Mission Elapsed Time
Encyclopedia
Mission Elapsed Time is used by NASA
during their space missions, most notably during their Space Shuttle
missions. Because so much of the mission depends on the time of launch, all events after launch are scheduled on the Mission Elapsed Time. This avoids constant rescheduling of events in case the launchtime slips. The MET-clock is set to zero at the moment of liftoff and counts forward in normal days, hours, minutes, and seconds. For example, 2/03:45:18 MET means it has been 2 days, 3 hours, 45 minutes, and 18 seconds since liftoff.
The International Space Station
(ISS) does not use an MET clock since it is a "permanent" and international mission. The ISS observes Coordinated Universal Time
(UTC/GMT). When the shuttle visits ISS the ISS-crew usually adjusts their workday to the MET clock to make work together easier. The shuttles also have UTC clocks so that the astronauts can easily figure out what the "official" time aboard ISS is.
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
during their space missions, most notably during their Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
missions. Because so much of the mission depends on the time of launch, all events after launch are scheduled on the Mission Elapsed Time. This avoids constant rescheduling of events in case the launchtime slips. The MET-clock is set to zero at the moment of liftoff and counts forward in normal days, hours, minutes, and seconds. For example, 2/03:45:18 MET means it has been 2 days, 3 hours, 45 minutes, and 18 seconds since liftoff.
The International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...
(ISS) does not use an MET clock since it is a "permanent" and international mission. The ISS observes Coordinated Universal Time
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
(UTC/GMT). When the shuttle visits ISS the ISS-crew usually adjusts their workday to the MET clock to make work together easier. The shuttles also have UTC clocks so that the astronauts can easily figure out what the "official" time aboard ISS is.