Dec 16 02:58L-30 minutesNow standing by for the final pre-flight weather assessment from the Space Force's launch weather officer.We are a half-hour away from our high-performance Atlas V 551 rocket heading to space carrying the next batch of Amazon Leo satellites. The launch team is not tracking any technical issues at this time.
Dec 16 02:59Weather is GOWeather is observed and forecast GO for liftoff a half-hour from now, according to the countdown's final planned briefing by the launch weather officer.
Dec 16 03:01The Automatic Determination and Dissemination of Just Updated Steering Terms, better known as the ADDJUST file, is being loaded into the Atlas V rocket's Inertial Navigation and Control Assembly (INCA) flight computer by the flight control operator here at the Launch Control Center.This is the planned steering parameters for the INCA to use based on today's upper level wind conditions.A series of weather balloons has been launched throughout the countdown from the Range weather station at the Cape to collect measurements of wind speeds and directions to determine if conditions aloft violate the controllability or structural loads on the rocket during ascent. The balloon data was transmitted to ULA engineers in Denver to select a steering profile that minimizes launch vehicle responses.
Dec 16 03:02The fuel fill sequence is beginning. This procedure releases RP-1 kerosene fuel into the RD-180 main engine in preparation for ignition.
Dec 16 03:03Our visibility graphic shows when the Atlas V rocket will rise into view for spectators across Florida and the Eastern Seaboard today. This nighttime launch should be visibile for hundreds of miles around.
Dec 16 03:05The live video broadcast of today's liftoff is about to begin in the embedded YouTube stream on this page.
Dec 16 03:08Now 20 minutes away from the opening of today's 29-minute launch window for Atlas V to take flight with Leo 4.Here's some key facts and figures about Amazon Leo. The initial constellation size is more than 3,000 satellites in low Earth orbit. The initial constellation will cover areas between 56 degrees north and south of the equator. Amazon Leo plans to expand the constellation over time, extending coverage to virtually any location on the planet.As for performance, the enterprise-grade terminal (Leo Ultra) will provide downlink speeds up to 1 Gbps. The compact, high-performance terminals Leo Pro and Leo Nano will provide downlink speeds up to 400 Mbps and 100 Mbps, respectively.Amazon Leo will connect tens of millions of customers around the world.
Dec 16 03:09Upper-level winds have been verified acceptable for launch.
Dec 16 03:11In the countdown, we have completed the fuel fill sequence to ready the first stage main propulsion system for launch.
Dec 16 03:12Status continues to be green across the board. Weather remains in our favor this morning, no technical issues are being addressed with the launch vehicle or pad systems and we are on schedule for liftoff.
Dec 16 03:13This is Atlas Launch Control, now passing L-minus 15 minutes for the Atlas V rocket and Amazon Leo, the low Earth orbit satellite broadband network. Its mission is to provide fast, reliable internet to customers around the world, including those in unserved and underserved communities, using a constellation of more than 3,000 LEO satellites.
Dec 16 03:14Vehicle Systems Engineer is polling the Denver technical team comprised of specialists in the various hardware and technology disciplines on the Atlas V. The experts have conducted evaluation of rocket data and systems performance throughout the countdown.The results of this poll will be routed to the ULA director of engineering, who will then supply his readiness to launch when polled by the ULA launch director.
Dec 16 03:16In just a few minutes, you'll hear ULA Launch Conductor Scott Barney, from his console in the Advanced Spaceflight Operations Center, perform the readiness poll to enter terminal count."The primary responsibility for the launch conductor (LC) is to lead the launch team to liftoff. The LC orchestrates the launch flow, allowing the individual systems operators to focus on their detailed tasks," Barney says."Much of this work is planned in advance of launch day with the know mission unique specifics that impact the launch count. On launch day, the LC needs to assess real-time changes that impact the operation and determine a path forward to meet the limited window."This is Barney's 29th Atlas V launch as the mission's launch conductor. He also has done 23 Delta IV launches, a pair of Delta II missions and one Vulcan.
Dec 16 03:17ULA Launch Conductor Scott Barney has been notified by the Amazon spacecraft team that the payload has successfully switched to flight mode. This puts the Amazon Leo hardware atop the Atlas V into the correct launch configuration.At T-minus 4 minutes and holding with 7 minutes remaining in the built-in hold, this is Atlas Launch Control.
