The US space agency, the National Aeronautics and Space Administration (Nasa), has reported that the Boeing CST-100 Starliner crewed space craft and its launch rocket, a United Launch Alliance (ULA) Atlas V, have been fully assembled at ULA’s Vertical Integration Facility (VIF) at Cape Canaveral Space Force Station, in the state of Florida. The Starliner is currently scheduled to be launched by the Atlas V on July 30.

This flight will be the Starliner’s second uncrewed demonstration test flight. This second such flight was made necessary by the failure of the first one, in December 2019, to meet all its required objectives. This resulted in a number of modifications being made to the Starliner, mainly regarding its software.

The Boeing Starliner is meant to be the competitor system to SpaceX’s Crew Dragon under Nasa’s Commercial Crew Programme (CCP). However, Boeing’s system is currently running 18 or more months behind that of SpaceX – already, two crews have been carried to the International Space Station (ISS) on commercial Crew Dragon flights (in addition to the original crewed test flight of the ship).

CCP was created by Nasa to allow it to buy space crew transport services from Earth to the ISS and back, on a commercial basis. This was partly so that the agency could get out of ‘space taxi’ activities and concentrate on developing and operating crewed deeper space exploration vessels (specifically, Orion), partly to reduce costs, and partly to further stimulate the US space industry.

The VIF is a 30-storey tall structure, located at Space Launch Complex-41. When the Starliner capsule arrived at the VIF, it was secured to a four-point lifting sling which was connected to the overhead crane. It was then carefully raised above the Atlas V and then lowered on to the launch vehicle adapter on the top of the rocket, which holds the spacecraft during launch and ascent.

The complete Atlas V/Starliner assembly stands upon a mobile launch platform. The next step is an integrated systems test. This checks out all the electrical systems from the tip of the Starliner to the tail of the Atlas V. Although the mission will be uncrewed, the spacecraft will dock with the ISS, returning to Earth five to ten days later, because the test is intended to confirm that the Starliner is ready to fly humans.