Turns out -- no, it permanently escapes to space with the help of the solar wind

zozbot234 3 hours ago | parent | next [-]

The overall amount of helium in the atmosphere is still more than enough for the foreseeable future, and it could be extracted (albeit at high energy cost) by augmenting existing air separation units (ASU's). Of course natural gas wells currently provide an easier to extract source, seeing as the concentration there is way higher.

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nradov 33 minutes ago | parent | next [-]

Helium is only 5ppm in the atmosphere. Extracting useful quantities of it that way will probably never be economically viable. In other words, if for some reason we can no longer get helium from natural gas wells then it will be cheaper to just let patients die instead of doing cryogenic distillation of helium from the atmosphere to run MRI machines.

	▲	zozbot234 24 minutes ago \| parent [-]
		We are already separating out the majority elements from air via ASU plants, so we should compare the abundance of helium in what is left from typical extraction. And that looks quite technically viable, if obviously uneconomic at present.

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2 hours ago | parent | prev [-]

[deleted]

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dguest 2 hours ago | parent | prev | next [-]

Space is at the top of the atmosphere right? That place is full of stars producing helium by the teragram.

GP ain't wrong, but the phrasing implied we'd have it closer by than it actually is.

	▲	nomel 2 hours ago \| parent [-]
		No, they're entirely incorrect because they used the word "near". There is no practically usable helium near the top of the atmosphere. But, I'm also confident they were making a silly joke.

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stvltvs 3 hours ago | parent | prev [-]

Even if it didn't, collecting it seems wildly expensive.

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subscribed an hour ago | parent [-]

Or free if we managed to run solar powered sails (or so) skirting the very top and autonomously sending the harvest down.

	▲	krisoft 40 minutes ago \| parent [-]
		If by “free” you mean “very very expensive” then i agree with you. It would cost a fortune to even just attempt a pilot project proving feasability. Then we would need to send up regular replacements to the “sending the harvest down” hardware at the minimum. Just imagining the cost of a tank which can be launched into space, autonomously dock with the collector sails, then deorbit and land makes my head spin. And then doing that at scale, paying people to launch it, paying people to operate the system. It could be free if we imagine some crazy advances in autonomous self-replicating spacecrafts. But by then we live in the post-scarcity diamond age probably.