UN Bans Mercury Satellite Propellants Under New Minamata Treaty Provisions

Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by jccooper on Monday March 28, 2022 @11:36PM (#30838476)

Maybe mercury is different (though I doubt it), but current electric propulsion sats use nothing like that much mass. A Boeing 702 HP (a big GEO comsat) Xenon propulsion system has a capacity for 266kg of Xenon; uses about 5kg per year for station keeping. Constellation sats are usually smaller; a Starlink sat is about 260kg total. Dunno how much krypton they carry, but probably in the low 10s of kg each.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by sjburt on Tuesday March 29, 2022 @12:40AM (#30838835)

I think the concern was that some organizations were considering big low-altitude constellations. Once you go below 400km or so the drag increases quite a bit so the idea would be to use near-constant thrust similar to GOCE or SLATS.

And there was at least one vendor (Apollo Fusion) proposing a mercury thruster, although I think they have backed off on that. It would have had about 3x the impulse per volume and 2x the impulse per mass of xenon.

I think banning it now is wise, if any small operators had started using it it would have been hard to block it for a megaconstellation and it was very clear that anything release in VLEO would be coming back into the atmosphere. Right now there are no users so you aren't really penalizing anyone.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by ars on Monday March 28, 2022 @11:55PM (#30838589)

I got it from Wikipedia: "The Dawn spacecraft broke the record, with a velocity change of 11.5 km/s (41,000 km/h), though it was only half as efficient, requiring 425 kg (937 lb) of xenon."

I rounded up to one ton, since we're only trying to figure out order of magnitude.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by skykooler on Tuesday March 29, 2022 @12:41AM (#30838841)

Dawn is an interplanetary probe, though, and requires orders of magnitude more fuel than satellite constellations. For a more realistic figure, the Starlink satellites are fueled with about 5 kg of krypton.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by Arainach on Tuesday March 29, 2022 @02:47AM (#30839577)

Starlink alone has launched more than 2,000 satellites already and plans a total of at least 12,000. That's a lot of fuel - and that's just one constellation.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by krisoft on Tuesday March 29, 2022 @06:58AM (#30841007)

> That's a lot of fuel - and that's just one constellation.

Is that a lot of fuel? 5kg times 12000 is about 60 tonne. That's the weight of two big truck approximately. In which sense is that a lot of fuel?

And besides krypton is a noble gas, it doesn't react with anything.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by Arainach on Tuesday March 29, 2022 @11:20AM (#30843752)

60 tons of Krypton, eh. 60 tons of Mercury is huge.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by krisoft on Thursday March 31, 2022 @06:35PM (#30872995)

I agree with you.

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Re:UN Bans Mercury Satellite Propellants Under New Minamata ... by rsynnott on Tuesday March 29, 2022 @08:52AM (#30841845)

It mentions communications _networks_. If you have 10,000 satellites with 10kg propellant each, there's your hundred tonnes of propellant.

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