Monica Grady: Could man survive on Mars?

Would it be possible for humans to live on Mars? It wouldn't be easy - without protective clothing, we would be fried by ultraviolet radiation. As well as the radiation problem, any human settlers would need to solve the problem of where to get oxygen to breath, as there is hardly any oxygen in Mars' thin atmosphere. We would need heated suits to guard against the very cold temperatures, and the suits would have to be pressurised so that the low atmospheric pressure didn't do odd things to the fluids in our body.

It might be possible to live underground, like the Antarctic micro-organisms, or in specially constructed habitats on the surface. But this wouldn't allow us to explore the planet freely. Eventually, perhaps, we would evolve to survive the natural conditions - what might we look like? How would we cope with a 40 per cent reduction in gravity? We would probably not live as long as on Earth, since bone tissue and muscle fibre would crumble or shrink from not having to work so hard against gravity.

Is there an alternative? Instead of humans adapting to Mars, could we adapt Mars to humans? We would need to change the composition of the atmosphere, and make it thicker so that liquid water would be stable. This would take many years, and would be difficult - but in theory it might be possible. But would it be sustainable - Mars has lost an atmosphere before, so why should it keep another one?

And probably more importantly - do we, as humans, have the right to alter another planet so completely, especially given the poor job we have done of maintaining our own planet? We certainly don't yet know enough about potential life-forms on Mars to contemplate destroying their specialised habitats.