This is the launch timeline to be followed by the Atlas 5 rocket’s ascent into orbit from Vandenberg Air Force Base in California with the commercial WorldView 4 Earth-imaging satellite for DigitalGlobe. Launch is scheduled for Friday at 10:30 a.m. local time (1:30 p.m. EST; 1830 GMT).
The United Launch Alliance Atlas 5 vehicle, designated AV-062, will lift off and begin a vertical rise away from Space Launch Complex 3-East at Vandenberg.
T+0:01:19.1: Mach 1 and Max Q<br />
The Atlas rocket achieves Mach 1 some 79 seconds into the flight, then passes through the region of maximum dynamic pressure at 94 seconds.
T+0:04:03.1: Main Engine Cutoff
The RD-180 main engine completes its firing after consuming the load of RP-1 kerosene fuel and liquid oxygen supply in the Atlas first stage.
T+0:04:09.1: Stage Separation
The Common Core Booster first stage of the Atlas 5 rocket separates from the Centaur upper stage. Over the next few seconds, the Centaur engine liquid hydrogen and liquid oxygen systems are readied for ignition.
T+0:04:19.0: Centaur Ignition No. 1
The Centaur RL10C-1 engine ignites for the longer of the two upper stage firings. This burn will inject the Centaur stage and WorldView 4 spacecraft into polar orbit.
T+0:04:27.1: Nose Cone Jettison
The two-piece, 14-foot-diameter payload fairing that protected the WorldView 4 spacecraft during the atmospheric ascent is separated to reveal the satellite to space.
T+0:15:36.9: Centaur Engine Cutoff No. 1
The Centaur engine shuts down after arriving in the planned sun-synchronous orbit of 379 by 390 miles tilted 97.96 degrees to the equator.
T+0:19:15.9: Spacecraft Separation
The high-resolution WorldView 4 imaging satellite is released into orbit from the Centaur upper stage to complete the primary objectives of the AV-062 launch.
T+2:11:45.9: Cubesat Separation
Seven tiny Cubesats being launched through a National Reconnaissance Office-sponsored rideshare, called the ENTERPRISE mission, are ejected from carriers mounted near the RL10 engine over a period of 14 minutes. The Centaur then executes another burn to escape Earth and enter solar orbit.
See earlier WorldView 4 coverage.
Our Atlas archive.
from Spaceflight Now spaceflightnow.com/2016/11/10/timeline-atlas-5worldview-4-ascent-profile/