Joe: I think that a manned mission to Mars would be a colossal waste of the taxpayers’ money for very little scientific benefit. Anything that could be learned from a manned mission could be learned at far less cost by unmanned missions. The billions that it would cost to send men their would yield vastly greater scientific returns if spent on ground-based or satellite-based telescopes, unmanned missions, or on research projects in other fields.
We have learned or will learn far more about the universe from the Hubble Space telescope, from satellites like PLANCK and WMAP, and from many other experiments and observatories than we would learn from landing people Mars.
Yes, astronauts jumping around on Mars would be sensational and excite people’s imaginations. That could stimulate interest in science and support for funding. In other words, its value is almost entirely as a publicity stunt. But it is an incredibly expensive publicity stunt. Most astrophysicists I have talked to think that a manned mission to Mars is a horribly inefficient use of research dollars. It will suck resources out of projects that are scientifically vastly more important.
If you love science, and care anything about the taxpayer, please don’t plan a manned mission to Mars!