now that you have a new version of the planet Mars with a new liquid core having destroyed everything else and probably lost all the atmospheric particles in the process of vaporizing the planet, you at least have magnetic fields now. It was a suggestion that needs to be thought out a bit better but it did amuse me.
Fraser: Right â€“ it almost sounds like domes are your way to go, right?
Fraser: You build a dome and then boom. You’ve got protection from the radiation; you have the temperature and pressure. You’ve got everything you need. Okay, so we’ve talked about the temperature and the pressure like rise in lock step. You give the impression that there is a limit to the pressure, right?
Pamela: There’s a limit to the pressure until you start bringing in things from other places. As you heat the planet up, you’re going to be melting ices and the gas from these ices slowly pop up the atmosphere. They add pressure to it by adding additional molecules.
This is similar to taking a balloon and dropping in a piece of dry ice and tying a knot. As that dry ice changes from ice to gas the balloon will blow up. With Mars, gravity acts as the walls of the balloon helping hold that gas to the surface of Mars. As you melt the ice the atmosphere gets thicker and thicker.
But, the thickness of the atmosphere is limited by how much material there is to melt. We’re still not fully sure of just what reserves there are within the soils that we can release. There is a limit â€“ a limit defined by what ice is trapped within the soil on Mars and at this point in the studies I’ve found, it looks like you’re going to get maybe a tenth of the atmosphere of Earth tops.
And that is standing at the bottom of the deepest chasms of Vales Marineris which I’m sure I’ve mispronounced thirty times in this series, standing down in the base of that chasm you might be able to start to get something that will at least allow you to stand outside and not have your skin bruised to badly as it is subjected to too low of a pressure.
Fraser: Right. Let’s talk about the third problem then, which is the lack of a magnetic field and the radiation that’s coming.
Pamela: Here is where we’re not sure how huge of a problem it is. We know that the radiation is such that you’re going to just blow right past the United States’ recommendations on radiation levels in the workplace. In a matter of days you will get the recommended level for a year. That’s bad.
At what point it becomes cancer causing, we don’t know. That’s an experiment that we haven’t done and can’t do because it is slightly immoral you might say. There’s a radiation problem. You can probably walk around on the surface a few hours at a time in a space suit without worrying for your life, but you do need a way to protect yourself during your day-to-day activities.
Burying yourself underground is sufficient. Air actually helps deter radiation but you’re starting to need a hundred meters or more of the atmosphere to get out (and that’s sea level what we have down here on earth atmospheric pressures) to start getting the radiation down to acceptable levels.
Fraser: Right, that’s what I was going to mention is that the atmosphere itself does help protect against the radiation. So that thickening of the atmosphere will really serve triple duty.
Pamela: If we can come up with a way to do what’s called either para terraforming or creating a world house, a giant greenhouse that combines a thick (defined as like a hundred meters) atmosphere beneath a lead-lined glass or leaded glass canopy that itself is fairly thick to help deter from radiation.
There are different types of high-energy particles that can’t penetrate through glass. Through this sort of combined construction that allows sunlight through that stops things like alpha particles from coming through, beta particles from coming through, it may be possible to lower the risks to the point that they’re acceptable.
Fraser: What about plants? Would you be able to grow plants on the surface of Mars?
Pamela: This is one of the cool ideas. I highly recommend anyone who is interested in terraforming go read the excellent book â€œRed Marsâ€ by Kim Stanley Robinson. There are different people who have hypothesized ways to basically take algaes that are perfectly happy to live on Mars today, release them and then slowly genetically engineer high altitude grasses, arctic grasses to get something that is both happy in the extremely frigid temperatures and in the extremely low pressures.
You also start finding ways to suppress the different plants’ chemical responses to trauma, putting the plants essentially on â€œhappy pillsâ€.
Fraser: Like giving them some Prozac.
Pamela: Through a combination of â€œbetter living through chemistry and genetic engineeringâ€ it may be possible to create agricultural products that will live beyond domed protection on Mars.
Fraser: And that could start fairly soon, right? As you said, there are algaes here on Earth that are almost able to live in the Martian environment.
Pamela: And there are those who think that actually we probably could just dump some of the algaes found on Earth on Mars and they would happily go off and do its little algae thing.
It’s somewhat frightening to imagine that just a cavalier accidental transportation of green slime from Earth to Mars could create new forms of life living on another planet. This is where the ethical considerations start to come in.
It’s not impossible to imagine piggybacking life here to there and if it hasn’t already happened via rocks which is probably possible. We certainly send enough metal debris over to Mars with our own contaminations on it. We might have already started the terraforming process without realizing it.
Fraser: Sure, there’s no doubt that we have sent bacteria to Mars from Earth on the Rovers, on things that have crashed on the planet. I know that for example when bacteria were on one of the Lunar missions, the Surveyor mission was sitting on the surface of the moon. When the astronauts landed near it, they pulled off its camera and brought it back to Earth and scientists were able to find bacteria that had made the journey, sat perfectly dormant on the surface of the Moon for five years or more and then they brought it back to Earth and were able to get it going again. It survived no problem.
