You know the one. The one where people go but don’t come back. They go to colonise and settle Mars.
The reason is, it’s very difficult to get stuff to Mars. And to get enough fuel for a return trip – enough fuel to launch a rocket from the surface of Mars and back to Earth – just makes the figures all but impossible. Enough mass, because rockets work on Newton’s Third Law. You’d almost certainly have to make the fuel for the return journey on Mars itself. Setting up a bunch of solar panels to make hydrogen and oxygen gas from water. Of which there is precious little, except by the South pole where the sun don’t shine. Getting people to Mars and back is about a hundred times as difficult as getting them to Mars and not back. So, if humans are going to go to Mars any time soon, a one-way trip is practical. A return trip, less so.
So these intrepid adventurers will go to Mars and start a colony. They’ll take plants and try to create a breathable atmosphere – but it will have to be inside pressure vessels. Big plastic tube-tents. Mars doesn’t have enough gravity to create an open atmosphere suitable for humans to breathe. They’ll live and die there, of boredom if not of cold, hunger or disease. And the idea is that they’ll breed.
They’ll land where there’s just enough ice, below the surface, to give them some water.
It will be cold, cold, cold.
It’s not suitable for human colonisation. It will never be a nice place to live; at least, not in our lifetime or the next few millennia. In a few hundred million years or so, it will be warmer as the sun expands. The Earth will get too hot, and then we should be thinking about getting there. But Mars isn’t just cold, it’s dry. Very dry. When the Sun gets too hot, our oceans will evaporate. Mars probably had oceans once too, and lost them because it doesn’t have our gravity.
If we are to live on Mars, as a staging post for a few million years before we have to find another solar system, we’ll need to put a decent amount of water there. Like a lot of water. How to do that? Crash a comet or two onto it. But that will have planetary consequences. The effects of the crash – crashes – would almost certainly wipe out any surviving settlement.
Consider this. Suppose, a long time (millioniennia?) hence, we do decide we need to colonise Mars properly and have the technology to divert comets to give it a reasonable amount of water. But there’s a few hardy souls still there, the descendants of a madcap plan to colonise it for a reality show in the early twenty-first century. Against the odds, they’ve survived. Evacuation is out of the question, but dropping a comet on the surface would wipe out the settlement. If we don’t colonise Mars, we know that the Earth will be uninhabitable in a few dozen generations. If we don’t drop the comets, Mars will be too dry for the size of the new settlement we have planned.
By far the most likely outcome of the Mars mission is that it doesn’t happen, and for the sake of the people who’ve signed up to go, I hope to God it doesn’t. But if it does, the next most likely outcome is that they all die, quite soon after arrival. Even if they do survive a year or two, and more supply missions follow, it’s going to need a lot of continuing resources to be delivered from Earth for a long time to have any chance of being sustainable. Which will need a lot of money, and eventually, people on Earth will get bored.
We’ve got enough to do here on Earth. Sort out climate change. Resolve conflict. We need the smarts and the resources being devoted to this nutty Mars trip used here.