Atlas 5 Launch Countdown From Cape Canaveral Begins – Spaceflight Now

Live coverage of the countdown and launch of a United Launch Alliance Atlas 5 rocket from Pad 41 at Cape Canaveral Space Force Station in Florida. The mission, known as USSF 12, will place the US Space Force’s Wide Field of View Testbed satellite and the USSF 12 ring spacecraft in geostationary orbit. Text updates will automatically appear below. follow us on Twitter.

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A United Launch Alliance Atlas 5 rocket is poised to launch two experimental US Space Force satellites into geostationary orbit in a six-hour mission starting Thursday from Cape Canaveral. The two-hour launch window opens at 6 p.m. EDT (2200 GMT).

The official launch forecast from the 45th Space Force Weather Squadron has a 40% chance of favorable weather when the window opens on Thursday. The forecast improves later in the window when there is a 60% chance of favorable launch conditions.

The mission, codenamed USSF 12, will be the fourth Atlas 5 flight of the year and the 94th launch of an Atlas 5 rocket overall. It is one of 23 Atlas 5s remaining in ULA’s inventory before the missile is retired. ULA, a 50:50 joint venture between Boeing and Lockheed Martin, is developing the next-generation Vulcan Centaur rocket to replace the Atlas and Delta rocket families.

One of the mission’s payloads is the Space Force’s Wide Field Of View (WFOV) testbed satellite to demonstrate a new infrared sensor capable of detecting and tracking missile launches and providing early warning of a possible attack by allied nations on the to warn the United States.

The WFOV spacecraft will fly into space in the upper part of the Atlas 5 rocket’s payload compartment. A secondary payload called the USSF 12 Ring will be positioned under the WFOV spacecraft for launch. It houses several payloads, experiments and prototypes, but details of their missions are classified.

A Space Force spokesman told Spaceflight Now the entire USSF 12 mission, including payloads and launch services, cost about $1.1 billion.

ULA’s Atlas 5 rocket on the launch pad prior to the USSF-12 mission. Photo credit: United Launch Alliance

The countdown to Thursday’s launch began at 10:40 am EDT (1440 GMT). ULA teams planned to turn on the Atlas 5 flight computer, check the missile’s guidance system, and then configure the vehicle to begin cryogenic refueling around 4:00 p.m. EDT (2000 GMT).

Almost 66,000 gallons of liquid hydrogen and liquid oxygen will be loaded into the two-stage Atlas 5 rocket. The Centaur upper stage’s Aerojet Rocketdyne RL10 engine burns the hydrogen-oxygen propellant mixture, and the Atlas first stage consumes liquid oxygen with 25,000 gallons of room-temperature kerosene fuel that was loaded into the rocket Wednesday, shortly after ULA ground crews confirmed the Atlas 5 rolled down the launch pad from the nearby Vertical Integration Facility.

Two built-in holding patterns are scheduled in the countdown, one at T-minus 2 hours and one at T-minus 4 minutes, before the final four-minute terminal countdown sequence begins in preparation for the launch of the Atlas 5 rocket.

The rocket’s fuel tanks are pressurized and the RD-180 engine ignites at T-minus 1 second. After building up thrust on the main engine, the Atlas 5 will send the command to fire four Northrop Grumman strap-on solid rocket boosters to propel Pad 41’s launch vehicle with 2.3 million pounds of thrust.

The version of the Atlas 5 launched on the USSF 12 mission is known as the “541” configuration, with the first number indicating the payload fairing size, the second number indicating the number of solid rocket boosters, and the third number indicating the number of engines on the Centaur stage.

The 59.7 meter tall Atlas 5 rocket, designated AV-094 for this mission, will fly east from Cape Canaveral to target the mission’s equatorial orbit more than 22,000 miles (almost 36,000 kilometers) above the Earth.

The Atlas 5 will surpass the speed of sound in 58 seconds, then shed its spent strap-on boosters at T+ plus 1 minute, 48 seconds. The 5.4 meter wide (17.7 ft) composite payload fairing will jettison at T+ plus 3 minutes 25 seconds and the Russian-made RD-180 core stage engine will fire at T+ plus 4 minutes 24 seconds.

This graphic illustrates the components of the Atlas 5 rocket for the USSF-12 mission. Photo credit: United Launch Alliance

The USSF-12 mission marks the 100th flight of an RD-180 engine since it was first launched in May 2000 on an Atlas 3 rocket.

Following the separation of the Atlas first stage, ULA’s Centaur upper stage will take over flight using three firings of its single RL10 engine to first place the two Space Force payloads in parking orbit and then the mission into higher orbits and into trajectory to bring the equator.

Built by Millennium Space Systems, the WFOV testbed spacecraft will separate from the Centaur upper stage at T+ plus 5 hours, 49 minutes. About 10 minutes later, an adapter structure is released, releasing the Northrop Grumman-built USSF 12-ring payload for separation at T+ plus 6 hours 5 minutes.

ROCKET: Atlas 5 (AV-094)


PAYLOAD: WFOV Testbed and USSF 12 ring

STARTING PLACE: SLC-41, Cape Canaveral Space Force space station, Florida


STARTING WINDOW: 18:00-20:00 EDT (2200-0000 GMT)

WEATHER FORECAST: 60% chance of acceptable weather



TARGET ORBIT: Approximately 22,440 miles, 0.0 degree inclination


  • T-00:00:01.0:RD-180 ignition
  • T+00:00:01.0: Take off
  • T+00:00:06.9: Begin pitch/yaw maneuvers
  • T+00:00:57.8: Mach 1
  • T+00:01:07.4: Maximum Aerodynamic Pressure (Max-Q)
  • T+00:01:48.4: Solid Rocket Launcher Drop
  • T+00:03:25.6: Payload Fairing Drop
  • T+00:04:24.3: Atlas Booster Engine Shutdown (BECO)
  • T+00:04:30.3: Atlas/Centaur stage separation
  • T+00:04:40.2: Centaur first main engine launch (MES-1)
  • T+00:10:58.2: Centaur first main engine shutdown (MECO-1)
  • T+00:23:13.6: Centaur second main engine launch (MES-2)
  • T+00:28:41.9: Centaur second main engine shutdown (MECO-2)
  • T+05:43:54.1: Centaur third main engine launch (MES-3)
  • T+05:46:20.0: Centaur Third Main Engine Shutdown (MECO-3)
  • T+05:49:36.0: WFOV testbed spacecraft separation
  • T+05:59:03.9: Booster Adapter Separation
  • T+06:05:21.0: USSF 12-ring spacecraft separation


  • 676th start for the Atlas program since 1957
  • 377. Atlas launch from Cape Canaveral
  • 265. Mission of a Centaur upper stage
  • 242. Centaur deployed by an Atlas missile
  • Launch of the 512th series RL10 engine
  • 40. RL10C-1 engine started
  • 100th flight of an RD-180 main engine
  • 94th launch of an Atlas 5 since 2002
  • 36th US Air Force / Space Force deployment of an Atlas 5
  • 14-17 GEM-63 solid rocket booster flown
  • 78. Launch of an Atlas 5 from Cape Canaveral
  • 4. Atlas 5 launch in 2022
  • 136th Evolved Expendable Launch Vehicle Flight
  • 151st United Launch Alliance flight overall
  • 86. Atlas 5 under United Launch Alliance
  • 109th United Launch Alliance flight from Cape Canaveral
  • 35th flight of the 500 series of the Atlas 5
  • 9. Atlas 5 flying in the 541 configuration
  • 105. Launch of Complex 41
  • 78. Atlas 5 to use Complex 41
  • 28th overall orbital launch from Cape Canaveral in 2022

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