So, who knows I guess if the kinds of bacteria that we have shipped off to Mars are the kind that can survive and even thrive in that kind of environment. So, I think you’re right we may have already begun that process.
It is an interesting ethical debate. I think it’s not one that we have much of a conversation about on Earth. We do it and that’s that. Humans have modified the environment of Earth to suit our needs and I a lot of people are concerned about what impact we’re having on the environment with the species lost, temperature changes through global warming and all those kinds of things. At the end of the day, it’s not should we not at all build houses or cut down forests or that kind of thing but rather to what extent.
It’s interesting to me to hear people say we shouldn’t modify Mars at all because we’re going to. It’s just inevitable. We will get to a point where Earth is full and colonists are living on Mars and they’re going to want to go and plant a plant outside. It’s just going to happen. [Laughter] I see it more.
It’s like we have a whole Solar System here that we have existed and it is just inevitable to the point that we are going to reshape the Solar System to match human needs. So, on the one hand I think it’s an interesting ethical debate, but for me it feels inevitable that we will reshape the whole Solar System to meet human needs.
There will come a day when we will control all of the energy output of the Sun. We will reshape the planets to provide as much habitable living space as possible. Ideally, we’ll keep some amount of green space and natural environments as we can but we will have torn apart the entire planet Earth, turned it into a ring or a sphere or who knows what it would be to collect every piece of sunlight from the Sun.
It’s a matter of when, when along that time-line do we want to reshape and destroy every environment in the Solar System. [Laughter]
Pamela: I think that this falls into the same category of keeping an archaeologist on hand when you’re digging around, building a new building. It’s worthwhile as we look to take over new environmental niches within the Solar System to have the biologists on hand to go in first to dig through first to figure out what is it we’re about to destroy and let’s scrape some up and stick it in a bottle and try to understand what it is within the environments that was there originally.
Let’s document the history of our Solar System before we remove the evidence for future generations. It’s a chance to be able to look back and see there used to be a dead Dodo bird on the planet Earth. We know there is nothing as exciting as the Dodo bird on the planet Mars unless it lives deep underground where the Rovers would fail to find it. Really I don’t think there is anything as exciting as the Dodo bird on Mars but I’ll always leave room for the amazing.
As we go and explore Mars it would be good for us to keep track of the microbes before and the potential algaes and lichens. I don’t think we’re going to find anything that complex either. But if we do, it needs to go somewhere like one of these preserve all the DNA we can crypts that exist here on Earth already.
Fraser: I think the other possibility is that as our technology improves and changes we’re going to have more and more robotic, artificial life happening in the Solar System. It’s very possible that on the time scales, we’re looking at hundreds and hundreds and maybe thousands of years to terraform Mars.
I would be very surprised if human beings were still the same hundreds of years from now that we really need to change Mars to suit our current form and that we may very well have a future form that is more integrated with technology and doesn’t need the planet to be changed so much. Our technology, the Mars Rovers are suited to live on Mars today. That might be what the future of life is going to look like so we have the old fleshy humans living here on Earth [Laughter] and the new robo-humans living on Mars and maybe the needs for terraforming aren’t so great.
I think a lot of this stuff is very interesting. As the technology improves, as our science improves, it completely changes our understanding of what’s involved and what the ethical issues are. I’m looking forward to see how these debates go in the future butâ€¦.
Pamela: Yeah, and you have a very creepy future living in your head with robo-humans living [Laughter] living on Mars.
Fraser: I know, just passing time until that last plucky black hole gives away to the future. [Laughter] Anyway, Mars is the most natural target that we would want to consider to terraform. But that’s not the only place in the Solar System we could have a go at. Venus strikes me as much closer. It has the mass, a thick atmosphere, what could we do to change Venus?
Pamela: The problem with Venus is it had a runaway greenhouse event at some point in its past where the atmosphere didn’t just trap some sunlight, it trapped all of it. In the process it boiled off any water that was in the soil to the point that plate techtonics can’t even exist anymore.
The soil has been completely desiccated of moisture and all that moisture went into continuing a run away greenhouse effect and now we have a planet with a temperature on the order of 500 degrees Celsius and that’s just not a way for any planet to be.
To fix that particular planet we need to strip the greenhouse gases out of its atmosphere finding some way to sequester all of the carbon-based molecules, the carbon monoxide, and carbon dioxide. Certainly we want to get that sulphuric acid out of the atmosphere as well while we’re at it.
Exactly how to do all of this is something that is not a well-defined pathway. It is not as if we can plant redwoods on the surface of Venus that will happily absorb all of these toxins. The planet is 500 degrees.
Fraser: Yeah, we drop spacecraft made of metal onto it and it barely survives more than a couple hours before they die.
Pamela: They melt.
