Spaceflight Now: Atlas launch report

AC-161 launch timeline
SPACEFLIGHT NOW
Posted: July 12, 2000

T-00:02.4 Engine start
Engine start Atlas booster and sustainer engines are ignited and undergo checkout prior to liftoff. The two ground-start boosters will light a half-second before launch.
T+00:00 Launch
Liftoff The Atlas 2AS rocket, designated AC-161, lifts off and begins a vertical rise away from launch pad 36B at Cape Canaveral Air Force Station, Florida.
T+00:08 Roll Program
Roll During vertical ascent, Atlas begins a seven-second roll maneuver to align itself with proper flight azimuth. Following the roll, the Centaur inertial guidance system controls pitch and yaw programs.
T+00:58.53 Air-lit SRB Ignition
Air-lit The remaining two solid rocket boosters strapped to the Atlas are ignited once onboard computer software determines the two ground-start SRBs have burned out, about two seconds earlier.
T+01:17.21 Jettison Ground-Lit SRBs
Ground-lit sep The two spent solid rocket boosters that were ignited on the ground are jettisoned to fall into the Atlantic Ocean.
T+01:55.57 Jettison Air-Lit SRBs
Air-let sep Computer software will determine the air-start solid rocket boosters have burned all their propellant and should be jettisoned from the Atlas vehicle. The two SRBs will fall into the Atlantic Ocean.
T+02:43.81 Booster Engine Cutoff
BECO BECO occurs when axial acceleration of 5.0 g is obtained. Sustainer engine provides the continued boost toward orbit for the Atlas rocket.
T+02:46.91 Jettison Booster Package
Booster sep The bottom engine structure with the two booster engines is separated from the Atlas vehicle.
T+03:24.81 Jettison Payload Fairing
Fairing separation The 14-foot diameter aluminum payload fairing that protected the EchoStar 6 satellite during launch is separated once heating levels drop to predetermined limits.
T+04:57.10 Sustainer Engine Cutoff
SECO SECO is commanded once minimum residual propellant is sensed inside the Atlas booster stage.
T+04:59.00 Atlas/Centaur Separation
Atlas separation The Atlas booster stage separates from the Centaur upper stage. Over the next few seconds, the Centaur liquid hydrogen and liquid oxygen systems are readied for engine ignition.
T+05:15.60 Centaur 1st Main Engine Start
MES-1 MES 1, the longer of the two Centaur firings begins to inject the upper stage and EchoStar 6 spacecraft into a low-altitude parking orbit around Earth.
T+09:51.40 Centaur Main Engine Cutoff
Coast MECO 1 occurs the Centaur engines are shutdown, arriving in a planned parking orbit. The vehicle begins a coast period over the mid-Atlantic before arriving at the required location in space for the second burn.
T+24:42.30 Centaur 2nd Main Engine Start
MES-2 MES 2 occurs over the Atlantic Ocean between the African Ivory Coast and Ascension Island before the rocket passes over the equator. The burn lasts until all the Centaur fuel is used, placing EchoStar 6 into the desired geosynchronous transfer orbit.
T+26:19.30 Centaur Main Engine Cutoff
MECO-2 At the point of MECO 2, the Centaur/EchoStar 6 vehicle should be in the required transfer orbit. Moments later, the stage begins aligning to the satellite separation attitude.
T+28:55.30 Spacecraft Separation
Spacecraft separation The EchoStar 6 direct-to-home television broadcast satellite is released into orbit from the Centaur upper stage to complete the AC-161 launch.

Image and data source: International Launch Services and Lockheed Martin Astronautics.
Next launch
Vehicle: Atlas 2AS (AC-161)
Payload: EchoStar 6
Launch date: July 14, 2000
Launch window: 0521-0720 GMT (1:21-3:20 a.m. EDT)
Launch site: SLC-36B, Cape Canaveral, Fla.

Flight profile
Track the major launch events for the Atlas 2AS rocket carrying the EchoStar 6 satellite on Spaceflight Now's interactive flight profile page (requires JavaScript).

Pre-launch briefing
Launch preview - Read our story for a complete preview of the EchoStar 6 launch.

Atlas 2AS vehicle data - Overview of the rocket that will launch EchoStar 6 into space.

EchoStar 6 - Description of the satellite to be launched on AC-161.


Video vault
Watch a movie about the planned sequence of events as the Atlas 2AS rocket carries the EchoStar 6 TV satellite into orbit.
  PLAY (1.0M, 2min 32sec QuickTime file)
An in-depth look at the Lockheed Martin Atlas 2AS rocket and Centaur upper stage that will launch EchoStar 6.
  PLAY (461k, 1min 03sec QuickTime file)

Learn more about the EchoStar 6 direct-to-home TV satellite that will expand services for DISH Network subscribers.
  PLAY (515k, 46sec QuickTime file)
Download QuickTime 4 software to view this file.




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