Terraforming Mars

[Nuke]

bombardment may provide the neccisary means of heating the existing material in the crust, even if you are not dropping comets.

[Idobox]

Idobox, there is no law against landing people on Mars, so it can't be "illegal".

"It's not like moving significant numbers of people there will ever happen"

Oh, it will happen, and probably in the first half of this century.

Article IX of the outer space treaty specifies that activities that could harm the exploration of a body can be objected.

In practice, the COSPAR fixes rules for sterilization. A lander anywhere on Mars requires class IV sterilization, which is fundamentally impossible if you have living humans on board.

Landing people on Mars would be a breach of the outer-space treaty, comparable to putting nukes in space. It's not technically illegal, just a legal reason for any superpower to declare war on you.

[SargeRho]

I don't remember SpaceX having signed the outer-space treaty. It only applies to the governments of the nations that signed it. Private corporations are not affected by it.

[Kryten]

In practice, the COSPAR fixes rules for sterilization. A lander anywhere on Mars requires class IV sterilization, which is fundamentally impossible if you have living humans on board.

COSPAR isn't a UN body, and their requirements are not relevant to UN treaties.

[Red Iron Crown]

I don't remember SpaceX having signed the outer-space treaty. It only applies to the governments of the nations that signed it. Private corporations are not affected by it.

Treaties have the force of law in the US once they are ratified. Corporations like SpaceX are definitely bound by them.

[John Crichton]

The key issue with terraforming Mars is the lack of a magnetic field protecting its atmosphere. So while you could theoretically start a greenhouse effect and create a more viable atmosphere, that same atmosphere would likely be sandblasted by cosmic rays.

On a very long timescale, sure, totally possible...but I think once we get to Mars, we'll be bound to stick to domes for a good while first (or caves because they're better protected against meteorite impacts).

[peadar1987]

Hmm... Let me crunch some numbers on it...

So let's say Mars needs an atmosphere with a mass of 2.5*10^18kg (same rough figure I was working off earlier, it should at least be of the right order of magnitude). I'll assume it is reduced to 1% of its original density after 10 million years (which I think is far faster than it would actually happen, but as a lower bound, it's conservative).

If the falloff in density follows an exponential curve, that means after 1 year there will be 99.95396% of the atmosphere left, or 0.04604% of it gone. This would be equivalent to a mass of 1.15*10^15kg. That's a block of ice 10km x 10km x 10km. Or five Halley's comets. That's a lot of mass! Comparable to the mass of the impactor that killed the dinosaurs.

If we say that the atmosphere is reduced to 1% after a billion years, that means you're multiply all the time scales by a factor of 100. You now only need to replenish 1.15*10^13kg of gas per year (your block of ice is now down to 2.2km x 2.2km x 2.2km). That's still a lot for one reentry, but what if it was spread out over the course of the year? Now you're looking at 3.15*10^10kg/day. Your cube of ice is now down to 315m x 315m x 315m. This is still a pretty big lump of ice, which means it's probably not the best idea to smash it into the surface of an inhabited planet (you'd supposedly get a 6km wide crater). To avoid having fragments hitting the ground, they need to be smaller than about 50cm in diameter. So you'd need to blow it into 250 million pieces to ensure that none of them reached the surface.

So yeah, orbital bombardment perhaps isn't the best way to go about ensuring Mars keeps an atmosphere, we'd probably be better off trying to manufacture it on the surface once there's an atmosphere in place.

That said, if whatever we're using as a buffer gas is heavy enough that it's not vulnerable to being stripped away by the solar wind, and the only thing we have to worry about is loss of hydrogen drying out the atmosphere, well, you might be down to just a few % of this mass, and one or two icy bodies a year burning up in the atmosphere could be plenty to replenish it.

On the legality of landing on Mars, governments have signed treaties, corporations haven't, but I doubt SpaceX are going to ruin their business model by making governments angry with them, seeing as they sort of rely on their good will a lot of the time.

[Idobox]

On the legality of landing on Mars, governments have signed treaties, corporations haven't, but I doubt SpaceX are going to ruin their business model by making governments angry with them, seeing as they sort of rely on their good will a lot of the time.

Companies have to follow the laws of their country. If SpaceX tries to land people on Mars without authorization by the UN, or at least the USA, it will not just lose business, it will face prosecution. The same as for a company that would want to drill for oil in Antarctica.

[Jart]

Call me skeptical but I see a lot of problems with what is proposed thus far.

- Dropping nukes to raise the temperature? OK, it might work but you'll irradiate the surface rendering it inhabitable for millennia.

