Not sure how close we are technologically to doing something like this, but Earth to Mars would only be a day or two. Think about how much less life support (food, water, etc.) needs to be sent along with the crew if the transit is that short. Also, if you're going to Mars, why not do .33G (Mars gravity equivalent) instead. Or start at 1G and slowly drop to .33G. Then there's little to no adaptation required when you get there.

Uh, no. It's about 1,66%. That is, if the probably is the same for each of the next 8 years (it isn't) and the probably of it *not* happening in the first year is 98,34%, then the probably of it *not* happening in the next 8 is 0.9834^8 = 87.5%.