Some people quite understandably, are a bit disappointed with the current Shuttle missions,and look forward to the return to the Moon and forward journeys to Mars.The Shuttle/ Space Station looks somewhat pedestrian in comparison, but I think we should take a deeper view. The return to the Moon, and missions to Mars with a view to a Mars base,are intended to be permanent- not flags and footprint exercises to score off a rival Power.
I believe that it is vital for our species' longterm health and future that we do these things, and address successfully the real issues faced by our organisms in doing so.
These are - 1/cosmic/solar radiation
2/physiological changes to heart/ bones, muscles, nervous systems and immunity
3/how much "G" do we need,as a minimum to assure comparative safety?
Much of the baseline data for these areas are and will be addressed by the longterm routine exposure of a variety of human subjects , of many ages and nationalities, to Space conditions . Remedies/treatments for these problems will require validation in a relatively safe low G environment,within a short journey time from Earth.It is not that long distance space travel is considered infeasible- just that there are still major unknowns which need constraining and addressing. In fact ,this year has seen major steops to completing the ISS, and within 18 months it should,forthe first time, have its intended full longterm crew of six- much more science in relation to maintenance.
On a practical plane , the complex assembly missions and spacewalks have given and will give a vast manual of experience for would-be builders and constructors elsewhere in our solar system. The physiological/biomedical knowledge learned in Space is and will quietly and unobtrusively find its way into earthly medical practice and treatment for the benefit of many.
Lastly, as an example of serendipity,many of you will recall that, in understanding the birth of our solar system , the later stages of accretion ( of medium sized planetesimals into planets by violent collisions) is well understood. However,the earlier stages- the assembly of microscopic dust grains into fluffy clumps and then small boulders - has been a mystery until the past couple of years.
On one ISS mission, one of the astronauts had a funny hobby; he used to take out bags of various powders and grains,and shake them up and down in microgravity just for fun- to make pretty patterns and see what would happen! Once,he did this and noted that a packet of very fine dust spontaneously clumped together into an assembly of fluffy aggregations - very peculiar! He was amazed to hear his colleague exclaim "You have just solved one of the greatest mysteries of planet formation!"
Earth's gravity swamps out this effect completely, but in micro gravity it was apparent that the first steps in the birth of the planets were not due to gravity - but electrostatics and van de Waal's forces- One major hurdle in assembling a solar system a al Kant and Laplace has fallen before the childlike experimentation of an astronaut in Space. This serves to demonstrate a principle that the most significant rewards of new assets are often those we never expected!
It is even possible that such electrostatics will solve some of the real problems of radiation and dust to be encountered by lunar and martian residents of tomorrow.
I am sure that as the ISS, with its European and Japanese additions, crank up to full productivity,there will be many more serendipitous surprises in store- some of which will pave the way to the planets for our descendants