Ask Glenn

Will we live on the Moon and on other planets?

Living on the Moon is possible, but with no air, no food and no water, it would take a lot of effort. Other planets might have air and water – or we could even make air and water on them – but we’d have to get there first. So while we could live on other planets, you’d have to ask yourself: is it worth the bother?

Mooncity

So what’s the big deal with living on other planets?

Well, basically the problem is that humans can’t live just anywhere, and most places are no good for us. Mars and the Moon included.

Why not? Why is it so difficult?

Because life on earth has spent the last 4.5 billion years adapting to survive on this particular planet. So take the results (the plants, animals or people) somewhere that’s not Earth, and the chances are we’ll have problems.

What kind of problems?

Let me give you a few examples. Our flimsy bodies evolved under the pressure of the atmosphere, and are influenced by the exact pulling power of Earth’s gravity. Stick us somewhere with too little pressure, and we explode. Too much, and we implode. Gravity too strong? We can’t move. Gravity too weak? Our muscles waste away.

Then there’s the temperature and the breathable atmosphere. Human beings have to maintain a body temperature of around 37°C to stay healthy. At just a few degrees higher or lower, we die of hypothermia (being too cold) or hyperthermia (being too hot). We also need to breathe oxygen – but if the air contains too little or too much, we die of hypoxia or oxygen toxicity.

Wow! I didn’t realize what a bunch of weenies we were. So we need good air, gravity and nice weather?

Right.

So how does the Moon measure up? Or Mars?

Not well, I’m afraid. You wouldn’t want to hold a party on either. The Moon has no atmosphere at all, and we can only describe the atmosphere on Mars as ‘bad’ (about 96% poisonous carbon dioxide). On top of that, Mars has a third of the surface gravity of Earth, and temperatures range from chilly 20°C down to a lethal –140°C. As for the Moon, that has six times less surface gravity, and temperatures go from an insanely hot 130°C down to an insanely cold –170°C. Not exactly what you’d call prime holiday destinations.

What about other planets? Can’t we just find one the same as Earth, and go there?

We’re already doing the first part. The search for Earthlike planets has been on for some time now. NASA’s Kepler satellite will orbit the Sun for four years as it studies distant stars for signs of Earth-like planets nearby. This will be followed by the Terrestrial Planet Finder – a huge telescope built in Space for a similar purpose. There’s a good chance we’ll find an Earth-like planet with one of these. Getting there, though, may be the more difficult part.

Why’s that? Would it be too far away?

Basically, yes. Even the closest planet outside our solar system would take hundreds of years to get to, so unless we develop much, much faster spacecraft, we’re stranded for the time being. If we were desperate to leave Earth, we could reach other planets within our solar system, like Mars, and try to build ourselves an artificial Earth-like environment. Perhaps the first few pioneers could build a survival station or dome, to be enlarged by later arrivals. But even that wouldn’t be easy. Aside from the distance (Mars is still over 48 million miles away, and it’d take nine months to get there), you’d have a major problem with the weight of the spacecraft. Just loading up the people plus enough fuel and food and water supplies for the round trip would make the craft too heavy to launch. And that’s without the building materials for the dome.

So we couldn’t even make it to Mars?

Well, we might be able to get around this by building the craft in space, or using the water and carbon dioxide on Mars to make methane fuel for the return trip. But the main thing is – if it’s so much effort to get there and make it liveable, then is it really worth going at all? The same goes for other, more distant planets – only more so, as they’d be even harder to get to.

What do you think?

I’d say right now, it isn’t worth it. But if conditions on Earth were to change – like if it became too overpopulated, too polluted, or too hot to live on – then maybe it would. Hopefully by then we’ll have figured out the transport problem, too, so it won’t take months or years to get there.

But for now, at least, I think I’ll stay at home. Besides – there’s a good film on telly tonight...