Mar 06 2017

Terraforming Mars

MarsTransitionVHow high a priority should we have for sending people to Mars? This seems to be a big question these days. NASA is developing the Space Launch System (SLS) and the Orion capsule specifically to have the capacity to send people to Mars. Elon Musk has stated that the real purpose of SpaceX is to colonize Mars.

The public imagination has also been sparked by movies such as The Martian (which was excellent). I also recommend National Geographics’ series “Mars” which is a combination of interviews with current scientists and engineers about the problems that a Mars colony would face, with a narrative about a future colonization mission.

The one fact that everyone agrees on is that colonizing Mars will be extremely difficult. Mars has an atmosphere about 1% that of Earth. This makes it just thick enough to be a problem but not thick enough to help with breaking while landing on Mars, and not thick enough to make the surface any more livable. A 1% atmosphere is effectively a vacuum, but it is enough to cause planet-wide dust storms that would make life on Mars challenging.

Transfer to Mars would take about 8 months with current rocket technology. Depending on the relative position of the planets and the transfer speed, 130-260 days are the figures most often cited. That means supply lines would be very difficult, and don’t expect any rescue missions.

If there is life on Mars, it is microscopic and would not help sustain a colony. Colonists would have to jump start a greenhouse ecosystem. They would also need water, oxygen, and energy. There is also the problem of radiation exposure, which would require highly shielded or underground facilities.

Can we create an atmosphere?

Many of the challenges of colonizing Mars would be solved if we could just thicken its atmosphere. An atmosphere close to the density of Earth’s would make facilities easier to build, since they would not need to be pressurized as much. Leaks would not be as catastrophic (no explosive decompression). An atmosphere would also warm the surface of Mars and protect the surface from radiation. It might be theoretically possible for colonists to walk on the surface of Mars under an atmosphere without a spacesuit, just with a supplemental oxygen supply.

Creating an atmosphere on a planet, however, seems like a daunting engineering problem – and it is. We know that Mars had a thick atmosphere in the past. Under the ancient Martian atmosphere, Mars was warm enough to have flowing water on its surface. However, over the intervening billions of years Mars lost most of its atmosphere due to solar winds.

There is a constant wind of ionized particles coming off the sun. The Earth is protected from this wind by our magnetic field. The ionized particles move along the magnetic field lines around the Earth. Occasionally, if they are strong enough, they dive down into the atmosphere at the magnetic poles, resulting in the Northern or Southern lights.

Mars lacks a planet-wide magnetic field. (It has small regional magnetic fields which are too weak to protect the atmosphere.) For this reason, over the years, the solar wind has slowly eroded away its atmosphere. The crust of Mars has also long since solidified, so there are no more volcanic eruptions to replenish the atmosphere.

If we are going to seriously terraform Mars, and give it back an atmosphere, there are therefore two things we can do – we can find a way to add gases to thicken the atmosphere, and we can find a way to increase Mars’ magnetic field. The former may be easier than you think. The poles of Mars contain frozen water and carbon dioxide. Raising the temperature on Mars would have a runaway effect because it would start to melt the poles, which would add more CO2 to the atmosphere, raise the temperature, which would melt the ice at the poles even more.

We don’t know exactly what Mars would be like at this point. We do know the water would cover vast areas of Mars meters thick, but that is substantially less than the water content of Earth. The atmosphere would be almost entirely CO2. There would likely still be some ice at the poles during winter. We could start converting CO2 into biomass and oxygen, but getting a breathable atmosphere would take about 1,000 years.

Adding additional volatiles to Mars could help. We could, for example, redirect icy asteroids to collide with Mars. Ideally we would complete this process before putting any colonies on Mars, and such a project could take centuries.

All of this would be temporary, however, as long as Mars still lacks a magnetic field. The water and CO2 would eventually get blown away by the solar wind. Even still, if we could make Mars livable for a million years, we can worry about the the long term effects later.

There are those, however, who think that if we could find a way to create a magnetic field on Mars that would help with everything. It would protect the surface from radiation to some extent, and protect any atmosphere we release on Mars. Creating a planet-wide magnetic field, however, is no easy task.  NASA, however, is thinking about doing just that:

At The Planetary Science Vision 2050 Workshop at NASA headquarters, Jim Green – NASA’s Planetary Science Division Director – is proposing launching a magnetic shield to do just that.

