Yes, it does have an atmosphere, but it's nothing like ours. Aside from being entirely different ratios of chemicals, there is much less air pressure. Air pressure at sea level on Earth is about 14.5 pounds per square inch, but Mars's air pressure averages about 1% of that.
As for Venus, it's FUBAR'ed. The air pressure is 90 times that of Earth's, the surface tempature is high enough to melt lead, and thick clouds of sulfuric acid completely cover the planet. I'm not sure, but I don't think we have any ideas on how to get rid of that atmoshpere, cool the planet down, or get rid of the sulfuric acid, and you'd need to do all of those to make the planet inhabitable. If your talking about living in airtight bubbles and such, your probably better off just making space stations in earth's orbit, that way you don't have to worry about the every-day natural disasters common to other planets, and you could probably have some emergency boosters to avoid collision with anything that heads your way. And that way it doesn't take 6 months to get there, and you could actually have telecommunications with people up there (a phone call to Mars would take 30 minutes to arrive there, and vice versa.
Mars on the other hand, has different problems we theoretically could fix, we could set up huge robot-operated air refineriess that would turn the carbon dioxide into oxygen, and give it a suitable atmoshpere, and create the greenhouse effect to heat up the planet to a livable temperature. The only problem with that is it could take thousands of years to create an entire atmoshpere. And then you'd still have to worry about gravity, unless we could create artificial gravity for an entire freaking planet, even with regular excercise, men's life expentancy would drop so much it wouldn't be worth it. For women, on the other hand, it wouldn't be that big of a deal... so please guys, stop f*cking up the Earth, because if we all have to move to mars, there's a good chance all the men will die out (the women multiplying by cloning sperm from other females' DNA- no, they don't even need us to make babies anymore)... could you imagine? An entire race without testosterone? Without big guns, fast cars, and violence? *shudder* It's just too horrible to think about. /infopop/emoticons/icon_frown.gif
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Shot four puppet governors in a line,
Shook all tha world bankers, who think they can rhyme,
Shot the landlords, who knew it was mine,
Yes, its a war from the depth of time!
[This message was edited by DeadeyeDan[ToA] on Jul 16, 2000 at 16:45.]