Starlink plans to use mercury propellant, 100s tons expected to enter atmosphere

https://twitter.com/KevinHBell/status/1508548997992095761

by throwaway2048 • 4 years ago

20 12 4 years ago

aluminum96• 4 years ago

What is the impact of "hundreds of tons" divided over the world's surface area? It of course sounds like a lot, but the Earth is also quite large, so it's hard to know if these are trace amounts, or large enough to have real health impacts.

wmf• 4 years ago

AFAIK burning coal releases mercury and radioisotopes into the atmosphere in addition to the CO2 and particulates that people worry about but somehow we haven't banned coal.

paulryanrogers• 4 years ago

Coal, much like alcohol and tobacco, is basically grandfathered in. If it were newly considered as an energy source with all the externalities we know now then it's unlikely we'd use it so widely.

lgats• 4 years ago

EPA estimates 50 tons a year from US coal plants. [1] Around 8.5% of global coal consumption is from the US [2], so a ballpark estimate would be 588 tons/year globally from coal. I would guess this estimate is a bit low as there are EPA standards to limit mercury emission by coal plants [3]. Top coal consumers like India and China are likely to have less mercury emission regulations, but I don't have a source for that. US coal varies in mercury content by up to 3x [1] so global mercury emissions are likely to be highly dependent on coal sources.

[1] https://pubs.usgs.gov/fs/fs095-01/fs095-01.html#:~:text=EPA%....

[2] https://www.worldometers.info/coal/coal-consumption-by-count...

[3] https://www.epa.gov/mats/cleaner-power-plants

quantified• 4 years ago

Of course, the last thing you want is to discover that you underestimated the hazard, now you’re screwed because it’s all over the place. We’re getting along just fine without the satellites now.

It will be a fitting irony if humankind lowers its IQ below the point where it can remediate its mistakes.

matheweis• 4 years ago

This is an extremely editorialized title.

The thread is about a law firm that got a un resolution passed to ban the use of mercury as a satellite propellant, on the basis of a company that used it in their thrusters, that was in the process of selling the tech to spacex.

What it doesn’t say:

* whether spacex bought it or not

* whether spacex ever used it or not

* whether spacex still plans to use it or not

… and if I’m reading it right, it sounds like the resolution was passed, which ought to mean that spacex doesn’t plan to use it, because that’d be a violation of un treaty.

Gravityloss• 4 years ago

Mercury is actually a very old electric thruster propellant.

Xenon is a later invention, revealed in public only after the fall of the soviet union.

perihelions• 4 years ago

This thread offers no evidence that SpaceX plans (or had ever planned) to use mercury as an ion propellant. I think the "Starlink plans" part of the title is an unjustified editorialization.

Starlink thrusters use krypton,

https://en.wikipedia.org/wiki/Starlink

edit: If you look at the text of the legal complaint, the only mention of SpaceX mercury is a *pure hypothetical*:

https://peer.org/wp-content/uploads/attachments/11_19_18_FCC...

- "If a corporation such as SpaceX, OneWeb, or another major space company were to deploy an entire proposed LEO constellation with cheaper and more powerful mercury-fueled thrusters on-board, they could be launching as much as 198 tonnes of mercury into orbit, which will then be fired off into the upper atmosphere."

jka2• 4 years ago

I mostly agree with you - the title of the post includes claims that aren't substantiated by the documentation, and that isn't great.

Something makes me uneasy though: a radical, risky innovation that could significantly reduce operational costs albeit at an environmental cost to be paid at a later date and/or even used as a point of leverage? It feels plausible (and dangerous) enough to warrant inquiry and consideration.

rspeed• 4 years ago

It would increase operational costs. The satellite lifetime is limited by propellant capacity (especially at the low altitudes where Starlink operates). Mercury thrusters would be significantly less efficient than the krypton thrusters they currently use, due to Mercury's higher atomic mass.

bob2222• 4 years ago

Lol this poor sap actually thinks the UN matters. Does he not know about the past 70 years?

jka2• 4 years ago

Potentially relevant FCC complaint from November 2018: https://ecfsapi.fcc.gov/file/111998371507/11_19_18_FCC_compl...

"Apollo tested several fuel types and found that if the corrosive effects of mercury on the spacecraft could be controlled, and they could keep the use of mercury secret, the ACE could seriously outperform its competitors indefinitely. To date, no other electric propulsion thruster can match the efficiency or power of the ACE, and leading experts in the plasma and fusion fields are convinced that Apollo has made a miraculous breakthrough because they all assume that the ACE uses xenon as a fuel source."

Starlink plans to use mercury propellant, 100s tons expected to enter atmosphere

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