Terraforming Mars

[m4rt14n]

We can bombard mars with icy comets... Turn them into water

[peadar1987]

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.

Not that I don't think this is a stupid idea, but nuclear weapons don't generally cause long-lasting fallout unless they are specifically engineered that way. The nukes dropped on Hiroshima and Nagasaki were particularly inefficient and dirty, but the cities were inhabitable just months after the bombings.

The problem would be releasing enough energy. I doubt we have enough nukes to raise the temperature by any appreciable amount.

- 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.)

In the short term, but the dust will settle, and the gases remain. And earth and Mars aren't really in any way close together, the risk of missing Mars and hitting earth are completely miniscule. If you're able to hit a target as small as Mars, hitting a target the size of everything-in-the-solar-system-except-earth is pretty trivial! The main problem is actually providing the energy to prospective bodies to put them on a collision course with Mars.

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

Agreed. Quite aside from the delta-V you'd need to get the moon into a stable orbit, the thrust you'd need to circularise would be literally astronomical.

[Red Iron Crown]

I think it may end up being cheaper and easier to genetically engineer organisms to be able to survive on Mars, rather than changing Mars to suit Earth organisms. People included, probably.

[Idobox]

It's actually very possible some Earth extremophile could survive or even thrive on Mars without genetic modifications.

It's one of the reasons we won't see humans on the surface of Mars for a very long time: we need to be sure our germs wouldn't destroy life of whatever traces it has left.

[Red Iron Crown]

Assuming there ever was life on Mars, which is far from a given. I agree, though, that terraforming Mars is as much a question of "should we" as "can we".

[SargeRho]

It's unlikely there's anything beyond simple bacteria on Mars. I'd say Earth life is more important than bacteria. So the answer to the question "should we" is "Yes.".

Edited February 22, 2014 by SargeRho

[Red Iron Crown]

I agree, but it likely won't be you or me making the decision. It'll be some politician who has to pander to talking heads who'll make out that terraforming Mars is as bad as stealing Indian land.

[Nuke]

i just realized that if you want to keep the plannet terraformed in the long term you are going to have to deal with phobos. you have to move it (its 10 trillion metric tons, so glhf). you only need to lower its periapsis to 2.1 martian radiuses to destroy it, that would probibly provide some heat. injecting heat energy into the planet is going to be good for terraforming. any nuclear winter as a result should speed up resolidification of the crust. it will spiral down on its own in 50 million years otherwise. its probibly better to deal with that first.

Edited February 22, 2014 by Nuke

[Sun]

After all of this terraforming, how would we keep the atmosphere? Blow up a gigantic nuke at the core of Mars to restart the magnetic field? I'm sure Jebediah Kerman would like that.

[Nuke]

if you are going to terraform it, you might as well go all the way.

[SargeRho]

You could mine phobos tho. I don't know what class of Asteroid it is, but surely it has a lot of metals? Or make it into a space station, and add some highly efficient engines to it.

[grawl]

Hello, I don't know if anybody thought about it and, probably, a bad idea ...

But..

Wouldn't slamming one of Mars' satellites on its surface be able to "reactivate" the planet ? (mind the quotes )

I'm thinking about making the core of the planet move a bit.

With some luck, and with a lot of time we could get free terraforming and beautiful lakes on Mars

[SargeRho]

I think Phobos is a grain of dust compared to the mass of Mars' core. I guess you could try and put Phobos and Deimos in eccentric orbits, to induce tidal stressses.

[Rondon]

Id have to say using bacteria/Lichen to change the composition of the atmosphere is probably the most practical way around terraforming, But unfortunately Mars's Mean is temperature −63 °C/-81ºF. Even if you could engineer life to accommodate that temperature , it probably wouldn't thrive in those temperatures, so maybe you could separate out some of the land, by putting a glass dome around an area of land maybe you could create the conditions useful for life to thrive and produce measurable amounts of the greenhouse gases you would want.

