A United Launch Alliance Delta 4 rocket will deliver the U.S. Air Force’s second GPS 3-series navigation satellite into an elliptical transfer orbit nearly two hours after liftoff from Cape Canaveral.
Liftoff is scheduled during a launch window opening at 9:00:30 a.m. EDT (1300:30 GMT) Thursday. The window extends to 9:27 a.m. EDT (1327 GMT).
The United Launch Alliance Delta 4 rocket takes off powered by an Aerojet Rocketdyne RS-68A main engine and two solid rocket boosters built by Northrop Grumman Innovation Systems. The hydrogen-burning main engine ignites at T-minus 5 seconds, following by ignition of the two boosters at T-minus 0, the release of four hold-down bolts and retraction of the launch pad’s three swing arms.
T+00:00:58.5 — Max-Q
Heading northeast from Cape Canaveral on an azimuth of roughly 60 degrees, the Delta 4 surpasses the speed of sound at T+plus 42 seconds, then experiences the most extreme aerodynamic pressures of the mission at T+plus 58.5 seconds.
T+00:01:40.0 — Solid Rocket Motor Separation
The Delta 4’s two GEM-60 solid rocket boosters are jettisoned in two pairs around seven seconds after consuming all their propellant.
T+00:03:55.9 — Booster Engine Cutoff
The Delta 4’s RS-68A main engine shuts down after burning its supply of super-cold liquid hydrogen and liquid oxygen.
T+00:04:02.4 — Stage Separation
The Delta 4’s Common Booster Core separates from the rocket’s second stage.
T+00:04:16.9 — First Second Stage Ignition
The Delta 4’s second stage Aerojet Rocketdyne RL10B-2 engine ignites and powers up to 24,750 pounds of thrust in the first of its two firings to place the GPS 3 SV02 satellite into a MEO transfer orbit.
T+00:04:26.9 — Payload Fairing Jettison
The Delta 4’s composite bisector fairing jettisons from the rocket once the launcher reaches a safe altitude above the dense lower layers of Earth’s atmosphere.
T+00:13:33.1 — First Second Stage Engine Shutdown
The second stage’s RL10B-2 engine shuts down after placing the GPS 3 SV02 satellite in a preliminary parking orbit, beginning a 53-minute coast before the engine reignites.
T+01:06:47.3 — Second Stage Engine Restart
The RL10B-2 second stage engine ignites again for a three-and-a-half-minute burn to send the GPS 3 SV02 spacecraft into a higher, elliptical transfer orbit.
T+01:10:14.6 — Second Stage Engine Shutdown
The Delta 4’s second stage engine shuts down after placing the GPS 3 SV02 spacecraft in a transfer orbit ranging between 745 miles (1,200 kilometers) and 12,542 miles (20,185 kilometers) above Earth, with an orbital plane tilted 55 degrees to the equator.
T+01:55:26.6 — GPS 3 SV02 “Magellan” Separation
The Lockheed Martin-built GPS 3 SV02 spacecraft, nicknamed “Magellan,” separates from the Delta 4’s second stage.
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