First Crewed Starliner Is Finally On The Launch Pad

Preparations for Boeing’s Starliner Crewed Flight Test (CFT) are ending as we approach the launch date, scheduled for May 7 from Cape Canaveral’s Space Launch Complex 41.

After a troubled development history, Boeing implemented the final modifications requested by NASA last year. Now, the CST-100 capsule is integrated on top of the United Launch Alliance (ULA) Atlas V rocket, ahead of its launch towards the International Space Station (ISS).

Final procedures

The Crew Module and the Service Module had previously been weighted to get highly accurate measurements of the individual elements and their center of gravity. On April 15 the teams conducted final weigh-ins of the spacecraft after being mated, loaded, and fueled. These measurements are crucial to the nominal performance of both the integrated spacecraft and launch vehicle during ascent, on-orbit maneuvers, and reentry.

The center of gravity of the mated modules has to be within a volume about the size of an American quarter. To make such highly accurate measurements an ultra-high sensitivity instrument is required. The Boeing CST-100 Starliner was tested on the WCG High-Accuracy Series developed by Raptor Scientific.

These instruments feature a load cell system to measure the location of the center of gravity using a weighted average and can test items up to 1300 kg with extreme accuracy in less than one minute.

After weight and CG measurements, on April 16, at 09:00 UTC, the Starliner rolled out from the Boeing Commercial Crew and Cargo Processing Facility. The spacecraft, on board the ULA’s transport vehicle known as KMAG, made a slow 16-kilometer trek to the launch complex.

Once there, technicians lifted and connected the spacecraft on top of the ULA’s Atlas V rocket. Work will continue to ensure the correct functioning of both the Starliner and the launcher, meanwhile, the astronauts Willmore and Williams will finish flight preparations in Huston and arrive at NASA Kennedy on April 25. The two NASA astronauts will stay on board the ISS for a week before returning to Earth.

Starliner: a long story

NASA’s Commercial Crew Program has worked with several American aerospace industry companies to facilitate the development of U.S. human spaceflight systems since 2010. The goal was to have safe, reliable, and cost-effective access to and from the ISS, and foster commercial access to other potential low-Earth orbit destinations.

NASA selected Boeing and SpaceX in September 2014, but since then Boeing’s Starliner faced many issues, extending its first crewed flight to May 2024, four years later than its counterpart, SpaceX’s Crew Dragon, which carried astronauts to the ISS for the first time in November 2020.

In December 2019, during the first Orbital Flight Test (OFT-1) a software error caused the spacecraft to activate the thrusters in a wrong way, right after separation from the launcher. This led NASA and Boeing to bring back the capsule without any approach with the ISS.

In May 2022, during the second Orbital Flight Test (OFT-2) the spacecraft docked with the ISS and achieved all flight test objectives, with only some issues to refine.

Subsequently, the first Crewed Flight Test, firstly scheduled for April 2023, was delayed to July 2023 due to additional tests on the parachute system and batteries. Another reason for the postponement was the significant traffic at ISS in spring 2023. 

After a period of testing, new concerns about the readiness of Starliner caused the crewed launch to be delayed indefinitely. Critical issues included ongoing integrated software testing and potential risks of battery sidewall rupture. It was then discovered a problem with the parachute system and flammable tape around the wiring harnesses inside the vehicle. 

A new target window was finally declared by NASA and Boeing during a media teleconference on August 7, 2023: the spacecraft would be ready for launch by March 2024.