- Dropping asteroids to supplement the atmosphere? It will kick up megatons of dust, blocking the already spares sunlight and reducing the temperature. (And it is extremely risky. One minor miscalculation and you'll wipe out all life on earth.)

- Moving an entire moon? I don't know what you guys have been smoking but it has seriously messed with your sense or reality.

- Biodomes. Finally a suggestion that makes sense. They are relatively easy to build and maintain. And they won't 'waste' resources on area's (continents) you don't use.

And now for the final nail to the coffin:

There is not nearly enough water on mars to transform it into another blue planet.

Both the northern and southern icecaps are between 2 and 3 kilometer thick and contain a combined volume of roughly 3.2 million cubic km of ice. Lets assume we can indeed melt it all. A significant portion of this will evaporate into the atmosphere while another large part will be soaked up by the bone dry soil. Spreading the remaining water over the planet surface will result in .... a muddy puddle and possible a hand full of minor lakes.

There simply is not enough water to cover the planet with vast lakes and oceans!

Water is not a problem. There is plenty of it floating around in a nearby asteroid belt. Pick the size that you can handle and bring them into the atmosphere. Pick a lot of little ones. Terra-forming a planet is going to take a few hundreds of years any way.

Edited February 26, 2014 by Jart

[SargeRho]

There actually is enough water to give the planet very large seas, the polar caps alone will probably suffice. And there's a lot of water under the surface.

[musketeer]

I would assume that mars' size makes it very difficult to maintain an atmosphere. An easier method would be setting up large domes, or enclosed underground bases. Natural resources can still be used, but we don't need to go to all the trouble of maintaining an entire planet's atmosphere.

[peadar1987]

I would assume that mars' size makes it very difficult to maintain an atmosphere. An easier method would be setting up large domes, or enclosed underground bases. Natural resources can still be used, but we don't need to go to all the trouble of maintaining an entire planet's atmosphere.

Actually, size isn't the problem, Titan is 80% the diameter of Mars, and 20% of its volume, and has one of the thickest atmospheres in the solar system (exceeded only by Venus', if we don't count the gas giants)

The main problem is stripping by the solar wind. So far nobody has had the knowledge to make an accurate prediction of how fast a thick Martian atmosphere would be stripped away

[peadar1987]

Okay, some light digging has turned up the following on wikipedia:

The relative importance of each loss process is a function of planet mass, its atmosphere composition, and its distance from its sun. A common erroneous belief is that the primary non-thermal escape mechanism is atmospheric stripping by a solar wind in the absence of a magnetosphere. Excess kinetic energy from solar winds can impart sufficient energy to the atmospheric particles to allow them to reach escape velocity, causing atmospheric escape. The solar wind, composed of ions, is deflected by magnetic fields because the charged particles within the wind flow along magnetic field lines. The presence of a magnetic field thus deflects solar winds, preventing the loss of atmosphere. On Earth, for instance, the interaction between the solar wind and earth's magnetic field deflects the solar wind about the planet, with near total deflection at a distance of 10 Earth radii.[2] This region of deflection is called a bow shock.

Depending on planet size and atmospheric composition, however, a lack of magnetic field does not determine the fate of a planet's atmosphere. Venus, for instance, has no powerful magnetic field. Its close proximity to the Sun also increases the speed and number of particles, and would presumably cause the atmosphere to be stripped almost entirely, much like that of Mars. Despite this, the atmosphere of Venus is two orders of magnitudes denser than Earth's.[3] Recent models indicate that stripping by solar wind accounts for less than 1/3 of total non-thermal loss processes.[3]

While Venus and Mars have no magnetosphere to protect the atmosphere from solar winds, photoionizing radiation (sunlight) and the interaction of the solar wind with the atmosphere of the planets causes ionization of the uppermost part of the atmosphere. This ionized region, in turn induces magnetic moments that deflect solar winds much like a magnetic field. This limits solar-wind effects to the uppermost altitudes of atmosphere, roughly 1.2–1.5 planetary radii away from the planet, or an order of magnitude closer to the surface than Earth's magnetic field creates. Beyond this region, called a bow shock, the solar wind is slowed to subsonic velocities.[2] Nearer to the surface, solar-wind dynamic pressure achieves a balance with the pressure from the ionosphere, in a region called the ionopause. This interaction typically prevents solar wind stripping from being the dominant loss process of the atmosphere.

There's also this article:

http://www.space.com/11187-earth-magnetic-field-solar-wind.html

Which is well worth the read.

