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MESSENGER launch timeline
Posted: July 28, 2004

T-00:00 Liftoff
The Delta 2 rocket's main engine and twin vernier steering thrusters are started moments before launch. The six ground-start strap-on solid rocket motors are ignited at T-0 to begin the mission.
T+01:16.4 Ground SRM Burnout
The six ground-start Alliant TechSystems-built solid rocket motors consume all their propellant and burn out.
T+01:19.0 Air-Lit SRM Ignition
The three remaining solid rocket motors strapped to the Delta 2 rocket's first stage are ignited.
T+01:20.5 Jettison Ground SRMs
The six spent ground-started solid rocket boosters are jettisoned in sets of three to fall into the Atlantic Ocean.
T+02:39.5 Jettison Air-Lit SRMs
Having burned out, the three spent air-started solid rocket boosters are jettisoned toward the Atlantic Ocean.
T+04:23.5 Main Engine Cutoff
After consuming its RP-1 fuel and liquid oxygen, the Rocketdyne RS-27A first stage main engine is shut down. The vernier engines cut off moments later.
T+04:31.5 Stage Separation
The Delta rocket's first stage is separated now, having completed its job. The spent stage will fall into the Atlantic Ocean.
T+04:37.0 Second Stage Ignition
With the stage jettisoned, the rocket's second stage takes over. The Aerojet AJ118-K liquid-fueled engine ignites for the first of two firings needed to place the upper stage and MESSENGER satellite into the proper orbit.
T+04:41.0 Jettison Payload Fairing
The 9.5-foot diameter payload fairing that protected the MESSENGER satellite atop the Delta 2 during the atmospheric ascent is jettisoned is two halves.
T+08:49.0 Second Stage Cutoff 1
The second stage engine shuts down to complete its first firing of the launch. The rocket and attached MESSENGER spacecraft are now in a coast period before the second stage reignites. The orbit achieved should be 90 miles circular and inclined 32.44 degrees.
T+46:01.0 Second Stage Restart
Delta's second stage engine reignites to raise the orbit.
T+48:52.3 Second Stage Cutoff 2
The second stage shuts down after a near-three-minute firing. The orbit achieved should be 4,136.6 miles at apogee, 84.2 miles at perigee and inclined 32.49 degrees.
T+49:33.2 Spin Up
Tiny thrusters on the side of the rocket will be fired to spin up the vehicle in preparation for stage separation.
T+49:35.3 Stage Separation
The liquid-fueled second stage is jettisoned from the rest of the Delta 2 rocket.
T+50:14.1 Third Stage Ignition
The Thiokol Star 48B solid-fueled third stage is then ignited to propel the MESSENGER satellite into orbit around the Sun.
T+51:39.3 Third Stage Burnout
Having used up all its solid-propellant, the third stage burns out to completed the powered phase of the launch sequence for MESSENGER.
T+56:43.7 Spacecraft Separation
NASA's MESSENGER space probe is released into space from the Delta 2 rocket for its five billion mile journey from Earth to the solar system's innermost planet -- Mercury.

Data source: Boeing.