{{Short description|Class of partially reusable crew capsules}} {{Use American English|date=June 2020}} {{Use mdy dates|date=February 2026}} {{Infobox spacecraft class | name = Boeing Starliner | names_list = Boeing CST-100 | image = Boeing's Starliner crew ship approaches the space station (iss067e066735) (cropped).jpg | image_caption = {{ComV|CST-100 Starliner|2|full=nolink}} approaching the ISS in May 2022, during [[Orbital Flight Test 2]] | manufacturer = [[Boeing Defense, Space & Security]] | website = {{URL|boeing.com/starliner}} | country = United States | operator = Boeing Defense, Space & Security | applications = [[International Space Station|ISS]] crew transport | spacecraft_type = [[Space capsule|Capsule]] | launch_mass = | dry_mass = | payload_capacity = To [[International Space Station|ISS]]: 4 crew and {{cvt|100|kg}} cargo<ref name="CCpresskit2">{{Cite news |date=October 1, 2015 |title=Commercial Crew Program Press it |url=https://www.nasa.gov/wp-content/uploads/2015/10/commercial_crew_press_kit_2.pdf?emrc=d5924a |url-status=live |archive-url=https://web.archive.org/web/20240326185648/https://www.nasa.gov/wp-content/uploads/2015/10/commercial_crew_press_kit_2.pdf?emrc=d5924a |archive-date=March 26, 2024 |access-date=March 28, 2024 |publisher=NASA}}</ref>{{efn|The first piloted [[Boeing Crew Flight Test]] mission carries 2 crew plus {{cvt|344|kg}} of cargo.<ref name="PackingStarline">{{Cite news |date=February 28, 2024 |title=Packing Starliner cargo is a balancing act |url=https://www.boeing.com/features/2024/02/packing-starliner-cargo-is-a-balancing-act |url-status=live |archive-url=https://web.archive.org/web/20240328140136/https://www.boeing.com/features/2024/02/packing-starliner-cargo-is-a-balancing-act |archive-date=March 28, 2024 |access-date=March 28, 2024 |publisher=Boeing}}</ref>}} | crew_capacity = Up to 7 | volume = {{cvt|11|m3}}<ref name="gunther">{{Cite web |last=Krebs |first=Gunther |date=April 2017 |title=Starliner (CST-100) |url=http://space.skyrocket.de/doc_sdat/cst-100.htm |url-status=live |archive-url=https://web.archive.org/web/20170503060306/http://space.skyrocket.de/doc_sdat/cst-100.htm |archive-date=May 3, 2017 |access-date=April 11, 2017 |publisher=Gunther's Space Page}}</ref> | orbits = [[Low Earth orbit]] | design_life = {{plainlist| * 60 hours (free flight)<ref name="Jonsey211">{{Cite conference |last1=Reiley |first1=Keith |last2=Burghardt |first2=Michael |last3=Wood |first3=Michael |last4=Ingham |first4=Jay |last5=Lembeck |first5=Michael |year=2011 |title=AIAA SPACE 2011 Conference & Exposition . September 27–29, 2011. Long Beach, California |doi=10.2514/6.2011-7101 |isbn=978-1-60086-953-2 |archive-url=https://web.archive.org/web/20130501135247/http://www.boeing.com/assets/pdf/defense-space/space/ccts/docs/Space_2011_Boeing.pdf |archive-date=May 1, 2013 |access-date=May 9, 2014 |chapter-url=http://www.boeing.com/assets/pdf/defense-space/space/ccts/docs/Space_2011_Boeing.pdf |chapter=Design Considerations for a Commercial Crew Transportation System |url-status=dead}}</ref> * 7 months (docked)<ref name="avweek20130724">{{Cite news |last=Carreau |first=Mark |date=July 24, 2013 |title=Boeing Refines {{nowrap|CST-100}} Commercial Crew Capsule Approach |url=http://aviationweek.com/awin/boeing-refines-cst-100-commercial-crew-capsule-approach |url-status=live |archive-url=https://web.archive.org/web/20140512224455/http://aviationweek.com/awin/boeing-refines-cst-100-commercial-crew-capsule-approach |archive-date=May 12, 2014 |access-date=May 8, 2014 |publisher=Aviation Week}}</ref> }} | length = {{cvt|5.03|m}} (Capsule and {{Abbr|SM|service module}})<ref name="boeing201108" /> | diameter = {{cvt|4.56|m|0}}<ref name="boeing201108">{{Cite web |last=Burghardt |first=Mike |date=August 2011 |title=Boeing CST-100: Commercial Crew Transportation System |url=http://www.boeing.com/assets/pdf/defense-space/space/ccts/docs/CCDev2%20Boeing%20CST-100%20Overview.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130501134630/http://www.boeing.com/assets/pdf/defense-space/space/ccts/docs/CCDev2%20Boeing%20CST-100%20Overview.pdf |archive-date=May 1, 2013 |access-date=May 8, 2014 |publisher=Boeing}}</ref> | status = Active | built = 3 | operational = 2 | retired = 1 | first = Uncrewed: December 20, 2019<br>Crewed: June 5, 2024 | launch_vehicle = [[Atlas V]] N22{{Efn|N22 designates that the Atlas V has no payload fairing, two solid rocket boosters, and two Centaur second-stage engines.|name=N22}} | insignia = [[File:Boeing Starliner logo.svg|250px|frameless|class=skin-invert]] | configuration_image = Diagram-of-CST-100-Starliner with labels.png | configuration_image_size = 300px | configuration_image_caption = Exploded view of the Starliner<br>A: Crew capsule, B: Service module<br>1: Nosecone, 2: Parachute compartment cover, 3: Crew access hatch, 4: {{Abbr|RCS|reaction control system}} thrusters for re-entry, 5: Airbags, 6: [[Atmospheric entry#Ablative|Heat shield]], 7: [[NASA Docking System]], 8: Parachutes, 9: Window, 10: [[Umbilical cable|Umbilical]], 11: Radiators, 12: "Doghouse" with {{Abbr|RCS|reaction control system}} and {{Abbr|OMAC|orbital maneuvering and attitude control}} thrusters, 13: Propellant tanks, 14: Roll control thruster, 15: [[RS-88]] engines for [[Launch escape system|launch escape]], 16: Solar panels }}
The '''Boeing Starliner''' (or '''CST-100'''){{efn|CST is an initialism for Crew Space Transportation.}} is a spacecraft designed to transport crew to and from the [[International Space Station]] (ISS) and other low-Earth-orbit destinations. Under development by [[Boeing]] under [[NASA]]'s [[Commercial Crew Program]] (CCP), it consists of a [[Reusable spacecraft|reusable]] crew [[Space capsule|capsule]] and an expendable [[service module]].
Slightly larger than the [[Apollo command and service module#Command module (CM)|Apollo command module]] or [[SpaceX Dragon 2#Crew Dragon|SpaceX Crew Dragon]], but smaller than the [[Orion (spacecraft)|Orion capsule]], the Starliner can accommodate a crew of up to seven, though NASA plans to fly no more than four. It can remain docked to the ISS for up to seven months and is launched on an [[Atlas V#N22|Atlas V N22]] rocket from [[Cape Canaveral Space Launch Complex 41]] in Florida.
In 2014, NASA awarded Boeing a US$4.2 billion [[fixed-price contract]] to develop and operate Starliner, while SpaceX received $2.6 billion to develop and operate [[Crew Dragon]]. By February 2025, Boeing's effort had exceeded its budget by at least $2{{Nbsp}}billion.
Originally planned to be operational in 2017, Starliner has been repeatedly delayed by problems in management and engineering. The first uncrewed [[Boeing Orbital Flight Test|Orbital Flight Test]] in December 2019 was deemed a partial failure, leading to a [[Boeing Orbital Flight Test 2|second Orbital Flight Test]] in May 2022, which was also subsequently declared a partial failure.
In June 2024, during a Starliner [[Boeing Crew Flight Test|Crew Flight Test]], the capsule's thrusters malfunctioned on approach to the ISS, and NASA concluded that it was too risky to return its astronauts to Earth aboard the spacecraft. Thereafter, in September 2024, the capsule was returned uncrewed. The mission's astronauts, [[Sunita Williams]] and [[Barry Wilmore]], eventually returned to Earth in March 2025 [[SpaceX Crew-9|aboard a SpaceX Dragon capsule]], which resulted in the Starliner mission being declared as a Type A mishap.
== Background == {{further|Development of the Commercial Crew Program}} [[File:KSC-20180619-PH BOE01 0004 (41276984680).jpg|thumb|right|2018 Starliner assembly process]]
As the [[Space Shuttle program]] drew to a close, NASA sought to foster the development of new spaceflight capabilities. Departing from the traditional model of government-owned and operated spacecraft, NASA proposed a different approach: companies would own and operate spacecraft while NASA would act as a customer, purchasing flights as needed. NASA offered funding to support the development of these new vehicles, but unlike previous [[cost-plus contract]]s these new contracts would be [[Fixed-price contract|fixed-price]], placing the [[financial risk]] of cost overruns on the companies themselves.
