Argon

Eight and a half bil- eight and a half minutes ago, they're in the center of the sun, they're generated by the, uh, sunlight-generated nuclear reactions.

Uh, and, um- Somebody, you probably have covered this on your program, uh, Ray Davis, not Ray Davis of the Kinks pop group, but, uh, Ray Davis, uh, American physicist, decided to put 100,000 gallons of cleaning fluid down a mine, one mile down a mine in, in South Dakota to try and detect neutrinos from the sun, because occasionally a neutrino would, would go through his detector and turn a chlorine atom in his cleaning fluid into an argon atom.

Argon's a gas.

You could collect that at the end of the month and find out whether any neutrinos came through.

And to...

And that's what everyone in government still does because their volume is low enough.

there's not really a good solution at large scale.

Argonne isn't really a good solution

at large scale.

Yeah, sure.

getting more and more ubiquitous as the technologies mature and become more relied upon.

Sure.

That makes sense where, you know, there's not an Argonne gas station anywhere up there.

There was a perceptible pause.

He was one of those rather adipose people who are not disconcerted by conversational gaps.' Are you working, too? Working at Argon, he said.

He is some kind of chemical investigator, I know.

He began at once to explain the most horribly complex things about elements to me.

"'She collects, and I will confess she does it with extraordinary skill.

The surreptitious addresses.

"'John,' she said over her shoulder, "'I wish you would tell Miss Smithers all those interesting things about Argon.' He gulped down his third cup and rose with the easy obedience of the trained husband.

Presently she returned to the tea-things.

Neon gives off an orange-red glow.

Argon glows a pale lavender.

Helium, a dusty pink.

Krypton, a silver-white, and xenon, a light purple.

All I can say is that they're feasting, they're having a good time, and then we get a huge digression.

for like two to three pages, where Anir takes Oscar to the tombs of his sons, Ruro and Argon, and laments that they both died at the hands of Kormalo.

Kormalo is Aneir's son-in-law, like his daughter was taken with Kormalo and ended up running away with him when Kormalo came to his court.

Kormalo originally was kind of terrorizing Aneir's court, but then Ruro and Aragorn showed up and they kicked his butt, but Kormalo resented this.

But xenon has a problem.

It is rare and expensive, around a thousand bucks a kilogram, which isn't a big deal for a billion dollar space probe, but starts being a big deal for constellations of satellites with ion drives for station keeping, whereas argon is under a dollar a kilogram.

Argon makes up almost 1% of Earth's atmosphere, while Helium is only a few parts per million and Xenon is less than a tenth of a part per million.

So Argon is more than 100,000 times more common in the air than Xenon.

Helium is cosmically abundant but not conveniently concentrated near Earth and is still awkward to store and handle.

That matters if we imagine a true space economy with thousands of tugs and faders, or a megaton colony ship that cannot casually fill its tanks with one of Earth's rarest atmospheric gases.

So Xenon is probably the premium propellant for today's ion drives.

Heavy, inert, compact, and easy to ionize, Argon is the cheaper industrial workhorse candidate.