Or maybe history doesn't end in a few decades, maybe technology doesn't completely shut down beyond the immediate planning horizon. In which case it's not at a

Or maybe history doesn't end in a few decades, maybe technology doesn't completely shut down beyond the immediate planning horizon. In which case it's not at a constrained resource at all: * Current helium consumption is 30,000 tons/year * There's 3 billion tons in the atmosphere (replenished at 3,000 tons/year), which we already know how to extract (liquefy air and distill the cryogenic liquids), and only lack a few orders of magnitude of industrial capacity * 1,000 terawatts of D+T fusion, a modest extrapolation (100x humanity's current energy level), would yield 100,000 tons/year of synthetic He-4. Numbers for fission are worse * The planet Jupiter is 10% helium