Boeing had an extensive history of developing vehicles for space exploration, having built the first stage ([[S-IC]]) of the [[Saturn V]] rockets, assembling the [[Lunar Roving Vehicle]]s, and serving as the prime contractor for the [[US Orbital Segment]] of the ISS since 1993. Hence, Boeing was suitable for the commercial spaceflight contracts.<ref>{{Cite news |last=Adam Mann |date=October 25, 2021 |title=The Boeing Company: From rockets to commercial crew |url=https://www.space.com/the-boeing-company |access-date=August 24, 2024 |work=[[Space.com]] |language=en}}</ref><ref>{{Cite web |last=Weiss |first=Stanley I. |date=May 31, 2019 |title=Boeing Company |url=https://www.britannica.com/explore/space/boeing/ |access-date=August 24, 2024 |website=SpaceNext50 {{!}} Encyclopedia Britannica |language=en}}</ref>
In 2010, Boeing unveiled its entry into NASA's Commercial Crew Program competition: the CST-100. The company received initial funding of $18 million in the first round of the Commercial Crew Development (CCDev 1) program to support Starliner's development.<ref name="Bnasa20100201">{{Cite press release |title=NASA Selects Commercial Firms to Begin Development of Crew Transportation Concepts and Technology Demonstrations for Human Spaceflight Using Recovery Act Funds |date=February 1, 2010 |publisher=NASA |url=http://www.nasa.gov/home/hqnews/2010/feb/HQ_C10-004_Commercia_Crew_Dev.html |access-date=June 9, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20100203061828/http://www.nasa.gov/home/hqnews/2010/feb/HQ_C10-004_Commercia_Crew_Dev.html |archive-date=February 3, 2010 |work=press release}}</ref> Additionally, United Launch Alliance, a joint venture between Boeing and Lockheed Martin, secured $6.7 million to develop the [[Emergency Detection System]] to allow its [[Atlas V]] rocket to be [[Human-rating certification|human-rated]] to launch Starliner.<ref name="Bnasa20100201" /> At the time, Boeing expressed optimism that the Starliner could be operational as early as 2015, contingent upon timely approvals and funding.<ref name="sfn20100721">{{Cite news |last=Clark |first=Stephen |date=July 21, 2010 |title=Boeing space capsule could be operational by 2015 |url=http://www.spaceflightnow.com/news/n1007/21boeing/ |url-status=live |archive-url=https://web.archive.org/web/20180622192837/https://spaceflightnow.com/news/n1007/21boeing/ |archive-date=June 22, 2018 |access-date=September 18, 2011 |work=Spaceflight Now}}</ref>
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]].<ref>{{Cite press release |title=NASA Signs Agreement with Space Florida to Reuse Kennedy Facilities |date=October 31, 2011 |publisher=NASA |url=http://www.nasa.gov/home/hqnews/2011/oct/HQ_11-349_KSC_Agreement.html |last1=Weaver |first1=David |last2=Curie |first2=Michael |last3=Philman |first3=Amber |access-date=November 1, 2011 |url-status=live |archive-url=https://web.archive.org/web/20200813001910/https://www.nasa.gov/home/hqnews/2011/oct/HQ_11-349_KSC_Agreement.html |archive-date=August 13, 2020 |first4=Tina |last4=Lange |first5=Paula |last5=Korn}} {{PD-notice}}</ref>
Over the next three years, NASA held three more rounds of development funding, awarding Boeing $92.3 million under CCDev{{Nbsp}}2 in 2011,<ref>{{Cite press release |title=NASA Awards Next Set Of Commercial Crew Development Agreements |date=April 18, 2011 |publisher=NASA |url=http://www.nasa.gov/offices/c3po/home/agreementsfeature.html |access-date=June 9, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20181110083048/https://www.nasa.gov/offices/c3po/home/agreementsfeature.html |archive-date=November 10, 2018}}</ref> $460 million under the Commercial Crew integrated Capability (CCiCap) program in 2012,<ref name="nasa20120803">{{Cite press release |title=NASA Announces Next Steps in Effort to Launch Americans from U.S. Soil |date=August 3, 2012 |publisher=NASA |url=http://www.nasa.gov/centers/kennedy/news/releases/2012/release-20120803.html |access-date=August 3, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120805185336/https://www.nasa.gov/centers/kennedy/news/releases/2012/release-20120803.htm |archive-date=August 5, 2012}}</ref> and $9.9 million under the Certification Products Contract (CPC) in 2013.<ref name="CPC1">{{Cite press release |title=NASA Awards Contracts In Next Step Toward Safely Launching American Astronauts From U.S. Soil |date=December 10, 2012 |publisher=NASA |url=http://www.nasa.gov/centers/kennedy/news/releases/2012/release-20121210.html |access-date=December 11, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20201021001939/https://www.nasa.gov/centers/kennedy/news/releases/2012/release-20121210.html |archive-date=October 21, 2020}}</ref>
NASA was expected to announce its selection for the lucrative Commercial Crew Transportation Capability (CCtCap) contract in September 2014. Boeing had lobbied NASA for a sole-source contract, arguing that it needed the program's full budget for the successful development of Starliner. Within NASA, there was considerable support for this approach, with many decision-makers expressing confidence in Boeing's capabilities and safety record. In fact, NASA officials had even drafted a justification for selecting Boeing as the sole provider.<ref name="Berger Reentry">{{Cite book |last=Berger |first=Eric |author-link=Eric Berger (journalist) |title=Reentry: SpaceX, Elon Musk, and the Reusable Rockets that Launched a Second Space Age |publisher=BenBella Books |year=2024 |isbn=978-1637745274 |pages=270–275}}</ref>
While [[William H. Gerstenmaier]], NASA's human exploration lead, had considered the Starliner proposal as stronger,<ref name="avweek20141013">{{Cite news |last=Norris |first=Guy |date=October 11, 2014 |title=Why NASA Rejected Sierra Nevada's Commercial Crew Vehicle |url=http://aviationweek.com/space/why-nasa-rejected-sierra-nevadas-commercial-crew-vehicle |url-status=dead |archive-url=https://web.archive.org/web/20141013135535/http://aviationweek.com/space/why-nasa-rejected-sierra-nevadas-commercial-crew-vehicle |archive-date=October 13, 2014 |access-date=October 13, 2014 |work=[[Aviation Week]]}}</ref> he was hesitant to award a sole-source contract. The multi-year Commercial Crew Program had been designed to foster competition and redundancy, and Gerstenmaier believed that selecting just one company would undermine these goals.<ref name="Gerstenmaier 2014">{{Cite web |last=Gerstenmaier |first=William H. |author-link=William H. Gerstenmaier |date=September 15, 2014 |title=Source Selection Statement for Commercial Crew Transportation Capability Contract |url=https://www.nasa.gov/wp-content/uploads/2019/08/CCtCap-Source-Selection-Statement-5083.pdf |access-date=August 24, 2024 |website=[[NASA]]}}</ref> Through his efforts, he successfully convinced NASA to delay the CCtCap announcement and secure additional funding to support two competing efforts.<ref name="Berger Reentry" />
On September 16, 2014, NASA announced that both Boeing and [[SpaceX]] would be awarded CCtCap contracts to develop crewed spacecraft. Boeing received a US$4.2 billion to complete and certify the Starliner, while SpaceX received a US$2.6 billion to complete and certify [[Crew Dragon]].<ref name="Gerstenmaier 2014" /> To receive the full contract amount, each company would need to successfully complete [[Launch escape system|an abort test]], an uncrewed orbital flight test, a crewed orbital flight test, and six crewed missions to the ISS. However, NASA would not need to pay for any failed tests and was only required to purchase two crewed missions to the ISS from each company.<ref name="September2014">{{Cite web |last1=Schierholz |first1=Stephanie |last2=Martin |first2=Stephanie |date=September 16, 2014 |title=NASA Chooses American Companies to Transport U.S. Astronauts to International Space Station |url=http://www.nasa.gov/press/2014/september/nasa-chooses-american-companies-to-transport-us-astronauts-to-international |url-status=live |archive-url=https://web.archive.org/web/20160609184223/http://www.nasa.gov/press/2014/september/nasa-chooses-american-companies-to-transport-us-astronauts-to-international/ |archive-date=June 9, 2016 |access-date=September 18, 2014 |publisher=NASA}} {{PD-notice}}</ref> Following the initial guaranteed missions, the companies would compete for launch contracts on an ongoing basis.
