Spaceflight Now | Delta Launch Report | Delta/GPS 2R-4 launch timeline

GPS 2R-4 launch timeline
SPACEFLIGHT NOW
Posted: April 20, 2000

T-00:00.0	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+01:03.0	Ground-Lit SRM Burnout
The six ground-start Alliant TechSystems-built solid rocket motors consume all their propellant and burn out.

T+01:05.0	Air-Lit SRM Ignition
The three remaining Alliant TechSystems-built solid rocket motors strapped to the Delta 2 rocket's first stage are ignited.

T+01:06.0	Jettison Ground-Lit SRMs
The six spent ground-started solid rocket boosters are jettisoned in sets of three at T+66 and T+67 seconds to fall into the Atlantic Ocean.

T+02:11.5	Jettison Air-Lit SRMs
Having burned out, the three spent air-started solid rocket boosters are jettisoned toward the Atlantic Ocean.

T+04:20.7	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+04:29.7	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+04:34.2	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 GPS 2R-4 satellite into the proper orbit.

T+04:50.0	Jettison Payload Fairing
The 9.5-foot diameter composite payload fairing that protected the GPS 2R-4 satellite atop the Delta 2 during the atmospheric ascent is jettisoned is two halves.

T+10:44.7	Second Stage Cutoff 1
The second stage engine shuts down to complete its first firing of the launch. The rocket and attached GPS 2R-4 spacecraft are now in a 9-minute coast period before the second stage reignites.

T+19:53.7	Second Stage Restart
Delta's second stage engine reignites for a short firing to continue the journey to space.

T+20:29.1	Second Stage Cutoff 2
The second stage shuts down after a 35-second burst. Over the next minute, tiny thrusters on the side of the rocket will be fired to spin up the vehicle in preparation for stage separation.

T+21:19.1	Second Stage Separation
The liquid-fueled second stage is jettisoned from the rest of the Delta 2 rocket having completed its role in the GPS 2R-4 launch.

T+21:59.1	Third Stage Ignition
The Thiokol solid-fueled third stage is ignited to complete GPS 2R-4's delivery into its intended orbit around Earth.

T+23:25.5	Third Stage Burnout
Having used up all its solid-propellant, the third stage burns out to completed the powered phase of the launch sequence. Over the next two minutes, two small yo-yo-like structures are released from the third stage to reduce the spinning motion the Delta rocket and GPS 2R-4 are experiencing in preparation for satellite separation.

T+25:19.1	GPS 2R-4 Separation
The U.S. Air Force's NAVSTAR Global Positioning System Block 2R-4 spacecraft is released into space full a vacant position in the GPS military navigation network. The Delta should have placed the satellite into a transfer orbit with a high point of 10,998 nautical miles and low point of 101 nautical mile. The satellite will circularize its orbit.

Data source: Boeing.

Flight Data File
Vehicle: Delta 2 (7925)
Payload: GPS 2R-4
Launch date: April 22, 2000
Launch window: 0305-0335 GMT (11:05-11:35 p.m. EDT on 21st)
Launch site: SLC-17A, Cape Canaveral, Fla.

Flight profile
profile

Track the major launch events for the Delta 2 rocket carrying the GPS 2R-4 satellite on Spaceflight Now's interactive flight profile page (requires JavaScript).

Pre-launch briefing
Launch Preview - Our story gives a complete report on the upcoming launch.

Orbit trace - A map shows the launch track for the mission.

Delta 2 rocket - Overview of the Delta 2 7925-model rocket used to launch GPS satellites.

Global Positioning System - Description of the U.S. Air Force's space-based navigation network.

GPS constellation - Chart shows the current status of the orbiting GPS satellite fleet.

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