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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

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 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_complaint.pdf 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."

jka 5y 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 5y 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.