In November 2015, NASA announced that it had dropped Boeing from consideration in the separate multibillion-dollar [[Commercial Resupply Services]] competition to fly cargo to the International Space Station.<ref name="sfinside20151106">{{Cite news |last=Rhian |first=Jason |date=November 6, 2015 |title=NASA delays CRS 2 awards again, drops Boeing from consideration |url=http://www.spaceflightinsider.com/missions/commercial/nasa-delays-crs-2-awards-again-drops-boeing-from-consideration/ |url-status=dead |archive-url=https://web.archive.org/web/20151122184847/http://www.spaceflightinsider.com/missions/commercial/nasa-delays-crs-2-awards-again-drops-boeing-from-consideration/ |archive-date=November 22, 2015 |access-date=November 21, 2015 |publisher=Spaceflight Insider}}</ref>
== Development == {{stack| [[File:Spaceships.svg|thumb|Operational crewed orbital spacecraft {{as of|2025|lc=y}}]] [[File:CST-100 pressure vessel.jpg|thumb|Starliner pressure vessel at the former [[Orbiter Processing Facility]], showing its [[isogrid]] construction, October 2011]] [[File:Boeing’s Wind Tunnel testing of the CST-100.jpg|thumb|Wind-tunnel testing of Starliner model, December 2011]] }}
The name CST-100 was first used when the capsule was unveiled to the public in June 2010.<ref name="bigelow">{{Cite press release |title=Bigelow Aerospace Joins the Commercial Spaceflight Federation |date=June 16, 2010 |publisher=Commercial Spaceflight Federation |url=http://www.commercialspaceflight.org/2010/06/bigelow-aerospace-joins-the-commercial-spaceflight-federation/ |last1=Gedmark |first1=John |last2=Gold |first2=Mike |access-date=May 9, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20170925132658/http://www.commercialspaceflight.org/2010/06/bigelow-aerospace-joins-the-commercial-spaceflight-federation/ |archive-date=September 25, 2017}}</ref> The acronym "CST" stands for Crew Space Transportation, while the number "100" represents to the [[Kármán line]], the unofficial boundary of space located at an altitude of {{Convert|100|km|sp=us}} above Earth.<ref>{{Cite web |date=July 28, 2023 |title=Commercial Crew Spacecraft |url=https://www.nasa.gov/humans-in-space/spaceships-and-rockets/commercial-crew-spacecraft/ |access-date=December 25, 2024 |website=NASA |language=en-US}}</ref> The design draws upon Boeing's experience with NASA's Apollo, Space Shuttle, and ISS programs, as well as the [[Orbital Express]] project.<ref name="sfn20100721" />
[[File:Starliner Capsule and SM.jpg|thumb|Starliner spacecraft consisting of capsule and service module]] The spacecraft consists of a reusable capsule and an expendable service module and is designed for missions to [[low Earth orbit]]. The capsule accommodates seven passengers, or a mix of crew and cargo. For [[NASA]] missions to the ISS it will carry four passengers and a small amount of cargo. The Starliner capsule uses a weldless, spun-formed structure and is reusable up to ten 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. Starliner features wireless Internet and tablet technology for crew interfaces.<ref name="Boeing20200708">{{Cite web |title=A 21st Century Space Capsule |url=http://www.boeing.com/space/starliner/ |url-status=live |archive-url=https://web.archive.org/web/20111215110455/http://www.boeing.com/defense-space/space/ccts/index.html |archive-date=December 15, 2011 |access-date=August 29, 2020 |publisher=Boeing}}</ref>
Starliner uses the [[NASA Docking System]].<ref>{{Cite news |last=Grondin |first=Yves-A. |date=August 5, 2013 |title=NASA Outlines its Plans for Commercial Crew Certification |url=http://www.nasaspaceflight.com/2013/08/nasa-outlines-plans-commercial-crew-certification/ |url-status=live |archive-url=https://web.archive.org/web/20171005005229/https://www.nasaspaceflight.com/2013/08/nasa-outlines-plans-commercial-crew-certification/ |archive-date=October 5, 2017 |access-date=January 9, 2014 |publisher=NASASpaceFlight.com}}</ref><ref>{{Cite AV media |url=https://www.youtube.com/watch?v=yGZWIR0Prhk&t=26m57s |title=Commercial Space Flight Panel |publisher=SpaceUp Houston |year=2011 |archive-url=https://ghostarchive.org/varchive/youtube/20211221/yGZWIR0Prhk |archive-date=December 21, 2021 |url-status=live |website=youtube.com}}{{cbignore}}</ref><ref>{{Cite web |last=Messier |first=Doug |date=March 23, 2011 |title=Update on Boeing CST-100 Crew program |work=Parabolic Arc |url=http://www.parabolicarc.com/2011/03/23/22339/ |url-status=live |archive-url=https://web.archive.org/web/20170925132648/http://www.parabolicarc.com/2011/03/23/22339/ |archive-date=September 25, 2017 |access-date=March 27, 2011 }}</ref> Boeing modified the Starliner design prior to OFT-2, adding a hinged re-entry cover below its expendable nosecone for additional protection of the docking port during [[atmospheric entry]]. This was tested on the OFT-2 mission. By contrast, the reusable [[SpaceX Dragon 2]] nosecone is hinged and protects its docking port during both launch and reentry.<ref name="SFN20200825" /><ref name="sfn20210118" /><ref name="space20210121" />
The capsule uses the Boeing Lightweight Ablator for its re-entry [[heat shield]].<ref name="sfin20150728">{{Cite news |last=Latrell |first=Joe |date=July 28, 2015 |title=Boeing's CST-100 takes shape at former NASA facility |url=http://www.spaceflightinsider.com/missions/commercial/boeings-cst-100-takes-shape-at-former-nasa-facility/ |url-status=live |archive-url=https://web.archive.org/web/20230430144633/https://www.spaceflightinsider.com/missions/commercial/boeings-cst-100-takes-shape-at-former-nasa-facility/ |archive-date=April 30, 2023 |access-date=August 3, 2018 |publisher=Spaceflight Insider}}</ref>
[[Solar cell]]s provided by Boeing subsidiary [[Spectrolab]] are installed onto the aft face of the service module, providing 2.9 kW of electricity.<ref>{{Cite web |date=November 17, 2016 |title=Spectrolab Solar Cells to Power Boeing's Starliner Spacecraft |url=http://www.compoundsemi.com/spectrolab-solar-cells-power-boeings-starliner-spacecraft/ |url-status=dead |archive-url=https://web.archive.org/web/20180805083305/http://www.compoundsemi.com/spectrolab-solar-cells-power-boeings-starliner-spacecraft/ |archive-date=August 5, 2018 |access-date=August 5, 2018}}</ref>
In addition to the capsule and service module, a {{cvt|1.78|m|ft|order=flip|adj=on}} structure called an aeroskirt is integrated into the [[Adapter (rocketry)|launch vehicle adapter]] of Atlas V. The aeroskirt provides aerodynamic stability and dampens the shock waves that come from the front of the rocket.<ref>{{Cite news |last=Mike Wall |date=December 19, 2019 |title=Boeing's Starliner Atlas V Rocket Ride Is Wearing a 'Skirt' for Launch. Here's Why. |url=https://www.space.com/boeing-starliner-atlas-v-rocket-aeroskirt-explained.html |url-status=live |archive-url=https://web.archive.org/web/20230403045725/https://www.space.com/boeing-starliner-atlas-v-rocket-aeroskirt-explained.html |archive-date=April 3, 2023 |access-date=April 2, 2023 |work=[[Space.com]]}}</ref>
The spacecraft's propulsion system is produced by [[Aerojet Rocketdyne]] and consists of 64 engines: * 12 × {{cvt|100|lbf|N}} MR-104J RCS ([[reaction control system]]) thrusters on the capsule, using hydrazine [[monopropellant]] and reserved for orienting the capsule during [[atmospheric re-entry]]<ref>{{Cite press release |title=Aerojet Rocketdyne Ships Starliner Re-entry Thrusters |date=March 15, 2018 |publisher=Aerojet Rocketdyne |url=https://www.globenewswire.com/news-release/2018/03/15/1438434/0/en/Aerojet-Rocketdyne-Ships-Starliner-Re-entry-Thrusters.html |access-date=August 26, 2024}}</ref> * 52 on the service module using [[monomethylhydrazine]] and [[nitrogen tetroxide]] bipropellant: ** 28 × {{cvt|85|lbf|N}} <!--[[R-4D]]?--> RCS thrusters on the service module for [[Spacecraft attitude control|attitude control]] during the majority of the flight ** 20 × {{cvt|1500|lbf|N}} <!--AR-40?--> OMAC (orbital maneuvering and attitude control) thrusters for altering orbits ** 4 × {{cvt|40000|lbf|N}} [[RS-88]] engines for [[launch escape system|launch escape capability]] in the event of an abort<ref>{{Cite news |last=Weitering |first=Hanneke |date=April 24, 2019 |title=The Emergency Launch Abort Systems of SpaceX and Boeing Explained |url=https://www.space.com/launch-abort-systems-of-spacex-boeing.html |url-status=live |archive-url=https://web.archive.org/web/20200525090718/https://www.space.com/launch-abort-systems-of-spacex-boeing.html |archive-date=May 25, 2020 |access-date=February 6, 2020 |work=[[Space.com]]}}</ref> The RCS and OMAC thrusters on the service module are grouped into four "doghouses" equally spaced around its perimeter. Each doghouse contains five OMAC thrusters (three aft-facing and two forward-facing) and seven RCS thrusters (two aft-facing, two forward-facing, one radial, and two tangential).<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=L96asfTvJ_A |title=Explaining Why NASA's Starliner Report Is So Bad |date=February 21, 2026 |last=Manley |first=Scott |author-link=Scott Manley |type=Video |access-date=February 24, 2026 |via=YouTube}}</ref>
To move in a straight line, the spacecraft fires pairs of thrusters in a balanced way so that the push goes through its center of mass, allowing it to shift position without spinning. To turn or change its orientation, it fires thrusters in an unbalanced way, creating a twisting force (torque) that rotates the spacecraft without significantly changing its overall path. The RCS thrusters are used mainly for steering and precise docking maneuvers, while the OMAC thrusters provide the stronger thrust needed for larger changes in orbit.