Basically, we don't know if Mars' atmosphere was or would be stripped away by the solar wind with any certainty, but we should all be very excited about the MAVEN probe, and what it discovers.

[RuBisCO]

Again people Zubin has already done the calculations for you. Assuming a certain amount of CO2 and water is sequestered in the Martian soil all that is needed is to bring up Mars's temperature a few degrees to start a global warming chain reaction, he's numbers show that it should be possible to bring Mar's surface to habitable pressures and temperatures in UNDER A CENTURY! Making enough oxygen would take a few centuries to a millennium longer. So we are talking roughly 1000 years to terraform mars with minimal energy imputs of a few GW a year. Also maybe we can do it all without having the slam in comets if there is enough CO2 and Water on Mars already, which is a big if, alot more science is needed to be done on Mars to answer the questions of how much water ice, permafrost and geological deposit still exist and how much CO2 is soaked up by the very cold-dry soil, the answers to this will determine if mars can be terraformed without need of outside sources of water, CO2 and nitrogen.

That last one is one Zubin barely talks about but is rather important. Human's may not be able to live in a majority CO2 atmosphere or >250 mbar, water there would have the pH of soda water (actually it would be soda water, it just would not bubble) Blood pH would also be shifted, I don't know if humans could adapt to that without significant genetic engineering.

http://www.globalunderwaterexplorers.org/carbon-dioxide-narcosis-and-diving

So the atmosphere is going to have to be made out of mostly nitrogen in the end, at most 50 mbar CO2 (if we can't adapt to higher physiologically) 150-200 mbar oxygen and then at least 150-200 mbar more nitrogen, total air-pressure of at least 40% earths or >350 mbar total. That is going to be alot of nitrogen at least 10^18 kg of nitrogen. If that was to be found as sodium or potassium nitrate deposits it would be ~2.7 million km^3 of nitrate salts, or equal to a cube of salt ~140 km wide! Or a layer of nitrate salts 20 meter deep across all of mars.

Alternatively if this amount of nitrates can't be found on mars, we could mine ammonia from comets, and outer solar system bodies. Base on what little we know of KBO and comets we know they have an ammonia content of 7-19% that of their water content So a comet that is 80% water is also roughly 9% ammonia. So we can say we need to go through roughly 10^19 kg of comets to get enough ammonia, we could either mine the ammonia directly or smack comets into mars. By the way from my calculations on Venus terraforming this is 1/100 to 1/1000 less matter needed for terraforming Mars then Venus.

I would forgo bashing Mars with comets, at least not directly. Mars's low gravity would mean a lot of atmosphere loss from the impact plums. Comets would at best need to be detonated somehow into snow to spread out their impact over a whole hemisphere of the planet. Forgoing that we would need to mine ammonia directly from a comet, ship it to Mars and dump it in smaller manageable amounts. ~10^18 kg of ammonia would also provide a lot of hydrogen (24% of that ammonia is hydrogen) that hydrogen would react with all the oxides and superoxides to form water. Adding a little more water to Mars, not much though that is between 1/10,000 to 1/100,000 the amount of water on earth. If Mars needs more water we can just take chucks out of comets and deliver them to mars without processing out the ammonia. Still 10^19 kg of water-ammonia is still 1/100 less water then on earth, so hopeful Mars already has lot of water stored in it poles and under its soil to make up the diffrence.

Terraformed Mars's atmosphere should be stable for millions of years, despite the lack of a magnetosphere and the loses from solar striping and low gravity. 50 mbar of CO2 though will not be enough to keep it very warm. We would need another greenhouse gas, like my favorite sulfur hexafluoride: that one we would need much less then a mbar of as it has a green house potential 22,000 times that of CO2!

[peadar1987]

And it has a huge molecular weight, making it far more resistant to being lost into space.

[Idobox]

RuBisCo

Giving Mars an atmosphere breathable by humans would be great, but is not really that useful.

Giving it conditions good enough to grow food outside and walk around with just a breathing apparatus (especially if it's just a CO2 scrubber) would already be a huge accomplishment.

Sulfur hexafluoride is great, but where would you find the fluor? There are other less potent gases that are much easier to manufacture, like methane for example.

[SargeRho]

Methane is also pretty combustible and is decomposed by UV radiation.

[RuBisCO]

RuBisCo

Giving Mars an atmosphere breathable by humans would be great, but is not really that useful.

because be able to breath is not really that useful?

