These are big constellations of LEO satellites. Starlink, for instance, has 1500 satellites today, with a goal of 30,000. If we assume 10kg of propellant per satellite, then that's 300 tonnes for the finished constellation (Starlink satellites use a noble gas, I believe, but anyone using mercury for a similar scheme would hit that).

The whole _world_'s atmospheric emissions only seem to be about 250 tonnes per year.

I'm not sure. Wankawilca, the world's great mercury mine, and the most valuable mine in the world for centuries, produced mercury on a similar scale as America produced silver. They produced so much silver! I'm reading California had 45,000 tons of mercury not recovered, used in placer mining from 1848 til today. Yeah, no, it's as common as silver in the earth's crust, and it still gets used for artisanal gold mining, the only figure that's not way off is the amount the spaceships use.

There's a lot of historical falsifications in mining, because mining produces silver and gold, which is money, and generally people lie about how much money they have, telling a different lie to every person.

So Atahualpa's gold, there's no idea how much it was, and further they don't talk about how hard it was to get people not to constantly steal from that room, like what? You think a Spanish soldier is going to just stare at 100 times his weight in gold and be like, I can't wait til King Charles gets his share so I can have mine. You think those guys didn't take bribes for themselves, like OK we'll say you gave all your gold to the gold room, but you get to hang on to this much, and I get this much, nobody's the wiser. It must have been 1000 years of gold production of the Andes. That was el Dorado, they found it right away. And sources tell totally different amounts, some say 200 tons, which is stupid, well do you think they followed GAAP accounting standards when they were eyeballing the gold? How could they measure it? The whole thing was an extortion operation! Obviously the Spanish Conquistadors couldn't let the future know they were torturing the king...publicly? Yeah publicly. And tons of others too. And mining is always like that, it frequently involves slavery too, in complex ways. Because those metals are money, so it's controversial, and private. GM can say how many cars are on the road, but gold mines? Good luck! And I recently dealt with a gold mine someone I know invested in that failed despite excellent deposits because they said the miners were stealing from them--of course, the owners were stealing too. Coming full circle, that's why mercury was so important to Spain, because controlling mercury was the only good way they had of taxing silver and gold mining.

But I must also admit my ignorance presently, I don't know how to find sources that I would find satisfying.

To be clear, the world's annual production of mercury is far more than 250t/year; it's just that most of it doesn't end up in the atmosphere. The mercury that _does_ end up in the atmosphere is largely incidental, mostly due to coal burning.