Boeing designed the capsule to make ground landings instead of a [[splashdown]], a first for a crewed capsule mission launched from the United States. After reentering the atmosphere, three parachutes are deployed, slowing the capsule to approximately {{convert|4|mph|ft/min m/s}}. Before reaching the ground, six airbags deploy to cushion the landing. There are four primary landing locations, including two sites inside the [[White Sands Missile Range]] in New Mexico, the [[Willcox Playa]] in Arizona and the [[Dugway Proving Ground]] in Utah. [[Edwards Air Force Base]] in California serves as a contingency landing location.<ref>{{Cite web |title=NASA's Boeing Crew Flight Test Mission Overview |url=https://www.nasa.gov/nasas-boeing-crew-flight-test-mission-overview/ |url-status=live |archive-url=https://web.archive.org/web/20240601175516/https://www.nasa.gov/nasas-boeing-crew-flight-test-mission-overview/ |archive-date=June 1, 2024 |access-date=June 1, 2024 |website=NASA |language=en-US}}</ref> All of the landing sites are in the Western United States, allowing the service module to be [[Jettison (aviation)|jettisoned]] for a [[destructive reentry]] over the Pacific Ocean. Boeing says that between all five landing sites, there are around 450 landing opportunities each year.<ref name="sfn20150922">{{Cite news |last=Clark |first=Stephen |date=September 22, 2015 |title=Boeing identifies CST-100 prime landing sites |url=https://spaceflightnow.com/2015/09/22/boeing-identifies-cst-100-prime-landing-sites/ |url-status=live |archive-url=https://web.archive.org/web/20180805203514/https://spaceflightnow.com/2015/09/22/boeing-identifies-cst-100-prime-landing-sites/ |archive-date=August 5, 2018 |access-date=August 5, 2018 |publisher=Spaceflight Now}}</ref>
Following the award of the Commercial Crew Transportation Capability (CCtCap) contract in 2014, NASA assigned a team of four experienced astronauts, [[Bob Behnken]], [[Eric Boe]], [[Doug Hurley]], and [[Sunita Williams]], to serve as consultants to engineers at both Boeing and SpaceX.<ref>{{Cite web |date=July 9, 2015 |title=NASA assigns 4 astronauts to commercial Boeing, SpaceX test flights |url=http://www.collectspace.com/news/news-070915a-commercial-crew-astronauts.html |access-date=August 24, 2024 |website=[[collectSPACE]]}}</ref> These astronauts were also slated to be the test pilots on the inaugural missions. Hurley recounted a stark contrast in the working relationships between the astronauts and the engineers at the two companies. While the SpaceX engineers were receptive to feedback, enthusiastic about collaborating, and attentive to suggestions, Hurley found the Boeing engineers to be indifferent, arrogant, and overconfident. He also said the Boeing team failed to inform the astronauts about the propellant leak that occurred during the [[Boeing Pad Abort Test|Pad Abort Test]]. Ultimately, Hurley told the [[chief of the astronaut office]] that he would not fly on Starliner. Hurley and Behnken later went on to command the Crew Dragon's historic [[Crew Dragon Demo-2|Demo-2]] mission, the first crewed flight of the spacecraft.<ref>{{Cite book |last=Berger |first=Eric |author-link=Eric Berger (journalist) |title=Reentry: SpaceX, Elon Musk, and the Reusable Rockets that Launched a Second Space Age |publisher=BenBella Books |year=2024 |isbn=978-1637745274 |pages=293–296}}</ref> Williams flew into space on the Boeing Crew Flight Test, but returned to Earth on a Crew Dragon, after thrusters malfunctioned on the Starliner.
Despite being initially awarded significantly more funding, Boeing faced substantial internal budget overruns for the Starliner program, exceeding $2{{Nbsp}}billion {{As of|2025|2|lc=y}}.<ref name=msn-20250205>{{cite news |url=https://www.msn.com/en-us/money/markets/boeing-lost-over-2b-on-starliner-program-so-far-flags-risk-of-more-losses/ar-AA1yrSzk?ocid=finance-verthp-feeds |title=Boeing lost over B on Starliner program so far, flags risk of more losses |publisher=MSN |date=February 5, 2025 |access-date=February 7, 2025}}</ref>
In November 2019, NASA's Office of Inspector General released a report revealing that a change to Boeing's contract had occurred in 2016,<ref name="sn20191114">{{Cite news |last=Foust |first=Jeff |author-link=Jeff Foust |date=November 14, 2019 |title=NASA inspector general criticizes additional Boeing commercial crew payments |url=https://spacenews.com/nasa-inspector-general-criticizes-additional-boeing-commercial-crew-payments/ |url-status=live |archive-url=https://web.archive.org/web/20240606021212/https://spacenews.com/nasa-inspector-general-criticizes-additional-boeing-commercial-crew-payments/ |archive-date=June 6, 2024 |access-date=October 28, 2021 |work=[[SpaceNews]]}}</ref> 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", and NASA and Boeing committed to six missions instead of the last four being optional.<ref>{{Cite web |date=November 14, 2019 |title=NASA's Management of Crew Transportation to the International Space Station |url=https://oig.nasa.gov/docs/IG-20-005.pdf |url-status=live |archive-url=https://web.archive.org/web/20211023035809/https://oig.nasa.gov/docs/IG-20-005.pdf |archive-date=October 23, 2021 |access-date=October 28, 2021 |website=OIG.NASA.gov}}</ref>
===Post Crew Flight Test=== In August 2024, after the setbacks experienced during the Crew Flight Test, NASA administrator [[Bill Nelson]] stated that Boeing CEO [[Kelly Ortberg]] committed to continuing the Starliner program.<ref name="Roulette 2024">{{Cite news |last=Roulette |first=Joey |date=August 24, 2024 |title=SpaceX to return Boeing's Starliner astronauts from space next year, NASA says |url=https://www.reuters.com/technology/space/spacex-return-boeings-starliner-astronauts-space-next-year-nasa-says-2024-08-24/ |access-date=August 24, 2024 |work=[[Reuters]]}}</ref> However, financial analysts expressed skepticism that Boeing would continue to invest in a money-losing program,<ref name="Johnsson 2024">{{Cite news |last=Johnsson |first=Julie |date=August 25, 2024 |title=New Boeing CEO Faces Hard Choices After NASA Snubs Starliner for SpaceX |url=https://www.bloomberg.com/news/articles/2024-08-25/boeing-ceo-faces-hard-decisions-after-nasa-s-starliner-rejection |access-date=August 27, 2024 |work=Bloomberg |language=en}}</ref> and in October ''[[The Wall Street Journal]]'' reported that Boeing was exploring a sale of some of its space division programs, including Starliner.<ref>{{Cite news |last1=Terlep |first1=Sharon |last2=Maidenberg |first2=Micah |date=October 25, 2024 |title=Boeing Explores Sale of Space Business |url=https://www.wsj.com/science/space-astronomy/boeing-explores-sale-of-space-business-fa7fa3a9 |access-date=October 25, 2024 |work=[[The Wall Street Journal]] |quote=The beleaguered company is exploring a sale of its storied NASA business, including the troubled Starliner space vehicle and operations that support the International Space Station, according to people familiar with the matter.}}</ref> But in March 2025, Commercial Crew Program manager Steve Stich stated that the next flight may happen in late 2025 or early 2026.<ref name="CCP 2025 plan">{{cite news|title=Starliner future plans still in limbo|first=Jeff|last=Foust|date=June 8, 2025|access-date=June 9, 2025|url=https://spacenews.com/starliner-future-plans-still-in-limbo}}</ref>
On July 10, 2025, Stich stated that the next Starliner flight would likely be an uncrewed cargo mission. Stich also elaborated on the main issues that Starliner was facing in its development, namely the oxidizer valves, more specifically, how the temperature controls required for effective pulses of fuel and oxidizer through these valves are not at a consistent level NASA deems acceptable. Stich stated that these valves were not designed to be opened and closed when the Starliner's RCS thrusters were also operating, as the RCS thrusters impacted the temperature in the valves and thus their ability to open and close. Stich stated that steady progress was being made, and concluded by saying NASA was optimistic that another crewed Starliner flight would take place for the second slot in the crew program in the later part of 2026.<ref>{{cite web |last1=Dinner |first1=Josh |title='Doghouse' days of summer — Boeing's Starliner won't fly again until 2026, and without astronauts aboard |url=https://www.space.com/space-exploration/international-space-station/doghouse-days-of-summer-boeings-starliner-wont-fly-again-until-2026-and-without-astronauts-aboard |website=[[Space.com]] |access-date=August 5, 2025}}</ref>
== Testing == Various validation tests began on test articles in 2011 and continued on actual spacecraft starting in 2019.
