My fear is that if realising the dream of space travel was ever achievable, we may have blown it by having placed the fate of humankind for far too long in the hands of the ideology of neoliberalism. This has ensured humankind's endowment of natural resources has been largely wasted to satisfy the shortsighted greed of the world's elite.

There may not be enough fossil fuels and other non-renewable resources left over to make possible the required effort to establish a self-sustaining human presence in space. If there are it may be politically difficult to safeguard these resources for space travel in the face of other demands for those resources.

Some arguments against the feasibiity of space travel which have been put to me are:

1. Any civilisation capable of creating the technology that would get us into space was bound to go mad due to its necessary complexity. (This is being sadly borne out as I speak, in spite of the best efforts of many of us.),

2. In the confined space of space colonies it would not be possible to sustain the kind of culture that would prevent the colonists from gong mad as is possible on earth.

3. The cost to the planet's environment of sustaining space travel on top of the othe demands of industrialised civilistion may be too great.

All of this is on top of the technological difficulties which need to be overcome.

Space exploration is just the eternal adolescent fantasy of "indepenndent" western boy/man extended into the "heavens".

The extension of cow-BOY "culture" always looking for a new frontier and opportunity while trampling the living-breathing beings, both human and non-human,that get in the way under foot.

Chop it down and shoot it if it moves.

Rape and trash the planet first and then extend the psycho-pathology else-"where".

By adolescent fantasy I mean the delusion never-ending "growth" as a means of avoiding cooperative responsibilty for the pattern of relationships in which we now exist. Family, the non-humans, community, region, state, country, planet.

Lets not forget the Holy Bible boys! It MAY JUST BE! that there is, as the Bible says, a great invisible war on earth between God and the now evil arch angel, Lucifer and his third of the angels (Ephesians 6:12-18 for this war). Christians believe because The Holy Spirit living in them confirms the Holy Bible truth. The war is so establishyed that nothing can really interfere with it including man and his adventures out into space. We are too far from Mars and the resources of the earth are simply not there. God is letting nothing interfere with the conclusion of the conflict. NASA isnt so dumb as not to know this...there are born again christians amongst them...they are just being apostate to the Word of God with their scientific goofing off and wasting money while people starve on USA streets.

re:
"That's just plain silly: did we fix Europe before embarking for the Far East and the Americas?"

No, I guess not.

By the same token, getting across the Atlantic, Pacific and Indian oceans, under sail, was vastly less energy-intensive than sending payloads into space. Let alone maintaining them in orbit. I don't expect space colonies would quickly become self-sustaining, in energy, materials or gene pool.

The assumption that we can "invent" our way out of population and resource problems by sending a few brave souls into space has always struck me as dubious. Invariably, the promoters are convinced that they, too, will be in the vanguard - and it will be the others who are left behind, paying the taxes.

I am interested in sustainability, down here, ASAP.

My preference is to leave the space exploration for a few centuries, and concentrate on balancing the energy and materials budgets here on earth.

Praise to the author! Yep, this lad’s got the answer – infinite growth is God.

That whiskery old Darwin didn’t have it right after all. But that was one and a half centuries ago – we’ve got smarter since then. And it does seem a pity that mathematicians also are not up to the current speed demonstrated by the author. They are like that physicist, Professor Bartlett from Boulder Colorado, who has been sending out messages for yonks about the impossibility of infinite exponential growth. Surely, the simple maths he uses is out of date.

We have conclusively demonstrated that it is possible to have six and a half billion people occupying this planet at the one time – we are doing it now, and the world hasn’t come to an end. What more proof is needed? Not having proved the capacity for more, what a brilliant concept – export the excess, just in case!

Be cautious, hold those numbers! Get cracking straight away, send the modern-day Chritopher Columbus and Ferdinand Magellan types on their journey immediately. Through the wide-blue yonder into the blackest of the dark unknown for some planet new and green, replete with enthusiasm for human arrival. Ah, the enthusiasm and excitement that Homo sapiens exhibits in relation to exploring new frontiers.

And we can’t delay – 6.5 billion, just perhaps, might be our limit here. Get them moving now – 80 million per year to be shifted; twenty-two thousand per day. Move those queues along at the launch pads; ensure the rocket fueling procedure is hunky dory. Set up the kiosks at their space-launch-ports to sell them their bottles of Perrier Water and DVDs for their (?) of lightyears journeys.

Oh, the sadness for us billions left behind to continue overconsuming the capital from the planet’s bank of resources – for ourselves, and for export as cabin luggage with those 80 million each year. Waving them off, teary-eyed to the tune of "will ye no come back again?"

I'm with Sir Vivor. I am all in favour of space exploration, and indeed without our first baby steps in that direction we would know a whole lot less about our planet and ourselves.

The concern of some posters here that launching things into space is too much of a drain on our terrestrial resources is not particularly well-founded. Yes, it's expensive, but it isn't inherently depleting of anything but the materials sent away (and in the very long term we might even bring as much back as we export). It is most expensive in terms of energy, but our local energy resource is limited only by the lifetime of the Sun, which we expect to outlast, and eventually destroy, the Earth itself if something isn't done to prevent it. I expect that well before that time we will have evacuation plans in place -- perhaps just for the population, or maybe we'll move the whole planet for heritage reasons.

But colonising space is just not a priority right now. Present practices on Earth *are* unsustainable, and a whole lot of human suffering is going to result before we get our priorities and our resource use straight. We are, after all, children of the universe; looking after one another and the planet of our birth is very much worthwhile.