When I did the last revision of the Deposed mission in February, I missed two bugs that will prevent the player from completing certain parts of the mission, and therefore from advancing beyond a certain point.
Apologies to everybody who fell victim to this! And thanks to mpswain, who made me aware of the fact.
If you want to do the Deposed-mission, just download the new version and put it in your AddOns-folder. Don't forget to remove the old version, and restart Oolite. Voilà!
And thanks to mpswain, who made me aware of the fact.