=== Abort and drop tests === {{Main|Boeing Pad Abort Test}}
[[File:Erickson Sky Crane helicopter 4312.jpg|thumb|An [[Erickson Skycrane]] (foreground) frames the Starliner (background) in 2012. During testing, the helicopter dropped the capsule from about {{convert|7000|ft|m|sigfig=1}} to test its parachutes and airbags.]] [[File:CST-100 Starliner drop.jpg|thumb|A close up of Starliner's six airbags during drop testing]]
In September 2011, Boeing announced the completion of a set of ground [[drop test]]s to validate the design of the airbag cushioning system. The airbags are located underneath the heat shield of the Starliner, which is designed to be separated from the capsule while under parachute descent at about {{cvt|1500|m|ft|order=flip|sigfig=1}} altitude. The airbags, manufactured by ILC Dover, are deployed by filling with a mixture of compressed nitrogen and oxygen gas, not with the pyro-explosive mixture sometimes used in automotive [[Airbag#Inflation|airbags]]. The tests were carried out in the [[Mojave Desert]] of southeast California, at ground speeds between {{cvt|10|and|30|mph}} in order to simulate crosswind conditions at the time of landing. Bigelow Aerospace built the mobile test rig and conducted the tests.<ref name="boeing20110912">{{Cite news |last=Memi |first=Edmund G. |date=September 12, 2011 |title=Space capsule tests aim to ensure safe landings |url=http://www.boeing.com/Features/2011/09/bds_cst_100_airbag_09_12_11.html |url-status=dead |archive-url=https://web.archive.org/web/20110924163725/http://www.boeing.com/Features/2011/09/bds_cst_100_airbag_09_12_11.html |archive-date=September 24, 2011 |access-date=September 18, 2011 |publisher=Boeing}}</ref>
In April 2012, Boeing dropped a mock-up of its Starliner over the [[Great Basin Desert|Nevada desert]] at the [[Delamar Dry Lake]], [[Nevada]], successfully testing the craft's three main landing parachutes from {{cvt|3400|m|ft|order=flip}}.<ref>{{Cite news |last=Clark |first=Stephen |date=April 3, 2012 |title=Parachutes for Boeing crew capsule tested over Nevada |url=http://www.spaceflightnow.com/news/n1204/03cst100drop/ |url-status=live |archive-url=https://web.archive.org/web/20120406185621/http://www.spaceflightnow.com/news/n1204/03cst100drop/ |archive-date=April 6, 2012 |access-date=April 3, 2012 |publisher=Spaceflight Now}}</ref>
Boeing reported in May 2016 that its test schedule would slip by eight months in order to reduce the mass of the spacecraft, address aerodynamics issues anticipated during launch and ascent on the Atlas V rocket, and meet new NASA-imposed software requirements.<ref name="spacenews-delay">{{Cite news |last=Foust |first=Jeff |author-link=Jeff Foust |date=May 12, 2016 |title=Boeing delays first crewed CST-100 flight to 2018 |url=http://spacenews.com/boeing-delays-first-crewed-cst-100-flight-to-2018/ |url-status=live |archive-url=https://web.archive.org/web/20240606021254/https://spacenews.com/boeing-delays-first-crewed-cst-100-flight-to-2018/ |archive-date=June 6, 2024 |access-date=May 14, 2016 |publisher=[[SpaceNews]]}}</ref> The [[Boeing Orbital Flight Test|Orbital Flight Test]] was scheduled for spring 2019. The booster for this Orbital Flight Test, an [[Atlas V|Atlas V N22]] rocket, was assembled at [[United Launch Alliance]]'s (ULA) facility at [[Decatur, Alabama]] by the end of 2017.<ref>{{Cite news |last=Rhian |first=Jason |date=January 4, 2018 |title=Boeing CST-100 Starliner one step closer to flight with completion of DCR |url=http://www.spaceflightinsider.com/organizations/boeing/boeing-cst-100-starliner-one-step-closer-flight-completion-dcr/ |url-status=dead |archive-url=https://web.archive.org/web/20180408010251/http://www.spaceflightinsider.com/organizations/boeing/boeing-cst-100-starliner-one-step-closer-flight-completion-dcr/ |archive-date=April 8, 2018 |access-date=April 8, 2018 |publisher=Spaceflight Insider}}</ref> The first crewed flight ([[Boeing Crew Flight Test|Boe-CFT]]) was scheduled for summer 2019, pending test results from [[Boeing Orbital Flight Test|Boe-OFT]]. It was planned to last 14 days and carry one NASA astronaut and one Boeing test pilot to the ISS.<ref>{{Cite news |last=Bergin |first=Chris |date=November 27, 2017 |title=Boeing Starliner trio preparing for test flights |url=https://www.nasaspaceflight.com/2017/11/boeing-starliner-trio-test-flights/ |url-status=live |archive-url=https://web.archive.org/web/20180209214642/https://www.nasaspaceflight.com/2017/11/boeing-starliner-trio-test-flights/ |archive-date=February 9, 2018 |access-date=April 8, 2018 |publisher=NASASpaceFlight.com}}</ref> On April 5, 2018, NASA announced that the first planned two-person flight, originally slated for November 2018, was likely to occur in 2019 or 2020.<ref>{{Cite news |last=Pasztor |first=Andy |date=April 5, 2018 |title=NASA, Boeing Signal Regular Missions to Space Station to Be Delayed |url=https://www.wsj.com/articles/nasa-boeing-signal-regular-missions-to-space-station-to-be-delayed-1522984513 |url-status=live |archive-url=https://web.archive.org/web/20180406032958/https://www.wsj.com/articles/nasa-boeing-signal-regular-missions-to-space-station-to-be-delayed-1522984513 |archive-date=April 6, 2018 |access-date=April 8, 2018 |work=The Wall Street Journal}}</ref>
A serious incident occurred during a hot-fire test in June 2018. A design flaw in the propellant system left four of eight valves open, leading to the release of over {{Convert|4,000|lb}} of toxic [[monomethylhydrazine]] propellant, resulting in a fireball that engulfed the equipment. The incident was reportedly exacerbated by animosity with the propulsion system subcontractor, Aerojet Rocketdyne, who Boeing refused to pay for design changes. While it informed NASA of the incident, Boeing attempted to keep the incident quiet, even withholding information from the astronauts involved in the project.<ref name="Berger May 2024">{{Cite web |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=May 6, 2024 |title=The surprise is not that Boeing lost commercial crew but that it finished at all |url=https://arstechnica.com/space/2024/05/the-surprise-is-not-that-boeing-lost-commercial-crew-but-that-it-finished-at-all/ |access-date=August 26, 2024 |website=Ars Technica |language=en-us}}</ref>
In October 2018, the first unpiloted orbital mission was delayed to April 2019, and the first crew launch was rescheduled to August 2019.<ref name="NASAblogcc">{{Cite web |date=October 4, 2018 |title=NASA's Commercial Crew Program Target Test Flight Dates |url=https://blogs.nasa.gov/commercialcrew/2018/10/04/nasas-commercial-crew-program-target-test-flight-dates-4/ |url-status=live |archive-url=https://web.archive.org/web/20181006060403/https://blogs.nasa.gov/commercialcrew/2018/10/04/nasas-commercial-crew-program-target-test-flight-dates-4/ |archive-date=October 6, 2018 |access-date=October 5, 2018}} {{PD-notice}}</ref><ref>{{Cite web |date=February 6, 2019 |title=Commercial Crew Program – February 6, 2019 |url=https://blogs.nasa.gov/commercialcrew/2019/02/06/ |url-status=live |archive-url=https://web.archive.org/web/20190302204511/https://blogs.nasa.gov/commercialcrew/2019/02/06/ |archive-date=March 2, 2019 |access-date=February 6, 2019 |website=blogs.nasa.gov}} {{PD-notice}}</ref> In March 2019, [[Reuters]] reported that these test flights had been delayed by at least three months,<ref name="reuters-20190320">{{Cite news |last=Eric M. Johnson |date=March 20, 2019 |title=Boeing delays by months test flights for U.S. human space program: sources |url=https://www.reuters.com/article/us-space-boeing/boeing-delays-by-months-test-flights-for-us-human-space-program-sources-idUSKCN1R12QR |url-status=live |archive-url=https://web.archive.org/web/20230602231920/https://www.reuters.com/article/us-space-boeing/boeing-delays-by-months-test-flights-for-us-human-space-program-sources-idUSKCN1R12QR |archive-date=June 2, 2023 |access-date=March 22, 2019 |work=Reuters}}</ref> and in April 2019 Boeing announced that the unpiloted orbital mission was scheduled for August 2019.<ref name="sfn-20190402">{{Cite news |last=Clark |first=Stephen |date=April 2, 2019 |title=Boeing delays first Starliner test flight to August, NASA extends duration of first crew mission |url=https://spaceflightnow.com/2019/04/02/boeing-confirms-delay-of-first-starliner-crew-capsule-test-flight-to-august/ |url-status=live |archive-url=https://web.archive.org/web/20230608213713/https://spaceflightnow.com/2019/04/02/boeing-confirms-delay-of-first-starliner-crew-capsule-test-flight-to-august/ |archive-date=June 8, 2023 |access-date=April 3, 2019 |publisher=Spaceflight Now}}</ref>