Fraser: In this case, our happy Mars Rovers would be burned alive if they were dropped on the surface of Venus. [Laughter] You need some mechanism for extracting and sequestering carbon out of the atmosphere of Venus. You would need to do a lot. The atmosphere on Venus is thicker than Earth, right?
Pamela: Yeah, so we would need to find a way to take these tens of atmosphere’s atmosphere and suck a lot of the gas out of it. There are different ways to imagine doing this using chemical reactions and catalysts where you basically rain through the atmosphere some sort of chemical that as it falls through the atmosphere, bonds with the different greenhouse gases.
This has huge energy requirements. This has huge requirements of just taking resources from planet Earth or resources that we figure out how to mine out of asteroids or comets that make the mistake of getting in our clutches.
Then we use those resources to rain chemical fear on the surface of Venus by changing everything. By changing its entire atmosphere, by transforming gases back into solids. That’s not an easy process. Again it’s something to keep the chemical engineers out there who like to dream big very busy.
Fraser: And I think I mentioned this before that in Venus if you can reach an altitude of about 50 kilometers, the temperature and pressure are the same as Earth. So, you could actually set up a floating balloon station on Venus and live there and go outside with just a breathing mask and feel perfectly normal.
Pamela: You can call yourself Lando Calrisian.
Fraser: Yeah exactly living in your cloud city. That would be awesome. [Laughter] Okay, so Venus you have to extract the carbons and maybe send it all to Mars. Pull out chunks of carbon in your cloud city and [Laughter] fire off rockets to Mars delivering fresh carbon to thicken Mars’ atmosphere.
Is there anywhere else maybe in the Solar System that could use a little terraforming?
Pamela: Well, there is a discussion that perhaps you could take Europa with its liquid seas, but the problem with Europa is while it has water, it also has high radiation.
A poor astronaut on the surface of Europa would have ten minutes to live before the radiation killed him. They probably wouldn’t want to be alive all of those ten minutes.
Fraser: Now this is coming from Jupiter, right?
Pamela: Yes, it’s the radiation field of Jupiter that unfortunately Europa has to deal with and any astronauts going there would have to deal with as well. There’s also discussion that maybe we could do something with Titan again. It’s a planet with a thick, organic rich atmosphere but orbiting Saturn, it’s kinda cold out there.
Fraser: Right, the temperatures are so low that hydrocarbons and methanes freeze out of the atmosphere and form lakes.
Pamela: It’s so cold out there and the Sun is so far away that Solar energy is no longer a particularly useful way of generating energy. Especially not once you get to the bottom of the big thick, fairly opaque atmosphere.
As you start to look at Titan you have to ask how exactly to get a large enough nuclear power source out there with me. While you’ve moved far enough away that Solar radiation is less of a problem, you no longer have a good way to keep yourself warm and again it has very low gravity. Humans tend to like to have gravity. It makes our bodies happy.
Fraser: As we go forward though, in time as the Sun’s energy output increases and especially as it nears the end of its life, a lot of these worlds are going to suddenly become very habitable, right?
Pamela: The moons of Saturn are going to become very appetizing.
Fraser: Yeah, as the habitable zone of the Sun expands outward, suddenly they will melt and will have oceans and maybe even atmospheres?
Pamela: It’s going to be a brave new Solar System. What will be interesting to see is with these moons that are extremely rich in ice just how much moon to you have left once you heat them up. That will be an interesting question to sort the answer out to.
Fraser: Yeah, a lot of them are half ice, right?
Pamela: Yeah. So we’re going to be melting the outer Solar System, which is an interesting picture.
Fraser: And then in the far future as the Sun nears its very end and its habitable zone extends out it might even include like Pluto and some of the Quaker Belt objects?
Pamela: Yeah, the things that are going to melt.
Fraser: I know you can imagine some far future when people are sitting on the beaches of Pluto [Laughter] right, where the Sun is completely different and it could actually be briefly the only place to live.
Once again there would be some terraforming involved to try and make it as human habitable as possible. But once again, if humans are the same six or seven billion years from now [laughter] we have a problem.
I would be quite amazed. I think that goes through the terraforming argument. I know this is sort of a sacred cow for a lot of people that we must terraform Mars and reshape it to our will so I look forward to your e-mails.
Pamela: And go read Red Mars by Kim Stanley Robinson.
Fraser: Absolutely, Red Mars, Blue Mars and Green Mars, right?
Pamela: Yeah, the whole trilogy.
Fraser: There are also some interesting articles written. The Mars Society has done a lot of thinking on this. There is great stuff on Wikipedia and a lot of other interesting books have been put out. Even some thinking was done at NASA.
We’ll have a whole bunch of links in our show notes that people can chase down. All right Pamela thanks again for a cool show. I think we’re done with Mars. We’ve given it six episodes so [Laughter] I think Mars’ Phoenix Lander can feel like we’ve given it a tribute and it will be awhile before we return back to Mars.
This transcript is not an exact match to the audio file. It has been edited for clarity. Transcription and editing by Cindy Leonard.