Rules Question: Shuffling Mission/Opposition decks

I may have missed it, but a question arose in our last game of GSF.

What happens when the opposition mission deck runs out? Do you shuffle the scrapped missions back to form a new deck? Leave it as empty and play no mission cards? Shuffle scrapped cards back in as soon as they're scrapped to prevednt just this situation? We shuffled the deck but that kept giving us the same mission over and over as we scrapped it and it wa the only scrapped mission card at the time. This seemed unsatisfying, so I'm asking the knowledgable people here for thoughts.

The same could apply to the Opposition deck, although there I'm more confident that you shuffle and keep going.

Thanks for the help.

I'v always placed scrapped Opp ships and scrapped Mission cards under the deck.

Foote has always done it correctly!

Thanks for the responses. Which means we played it more or less correctly. However, you would not believe how many times that meant the blasted phantom turned up. It could also have meant the Cryoshade could have turned u twice as there weren't many missions in the deck fo the Solar Blockade could have recycled (if we hadn't won before it arrived)

I don't think the starting mission cards recycle