Millions Living Underground

The only way for our species to avoid extinction is to leave Earth and establish self-sustaining colonies on other worlds. Very few people would disagree with that. But such an endeavour is proving to be almost impossible for the world's governments to get to grips with. The only projects making any progress are private enterprises focusing exclusive on Mars, most notably Mars One. But the funding for such projects to actually achieve their aims is uncertain at best.

The economic and political turmoil in the world is unlikely to diminish for many decades, if not centuries, which will make make governments unlikely to commit to or cooperate on any off-world colonisation efforts. This puts the continuation of human civilisation at considerable risk. The next best thing, and something governments may well consider, would be to create places on Earth where humans could survive global catastrophes. There are some examples of this, mostly created during the cold war. The USA, Soviet Union and China created some quite significant underground shelters. But those would protect just a few thousand people for a few months.

What is needed are facilities around the world that could protect millions of people for decades, or longer.  Such facilities would need to be deep underground, deep enough to survive even a very close and large asteroid strike, and have no reliance on resupply from the surface.

No matter how large and well designed such a facility is, it could never be permanent.  The Earth will still become utterly uninhabitable one day. The humans living there would have to continue researching and planning their eventual evacuation of of the planet. To facilitate this a level of high-technology would need to be maintained. This technology must include the ability for large and regular space launches. Having to live in such an enclosed environment, with the knowledge that the surface is most likely uninhabitable, would focus the minds of scientists and engineers (and probably the entire population, including the government) on the goal of leaving the Earth.

There's an interesting short story on this subject, called 'Under Pindar', about a massive secret cavern deep beneath London. The background to the story can be read here.

The entrance to a suspected lava tube on the moon

The very act of designing and constructing such subsurface habitats would lead to advances in knowledge and skills that would be very useful when we do come to colonise planets and moons in our solar-system and beyond. The ability to build well-protected underground habitats would be preferred to surface habitats on airless worlds such as most moons, and planets with thin atmospheres such as Mars. Utilising natural underground chambers, such as lava tubes, would save excavation time. There is evidence to suggest that such lava tubes do indeed exist on the moon and Mars, and that due to the low gravity they may be very large indeed, some being tens of metres or more in diameter. There is even a likelihood that channels up to a kilometre in diameter may be possible. The potential for spacious habitats in such locations is tremendous.

An interesting study on the potential of lunar lava tubes can be read here.

Perhaps digging should be our first instinct, before we aim outwards?