So I went to play the mission 'knock knock' (mars), and halfway through had to go do something in the shiny real world which took longer than I thought it would. Came back to the usual idle for too long, returned to orbit spiel. Went back to to the mission again and it had gone! However, the quest step from variks that needed it completed had been done and onto the next step... So while I can continue with this wolves on mars quest, I cannot redo the knock knock mission! Is this a glitch or is it meant to disappear having 'completed' it? Any ideas on how to get it to reappear? tl;dr 'knock knock' mission no longer available, did not complete