Physicist: In terms of feasibility: no. In terms of being remotely possible: yes, but probably not permanently.
Mars is much colder than Earth, has no water, and effectively no air. On the up side, unlike many planets, you can stand on Mars (it’s solid), and its day is nearly the same as Earth’s (24 hours, 40 minutes). Despite the bad news that follows, Mars is the best candidate for terraforming (making more Earth-like).
First problem: Mars is cold. The most searing heat wave on Mars would barely melt water. Unfortunately, this is a problem with Mars’ distance from the Sun. The only way to get Mars warm would be to create an intense greenhouse effect by mixing up the right atmosphere.
The size of the Sun as seen from Earth (left) compared to the size of the Sun as seen from Mars (right). There's not much sunlight, and not much that can be done about it.
So we need to add an atmosphere, which is pretty hard to come by. Mars has a little under 1% of the atmosphere we enjoy on Earth, so we’d be practically starting from scratch.
Our atmosphere is 99% nitrogen and oxygen. The last 1% is almost all argon. Carbon dioxide makes up a paltry 0.04% of our air. Moral is: we have a big, complicated atmosphere.
Mars did, at one time, have an atmosphere. The best theory today is that when Mars lost its magnetic field the Solar wind, that would otherwise be deflected, was free to gradually strip away Mars’ air. Mars also has about 1/3 of Earth’s gravity, making the process substantially easier.
So there’s some possibility that even if we did manage to establish a dense, warm atmosphere that it would suffer the same fate as the first atmosphere (after several thousand years). Every couple of millennia it may be necessary to touch-up the atmosphere.
The amount of green house gasses you’d need to keep the surface water liquid is very likely to be toxic. It’s been shown that human beings can survive CO2 concentrations as high as 4% (the research so far hasn’t killed anybody, but it has made some people sick). Unfortunately, concentrations higher than 4% are likely to be necessary to maintain a liquid water environment, and even 1% isn’t particularly healthy.
The atmosphere of Mars at the same scale as the picture above. If you were to stand on Mars without a space suit you would get a spectacular full-body hickey. In fact, the low (almost zero) pressure is probably the first thing that would kill you, so wear a space suit if you're going to Mars.
Other gases can be substituted for CO2 to create a green house effect. But most have other problems: too much methane could make the atmosphere explosive, and nitrous oxide tends to make people… weird. The best candidate is probably sulfur-hexafluoride (SF6), which is more than 20,000 times more effective than CO2 as a greenhouse gas, and is non-toxic. There are, however, more subtle drawbacks to SF6 and it would be pretty difficult to synthesize enough.
As the Sun gets brighter, we should find that in a couple billion years Mars will be in the “goldilocks zone” (and Earth won’t) and that whole “toxic concentrations of green house gas” problem becomes moot. It’ll be naturally warm enough in Mars’ orbit for liquid water.
It would also be nice to have oceans on Mars. Oceans are really good at circulating heat, “smoothing out” temperature fluctuations, and generally give rise to climatological niceness. Our oceans can store and release just a hell of a lot more heat than our atmosphere. In order to create oceans on 2/3 of Mars’ surface with a depth of 3 to 4 km (like our oceans) would require about 350 million cubic km of water. Luckily, we’ve got big blobs of water (or ice at least) flying around the solar system in the form of comets. But to top off Mars’ oceans would take somewhere around 3 to 4 million comets. To date there are only around 6,000 known comets, but there are likely to be billions or trillions more out past Pluto’s orbit. I wonder if Halley’s comet would be protected as a historical landmark?
Comets are convenient because the water they carry doesn’t have to be hauled off of another planet’s surface (which costs a lot of energy). Instead you can “nudge” them into orbits which intersect Mars. It’s worth noting: you wouldn’t want to be anywhere on the surface when the oceans are being set up.
The oceans of Mars: step 1.
Water is a great material because it’s mostly oxygen, which is the most important part of the atmosphere (in my very humble opinion). You could turn some of the new Martian seas into the bulk of the new atmosphere with gigantic electrolysis plants, which would use electricity to break down the water (H2O) into hydrogen and oxygen.
