The Boeing CST-100 Starliner and United Launch Alliance (ULA) Atlas V rocket soared across the sky May 19 for the Orbital Flight Test-2 (OFT-2), lifting off at 6:54 p.m. ET.
The Atlas V RD-180 main engine and two solid rocket boosters ignited, generating more than a million and half pounds of thrust to lift the rocket away from the pad. The Atlas V immediately began pitching over to attain the proper flight path, while minimizing the dynamic pressure the vehicle experiences during flight.
Ten seconds after liftoff, flight controllers confirmed the Starliner’s Mission Elapsed (MET) timer was operating as intended. Twelve seconds into the flight, the Atlas V rolled to a “heads up” position and used booster engine throttling to limit the vehicle’s acceleration to 3.5 g’s. This will provide crew safety and comfort during future flights with astronauts for NASA’s Commercial Crew Program.
At about 45 seconds, the rocket carrying Starliner entered Max Q, or maximum aerodynamic pressure. This was the moment where the rocket experienced the highest mechanical stress. A little over a minute into the flight, the Atlas V reached Mach One or the speed of sound.
One minute and 35 seconds after liftoff, the solid rocket boosters (SRBs) burned out, running out of fuel. About a minute later, the SRBs successfully jettisoned or separated from the rocket.
The Starliner’s ascent cover jettisoned nearly five minutes after liftoff. The ascent cover protected critical hardware on top of the spacecraft and provided an aerodynamic shape for ascent through the atmosphere.
The Centaur upper stage then ignited, pushing Starliner to near orbital speeds. The Centaur generated 44,600 pounds of thrust to shape the desired trajectory for Starliner to reach the International Space Station. The single burn of the Centaur lasted about 7 minutes and 10 seconds.
Out of the Earth’s atmosphere and no longer needing the additional aerodynamic support, the Starliner then jettisoned its aeroskirt. The aeroskirt extended the Starliner’s surface, enhancing its aerodynamic characteristics and stability. It also minimized the loads of this unique crewed configuration.
Nearly 12 minutes into flight, the Centaur’s upper stage main engines cut off, also known as MECO. The mission has now entered a sub-orbital coast phase in preparation for spacecraft separation.
Centaur’s sub-orbital trajectory design enhances crew safety by providing a shallow orbit more favorable for an abort if required, and ensures the Centaur will naturally de-orbit, impacting the ocean off the southwest coast of Australia.
At about 14 minutes and 55 seconds, Centaur released the Starliner. Coming up next is the orbital insertion burn of the Starliner spacecraft.