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NASA, Boeing prepares its Starliner OFT to dock with ISS

Updated: May 20, 2022

Spacecraft will make a second unmanned flight, and it should dock with the ISS

Atlas V N22 AV-082

NASA and Boeing will launch the Starliner CST-100 spacecraft, (designated number S2.1) designed to transport astronauts to the International Space Station, on its second unmanned test flight. The liftoff time today, May 19, 2022, has been established for the Atlas V rocket to send Starliner into convergence orbit with the International Space Station. Based on the most recent calculations of when the station's orbital plane will pass over the Cape Canaveral platform, the launch will take place at 18:54:47 EDT (22:54:47 UTC). Liftoff will be from Space Launch Complex-41 at Cape Canaveral Space Force Station, Florida. The United Launch Alliance Atlas V N22 Rocket (with tail number AV-082) assigned for this OFT-2 mission, will launch the Boeing spacecraft.

Part of NASA's Commercial Crew Program (CCP), the unmanned OFT is Starliner's second launch. The second uncrewed test flight will demonstrate the end-to-end performance of the rocket and spacecraft, including the guidance, navigation and control systems, ground systems and operations teams, as well as in orbit, docking, entry and landing operations. Starliner will land at one of five designated locations in the western United States.

The mission, called Orbital Flight Test 2, OFT-2, is a redo – this time complete, it is expected – of the OFT-1 launched in December 2019 and which suffered software glitches that prevented docking with the station. This test flight is the last major step before the Atlas V and Starliner capsule will take American astronauts to the ISS as part of NASA's Commercial Crew Program.

Atlas V atop Starliner SC2.1 poised at LC-41, Cape Canaveral (Photo Credit: NASA)

The rocket will take the spacecraft on a suborbital trajectory of 181.496 km. The first stage will follow a trajectory that will place the Centaur stage in a 182 km x 73 km orbit, with the spacecraft making a perigee lift thrust 16 minutes after separation. In an animation by the ULA of last May 12, the altitude at which the separation of Starliner from Centaur would occur would be even lower: 162 km at the moment of Tcp + ~ 890 seconds.

Risk factor; The specific impulse of OMAC engines, which perform orbital maneuvers, is about 288 seconds, with a thrust of 7,000 newtows (7 kN). The time to reach 90% thrust is less than 5 milliseconds. With a launch weight of the spacecraft at around 13,250 kg, the propellant consumption should be more than enough for the docking with the ISS and still allow clearance in subsequent maneuvers.

After the separation of the Atlas V, the engines of Starliner will be activated, taking it for the rest of the trajectory in orbit to the space station, docking with the PMA-2/IDA-2 forward docking port on the American module Harmony.

ATLAS V N22/ CFT-100 Starliner Factsheet (Credit: NASA)

Modified specifically for the CST-100, the Atlas V configuration does not include a payload fairing. Instead, the craft's insulated surfaces replace the usual head fairing to protect the unmanned spacecraft during ascent. The length of the rocket with the spacecraft is approximately 52.4 meters.