If the goal is just to have life on Mars, as opposed to human life, then we may already be able to engineer something that could scratch out a living on Mars. Bacterial extremophiles, maybe water bears, that sort of thing. There’s a decent chance that there are patches of damp dirt deep below the Martian surface that could support some forms of bacteria.
The Mars impact picture was painted by Don Dixon.
Any reader of the Edgar Rice Burroughs’ “John Carter of Mars” series of novels knows that mars has an atmosphere factory which pours out oxygen rich air. Terraforming is hardly necessary.
The factory easily keeps up with the loss to the solar wind. Barsoom should be quite nice as it is.
Seriously, Physicist, you are such a killjoy. Kim Stanley Robinson said we could do it, so I’m sure it’s possible. Also, who names their baby boy Kim?
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It’s not that I hate joy, it’s just that disappointment is hilarious.
The one problem that was not addressed was radiation. As you stated, Mars lacks a magnetic field.
That One Guy: If we throw enough asteroids at it, or maybe Mercury, we should be able to melt the core again and get a magnetic field started back up.
Also: what about Venus? Blowing some atmosphere off a planet should be easier than trying to get some to stick, right?
Suck it Mercury! Or should I say “Jerkury”!
Also, Venus has it’s own bag of issues. It’s a lot easier to warm a planet up, than to cool it off.
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Terraforming the entire planet may be difficult. But it seems pretty obvious to me that the master plan would go something like this:
Humans create autonomous nanorobots programmed to build what’s needed, including other nanorobots programmed to build what’s needed, from raw materials on the surface of Mars.
For example, we launch 100,000 micro and nanorobots in a lander that we land in a crater on on Mars. Some are programmed to crawl on the surface and pick up individual crystals in the sand or soil and return to the base. Piece by piece, they build a silicon dome. Other robots are programmed to insert themselves in an orderly manner in the growing dome. As the dome closes, they pump individual molecules, or preferentially transfer individual molecules, of oxygen and nitrogen into, and CO2 out of, the dome. Within and outside the dome, robots programmed to build robots that are programmed to build robots could build, in a human generation, water supplies isolated from the atmosphere or poles; canals, transport soil most suitable for farming,,, All of these bots are solar powered, of course. When we land, the bots will already be busy working on the next colony in a nearby crater and digging and reinforcing submarsian transport tubes. I’m probably not the first to think of this, but when we land and our homes are ready-made, our energy, water, and waste recycling supply systems are in place, we will have finally put our creative minds to work.
Earth has a magnetic field because of the molten nickle iron core via Our moon 1/3 the size of earth and plate tectonics. (keeping the cookie gooey inside). Well mars doesn’t have a magnetic field could we move the asteroid Ceres (1/3 the size of mars) into orbit around mars. (new big moon) wouldn’t tidal force warm up its interior, causing plate tectonics, magnetic field and out gassing of frozen volatiles? OK, somebody tell me I’m crazy cuz we need another place to go, we need to learn how to terraform and we need to learn how to move asteroids (barney is the last of his kind)
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Since this is all theoretical “what ifs”, we might as well assume we can design a wormhole with one end on Mars (surface) and the other on Venus (atmosphere).
i) Assuming such a connection is, possible, how much would it take (theoretically, not actual full amount) of Venusian atmosphere to warm up Mars?
ii) Would the depleted amount be enough to cool off Venus to habitability? If not, is it even possible to estimate a possible temperature/air pressure drop? XDDD
i) Ballpark guesstimate: most of it.
ii) Even with no greenhouse effect at all, Venus is too hot for life. Terraforming enthusiasts sometimes talk about giant reflectors and orbital sun shades to help deal with the problem. Even so, Venus turns so slowly that only small colonies at the poles are likely to maintain non-fatal temperature extremes.
Huh, so in addition to atmosphere removal, you’d also have to try and slam something in to Venus to try and get it to rotate faster?
This sort of ties in to the ‘non-rotating earth’ hypothesis, then … as Venus currently rotates longer than its years, are there any guesses to how ‘fast’ (in earth days or hours) it needs to rotate for non-fatal temperature extremes?
No idea.