Re:Will We Run Out of Helium?
by Robotbeat on Tuesday December 17, 2019 @10:45AM
(#21814634)
Cost depends on quantity. If it returned a few kilograms or grams, it'd probably be extremely expensive (although rare isotopes would be more expensive, they're measured in nanograms).
If you managed to produce ten thousand tons per year (out of a market of about 25,000-30,000 tons per year currently, although perhaps set to grow along with the global economy), the cost could be manageable.
It depends on launch costs and cost per kg of the material. Market price of refined helium is what, around $40-100/kg? Maybe up to $400/kg in the case of supply crunches and in refined liquid form?
And it probably depends on development of nuclear thermal rockets/ramjets to enable you to reach orbital velocity of Uranus in one or two reusable stages. As well as improved thermal protection systems (TPS) to enable reusable TPS at the higher velocities of reentry for Uranus. Currently, with chemical rockets, we can probably get costs down to $10/kg for bulk liquids to LEO (see here: https://www.spacex.com/sites/spacex/files/making_life_multip... slide 41, do the math and the tanker costs per kg of propellant to LEO is less than $10/kg to LEO).
It's not impossible for nuclear thermal rockets to get prices down low enough. Even assuming fairly low efficiency (say, 1000s Isp with about 20 kg of propellant needing to be expelled for each kg of payload to escape velocity... taking into account dry mass ratio of about 20 due to the exponential rocket equation and Uranus's 21.5km/s escape velocity) and non-breeder reactors (where the fuel cost is about $0.15/MWh), the energy cost of the uranium to push a kilogram of material from the cloud layer of Uranus to escape velocity is still on the order of cents per kg. Of course, it then requires years in transit, so it'd only be feasible if financial/market conditions were exceedingly stable.
So in principle, it's possible to imagine that in 100 years hence, it could be feasible to mine Uranus for helium and meet near-current market prices. But the current ~$2 billion/year market for helium is probably much too small. But when it's a more-lucrative $20 billion/year market? More realistic.
But helium-3 for low(ish) neutron fusion may be a larger market by then, and THAT could be a significant market as well, with less challenge for getting price per kg to orbit reasonable (say, on the order of $10,000/kg or more for energy purposes, and it may be feasible to use expendable rockets for such small amounts of material, thus avoiding the more extreme performance requirements for the TPS and structure). Perhaps helium-4 mining would be an off-shoot of helium-3 mining, then.
If you managed to produce ten thousand tons per year (out of a market of about 25,000-30,000 tons per year currently, although perhaps set to grow along with the global economy), the cost could be manageable.
It depends on launch costs and cost per kg of the material. Market price of refined helium is what, around $40-100/kg? Maybe up to $400/kg in the case of supply crunches and in refined liquid form?
And it probably depends on development of nuclear thermal rockets/ramjets to enable you to reach orbital velocity of Uranus in one or two reusable stages. As well as improved thermal protection systems (TPS) to enable reusable TPS at the higher velocities of reentry for Uranus. Currently, with chemical rockets, we can probably get costs down to $10/kg for bulk liquids to LEO (see here: https://www.spacex.com/sites/spacex/files/making_life_multip... slide 41, do the math and the tanker costs per kg of propellant to LEO is less than $10/kg to LEO).
It's not impossible for nuclear thermal rockets to get prices down low enough. Even assuming fairly low efficiency (say, 1000s Isp with about 20 kg of propellant needing to be expelled for each kg of payload to escape velocity... taking into account dry mass ratio of about 20 due to the exponential rocket equation and Uranus's 21.5km/s escape velocity) and non-breeder reactors (where the fuel cost is about $0.15/MWh), the energy cost of the uranium to push a kilogram of material from the cloud layer of Uranus to escape velocity is still on the order of cents per kg. Of course, it then requires years in transit, so it'd only be feasible if financial/market conditions were exceedingly stable.
So in principle, it's possible to imagine that in 100 years hence, it could be feasible to mine Uranus for helium and meet near-current market prices. But the current ~$2 billion/year market for helium is probably much too small. But when it's a more-lucrative $20 billion/year market? More realistic.
But helium-3 for low(ish) neutron fusion may be a larger market by then, and THAT could be a significant market as well, with less challenge for getting price per kg to orbit reasonable (say, on the order of $10,000/kg or more for energy purposes, and it may be feasible to use expendable rockets for such small amounts of material, thus avoiding the more extreme performance requirements for the TPS and structure). Perhaps helium-4 mining would be an off-shoot of helium-3 mining, then.