Assuming humanity gets over the existential hump all civilisations must traverse – where we’re just smart enough to invent nuclear weapons and fossil fuelled power stations, but not smart enough to not to use them – then I fully expect us to one day colonise the stars. Or at least the planets orbiting those stars. Starting with the red planet orbiting our star.

However, that lofty vision has been given added impetus by Professor Stephen Hawking in a speech he gave at the Cedars-Sinai Medical Center in the US this week. He told his audience – as he has argued before – that we ought to set our sights on reaching for the skies soon lest we find ourselves stuck on our crumbling homeworld.

Hawking reckons we have about 1,000 years before the Earth is thoroughly exhausted from our meddling, and we had better have a Plan B ready to go when that happens.

Now, I’m all for space exploration. I’m all for surveying distant extra-solar planets. I’m even for space colonisation. But terraforming – the process of transforming a previously inhospitable world into a new garden of Eden – a replacement Earth before we burn up this one is a whole other kettle of Babelfish.

It’s not the scientific hurdles that concern me, although they are manifold: finding a suitable candidate planet with the right gravity, temperature, water and magnetosphere; getting there; building an atmosphere amenable to humans, both in pressure and composition; seeding the planet with life that will find a happily stable equilibrium; managing the time scales, which could be counted in millennia; establishing a delicate balance of environment and life, and maintaining it; among others.

It’s not the engineering hurdles either, although they’re no small potatoes: building craft to travel through the void for potentially hundreds of years on end; developing a power source – possibly fusion – to run everything; building atmospheric processors on a global scale; managing waste and pollution; protecting fragile humans from the harshness of space and foreign planets, until they are habitable; and so on.

It’s not even the psychological issues, such as selecting pioneers who can venture for decades with little or no hope of return home, or anticipating the effects of prolonged confinement; or how those born off-Earth will think of themselves.

Nor is it the financial and political hurdles: the lowest estimate I’ve seen for terraforming Mars is $4 trillion, and I’d expect the real figure to be many times that; no matter what it costs, who will pay for it? Governments won’t use today’s taxpayer’s money to fund something that will come to fruition 1,000 years from now, and private investors won’t fund something that won’t give a return for a millennium; periods of colonisation characteristically include conflict and war, as new outposts exploit untapped resources and begin to rival their founders; how will interplanetary government work when we can’t even figure out global governance?

What troubles me about Hawking’s idea is the fact that if we start colonising space before we fix our problems back here on Earth, then we’ll very likely take those very same problems with us elsewhere. It’s like baking a cake to a dodgy recipe so it comes out burnt and inedible. Then thinking you’ll just start over and everything will be OK, but then using the same recipe again.

The Earth has effectively been designed for us (albeit etiologically not teleologically) over hundreds of millions of years. We will never find another planet so ideally suited to our habitation, no matter how long we look. The idea we can just pop off and terraform a couple of backup Earths that will be just as good is vain at best, and naive at worst.

There is just no escaping it: we need to get Earth right no matter what else we do.

So, in the sense that exploring and colonising space is the next great adventure for humanity, and one I think we should strive for, it should not be used as a crutch to excuse our mistreatment of our home, but as a way we can spread what is noble – not what is corrupt – about humanity further throughout the universe. If we’re going to colonise space, we really should make sure we do it for the right reasons.