[[File:CST-100 Starliner - Pad Abort Test,49013402052 f3852e9b3d o.jpg|thumb|Starliner Spacecraft 1 ignites its [[RS-88]] abort engines during the [[Boeing Pad Abort Test]] in November 2019.]] In May 2019, all major hot-fire testing, including simulations of low-altitude abort-thruster testing, was completed using a full up-to-service module test article that was "flight-like," meaning that the service module test rig used in the hot-fire testing included fuel and helium tanks, reaction control system, orbital maneuvering, and attitude-control thrusters, launch abort engines and all necessary fuel lines and avionics that will be used for crewed missions. This cleared the way for the pad abort test and the subsequent uncrewed and crewed flights.<ref>{{Cite news |last=Clark |first=Stephen |date=May 25, 2019 |title=Boeing's Starliner crew capsule completes major propulsion test |url=https://spaceflightnow.com/2019/05/25/boeings-starliner-crew-capsule-completes-major-propulsion-test/ |url-status=live |archive-url=https://web.archive.org/web/20230425155849/https://spaceflightnow.com/2019/05/25/boeings-starliner-crew-capsule-completes-major-propulsion-test/ |archive-date=April 25, 2023 |access-date=May 30, 2019 |work=Spaceflight Now}}</ref>
A pad abort test took place on November 4, 2019.<ref name="Capsule Abort system test" /> The capsule accelerated away from its pad, but then one of the three parachutes failed to deploy, and the capsule landed with only two parachutes.<ref>{{Cite news |last=Berger, Eric |date=November 4, 2019 |title=Starliner flies for the first time, but one of its parachutes failed to deploy |url=https://arstechnica.com/science/2019/11/starliner-flies-for-the-first-time-but-one-of-its-parachutes-failed-to-deploy/ |url-status=live |archive-url=https://web.archive.org/web/20191210173113/https://arstechnica.com/science/2019/11/starliner-flies-for-the-first-time-but-one-of-its-parachutes-failed-to-deploy/ |archive-date=December 10, 2019 |access-date=November 5, 2019 |publisher=Ars Technica}}</ref><ref>{{Cite press release |title=Boeing statement regarding CST-100 Starliner pad abort test |date=November 4, 2019 |publisher=Boeing |url=https://boeing.mediaroom.com/2019-11-04-Boeing-statement-regarding-CST-100-Starliner-pad-abort-test |access-date=November 4, 2019 |url-status=live |archive-url=https://web.archive.org/web/20191104191046/https://boeing.mediaroom.com/2019-11-04-Boeing-statement-regarding-CST-100-Starliner-pad-abort-test |archive-date=November 4, 2019}}</ref> Landing was, however, deemed safe, and the test a success. Boeing did not expect the malfunction of one parachute to affect the Starliner development schedule.<ref name="Capsule Abort system test">{{Cite news |last=Clark |first=Stephen |date=November 4, 2019 |title=Boeing tests crew capsule escape system |url=https://spaceflightnow.com/2019/11/04/boeing-starliner-pad-abort/ |url-status=live |archive-url=https://web.archive.org/web/20191214044139/https://spaceflightnow.com/2019/11/04/boeing-starliner-pad-abort/ |archive-date=December 14, 2019 |access-date=August 29, 2020 |work=Spaceflight Now}}</ref>
=== First orbital flight test (uncrewed) === [[File:KSC-20180619-PH BOE01 0001 (42369668434).jpg|thumb|The upper and lower domes of {{ComV|CST-100 Starliner|Calypso|full=nolink}} being mated inside the Commercial Crew and Cargo Processing Facility (C3PF) at [[Kennedy Space Center]] on June 19, 2018]] [[File:Boeing CST-100 Starliner Landing (NHQ201912220104).jpg|thumb|right|{{ComV|CST-100 Starliner|Calypso|full=nolink}} landed at [[White Sands Missile Range]] in [[New Mexico]] following an uncrewed Orbital Flight Test in December 2019.]] {{Main|Boeing Orbital Flight Test}}
{{Redirect-distinguish|Rosie the Rocketeer|Rosie the Rocketer|Rosie the Riveter}}
The uncrewed Boeing Orbital Flight Test (OFT) launched on December 20, 2019, bearing an [[Crash test dummy|Anthropomorphic Test Device]] nicknamed "Rosie the Rocketeer" and clothed in Boeing's blue IVA spacesuit<ref name="FloridaToday-20191121">{{Cite news |last=Rachael Joy |date=November 21, 2019 |title=Remember Rosie the Riveter? Meet Rosie the Rocketeer |url=https://www.floridatoday.com/story/tech/science/space/2019/11/21/boeing-names-test-dummy-fly-aboard-first-starliner-flight-after-iconic-rosie-riveter/4230233002/ |url-status=live |archive-url=https://web.archive.org/web/20191221230937/https://www.floridatoday.com/story/tech/science/space/2019/11/21/boeing-names-test-dummy-fly-aboard-first-starliner-flight-after-iconic-rosie-riveter/4230233002/ |archive-date=December 21, 2019 |access-date=May 26, 2022 |work=Florida Today}}</ref> as well as a Plush toy of Jebediah Kerman from [[Kerbal Space Program]].<ref>{{Cite web |author1=Robert Z. Pearlman |date=May 21, 2022 |title=Video game character becomes real 'Kerbalnaut' on Boeing Starliner |url=https://www.space.com/boeing-starliner-oft2-kerbal-jeb-zerog-indicator |access-date=October 2, 2024 |website=Space.com |language=en}}</ref> It landed two days later, having nearly ended in catastrophic failure. The mission was ultimately declared a partial failure.<ref name="Berger May 2024" />
After launch, the spacecraft captured a "[[Mission Elapsed Time|mission elapsed time]]" from its Atlas V launch vehicle that was 11 hours off. Consequently, when the spacecraft separated from the rocket, instead of briefly firing its reaction control thrusters to enter orbit, its computers commanded them to fire for far longer, consuming so much fuel that the spacecraft no longer had enough to dock with the ISS.<ref name="Berger May 2024" /><ref>{{Cite news |last=Foust |first=Jeff |author-link=Jeff Foust |date=December 20, 2019 |title=Starliner suffers "off-nominal" orbital insertion after launch |url=https://spacenews.com/starliner-suffers-off-nominal-orbital-insertion-after-launch/ |url-status=live |archive-url=https://web.archive.org/web/20240606015657/https://spacenews.com/starliner-suffers-off-nominal-orbital-insertion-after-launch/ |archive-date=June 6, 2024 |access-date=December 20, 2019 |publisher=[[SpaceNews]]}}</ref><ref>{{Cite news |last=Sheetz |first=Michael |date=December 20, 2019 |title=Boeing Starliner fails mission, can't reach space station after flying into wrong orbit |url=https://www.cnbc.com/2019/12/20/boeings-starliner-flies-into-wrong-orbit-jeopardizing-trip-to-the-international-space-station.html |url-status=live |archive-url=https://web.archive.org/web/20210208170927/https://www.cnbc.com/2019/12/20/boeings-starliner-flies-into-wrong-orbit-jeopardizing-trip-to-the-international-space-station.html |archive-date=February 8, 2021 |access-date=December 20, 2019 |publisher=CNBC}}</ref> As the capsule was prepared for re-entry, another software error was discovered; it could have caused a catastrophic collision between the service module and crew capsule.<ref name="Berger May 2024" /><ref name="SFN20200207">{{Cite news |last=Harwood |first=William |date=February 7, 2020 |title=NASA, Boeing managers admit problems with Starliner software verification |url=https://spaceflightnow.com/2020/02/07/investigators-fault-boeing-for-potentially-catastrophic-software-errors-in-starliner-test-flight/ |url-status=live |archive-url=https://web.archive.org/web/20230531044623/https://spaceflightnow.com/2020/02/07/investigators-fault-boeing-for-potentially-catastrophic-software-errors-in-starliner-test-flight/ |archive-date=May 31, 2023 |access-date=August 29, 2020 |work=Spaceflight Now}}</ref>