This is in the pure speculation phase, but it is an interesting idea. Details are sketchy at this point. One idea is to create solar-powered magnetic coils in orbit around Mars. These would be huge, and there would have to a lot of them to surround the planet. This would be a non-trivial engineering feat.

Once in place, however, it would make it easier to build up an atmosphere on Mars again.

All of these ideas for Terraforming Mars are interesting, but they are for the long term. This century, if we are going to go to Mars, we will have to deal with its harsh environment. There is no reason why we cannot do it. It will just be expensive and difficult, but existing technology could theoretically get the job done.

11 responses so far

11 Responses to “Terraforming Mars”

  1. Kabboron 06 Mar 2017 at 10:28 am

    The long term possibility of a Mars that is terraformed to be Earth-like is a very appealing concept from the perspective of safeguarding humanity from annihilation. For the near future, we would have to have a pressurized colony that has to simulate all the benefits we have here on earth, so apart from the higher gravity, is there a compelling reason to do this on Mars over our moon? I am curious if there are other benefits to choosing Mars prior to terraforming.

    Speaking of terraforming… how much would it cost to throw a massive umbrella in synchronous orbit between Venus and the sun? I want humans to be at least a three planet species!

  2. daedalus2uon 06 Mar 2017 at 11:34 am

    Venus is the easiest planet to colonize via floating cities. At ~ 1 atm in the Venus atmosphere, temperatures are near the melting point of ice. Breathable air (80/20 N2/O2) is a good lifting gas in the Venus atmosphere (almost pure CO2).

    Venus has an atmosphere, so there is already radiation and meteor protection, so inflatable habitats are all you need. The atmosphere also allows for aerobraking which makes getting there cheaper and faster.

    There is plenty of solar power (~1.4x Earth).

    Carbon, hydrogen, oxygen, nitrogen sulfur and a few others are available from the atmosphere. Solid elements are available from the surface via remote collection.

    There is considerable uncertainty as to what the surface of Venus is like, but that uncertainty only reflects design specifics, none of the details would preclude operation there.

    The “advantages” of Mars, in that it has a solid surface, might not be an advantage if the perchlorate level is so high it is toxic.

  3. Steven Novellaon 06 Mar 2017 at 2:17 pm

    Gravity alone is a decent reason. Mars is also bigger. There is also a lot more water on Mars. The moon has some water in deep polar craters, but not much comparatively. If you have access to water and energy, you are most of the way to self-sufficiency.

    Terraforming Venus is interesting. Floating habitats is interesting, but we would probably want to eventually colonize the surface. The atmosphere is too thick, and is full of sulfuric acid, so very unfriendly. We would have to get rid of most of the atmosphere on Venus, and all the acid. There are several complicated proposals for how to do this. This will be much harder than terraforming Mars.

  4. Kabboron 06 Mar 2017 at 3:07 pm

    Yeah, water and gravity are both pretty important. I fear that once a permanent settlement is in place we reduce our options for serious terraforming. We might one day have readily available solutions to make Mars a thriving earth-like planet.. if only a few thousand people didn’t live there already in colonies. On that front progress today might hinder progress tomorrow.

    That said, people living on Mars would certainly provide a greater motivation to innovate on that front.

  5. Nareedon 06 Mar 2017 at 7:21 pm

    I’m not asking or suggesting this as a practical matter, but would a massive satellite, say like one of the Galilean moons of Jupiter, placed in orbit around Venus help in removing some of the atmosphere?

    The other problem with Venus is the length of the day. Even if she had an Earth-like atmosphere, the long day would still bake the day side and freeze the night side.

    Could you impart momentum through a large satellite and make the day shorter?

    Again, not serious or practical. But who knows what engineers in the 30th century might be capable of.

  6. Steven Novellaon 06 Mar 2017 at 10:37 pm

    Venus does not have a moon because it’s too close to the Sun, which would steal its moon.

    It is beyond impractical to try to speed up venus’s rotation. It is tidally locked. If there was robust convection from the day side to the night that would distribute the heat somewhat and it could still be good.

  7. bachfiendon 06 Mar 2017 at 11:52 pm


    Venus isn’t tidally locked with the sun. The length of its day is 243 Earth days, and it’s retrograde. Its year is 224 Earth days, and as a result a solar day on Venus lasts 117 Earth days.

