lunedì 1 novembre 2010

Timeline Lancio di uno Space Shuttle

T-43 hours and counting
The Shuttle Test Director performs the traditional call to stations and the countdown clock is activated.
  • Begin final vehicle and facility close-outs for launch
  • Check out backup flight systems
  • Review flight software stored in mass memory units and display systems
  • Load backup flight system software into the orbiter's general purpose computers
  • Remove middeck and flight deck platforms
  • Activate and test navigational systems
  • Complete preparation to load power reactant storage and distribution system
  • Complete flight deck preliminary inspections
T-27 hours and holding
This is the first built-in hold and typically lasts four hours.
  • Clear launch pad of all non-essential personnel
  • Begin loading cryogenic propellants into orbiter's power reactant storage and distribution (PRSD) system
T-27 hours and counting
  • Begin operations to load cryogenic reactants into the orbiter's fuel cell storage tanks
T-19 hours and holding
This built-in hold typically lasts four hours, but may be extended if PRSD offload is required.
  • Demate the orbiter's midbody umbilical unit
  • Clean and vacuum crew module
  • External tank nosecone purge
T-19 hours and counting
  • Begin final preparations of the orbiter's three main engines for main propellant tanking and flight
  • Fill launch pad sound suppression system water tank
  • Resume orbiter and ground support equipment close-outs
  • Close out the tail service masts on the mobile launcher platform
T-11 hours and holding This built-in hold varies between 13 to 14 hours.
  • Weather and engineering briefings
  • Pad debris inspection and closeout
  • Flight crew equipment late stow
  • Move rotating service structure to "park" position
  • Activate the orbiter's inertial measurement units and communications systems
  • Perform ascent switch list
T-11 hours and counting
  • Activate the orbiter's fuel cells
  • Clear the blast danger area of all nonessential personnel
  • Switch the orbiter's purge air to gaseous nitrogen
T-6 hours and holding
This built-in hold typically lasts two hours, or one hour for a 24- or 48-hour scrub.
  • Mission Management Team and launch director receive weather update
  • Launch team verifies no violations of launch commit criteria before loading the external tank with propellants
  • Clear pad of all personnel
  • Chill-down of propellant transfer lines
  • Begin loading the external tank with about 500,000 gallons of cryogenic propellants
T-6 hours and counting
  • Finish filling the external tank with its flight load of liquid hydrogen and liquid oxygen propellants
T-3 hours and holding
This built-in hold typically lasts two-and-a-half hours.
  • External tank loading enters stable replenish
  • Perform inertial measurement unit preflight calibration
  • Align Merritt Island Launch Area (MILA) tracking antennas
  • Final Inspection Team proceeds to the launch pad to conduct a detailed analysis of the vehicle as the team walks up and down the entire launch tower
  • Closeout Crew proceeds to the launch pad to configure the crew module for countdown and launch and assist the astronauts with entry into the orbiter
  • Televised weather briefing
  • Flight crew weather briefing
  • Astronaut Support Person enters crew module and begins comm checks
T-3 hours and counting
  • Crew departs for the launch pad and, upon arriving at the pad, begins entry into the orbiter via the White Room
  • Complete close-out preparations in the launch pad's White Room
  • Check cockpit switch configurations
  • Astronauts perform air-to-ground voice checks with Launch Control (Kennedy Space Center) and Mission Control (Johnson Space Center)
  • Close the orbiter's crew hatch and check for leaks
  • Complete White Room close-out
  • Close-out crew retreats to fallback area
T-20 minutes and holding This built-in hold typically lasts 10 minutes.
  • NASA Test Director conducts final launch team briefings
  • Complete inertial measurement unit preflight alignments
T-20 minutes and counting
  • Transition the orbiter's onboard computers to launch configuration
  • Start fuel cell thermal conditioning
  • Close orbiter cabin vent valves
  • Transition backup flight system to launch configuration
T-9 minutes and holding This is the final built-in hold, and varies in length depending on the mission.
  • Final launch window determination
  • Activate flight recorders
  • Final "go/no-go" launch polls conducted by NASA Test Director, Mission Management Team and launch director
T-9 minutes and counting
  • Start automatic ground launch sequencer
  • Retract orbiter access arm (T-7 minutes, 30 seconds)
  • Start auxiliary power units (T-5 minutes, 0 seconds)
  • Arm solid rocket booster range safety safe and arm devices (T-5 minutes, 0 seconds)
  • Start orbiter aerosurface profile test, followed by main engine gimbal profile test (T-3 minutes, 55 seconds)
  • Retract gaseous oxygen vent arm, or "beanie cap" (T-2 minutes, 55 seconds)
  • Crew members close and lock their visors (T-2 minutes, 0 seconds)
  • Orbiter transfers from ground to internal power (T-50 seconds)
  • Ground launch sequencer is go for auto sequence start (T-31 seconds)
  • Activate launch pad sound suppression system (T-16 seconds)
  • Activate main engine hydrogen burnoff system (T-10 seconds)
  • Main engine start (T-6.6 seconds)
  • Solid rocket booster ignition and liftoff!  
  • fonte: NASA

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