They shut it down last September. It’s nsfw spinoff redgifs is still up.
Mercury would be a denser propellant than xenon/other Nobel gasses used for ion thrusters in orbit. There’s been a ton of other insane fuel types proposed over the years which thankfully haven’t been used (although a lot of rockets have and still use toxic hypergolic fuels like hydrazine)
Good vid going over some of these fuels: https://youtu.be/_wLk2j7_KB0
At least for us amateurs satellite trails get completely rejected out during image stacking. They’ll definitely be more of a problem for professional observatories, especially large survey scopes like Vera Rubin
Only 7 years ago!
https://www.youtube.com/watch?v=qU7FuAswPW0