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

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: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...