    If you could somehow put a Galilean-sized moon in orbit around Venus, to speed up its rotation the moon would need to be orbiting much faster than Venus is rotating, so that the moon loses momentum as Venus gains momentum (it would be the reverse of the Earth-Moon system, with the Earth’s rotation slowing down as the Moon recedes). Meaning the the Galilean-sized moon would be continually approaching Venus, until it reaches the Roche limit and disintegrates.

    So no – it’s not possible.

    If 30th century technology was capable of moving a Galilean-sized moon into the inner solar system, then it would be easier to just use the moon as a new habitat.

  8. Nareedon 07 Mar 2017 at 12:18 am

    Oh, the Galilean moon would get used for something far more interesting…

    Just an old story idea I had once.

    Ok, if we can’t speed up Venus, I suppose we could put up mirrors (gigantic ones) in orbit around it and deflect sunlight from the day side to the night side to keep temperatures tolerable on both sides.

    Does that ruin the night? Maybe. But with a day longer than a year, the night was pretty messed up to begin with.

    It’s just fun to think about.

    Now, if we could make Mars and Venus trade places…

  9. Johnnyon 07 Mar 2017 at 6:05 pm

    “This century, if we are going to go to Mars, we will have to deal with its harsh environment. There is no reason why we cannot do it. It will just be expensive and difficult, but existing technology could theoretically get the job done.”

    Agreed. The main reason that we are not currently doing it is because there is a lack of political will to do so.

    I have encountered the idea of colonizing (but not necessarily terraforming) the Moon as an intermediate step toward colonizing Mars. Do you think that is a good idea or not?

    Meanwhile, here is a message from Carl Sagan to future colonists on Mars:

  10. MosBenon 13 Mar 2017 at 1:26 am

    Gravity is the one problem that I don’t see discussed in many Mars terraforming discussions. Mars has enough gravity for us to visit and have a good time, but people living years or decades on Mars, or perhaps being born there, would likely have pretty significant problems due to the reduced gravity. And unlike the magnetic field or lack of atmosphere, I’m not sure that there is a solution outside of crashing larger chunks of the asteroid belt into Mars to increase its mass.

  11. daedalus2uon 13 Mar 2017 at 1:02 pm

    “In theory”, you could speed up the rotation of Venus via close approach of asteroid-sized objects many times.

    The optimum way to do this would be via numerous 3-body interaction, where the asteroid would be on a trajectory that takes it past Venus, and then past Jupiter which takes it on a trajectory past Venus, and so on, many times.

    “In theory”, these trajectories are differentially sensitive to initial conditions, the equivalent of the “butterfly effect”, so if you had precise enough measurements and ongoing control, you could “control” the trajectory so that it did just what you wanted it to do. That might require controlling the trajectory some large number of orbits in advance (20?).

    It is like the “butterfly effect” idea of weather control, based on the idea that a butterfly’s wing can affect the course of a hurricane a month in advance. In principle it can, and in principle if you could control all butterfly-level fluctuations in the atmosphere you could use that to direct the course of hurricanes. The difficulty is that you need to know and be able to control all butterfly-level interactions that influence the outcome, not the single butterfly at a single instant; but rather all butterfly level perturbations in the volume of atmosphere that matters (likely at least hemisphere level volumes).

    It should be easier to do trajectory control because gravity is the major long distance force, the second major force is mediated through sunlight. You would need to put sensors on essentially every body that has enough mass to have gravitational effects and keep track of all of them.

    Once the Solar System was instrumented like this, then gravitational swing-by could be used to move large objects. It may take a long time, but in principle the Earth could be “rescued” from the Sun becoming a red giant. Just move the Earth out to the orbit of Mars, or set it “free” and send it to orbit around another star. A close approach of the Earth to Jupiter would be able to give it enough velocity to escape the Sun.

    Getting started is the hard part. Large asteroids are in pretty stable orbits and perturbing them enough to start to get gravitational interactions that could be controlled and used would be difficult. Collisions might be necessary in the beginning, those are going to be more difficult to work with because the objects can break apart and pieces fly off which greatly complicates things (breakage isn’t going to be calculable the way gravitational interactions are).

    It would likely take millions of close approaches, which would take at least tens of millions of years to implement.

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