Iridium Corp. has spent $3.5 billion over the past decade developing a satellitebased telecommunication system. It is currently trying to decide whether to spend an additional $350 million on the project. The firm expects that this outlay will finish the project and will generate cash flow of $15 million per year over the next 5 years. A competitor has offered $450 million for the satellites already in orbit. Classify the firm's outlays as sunk costs or opportunity costs, and specify the relevant cash flows.