When I was born there were 2 billion people in the world. Now there are 6 billion people in ten years there will be 12 billion people. I don't believe the world can support so many people. There must be colonization of other worlds, if only to give us breeding space. Mars has water. This is the only habitable planet within our reach. Air can be made from water and plants. Unfortunately, there is little interest to fund this venture. The Russian space program has more resources for long term space flight. NASA has better technology. A joint venture would seem paramount. If the two countries weren't fighting over geopolitics. Much of the delivery problems are mass versus fuel. I have made a suggestion. Reduce the living quarters. The first exploration of Mars was done with robots. It was slow, because of the time lapse in remote control. What is needed is human decision making at the planet. This does not require a body; just a head. Russian scientist have kept a dogs head alive for a year. A human head could be sent to Mars. The lapse time in remote control robotics would be gone. In a years research on Mars, valuable data would be gathered for colonization. Other heads could be sent to start a green house effect with Co2 factories. The polar caps would begin to melt and life would grow. In a few hundred years a livable apmosphere would appear. I have not yet received any reply to my proposal. Happy 2011!