Complex sentence: SpaceShipTwo uses a feathered reentry system, feasible due to the low speed of reentryby contrast, the Space Shuttle and other orbital spacecraft re-enter at orbital speeds, closer to, using heat shields.
Split into simpler sentences: SpaceShipTwo uses a feathered reentry system, feasible due to the low speed of reentry. In contrast, the Space Shuttle and other orbital spacecraft re-enter at orbital speeds, closer to, using heat shields.