Giving it conditions good enough to grow food outside and walk around with just a breathing apparatus (especially if it's just a CO2 scrubber) would already be a huge accomplishment.

Wll sure and we could potentially acheive that in just a century from starting out.

Sulfur hexafluoride is great, but where would you find the fluor? There are other less potent gases that are much easier to manufacture, like methane for example.

Methane will not last long if we ever want the atmosphere to be breathable. Methane also has a very poor half-life on mars, because of the UV and because of unknown methane sequestration mechanism.There is plenty of sulfur and flouride salts on mars nad sulfur hexaflouride is incredibly stable.

Another way of keeping Mars warm without need so much greenhouse gases would be orbital mirrors, lots of them, big ones at that, We coud have low CO2 and a breathable atmosphere that won't explode because of all the methane, the only sacrifice would be no more nighttime. Imagine when the sun sets a ring of "suns" rises.

Edited February 28, 2014 by RuBisCO

[Idobox]

because be able to breath is not really that useful?

Even with a breathable atmosphere, Mars would remain cold and dim, not exactly a nice place to have a stroll in a tank top. Considering the difficulty of making a breathable atmosphere, and the difference between wearing heavy winter gear with UV protection or the same with a breathing apparatus, I don't think it would be worth it.

Now, if you start putting mirrors in orbit, it's a different story.

Methane will not last long if we ever want the atmosphere to be breathable. Methane also has a very poor half-life on mars, because of the UV and because of unknown methane sequestration mechanism.There is plenty of sulfur and flouride salts on mars nad sulfur hexaflouride is incredibly stable.

How fluoride would you need?

There is methane in Earth atmosphere, and it doesn't explode. You would obviously need a higher concentration, but you can keep it below flash point. There are probably other gases that are less explodey and still easy to make.

And yeah, you would need to replenish methane more or less constantly to keep the concentration up. What would be the half life?

[Headhunter09]

For anybody interested in this subject, you should read Red Mars. It discusses the subject in depth and is well-researched.

In the book, they do a couple of things:

-Drill moholes to add heat

-Breed extremophile bacteria, lichen, etc. to eat salts in the soil and rock and emit gasses

-Spread black powder (or black lichen) on the polar caps

-Shift icy asteroids to graze the atmosphere, adding heat and gasses to thicken the atmosphere

-Breaking open underground aquifers to add water to the surface

[Red Iron Crown]

The sequels Green Mars and Blue Mars are good, too. Not just terraforming, but how the culture of Mars develops very differently from Earth (Randomly chosen leaders? Gift-based economy?). The author is Kim Stanley Robinson, for those who might be looking for them. Fantastic books, strongly recommended if terraforming is interesting to you.

[Iforgotthis]

Lets say thousands of years in the future, Mars has been completely terraformed, but to do so we have placed bacteria from Earth (genetically modified or other) on the surface. This bacteria then goes on to evolve until it reaches small fish/land animal size. Would this be considered alien life, or terrestrial life? Although it developed on Mars, its origins are Earth.

[Red Iron Crown]

I would consider it Earth life, though the timeframe you are describing is very, very short for such evolution to occur.

[Tex_NL]

Lets say thousands of years in the future, Mars has been completely terraformed, but to do so we have placed bacteria from Earth (genetically modified or other) on the surface. This bacteria then goes on to evolve until it reaches small fish/land animal size. Would this be considered alien life, or terrestrial life? Although it developed on Mars, its origins are Earth.

Evolution from bacterial life to complex, multi-celled life takes millions of years. Not a few thousand.

If those engineered bacteria do indeed evolve this fast and form a totally new and uniques strain of life I guess it would be called Martian life as it is neither alien nor truly terrestrial.

[Rondon]

Actually here's one, if you want to heat up mars you could place a mirror extremely close to the sun and direct the energy towards mars. Its not even that ridiculous , MIT have already created a perfect mirror in the their labs, (potentially) negating dangers due to extreme heat.

If, presuming you can get as close as twice the radius of the sun, (o.o1 AU) then with "Just" 1.5 square kilometers of mirror you could double the energy mars receives, cant quite find a figure for the delta v required to get that close to the sun, but it would be something giant so lets say about, 100 km/s delta V. it might be possible to make it lot thinner but for simplicity lets just say a 50 mm wafer is used, then the mass of the mirror in total is "only" 4 thousand Tons, then with the guesstimated delta V, it would only need 3.6x10^11 joules of energy!

All that said its a giant Delta V, its hard even imagining theoretical, highly efficient designs being able to get there without massively increasing the mass due to the extra fuel that's required.