Have you ever tried walking up all the stairs in a very tall sky scraper? This gives you a very human feeling of the extent of the gravity well in which we sit, due to the mass of the Earth. It takes a ridiculous amount of energy just to get away from Earth. Then add to this the problem of cosmic rays and having enough of everything to get there and back, and I really have to wonder why so much thought and money and time goes into the idea that we will go to Mars. Until we have better sources of energy or a breakthrough in physics so that we can teleport places, don't you think it's a bit of a waste of time and resources to think we can take a trip to Mars? If not, why not? Basically, I'm saying, let's just explore and take care of this planet a lot better first, before we go anyplace else.