But if say you built even a dome 100km in radius with a thickness of 1 cm then you would need about 800 billion kilograms of silica, to make that silica into the glass required you would need to heat it by about 2000 degrees, which given silica's specific heat capacity requires 1x10^18 joules in total, and for all that energy you would only occupy about one 5000th of mars surface area, but about 2x10^17 joules would be radiated into the dome, if you can regulate the conditions, maybe make it possible for Aerobic organism inside the dome you could maximize the reduction of the soil and send over the life that would create the best greenhouse gases, you can then pump the greenhouse gases outside, the most effective of these gases are made from Florine which is present at only 32ppm but given that it can be up to 7700 times stronger than CO2, depending on the rate the life reduces material, the planet could be warmed over a "practical" period of time.

[Nuke]

You could mine phobos tho. I don't know what class of Asteroid it is, but surely it has a lot of metals? Or make it into a space station, and add some highly efficient engines to it.

move it piece by piece or all at once, you are still moving it

[Idobox]

It's unlikely there's anything beyond simple bacteria on Mars. I'd say Earth life is more important than bacteria. So the answer to the question "should we" is "Yes.".

No, it's not. Extraterrestrial life, even stupid, half broken prokaryotes, even dead, are of tremendous scientific importance. And the more different from us they are, the more important they are. It would be like finding the ruins of the first human city and bulldozing it to build a parking lot, a terrible loss for science that's not even a big gain for anything else.

Now, once you have had robots take samples every where and you feel sure there isn't much left to learn, and assuming you don't find anything cute or smart, you can destroy all you want.

[Nuke]

i have to agree there, were not going to even consider terraformimg mars until we have already colonized it and allowed the scientists to scour the planet for a few hundred years to study life and geology. if in that process if the colony expands such that it is impossible to relocate the population, then any teraforming that takes place will not involve planetary bombardment.

[SargeRho]

Scientific importance, yes. But scientific value is not the only thing we do (or even should) consider.

[Idobox]

Scientific importance, yes. But scientific value is not the only thing we do (or even should) consider.

Why do you want to send people to Mars, then?

It's not like moving significant numbers of people there will ever happen, and delaying sending humans on the surface by 50 years to be sure you don't stomp one of the most important scientific discoveries of history doesn't appear to be huge price to me. Anyway, the powers-that-be have decided long ago spreading our germs everywhere is a bad idea, and landing people on Mars is illegal until we can prove it doesn't put the local life at risk.

[IsicDiscontinuity]

Hello, I don't know if anybody thought about it and, probably, a bad idea ...

But..

Wouldn't slamming one of Mars' satellites on its surface be able to "reactivate" the planet ? (mind the quotes )

I'm thinking about making the core of the planet move a bit.

With some luck, and with a lot of time we could get free terraforming and beautiful lakes on Mars

De-orbiting a captured moon would take a tremendous amount of energy, which would lose the benefit of most of the "free" momentum you'd be after.

It would be much more efficient to adjust the orbit a comet or asteroid which is making a near pass. Were we remotely prepared, nudging something like Comet C/2013 A1 onto a definite impact trajectory would be much more useful (and contribute a heck of a lot of water and gas to help thicken up the atmosphere). That one is notable because it's on a retrograde orbital trajectory, so the energy of the impact would be huge.

[SargeRho]

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.

[OTehNoes]

I think the biggest problem with terraforming mars that you'll have is that any atmosphere that you try to establish is going to be picked off by solar wind as Mars has lost its regular magnetic field long ago. You could maybe do it if you built things within pressurized magnetic domes though.

[peadar1987]

Some (seemingly) good maths done by a poster on Yahoo Answers here:

http://answers.yahoo.com/question/index?qid=20090124045334AAzB8o4

The average speed, v1, of a molecule or atom of mass m (kilograms), at temperature T (Kelvins) is

v1 = sqrt ( 3 k T / m )

Where k is the Boltzmann constant,

k = 1.3806503e-23 m^2 kg sec^-2 K^-1

The escape speed, v2, from a planet of mass M (kilograms) and radius R (meters), is

v2 = sqrt ( 2 G M / R )

Where G is the gravitational constant,

G = 6.67428E-11 m^3 kg^-1 sec^-2

Approximately, the depletion time = 10^(v2/v1) years.

