A United Launch Alliance Delta 4 rocket will deliver the U.S. Air Force’s tenth Wideband Global SATCOM communications satellite to a supersynchronous transfer orbit around 37 minutes after lifting off from Cape Canaveral.
Liftoff is scheduled during a launch window opening at 6:56 p.m. EDT (2256 GMT) Friday. The window extends to 9:05 p.m. EDT (0105 GMT).
The United Launch Alliance Delta 4 rocket takes off powered by an Aerojet Rocketdyne RS-68A main engine and four solid rocket boosters built by Northrop Grumman Innovation Systems. The hydrogen-burning main engine ignites at T-minus 5 seconds, following by ignition of the four boosters at T-minus 0, the release of four hold-down bolts and retraction of the launch pad’s three swing arms.
T+00:00:47.2 — Max-Q
Heading east from Cape Canaveral with a launch azimuth of 93.46 degrees, the Delta 4 experiences the most extreme aerodynamic pressures at this point in the mission.
T+00:01:40.0 — Solid Rocket Motor Separation
The Delta 4’s four GEM-60 solid rocket boosters are jettisoned in two pairs around seven seconds after consuming all their propellant.
T+00:03:19.0 — Payload Fairing Jettison
The Delta 4’s composite bisector fairing jettisons from the rocket once the launcher reaches a safe altitude above the dense lower layers of Earth’s atmosphere.
T+00:03:55.8 — Booster Engine Cutoff
The Delta 4’s RS-68A main engine shuts down after burning its supply of super-cold liquid hydrogen and liquid oxygen.
T+00:04:02.3 — Stage Separation
The Delta 4’s Common Booster Core separates from the rocket’s second stage.
T+00:04:15.3 — First Second Stage Ignition
The Delta 4’s second stage Aerojet Rocketdyne RL10B-2 engine ignites and powers up to 24,750 pounds of thrust in the first of its two firings to place the WGS 10 satellite into a supersynchronous transfer orbit.
T+00:19:29.6 — First Second Stage Engine Shutdown
The second stage’s RL10B-2 engine shuts down after placing the WGS 10 satellite in a preliminary parking orbit, beginning a 10-minute coast before the engine reignites.
T+00:29:29.6 — Second Stage Engine Restart
The RL10B-2 second stage engine ignites again to send WGS 10 into a higher, elliptical supersynchronous transfer orbit.
T+00:32:50.0 — Second Stage Engine Shutdown
After a burn lasting nearly three-and-a-half minutes, the RL10B-2 second stage engine shuts down to end its second firing on the WGS 10 mission.
T+00:36:50.0 — WGS 10 Separation
The Boeing-built WGS 10 communications satellite separates from the Delta 4 rocket’s second stage in a targeted orbit ranging between 269 miles (433 kilometers) and 27,536 miles (44,315 kilometers) in altitude, with an inclination of 27 degrees to the equator. WGS 10 will use its on-board propulsion system, using a liquid-fueled main engine and plasma thrusters, to maneuver into a circular geostationary orbit around four months after launch, where it will begin final checkouts and enter service for the U.S. Air Force. The Delta 4’s RL10B-2 engine will reignite at T+plus 1 hour, 12 minutes, for a 10-second firing to aim for a destructive re-entry over the Pacific Ocean around 12 hours after liftoff.
Keith Gendreau, an astrophysicist at NASA’s Goddard Space Flight Center, recently spoke with Spaceflight Now about a new experiment on the International Space Station to demonstrate X-ray communications in space for the first time.
A United Launch Alliance Atlas 5 rocket departs Vandenberg Air Force Base today at 10:30 a.m. local time (1:30 p.m. EST; 1830 GMT) to deliver the commercial WorldView 4 Earth-imaging satellite into polar orbit for DigitalGlobe.
Elon Musk, SpaceX’s founder and CEO, did his best to set low expectations heading into the first test flight of the gargantuan Super Heavy booster and Starship rocket this week. “Just don’t blow up the launch pad,” Musk said.