The spacecraft landed at [[White Sands Missile Range]], [[New Mexico]], two days after launch.<ref name="bbc201219">{{Cite news |last=Amos |first=Jonathan |date=December 20, 2019 |title=Boeing astronaut ship stalls in orbit |url=https://www.bbc.com/news/science-environment-50855395 |url-status=live |archive-url=https://web.archive.org/web/20230117130936/https://www.bbc.com/news/science-environment-50855395 |archive-date=January 17, 2023 |access-date=December 20, 2019 |publisher=BBC News}}</ref> After its landing, NASA astronaut [[Sunita Williams]] named the spacecraft ''Calypso'' after the [[research vessel]] {{ship|RV|Calypso}} used by [[oceanographic]] researcher [[Jacques Cousteau]].<ref name="nasa221219">{{Cite news |last=Lewis |first=Marie |date=December 22, 2019 |title=Tune in for Starliner Postlanding News Conference |url=https://blogs.nasa.gov/commercialcrew/2019/12/22/tune-in-for-starliner-postlanding-news-conference/ |url-status=live |archive-url=https://web.archive.org/web/20230529215303/https://blogs.nasa.gov/commercialcrew/2019/12/22/tune-in-for-starliner-postlanding-news-conference/ |archive-date=May 29, 2023 |access-date=December 22, 2019 |publisher=NASA Commercial Crew Program}} {{PD-notice}}</ref>
After the mission, Boeing vice president John Mulholland acknowledged that the company had not conducted integrated end-to-end tests for the entire mission, but had instead performed tests of smaller segments. This approach contributed to the software errors that led to the near-catastrophic failures during the flight test. Mulholland insisted that Boeing cut no corners, and that end-to-end tests were not omitted to save money. NASA was also faulted for not pressing Boeing to conduct an end-to-end test.<ref name="Berger May 2024" />
The subsequent NASA–Boeing investigation into the flight made scores of recommendations for Boeing and NASA. Boeing declared these to be proprietary, so the only ones publicly known are the ones that officials deliberately disclosed. In 2020, company officials said they were addressing 80 of the recommendations.<ref name="NASA20200707">{{Cite web |date=July 7, 2020 |title=NASA and Boeing Complete Orbital Flight Test Reviews |url=https://www.nasa.gov/feature/nasa-and-boeing-complete-orbital-flight-test-reviews |url-status=dead |archive-url=https://web.archive.org/web/20230327192048/https://www.nasa.gov/feature/nasa-and-boeing-complete-orbital-flight-test-reviews/ |archive-date=March 27, 2023 |access-date=August 29, 2020 |publisher=NASA}} {{PD-notice}}</ref>
=== Second orbital flight test (uncrewed) === [[File:Main Parachutes Open, Airbags Inflate 4-3-12.jpg|thumb|{{ComV|CST-100 Starliner|2|full=nolink}} ahead of landing at [[White Sands Missile Range]] in [[New Mexico]] following OFT-2 in May 2022]] {{Main|Boeing Orbital Flight Test 2}}
Because the first OFT did not achieve its objectives, Boeing officials said on April 6, 2020 that the Starliner crew capsule would fly a second uncrewed demonstration mission, [[Boeing Orbital Flight Test 2]] (OFT-2), before flying astronauts. NASA said that it had accepted a recommendation from Boeing to fly a second unpiloted mission. ''The Washington Post'' reported that the second orbital flight test, with much the same objectives as the first, was expected to launch from Cape Canaveral "sometime in October or November 2020". Boeing said that it would fund the unplanned crew capsule test flight "at no cost to the taxpayer". Boeing told investors earlier in 2020 that it was taking a US$410 million charge against its earnings to cover the expected costs of a second unpiloted test flight.<ref>{{Cite news |last=Clark |first=Stephen |date=April 7, 2020 |title=After problem-plagued test flight, Boeing will refly crew capsule without astronauts |url=https://spaceflightnow.com/2020/04/06/after-problem-plagued-test-flight-boeing-will-refly-crew-capsule-without-astronauts/ |url-status=live |archive-url=https://web.archive.org/web/20200525042652/https://spaceflightnow.com/2020/04/06/after-problem-plagued-test-flight-boeing-will-refly-crew-capsule-without-astronauts/ |archive-date=May 25, 2020 |access-date=August 29, 2020 |work=Spaceflight Now}}</ref> Boeing officials said on August 25, 2020 that they set the stage for the first Starliner demonstration mission with astronauts in mid-2021.<ref name="SFN20200825">{{Cite news |last=Clark |first=Stephen |date=August 25, 2020 |title=Boeing plans second Starliner test flight in December 2020 or January 2021 |url=https://spaceflightnow.com/2020/08/25/boeing-plans-second-starliner-test-flight-in-december-or-january/ |url-status=live |archive-url=https://web.archive.org/web/20220517123040/https://spaceflightnow.com/2020/08/25/boeing-plans-second-starliner-test-flight-in-december-or-january/ |archive-date=May 17, 2022 |access-date=August 26, 2020 |work=Spaceflight Now}}</ref> Boeing modified the design of the Starliner docking system prior to OFT-2 to add a re-entry cover for additional protection during the capsule's fiery descent through the atmosphere. This re-entry cover is hinged, like the SpaceX design. Teams also installed the OFT-2 spacecraft's propellant heater, thermal-protection tiles, and the airbags used to cushion the capsule's landing. The crew module for the OFT-2 mission began acceptance testing in August 2020, which is designed to validate the spacecraft's systems before it is mated with its service module, according to NASA.<ref name="SFN20200825" /><ref name="sfn20210118" /><ref name="space20210121" /> On November 10, 2020, NASA's Commercial Crew Program manager Steve Stich said that the second orbital flight test would be delayed until first quarter 2021 due to software issues.<ref>{{Cite news |last=Malik |first=Tariq |date=November 11, 2020 |title=NASA says Boeing's next Starliner test flight won't launch until 2021 |url=https://www.space.com/boeing-orbital-flight-test-2-early-2021-launch |url-status=live |archive-url=https://web.archive.org/web/20201113141532/https://www.space.com/boeing-orbital-flight-test-2-early-2021-launch |archive-date=November 13, 2020 |access-date=November 16, 2020 |work=[[Space.com]]}}</ref> The uncrewed test continued to slip, with the OFT-2 uncrewed test flight being scheduled for March 2021 and the crewed flight targeted for a launch the following summer.<ref name="Boeing20201209">{{Cite web |date=December 9, 2020 |title=NASA and Boeing Target New Launch Date for Next Starliner Flight Test |url=https://starlinerupdates.com/nasa-and-boeing-target-new-launch-date-for-next-starliner-flight-test/ |url-status=live |archive-url=https://web.archive.org/web/20220517122009/https://starlinerupdates.com/nasa-and-boeing-target-new-launch-date-for-next-starliner-flight-test/ |archive-date=May 17, 2022 |access-date=December 9, 2020 |publisher=Boeing}}</ref> The launch date of OFT-2 moved again with the earliest estimated launch date set for August 2021.<ref name="starliner-20210506">{{Cite web |date=May 6, 2021 |title=Boeing and NASA Update Launch Target for Next Starliner Test Flight |url=https://starlinerupdates.com/boeing-and-nasa-update-launch-target-for-next-starliner-test-flight/ |url-status=live |archive-url=https://web.archive.org/web/20210507044414/https://starlinerupdates.com/boeing-and-nasa-update-launch-target-for-next-starliner-test-flight/ |archive-date=May 7, 2021 |access-date=May 6, 2021 |publisher=Boeing}}</ref>
