Autonomous Entry Vehicle C728 is a small two-person entry craft that disappeared from the Castores around the time of a mysterious electrical fire. A smaller version of the Buran, STS, or Dream Chaser, the AEV is a reusable lifting body designed to transport a pilot and passenger or two passengers via a pre-programmed entry plan from planetary orbit to a planetary landing strip. It cannot attain orbit under its own power, relying on a booster like the X-20 or riding in a payload fairing like the X-37.