HESSI launch timeline
Updated: February 4, 2002

T+00:00 Drop
The Pegasus XL rocket is released from the Orbital Carrier Aircraft at an altitude of 39,000 feet above the Atlantic Ocean, about 75 miles east of Palm Bay, Florida.
T+00:05 Ignition
The first stage solid-fueled motor of Pegasus is ignited to begin the powered journey to orbit with HESSI.
T+01:15 Stage 1 Burnout
The Orion 50S XL first stage motor consumes all of its solid-fuel propellant and burns out. A short ballistic coast period begins now.
T+01:30 Stage 1 and 2 Separation
The spent first stage motor is jettisoned to prepare for the second stage of flight. The first stage casing falls into the Atlantic Ocean.
T+01:31 Stage 2 Ignition
The Pegasus rocket's Orion 50 XL second stage begins firing to continue the trip to orbit.
T+02:06 Jettison Payload Fairing
The payload fairing that protected the HESSI satellite during atmospheric ascent is separated once heating levels drop to predetermined limits.
T+02:43 Stage 2 Burnout
Having consumed its supply of solid-fuel propellant, the second stage motor burns out. A coast period now begins before releasing the spent stage.
T+07:23 Stage 2 and 3 Separation
With its job complete, the Pegasus rocket's second stage is jettisoned from the third stage.
T+07:34 Stage 3 Ignition
The solid-fueled Orion 38 third stage ignites to deliver the HESSI spacecraft into the desired orbit around Earth.
T+08:42 Stage 3 Burnout
The third stage burns out after using all its solid propellant, completing the powered phase of launch. Orbit insertion has now occurred.
T+09:42 Spacecraft Separation
NASA's High Energy Solar Spectroscopic Imager satellite, or HESSI, is released into space from the third stage to complete the Pegasus rocket's 31st launch.

Data source: Orbital Sciences

Flight data file
Vehicle: Pegasus XL
Payload: HESSI
Launch date: Feb. 5, 2002
Launch window: 3:21-5:21 p.m. EST (2021-2221 GMT)
Mission staging site: Cape Canaveral, Fla.

Pre-launch briefing
HESSI - Facts and info on the NASA satellite being launched.

Pegasus - Overview of the air-launched Orbital Sciences rocket.




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