CST-100

The Boeing CST-100 Starliner
is a class of two partially reusable spacecraft designed to transport crew to the International Space Station (ISS) and other low-Earth-orbit destinations. It is manufactured by Boeing for its participation in NASA's Commercial Crew Program (CCP). The spacecraft consists of a reusable crew capsule and an expendable service module.

The capsule has a diameter of , which is slightly larger than the Apollo command module and SpaceX Dragon 2, and smaller than the Orion capsule. The Boeing Starliner holds a crew of up to seven people and is designed to be able to remain docked to ISS for up to seven months with reusability of up to ten missions. Starliner launches atop the Atlas V launch vehicle.

After several rounds of competitive development contracts within the Commercial Crew Program starting in 2010, NASA selected the Boeing Starliner, along with SpaceX Crew Dragon, for the Commercial Crew Transportation Capability (CCtCap) contract round. The first crewed test flight test was initially planned to occur in 2017.

In late 2019, the uncrewed Boeing Starliner Orbital Flight Test (Boe-OFT) launched on an Atlas V N22 and reached orbit, but the flight was not successful, failing to meet test objectives and returning to earth early. NASA allowed Boeing a repeat test flight, Boe-OFT 2, which was to launch in August 2021, but was scrubbed before launch due to inoperable valves in the propulsion system. After replacing the spacecraft's service module, Boeing targeted OFT-2 to occur in May 2022 at the earliest. OFT-2 ended up launching on May 19, 2022. The craft suffered several anomalies during its flight but controllers were able to work around them and Boeing and NASA expressed confidence in the spacecraft. The first crewed launch is scheduled for no earlier than April 2023.

Spacecraft characteristics

Boeing's Starliner spacecraft is designed to accommodate seven passengers, or a mix of crew and cargo, for missions to low Earth orbit. For the NASA service missions to the ISS, it will carry four passengers and small cargo. Starliner uses a weldless structure and is reusable up to 10 times with a six-month turnaround time. Boeing plans to alternate between two reusable crew modules for all planned Starliner missions. Each flight uses a new service module, which provides propulsion and power-generation capacity for the spacecraft. It features wireless Internet and tablet technology for crew interfaces.

Starliner uses the NASA Docking System for docking. Boeing modified the design of the Starliner docking system prior to OFT-2, adding a hinged re-entry cover below the expendable nosecone for additional protection during the capsule's fiery descent through the atmosphere, similar to the one used in the SpaceX Dragon 2 nosecone. This was tested on the OFT-2 mission. This re-entry cover is hinged, like the SpaceX design. The capsule uses the Boeing Lightweight Ablator for its heat shield.

Solar cells, provided by Boeing subsidiary Spectrolab, are installed onto the aft face of the spacecraft's service module, and provide 2.9  kW of electricity. Also on the service module are four Rocketdyne RS-88 engines burning hypergolic propellants, which will be used for launch escape capability in the event of an abort. Starliner is designed to be compatible with multiple launch vehicles, including the Atlas V, Delta IV, and Falcon 9, as well as the in-development Vulcan Centaur.

In addition to the capsule and service module, a structure is integrated into the launch vehicle adapter of Atlas V, called aeroskirt, to provide aerodynamic stability and dampen the shock waves that come from the front of the rocket.

History

Starliner was unveiled in 2010 as the ''CST-100'', as Boeing's first commercially developed space capsule, where the company would take on the financial risk for development, rather than the US government under cost-plus contract, Space Shuttle and ISS programs as well as the Orbital Express project sponsored by the Department of Defense. The new design was intended to be compatible with multiple launch vehicles, including the ULA Atlas V and Delta IV, and the SpaceX Falcon 9 at the time, In July 2010, Boeing stated that the capsule could be operational as early as 2015 with sufficient near-term approvals and funding.

In October 2011, NASA announced that the Orbiter Processing Facility-3 at Kennedy Space Center would be leased to Boeing for manufacture and test of Starliner, through a partnership with Space Florida.

On September 16, 2014, NASA chose Boeing (Starliner) and SpaceX (Crew Dragon) as the two companies to be funded to develop systems to transport U.S. government crews to and from the International Space Station. Boeing won a US$4.2 billion contract to complete and certify the Starliner by 2017, while SpaceX won a US$2.6 billion contract to complete and certify their crewed Dragon spacecraft. The contracts include at least one crewed flight test with at least one NASA astronaut aboard. Once the Starliner achieves NASA certification, the contract requires Boeing to conduct at least two, and as many as six, crewed missions to the space station. NASA's William H. Gerstenmaier had considered the Starliner proposal as stronger than the Crew Dragon and Sierra Nevada's Dream Chaser spacecraft.
, the capsule was to include one space tourist seat, and the Boeing contract with NASA would allow Boeing to price and sell passage to low-Earth orbit using that seat.

On September 4, 2015, Boeing announced that the spacecraft would officially be called the CST-100 Starliner, following the naming conventions of the 787 Dreamliner produced by Boeing Commercial Airplanes. In November 2015, NASA announced that it had dropped Boeing from consideration in the multibillion-dollar Commercial Resupply Services second-phase competition to fly cargo to the International Space Station.

In May 2016, Boeing delayed its first scheduled Starliner launch from 2017 to early 2018. Then in October 2016, Boeing delayed its program by six months, from early 2018 to late 2018, following supplier holdups and a production problem on the Spacecraft 2. By 2016, they were hoping to fly NASA astronauts to the ISS by December 2018.

In April 2018, NASA suggested that the first planned two-person flight of the Starliner, slated for November 2018, was now likely to occur in 2019 or 2020. If there are no further delays, it would be expected to carry one additional crew member and extra supplies. Instead of staying for two weeks, as originally planned, NASA said that the expanded crew could stay at the station for as long as six months as a normal rotational flight.

In November 2019, NASA's Office of Inspector General released a report revealing that a change to Boeing's contract had occurred, stating: "For Boeing’s third through sixth crewed missions, we found that NASA agreed to pay an additional $287.2 million above Boeing’s fixed prices to mitigate a perceived 18-month gap in ISS flights anticipated in 2019 and to ensure the contractor continued as a second commercial crew provider".

After the failure of its first uncrewed orbital test flight in late 2019, NASA agreed that Boeing would fund another uncrewed orbital test in August 2021. That launch was stopped late in the countdown due to valve problems. By late September 2021, Boeing had not determined the root cause of the problem, and the flight was delayed indefinitely. The first crewed test will be deferred until after this uncrewed test.

Funding

Boeing funded development of Starliner in 2010 only after both commercial space station opportunities and NASA commercial crew contracts on offer allowed the business case to close. While the company had received $18 million under the NASA Commercial Crew Development (CCDev) contract by 2010 for early design work, substantial Boeing private funds would be required to complete development, even with Boeing competing for additional NASA contracts. This exposed Boeing to ordinary business financial risk that had not been a large part of traditional cost-plus contract

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