The nagging problem is this: Space sucks.
Most of the solar system will never be settled, and the least-bad places still have high radiation, dangerous soil, and low gravity with unknown medical effects. Also there’s no air, no running water, and despite cost-drops and new tech, the best options are far away, insanely expensive, or both.
If you can do something in space, you invariably can do it more cheaply and easily on Earth. This isn’t only a financial problem or a dying-in-space problem—space proposals are environmentally dubious too. Rockets are about 80% propellant, all of which is burned on the ride to space. Advocates sometimes note that in principle, propellant can be generated using only renewable energy, but in practice, this isn’t yet happening. Adding vast numbers of megarockets to the needs of a grid already struggling to go green seems, to say the least, more likely to contribute to climate change than solve it.
Despite what many of its proponents believe, space is neither a solution to current environmental challenges, nor an escape hatch in case of environmental calamity. We’re here to cast some skepticism on the most popular ideas, not because it’s what we want to believe, but it’s where the data led us.