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If an atmosphere were created one way or another on Mars, would it not be stripped away again by solar winds? I thought the lack of a magnetic field is the reas
by prennert 7y ago
If an atmosphere were created one way or another on Mars, would it not be stripped away again by solar winds? I thought the lack of a magnetic field is the reason why Mars has so little atmosphere left.
- therein 7y agoThinking back to a comment I read on HN months ago, while this adds up over a few millennia, it is actually rather insignificant on an annual basis and therefore easy to counter.
- throwawaycert 7y agoYes but that happens over tens, hundreds, thousands, millions of years. It may be practical one day to stay ahead of it.
- cnlevy 7y agoYes, but it's very slow for human lifetimes; it would take millions of years https://en.m.wikipedia.org/wiki/Atmospheric_escape#Mars https://en.m.wikipedia.org/wiki/Atmospheric_escape#Mars
- stevenwoo 7y agoYou may be interested in watching The Planets (2019). It's a entertaining summary of space exploration/theories of the last two decades, and it talks about Mars and Venus (including the atmospheric loss theory on Mars versus Venus retaining an atmosphere) for an episode.
- bayesian_horse 7y agoA more problematic consequence of the lack of magnetic fields is that Mars is not protected from cosmic radiation. However, the "habitable" space under the aerogel may mainly be used for agriculture or as a temporary working area for people in vacuum-proof suits. One thin sheet of aerogel also sounds like a flimsy way of keeping atmospheric pressure.
- hyperpallium 7y agoCan we give Mars a magnetic field? Crash a million iron-rich asteriods on it, and magnetize them? Or do you really need a hot iron core?
- bayesian_horse 7y agoI'm really no expert. I guess the iron core of the earth is too big to be feasibly replaced by asteroids "crashing" on mars. I'd further guess that it would be easier to do the same with some sort of electromagnetic field. To enclose the whole planet would also be a giganteous undertaking. Much easier would be local field generators on the surface, maybe powered by a fusion generator. At best this would be centuries in the future, at worst this doesn't make sense at all because it would require less energy/resources to construct huge greenhouses/domes that achieve the same thing and more. The more immediate obstacles to colonizing Mars seem to be getting there in the first place, getting enough stuff there on a permanent/continuing basis for a few dozen people to live there for a few years, including radiation shielding. It would be a really long time until there is a financially self-sustaining "colony", let alone one that can produce all of its own foods and much of its own technology and other resources. I figure it will be centuries until people even think about anything terraforming-related seriously.
- wongarsu 7y agoThe most viable proposal so far is to place a strong electro magnet on the Lagrange point between Mars and the sun. If sized correctly this acts as a radiation shield similar to a planet's magnetic field, with the restriction that it only works for radiation from the direction of the sun (which is the overwhelming majority). Such a project would be achievable in the near future. I think we don't quite have sufficiently strong magnets yet, and it wouldn't be cheap.
- pfdietz 7y agoOne could run superconducting cables around the planet. The mass required is prodigious, but the energy requirements would be surprisingly small. The magnetic field of Earth above the surface stores about 100 megatons of magnetic energy; on Mars, and if the field were a bit weak, the energy needed would be much less.
- rmtech 7y agoyes but it takes millions of years so no need to worry, and the replacement rate you need is small.