In order for a gaseous element or compound to be stable in a planet's atmosphere for ~ 10 billion years against evaporation losses by thermal agitation, it is necessary that

v2 > 10 v1

So let's determine the boundary condition, in which v2 = 10 v1.

sqrt ( 2 G M / R ) = 10 sqrt ( 3 k T / m )

m = 150 k T R / GM

m = (3.1029E-11 m^-1 kg^2 K^-1) T R / M

The temperature T is the equilibrium blackbody temperature of a planet at its perihelion.

T = { L / [16 pi s a^2 (1-e)^2] }^(1/4)

Where is the Stefan-Boltzmann constant,

s = 5.6704E-8 W·m^-2·K^-4

Where L is the sun's luminosity,

L = 3.826E+26 watts

a = the semimajor axis of the planet's orbit

e = the eccentricity of the planet's orbit

Here's the whole expanded equation,

m = (7.552E-10 m^-1 kg^7/4 s^3/4) { L / [a^2 (1-e)^2] }^(1/4) R / M

If you assume that the sun is the only significant source of heat,

m = (0.00334 m^-1/2 kg^2) R / { M sqrt [a (1-e)] }

For Earth,

a = 1.49598E+11 meters

e = 0.01672

R = 6378000 meters

M = 5.974E+24 kilograms

T = 280.6K

m = 9.296E-27 kg = 5.598 atomic mass units

This means that Earth's gravity is strong enough to hold any gas having a molecular weight of 5.598 amu, or more, for several billion years. The only gases Earth couldn't hold on to, anyway not in the free atmosphere, were hydrogen (2 amu) and helium (4 amu).

Now, do it for Mars and see what you get.

For Mars,

a = 2.27944e11 meters

e = 0.09340

R = 3396200 meters

M = 6.4185e23 kilograms

T = 236.8K

m = 3.8875e-26 kg = 23.411 atomic mass units

So Mars can hold on to CO2 gas (molecular weight 44) for longer than 10 billion years. It could hold free oxygen (32), too, but oxygen reacts with surface minerals and depletes from an atmosphere that way. It seems likely that Mars could keep gaseous nitrogen (28), as well, but for some reason doesn't have any. Water vapor (18) would deplete from Mars over several billion years, but the surface temperature on Mars would probably keep water locked up in surface and subsurface ice.

I know that only takes into account thermal effects, but still, people are greatly overstating the problem of having no magnetic field to speak of. It took 5 billion years (with a solar wind far stronger than it is today) to strip away 99% of Mars' original atmosphere, possibly with the help of impacts from foreign bodies. Mars could hold a dense atmosphere for tens of millions of years with today's solar wind without too much of a problem. Tens of millions of years is a long time!

[OTehNoes]

I suppose so but would that be long enough to effectively establish anything there? It would be VERY hard to build up a suitably thick atmosphere on Mars, once that's done you can get started on the whole terraforming process but still, tens of millions of years still isn't THAT long for life to properly develop. That said, there are pockets of magnetic field on Mars, but still, the atmosphere will still get picked off eventually. We'd certainly have to get atmospheric production proficient enough that it could compensate for what gets lost to space anyhow.

[peadar1987]

I suppose so but would that be long enough to effectively establish anything there? It would be VERY hard to build up a suitably thick atmosphere on Mars, once that's done you can get started on the whole terraforming process but still, tens of millions of years still isn't THAT long for life to properly develop. That said, there are pockets of magnetic field on Mars, but still, the atmosphere will still get picked off eventually. We'd certainly have to get atmospheric production proficient enough that it could compensate for what gets lost to space anyhow.

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.