|The Russian-designed RD-180 main engine is ignited and undergoes checkout prior to launch.
|The two strap-on solid rocket boosters are lit as the Atlas 5 vehicle, designated AV-020, lifts off and begins a vertical rise away from Complex 41 at Cape Canaveral Air Force Station, Florida.
|Main Engine Cutoff
|The RD-180 main engine completes its firing after consuming its kerosene and liquid oxygen fuel supply in the Atlas first stage.
|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.
|Centaur Ignition 1
|The Centaur RL10 engine ignites for the longer of the today's two upper stage firings. This burn will inject the Centaur stage and spacecraft into a parking orbit.
|Nose Cone Jettison
|The payload fairing that protected the LRO and LCROSS spacecraft during launch is separated once heating levels drop to predetermined limits.
|Centaur Cutoff 1
|The Centaur engine shuts down after arriving in a planned parking orbit. The vehicle enters a short coast period before arriving at the required location in space for the second burn.
|Centaur Ignition 2
|The Centaur re-ignites to accelerate the payloads out of the temporary parking orbit achieved earlier in the launch sequence.
|Centaur Cutoff 2
|At the conclusion of its second firing, the Centaur will have propelled the LRO and LCROSS spacecraft on their trajectory toward the Moon.
|NASA's Lunar Reconnaissance Orbiter is released from the Centaur upper stage to begin its four-day cruise to the Moon.
|The Centaur upper stage begins a safing sequence to deplete its remaining propellant and maneuvering fuel in preparation for the LCROSS mission. Official handover of the rocket stage to LCROSS is expected at T+plus 4 hours, 1 minute and 14 seconds.