What lies ahead for the foreseeable future of crewed spaceflight? Could we really live and spend a day on Mars?
Is this something that's likely to happen in our lifetimes?
Establishing a lunar base is by no means out of the question within the next couple of decades, provided that we do not indulge in any more senseless wars.
Never mind the question as to whether we could live on Mars. The question should perhaps rather be could humans survive the journey to Mars?
The problems are immense, one of the worst being the danger from solar radiation during the journey. A violent solar storm would be disastrous.
Mars is not exactly welcoming, but it is less unlike the Earth than any other body in the Solar System. One trouble is that from our point of view, the atmosphere is of little use.
It is painfully thin, and it is made up almost entirely of carbon dioxide. Mars might not be somewhere we could live.
We are not sure how effective Mars's atmosphere would be as a radiation shield (how will astronauts hide from radiation on Mars?)
And we must remember that the explorers will have to spend a long time on the planet.
There can be no quick there-and-back dash, as with the Moon.
After the astronauts have landed there will be a prolonged delay before Earth and Mars are suitably placed for a return journey.
Establishing a base to live on Mars
The first Martian bases will be far from luxurious, but if all goes well they will be made much more comfortable once we are sure that permanent bases really can be established.
At least there are no hidden dangers, so far as we know, and though dust storms will be common, they will have relatively little force in that thin atmosphere.
Neither is there likely to be any trouble from Marsquakes; the great volcanoes are quiet, and are not likely to erupt again.
Yet the fact remains that the astronauts will be unable to live on Mars except in very restricted conditions; they will have to stay inside their capsules, inside a base or inside their space suits. Mars is not suited to human visitors.
But can we change this?
Terraforming Mars
Much has been heard about ‘terraforming’: ending up with a Mars on which conditions are much the same as they are on Earth.
Arthur C Clarke wrote about a future Mars with blue skies, extensive oceans, widespread forests and breathable air.
Even if such a Mars we could live on can be achieved, it will take centuries, and the problems involved are only too clear.
For example, we must thicken the atmosphere, changing its composition and making certain that it does not leak away, as the first atmosphere presumably did (remember that the escape velocity of Mars is only just over three miles per second).
We must also raise the surface temperature, perhaps by introducing greenhouse gases or by melting the polar ice caps.
Persuading plants to grow on the surface of the terraformed Mars will be difficult, but can probably be done.
Eventually we will end up with a Mars where there are large cities, supporting a population of thousands or even millions.
Should we colonise Mars?
But... if we could achieve all this, are we sure that it is the right thing to do?
If there were advanced life forms on Mars it is tempting to say that the answer would have to be no, because the introduction of Earth-type beings would unquestionably mean that the indigenous Martians would be doomed.
However, there are no indigenous Martians, and certainly nothing nearly as intelligent as a beetle, which removes the most serious moral objections.
On the other hand we must agree that if we did live on Mars, the planet would be irreversibly contaminated.
And any organisms there would become extinct very quickly, even before scientists had had the time to examine them properly.
The risk may be low, but many people regard it as unjustifiable.
We may have contaminated Mars even now, despite all our efforts to sterilise the vehicles landing there.
There is also the purely practical aspect.
A terraforming programme would be vastly expensive by any standards, and would strain the resources of even a wholly united Earth.
What would be the benefits? Mars is not likely to contain any materials unobtainable at home.
The counter-argument here is that a terraforming programme could not be started except by a world in a state of permanent peace, with mutual friendship and trust between all nations.
This may be a Utopian dream in 2005, but perhaps things will be better in, say, 3005.
A terraformed Mars will have to become self- supporting, and will not have to depend upon help from Earth.
This means a well-regulated system ofgovernment, which will have to be global and will have to work better than ours does at themoment.
Of course, recreation will be an important part of life on Mars, but we may well hope that there will be noriots and no arrests at the end of a game of football between, say Syrtis Major United and Hellas Rovers!
We always have to reckon with the defects in human nature; has it ever struck you that the only creatures that wage organised war on each other are humans and ants?
There are bound to be calls of: "Leave Mars alone; we have done enough harm on Earth."
Terraforming, it is claimed, will be not only a criminal waste of money, but will also have adverse effects upon our way of life on Earth.
In any case, what right have we to interfere with the evolution of another planet?
Personally, I would like nothing better than to have the opportunity to visit Mars, but I admit that I would not be at all keen to exchange my Selsey home for a des res on the slopes of Olympus Mons.
This article originally appeared in the October 2005 issue of BBC Sky at Night Magazine.
