You say that, but I once suggested that humans weren't going to colonize Mars in this century, and got downvoted - here on HN. A lot of people seem to think, h

You say that, but I once suggested that humans weren't going to colonize Mars in this century, and got downvoted - here on HN. A lot of people seem to think, hmm, we've been watching fictional people go to Mars since Buck Rogers; it must be pretty achievable. (Hint: it's not.)