Spaceflight Now: B-41 Launch Report
B-41 launch timeline
Posted: February 25, 2001

T+0:00:00 Liftoff
The twin Solid Rocket Motor Upgrade (SRMU) boosters are ignited and the Titan 4B rocket launches from Complex 40 at Cape Canaveral Air Force Station, Florida.
T+0:00:07 Roll Program
Rocket beings a roll maneuver to the flight azimuth of 93 degrees for the travel downrange from launch site.
T+0:02:11 Stage 1 Ignition
The Titan 4B rocket's core vehicle stage 1 engines -- Aerojet LR87-AJ-11 -- is ignited. The liquid-propellant powerplants burns Aerozine-50 fuel and nitrogen tetroxide oxidizer.
T+0:02:26 SRMU Separation
Having consumed all their solid-propellant, the two Alliant Techsystems-built solid rocket boosters are jettisoned to fall into the Atlantic Ocean.
T+0:03:35 Jettison Payload Fairing
The tri-sector payload fairing buit by Boeing that protected the Milstar satellite during launch is separated once heating levels drop to predetermined limits.
T+0:05:25 Staging of Titan Core
The first stage engine shuts down and the second stage Aerojet LR91-AJ-11 engine is ignited. The spent first stage is jettisoned from the rest of the space-bound Titan 4B rocket one second after the second stage is started.
T+0:09:06 Stage 2 Shutdown
The liquid-fueled second stage engine completes its firing and begins a momentary coast period before deployment of the upper stage and Milstar payload.
T+0:09:14 Stage 2/Centaur Separation
The Lockheed Martin-built Centaur upper stage (TC-22) is released from the Titan rocket's core vehicle, which has completed its role in the launch.
T+0:09:36 Centaur Burn 1
The liquid-fueled Centaur stage is ignited for the first of three firings needed to deliver the Milstar satellite into the desired geostationary orbit.
T+0:11:34 Centaur Cutoff 1
The Centaur completes its first burn to achieve a stable low-Earth orbit with the attached Milstar satellite.
T+1:05:02 Centaur Burn 2
After quiet coast period through space, the Centaur stage is restarted in the first of a two-step process to propel Milstar in geostationary orbit.
T+1:10:13 Centaur Cutoff 2
The Centaur engines are shut down following the firing that should raise one side of the orbit to geostationary altitude of 22,300 miles.
T+6:22:24 Centaur Burn 3
Following a lengthy coast to the high point of its orbit -- around geostationary altitude -- the Centaur engines are again reignited to circularize the orbit by raising the low end of the orbit. This will deliver Milstar into a geostationary orbit 22,300 miles above the planet.
T+6:24:36 Centaur Cutoff 3
Shut down of the Centaur engines occur to complete the powered phase of this launch. The stage now prepares to release the Milstar satellite. Centaur will later perform a collision avoidance maneuver, propellant blowdown and hydrazine depletion after spacecraft separation.
T+6:34:49 Spacecraft Separation
The Milstar 2-F2 secure military communications satellite is deployed into space from the Centaur upper stage to complete the Titan B-41 launch.

Data source: U.S. Air Force.

Flight data file
Vehicle: Titan 4B/Centaur
Payload: Milstar 2-F2
Launch date: Feb. 27, 2001
Launch window: 1857-2257 GMT (1:57-5:57 p.m. EST)
Launch site: SLC-40, Cape Canaveral AFS, Florida

Pre-launch briefing
Titan 4B - Description of America's most powerful unmanned rocket.

Milstar satellite - A look at the Military Strategic and Tactical Relay satellite program.

Communications - Overview of Boeing's Medium Data Rate and crosslink payloads on Milstar.

Antennas - Technical description of Milstar's medium data rate nulling antennas made by TRW.

DPS - TRW's digital processing subsystem on Milstar is key to payload.

Restricted zone - Map outlining the Launch Hazard Area where mariners should remain clear for the liftoff.