I know this is slightly speculative, but it is all based on real science so please bear with me. I don't get why some people are so interested in terraforming other planets. Wouldn't it be much much easier to develop a medical device that can extract the elements of the planet's atmosphere necessary for human breathing? I mean, we already have hearing aids, speech aids, seeing aids (i.e. glasses), etc. Actually we also have breathing aids. All we would need is a breathing aid made for a different environment. Maybe it'll take a few centuries before the technology is ready, but surely it would be less time-consuming than terraforming. No?