Gravity

NASA Space Shuttle Explorer, commanded by veteran astronaut Matt Kowalski, is in Earth's orbit on Mission STS-157 to service the Hubble Space Telescope. Dr. Ryan Stone is aboard on her first space mission as a mission specialist, to perform a set of hardware upgrades on the Hubble. During a spacewalk, Mission Control in Houston warns Explorer's crew about a Russian missile strike on a defunct satellite, which has inadvertently caused a chain reaction forming a rapidly-expanding cloud of space debris, and orders the crew to return to Earth immediately. Communication with Mission Control is lost shortly thereafter as more and more communication satellites are knocked out by the debris.