The exploration of Mars seems to be the path of choice for many in the space movement. The problem is Mars is the Easter Island of space, far from everything, few unique resources and mainly of interest because of the evidence of past life there. The Moon has a much greater development potential than Mars but she is totally ignored. The Moon is the girl next door and Mars is the Hollywood sweet heart. Nothing shatters a romantic image faster than reality. So maybe we need to go to Mars so we can get past the fixation and really move forward with development.
The development of space solar power is quickly becoming a necessity for the continued economic survival of our society. By default it seems to be our only hope for sufficient amounts of carbon free base load power. Terrestrial solar and wind do not provide base load power, clean coal maybe unworkable, nuclear is too dangerous to spread widely to less stable countries. Space solar power is the ultimate in clean energy source when made from lunar materials, since nothing would imapct earth's environment except the power. The Moon is actually closer to geostationary orbit energy wise than the earth. Providing a reasonable percent of the Earth's power needs with space solar power would most cost effectively be done through developing the Moon. This would seem great for space settlement, but unfortunately the current plans for mining the Moon and building space solar power would be done with automation. The new Movie "The Moon" shows what it might be like, one man one the Moon supervising an automated base. This doesn't bode well for space settlement.
Space settlement must be our ultimate goal. We must have thriving communities off of Earth or we are doomed to extinction on the Earth, it is just a matter of time. Why should humans go into space? There is one reason that can never be automated and isn't dependent on economic justification. That is science. We will never really be able to automate science. While we can automate particular experiments. The scientific exploration is testing the unknown automation can only be done where you know what you are trying to do. To fully understand the history of life on Mars, and the geology of the Moon will require humans on the Moon and Mars for long periods of time. To use the far side of the Moon's radio silence for all the possible radio astronomy observations and the lunar stability and vacuum for all the possible physics experiments would take large numbers of scientists, engineers and support staff. To do these experiments will take years not days. So the scientists will be the settlers of space. Around the science bases the cities will form because they will be the first markets in space.
While many argue that science can be done more effectively on the ground, this will not always be true. First, if we go to Mars and develop space solar power, the cost of space travel will have dropped dramatically. Second, if the goal is science than we will be sending scientist to do their own research. Not doing science by proxy or as an add on to a mission with other purposes. Third, eventually we will research the limits of the the experiments possible on Earth. Eventually, science in space will be justified in terms of cost/ benefit once launch cost go down, missions are designed for science as the main purpose, and as we push the limits of Earth.
Getting beyond the limits of Earth is why we have to explore, develop and settle space. While the paths of these are diverging because we have already explored the best place to develop and development may no longer require humans. We must continue to strive for the exploration, development and settlement of space even if these goals are pursued separately.