How will your spacecraft collect orbital debris? Since this would be an entirely new mission for NASA, there is no tested technology for such a task. You may want to consider variations on the Whipple Shields. You may also want to look at the materials used, or considered for use, in the STARDUST mission: aerogel, foam, and plastic tubes.
Remember, though, how your mission differs from STARDUST. Its engineers wanted to capture a relatively small number comet particles intact and uncontaminated. Your challenge is to collect debris of similar size and velocitybut day after day for many years! How will that affect your design decisions?
Think about how your spacecraft will collect debris. Then explore another briefing topic, or begin designing your spacecraft!