I'm not necessarily promoting moon colonies. What I am saying is there is some basic information that needs to be gathered before it makes sense to make any plans. Unless water is found on the moon, it would be very difficult to sustain any kind of colony on the moon.

No colony plans should be made until we understand health effects of low gravity. Premature rushed missions to mars will be a repeat of the Apollo program. That program is hailed as a great success, but while it was a public relations achievement it bypassed the path to sustainable presence in space. As a result, its effect was really to slow our reach into the solar system. It did show how damn expensive getting into space is. We attempted to lower the expense with the space shuttle, but can never seem to admit that failure.

If we were to put all the eggs in the Mars basket right now, you're talking 100's of billions, maybe a trillion dollars with NASA setting priorities like sample return. What would be achieved that couldn't be achieved with a few more rovers?

I don't know how long this stuff will take, but it is clear there is some order to actions that must be undertaken for long term success. The ISS was put up for the same reasons you are talking about a Mars trip now. It was put up for no scientific reason, but to have something for the shuttle to do and to put a human face on "exploration." The irony is the humans haven't done any exploration to speak of. 99% has been done by robotic probes.

If you think the instant gratification public is going to get excited about a 20 year plan to get to Mars I have to laugh. The same small segment will follow it, but the public won't be engaged until launch at best. It is not a matter of "go slow", but simply do what has to be done. If we know, we need "centrifuge beds" for habitation on other worlds, we can plan and make cost adjustments and tradeoffs. If we can easily access lunar material, maybe that means the first colonies should be floating space habitats. Or possibly the material can be used to lower the cost to build and transport large cargos to Mars.

Manned space advocates really need to come up with a better reason to spend 100's of billions than the public will be entertained. The current private space endeavors have a much better chance of utilizing entertainment effectively than NASA. Making policies from a place of ignorance is the standard for our politicians I know, but as an engineer I think it is stupid. These things take steps. Kepler will find out percentages of "earths" in habitable zones. The follow up telescope designs will be affected by what is found out.

Finally, it is a useless exercise to make 20 or 30 year plans except as very loose guides. How long was building the ISS supposed to take and at what cost? You can lay out goals, and by inference milestones and knowledge that must be learned on the path to those goals. My point is that the goal for manned space should not be currently targeted anywhere specifically. The goal should simply state that we are seeking to achieve manned sustainable presence off planet at a reasonable cost (ultimately paying for itself). Having stated that goal, the critical path starts to become clear. Gravity research is at or near the top. If ISS can be used for this fine. If it can't I would just as soon scrap the thing and get on with finding out what we really need to know elsewhere. Heavy robotic capability is clearly required. Delivery of men to a single place at some point is the EASIEST of all the issues. Having a base capable of sustaining them indefinitely with almost no resupply is the difficult part. Lets start finding out what it takes to do that (and use cheap robots so that we can possibly achieve it in our lifetimes).