chunk: High-speed debris from the Russian satellite strikes the Explorer and Hubble, detaching Stone from the shuttle and leaving her tumbling through space. Kowalski, using a Manned Maneuvering Unit (MMU), recovers Stone and they return to the Explorer. They discover that it has suffered catastrophic damage and the rest of the crew is dead. They decide to use the MMU to reach the International Space Station (ISS), which is in orbit about 1,450 km (900 mi) away. Kowalski estimates they have 90 minutes before the debris field completes an orbit and threatens them again.