SimEarth: Terraforming Mars by the Numbers

An anonymous reader writes "Today NASA has an online terraforming simulation based on the McKay/Zubrin/Fogg model of Mars' weather modification. The simulation shows that the greening of Mars can be done in at least three ways: 1) mirrors melting stored carbon dioxide in tropical soil and polar dry ice; 2) a fluorocarbon (CFC) factory; 3) blowing a vent thruster in the side of a methane-rich asteroid and engineering a collision (perhaps many impacts, but a mere 0.3 km/s impulse drive if using an outer solar system asteroid, such as Chiron, beyond Saturn). Irrespective of the merits or wisdom of these huge engineering projects, their simulation allows moving back the clock to a previous time when Mars was blanketed by greenhouse gases, and thus much warmer."

Comments

The Martians won't allow this

[uncoveror]

We will never terraform Mars. We will never colonize Mars. It is already inhabited by an advanced underground civilization called the Zhti Ti Kofft, and they are getting tired of us. We better leave Mars alone, or we could be toast!

Magnetic field.

[gmiller123456]

What do they plan to do about the fact that Mars has a very weak magnetic field, which is why it lost its atmosphere to begin with?

Without creating a large magnetic field to shield mars from the solar wind, any terraformation will only be temporary.

Re:Magnetic field.

[Bob Kopp]

It's not clear whether Mars had a thick atmosphere to lose. If it did, though, there's only two things that could have happened to the heavy molecules (e.g. CO2) that it contained: they could have been sequestered in reservoirs such as carbonates (not much of which have been yet found), or they could have been lost to space through non-thermal processes. In the last 3.5 billion years on so, the major non-thermal loss process is sputtering by the solar wind, as you say.

Whether a terraformed planet is usably terraformed is a matter of time scales. Models suggests that between 0.1 and 3 bar CO2 could have been lost through sputtering over a period of about 3.5 billion years. Taking the maximum rate, this is an annual loss of less than 1 part per billion per year, or 0.1 bar in 100 million years. Thus no significant loss due to sputtering would occur on the time scale of human civilization.

I vaguely recall seeing calculations for the duration of an atmosphere on a terraformed Moon. IIRC, even such an atmosphere might last for useful time scales; a 1 bar Earth-like atmosphere might last for several thousand years before being lost due to thermal escape and sputtering.

Re:Magnetic field.

[Alsee]

we just need to add enough fissionable material so that the overall radioactivity of the martian core goes up just enough to [melt the martian core]

You are completely missing the scale of energy here. A nuke is zero compared to the core of Mars.

The entire Earth's stockpile of nuclear weapons is about 5000 megatons explosive yeild. 1 megaton is 4.2e+15 joules. The entire nuclear stockpile is then 2.1e+19 joules. There's 1055 joules in a BTU (sorry for jumping units, it was the most convient method when I was researching the numbers). So the stockpile is 2e+16 BTU. It takes about 50 BTU to heat 1 cubic foot of iron or dirt by 1 degree F (sorry, I'm American chuckle).

You can therefore heat a 51.4 mile cube of Mars by 1 degree F.

If you preffer metric, you can heat a 42.3 km cube of Mars by 1 degree C. (km is smaller than mile, but a degree C is bigger than a degree F)

Nukes are great at vaporizing buildings and flattening SQUARE miles, but they are useless melting BILLIONS of CUBIC miles of anything. A nuke has zero energy when you start talking about planets.

-

Re:speaking of SimEarth...

[eggstasy]

Erm, there is no such thing as abandonware... All PC game copyrights will expire long after we're all dead and buried unless someone in the government decides to shorten them or the original author forfeits them.
Downloading old games is as illegal as downloading newer ones. Even if no one is selling them. Even if the company is long gone and all programmers died. It's still copyright infringement because it's still copyrighted, what with the insane length copyrights have these days...

Re:speaking of SimEarth...

[Unordained]

if i own an object and drop it on the side of the road, and don't come back for months ... that doesn't change the fact that i own the object. if someone else comes along and asks if it's been abandoned -- the answer is probably yes. the question is then: if he/she picks it up and uses it, is that illegal? will anyone come after him/her for doing so?

even if i own the object and -could- complain, by having abandoned it i've stopped paying attention. thus, it's rather safe to use, even though it's someone's property. not by legality, but by practicality.

Never had a long term atmosphere...

[Ioldanach]

Or, it could all be futile. New analyses indicate that the martian atmosphere came and went in spurts. Not only was there never a long term atmosphere, there wasn't a long term body of water. That is to say, occasionally there were impacts large enough to transform the planet into an atmosphered planet with liquid water, they lasted no more than a few (hundred) years at a time.

Practicality Arguement

[Rick the Red]

Oh? If the copyright owner is out of business and the item out of print, who's going to sue me for copyright infringement? The RIAA or MPAA, out of spite?

Re:O, really?

[Rick the Red]

"Insightful"? Insightful is realizing the trip to Mars doesn't have to be zero-G. Ever hear of a centrifuge? Send two ships. Tether them. Spin about common CG.

Re:O, really?

[Idarubicin]

How are we going to get around the fact that being away from Earth for approx three years would mean that every cell of your body would be transversed by a galactic ray?

I'm going to assume that you're making a statistical argument about cosmic rays, and not talking about some novel weapon developed by Martians for the war of the worlds.

Estimates of radiation exposure for interplanetary travel (that I've seen) are typically around 50 to 100 rem per year of exposure. Delivered over a brief period, this dose would indeed cause serious effects. Spread out evenly over the course of a pair of six month trips (say) this dose is much more manageable. Radiation workers in Canada and the United States are already permitted up to 5 rem per year. I know a few people (doctors who have been involved in clinical radiation therapy) who have received lifetime work related doses of more than 50 rem, and they seem pretty healthy still. There would be a continuous low level of cellular damage, but not above the rate that the body can easily repair. There would also be an increase in lifetime cancer risk of anywhere from 0.1 to 10% depending on who you ask. I'd certainly be willing to take that chance for the opportunity to go to Mars. Even a dose of 150 rem associated with a three-year journey is not intolerable, since it is delivered over an extended period of time. I have to die of something; it might as well be cancer. The health data associated with my demise could also be quite valuable.

Incidentally, even if every cell in your body was exposed to a cosmic ray, that's not particularly alarming. Damage would have to be done to genetic matter in the cell nucleus to kill or mutate the cell--and the nucleus isn't that big a target. Cells can also repair some types of radiation-induced damage to DNA.