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Delta 4/DMSP launch timeline
Posted: November 2, 2006

T-0:00:05.5 Engine start
The Rocketdyne RS-68 main engine begins to ignite as the liquid hydrogen fuel valve is opened, creating a large fireball at the base of the rocket. The engine powers up to full throttle for a computer-controlled checkout before liftoff.
T-00:00.0 Liftoff
The four hold-down bolts are released and the Delta 4 lifts off from Vandenberg Air Force Base's Space Launch Complex 6 pad. The pad's two swing arms retract at T-0 seconds.
T+01:23.3 Max-Q
The vehicle experiences the region of maximum dynamic pressure. The RS-68 liquid hydrogen/liquid oxygen engine continues to fire as the vehicle heads downrange, arcing over the Pacific along a 189-degree flight azimuth.
T+03:52.8 Begin engine throttling
With engine cutoff nearing, the RS-68 powerplant starts throttling down from 102 percent. It will achieve a 57 percent throttle in five seconds.
T+04:04.2 Main engine cutoff
The hydrogen-fueled RS-68 rocket engine completes its firing and shuts down to complete the first stage Common Booster Core burn.
T+04:11.5 Stage separation
The Common Booster Core first stage and the attached interstage are separated in one piece from the Delta 4's upper stage. The upper stage engine's extendible nozzle drops into position as the first stage separates.
T+04:26.0 Second stage ignition
The upper stage begins its job to place the DMSP F17 weather satellite into space. The stage features a Pratt & Whitney RL10B-2 liquid hydrogen/liquid oxygen engine.
T+04:36.5 Jettison nose cone
The four-meter diameter composite payload fairing that protected the DMSP spacecraft atop the Delta 4 during the atmospheric ascent is no longer needed, allowing it to be jettisoned in two halves.
T+14:57.9 Upper stage shutdown
The RL10 upper stage engine shuts down to complete its firing. The rocket and attached spacecraft reach an orbit of 457 by 459 nautical miles with an inclination of 98.777 degrees.
T+18:18.0 Spacecraft separation
The Defense Meteorological Satellite Program F17 spacecraft is released from the Delta 4 rocket, completing the second West Coast Evolved Expendable Launch Vehicle mission.
T+111:43.0 Restart upper stage
The upper stage will coasts after deploying its payload. Then the RL10 engine reignites to deplete the remaining fuel reserves. The burn results in the stage entering a suborbital trajectory and falling back to Earth.
T+114:37.9 Upper stage shutdown
The depletion burn concludes, putting the upper stage on a course to reenter the atmosphere over the Pacific Ocean. The altitude for breakup is expected at T+plus 117 minutes and impact at T+plus 121 minutes.

Data source: Boeing