NASA should stick with what they do best - robot explorers. Jupiter, Saturn, Uranus, Neptune, soon Pluto, plus Mercury, and the famous Mars twins - all excellent and great ROI projects. Lots of science, lots of knowledge. Their Humans in space program is dismal at best, and a complete waste of money at worse. Robots do it better, faster, and way way way cheaper with no significant risk. Humans in space is nothing but a political boondoggle.