During the August 2021 launch window some issues were detected with 13 propulsion-system valves in the spacecraft prior to launch. The spacecraft had already been mated to its launch rocket, United Launch Alliance's (ULA) [[Atlas V]], and taken to the launchpad. Attempts to fix the problem while on the launchpad failed, and the rocket was returned to the ULA's VIF (Vertical Integration Facility). Attempts to fix the problem at the VIF also failed, and Boeing decided to return the spacecraft to the factory, thus cancelling the launch at that launch window.<ref name="starliner-20210813">{{Cite web |date=August 13, 2021 |title=Starliner Returning to Factory to Resolve Valve Issue |url=https://starlinerupdates.com/starliner-returning-to-factory-to-resolve-valve-issue/ |url-status=live |archive-url=https://web.archive.org/web/20220517112233/https://starlinerupdates.com/starliner-returning-to-factory-to-resolve-valve-issue/ |archive-date=May 17, 2022 |access-date=August 13, 2021 |website=[[Boeing]]}}</ref><ref name="CNBC20120813">{{Cite news |last=Sheetz |first=Michael |date=August 13, 2021 |title=Boeing delays test flight of Starliner crew spacecraft for at least two months after valve problems |url=https://www.cnbc.com/2021/08/13/boeing-further-delays-starliner-oft-2-crew-spacecraft-test-flight.html |url-status=live |archive-url=https://web.archive.org/web/20220517113807/https://www.cnbc.com/2021/08/13/boeing-further-delays-starliner-oft-2-crew-spacecraft-test-flight.html |archive-date=May 17, 2022 |access-date=August 13, 2021 |work=[[CNBC]]}}</ref> There was a commercial dispute between Boeing and Aerojet Rocketdyne over responsibility for fixing the problem.<ref name="guardian-20220521">{{Cite news |date=May 21, 2022 |title=Boeing's Starliner capsule docks for first time with International Space Station |url=https://www.theguardian.com/science/2022/may/21/boeings-starliner-capsule-docks-for-first-time-with-international-space-station |url-status=live |archive-url=https://web.archive.org/web/20240606015659/https://www.theguardian.com/science/2022/may/21/boeings-starliner-capsule-docks-for-first-time-with-international-space-station |archive-date=June 6, 2024 |access-date=May 21, 2022 |work=The Guardian |agency=Reuters}}</ref> The valves had been corroded by intrusion of moisture, which interacted with the propellant, but the source of the moisture was not apparent. By late September 2021, Boeing had not determined the root cause of the problem, and the flight was delayed indefinitely.<ref name="WP20210924">{{Cite news |last=Davenport |first=Christian |date=September 24, 2021 |title=Nearly two months after discovering a problem with its Starliner spacecraft, Boeing is still searching for answers |url=https://www.washingtonpost.com/technology/2021/09/24/boeingnasastarlinerdelay |url-status=live |archive-url=https://web.archive.org/web/20220517114055/https://www.washingtonpost.com/technology/2021/09/24/boeingnasastarlinerdelay/ |archive-date=May 17, 2022 |access-date=September 27, 2021 |newspaper=The Washington Post}}</ref> Through October 2021, NASA and Boeing continued to make progress and were "working toward launch opportunities in the first half of 2022",<ref name="SC20211009">{{Cite news |last=Wall |first=Mike |date=October 9, 2021 |title=Boeing's next Starliner test launch for NASA slips to 2022 |url=https://www.space.com/boeing-starliner-test-flight-oft-2-early-2022 |url-status=live |archive-url=https://web.archive.org/web/20211009114322/https://www.space.com/boeing-starliner-test-flight-oft-2-early-2022 |archive-date=October 9, 2021 |access-date=October 9, 2021 |work=[[Space.com]]}}</ref> In December 2021, Boeing decided to replace the entire service module and anticipated OFT-2 to occur in May 2022.<ref name="2021-12-20">{{Cite news |last=Foust |first=Jeff |author-link=Jeff Foust |date=December 20, 2021 |title=Boeing Starliner test flight planned for spring 2022 |url=https://spacenews.com/boeing-starliner-test-flight-planned-for-spring-2022/ |url-status=live |archive-url=https://web.archive.org/web/20240606015702/https://spacenews.com/boeing-starliner-test-flight-planned-for-spring-2022/ |archive-date=June 6, 2024 |access-date=December 25, 2021 |work=[[SpaceNews]] |language=en-US}}</ref><ref>{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=December 14, 2021 |title=Leaky valve issue forces Boeing to swap out Starliner's service module |url=https://arstechnica.com/science/2021/12/boeing-to-replace-starliner-service-module-make-mid-2022-launch-attempt/ |url-status=live |archive-url=https://web.archive.org/web/20211225070743/https://arstechnica.com/science/2021/12/boeing-to-replace-starliner-service-module-make-mid-2022-launch-attempt/ |archive-date=December 25, 2021 |access-date=December 25, 2021 |work=[[Ars Technica]] |language=en-us}}</ref>
The OFT-2 mission launched on May 19, 2022.<ref name="NSF-2022-05-19">{{Cite news |last=William Graham |date=May 19, 2022 |title=Starliner OFT-2 launch makes it to orbit, heading to ISS |url=https://www.nasaspaceflight.com/2022/05/starliner-oft2-launch/ |url-status=live |archive-url=https://web.archive.org/web/20221007052124/https://www.nasaspaceflight.com/2022/05/starliner-oft2-launch/ |archive-date=October 7, 2022 |access-date=May 26, 2022 |publisher=NasaSpaceFlight.com}}</ref> It again carried Rosie the Rocketeer test dummy suited in the blue Boeing inflight spacesuit.<ref name="boeing-2022-05-21">{{Cite tweet |number=1528045424317169664 |user=BoeingSpace |title=@NASA_Astronauts open Starliner's hatch on @Space_Station for the first time and welcome #RosieTheRocketeer and Jebediah Kerman. |archive-url=https://web.archive.org/web/20220523164110/https://twitter.com/BoeingSpace/status/1528045424317169664 |archive-date=May 23, 2022 |url-status=live}}</ref><ref name="Space-2022-05-16">{{Cite news |last=Elizabeth Howell |date=May 16, 2022 |title=Rosie the Rocketeer: Meet the dummy flying on Boeing's OFT-2 test flight this week |url=https://www.space.com/rosie-rocketeer-dummy-boeing-starliner-oft-2 |url-status=live |archive-url=https://web.archive.org/web/20220526180815/https://www.space.com/rosie-rocketeer-dummy-boeing-starliner-oft-2 |archive-date=May 26, 2022 |access-date=May 26, 2022 |publisher=Space.com}}</ref> Two Orbital Maneuvering and Attitude Control (OMAC) thrusters failed during the orbital insertion burn, but the spacecraft was able to compensate using the remaining OMAC thrusters with the addition of the Reaction Control System (RCS) thrusters. A couple of RCS thrusters used to maneuver Starliner also failed during docking due to low chamber pressure. Some thermal systems used to cool the spacecraft showed extra cold temperatures, requiring engineers to manage it during the docking.<ref name="theverge-2022.05">{{Cite news |last=Grush |first=Loren |date=May 25, 2022 |title=Boeing's Starliner spacecraft returns to Earth, wrapping up critical test mission |url=https://www.theverge.com/2022/5/25/23138395/boeing-cst-100-starliner-nasa-undocking-landing-oft-2 |url-status=live |archive-url=https://web.archive.org/web/20220920172341/https://www.theverge.com/2022/5/25/23138395/boeing-cst-100-starliner-nasa-undocking-landing-oft-2 |archive-date=September 20, 2022 |access-date=September 19, 2022 |work=The Verge}}</ref><ref name="gizmodo-2022.05">{{Cite news |last=Rabie |first=Passant |date=May 20, 2022 |title=Boeing's Starliner On Track to Reach ISS Despite Propulsion Glitch |url=https://gizmodo.com/boeing-starliner-nasa-iss-spacecraft-1848954308 |url-status=live |archive-url=https://web.archive.org/web/20220920173535/https://gizmodo.com/boeing-starliner-nasa-iss-spacecraft-1848954308 |archive-date=September 20, 2022 |access-date=September 19, 2022 |work=[[Gizmodo]]}}</ref>
On May 22, 2022, the capsule docked with the International Space Station.<ref name="CNET-2022-05-21">{{Cite news |last=Eric Mack |date=May 21, 2022 |title=Boeing Successfully Docks Starliner Capsule With ISS Years After Failed First Try |url=https://www.cnet.com/science/space/boeing-docks-starliner-capsule-with-iss-years-after-failed-first-try/ |url-status=live |archive-url=https://web.archive.org/web/20220526214607/https://www.cnet.com/science/space/boeing-docks-starliner-capsule-with-iss-years-after-failed-first-try/ |archive-date=May 26, 2022 |access-date=May 26, 2022 |publisher=CNET}}</ref> On May 25, 2022, the capsule returned from space and landed successfully.<ref name="CollectSpace-2022-05-25">{{Cite news |date=May 25, 2022 |title=Boeing Starliner completes Orbital Flight Test-2 with safe touchdown |url=http://www.collectspace.com/news/news-052522a-boeing-starliner-oft2-landing.html |url-status=live |archive-url=https://web.archive.org/web/20220526214607/http://www.collectspace.com/news/news-052522a-boeing-starliner-oft2-landing.html |archive-date=May 26, 2022 |access-date=May 26, 2022 |publisher=CollectSpace}}</ref> During reentry one of the navigation systems dropped communication with the GPS satellites, but Steve Stich, program manager for NASA's Commercial Crew Program, said this is not unexpected during reentry.<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=oiS-SzU8UM0 |title=NASA Boeing Starliner OFT-2 Post-Landing Press Conference, May 25, 2022 |date=May 25, 2022 |last=Steve |first=Stich |publisher=Space SPAN |access-date=September 19, 2022 |archive-url=https://web.archive.org/web/20220919133017/https://www.youtube.com/watch?v=oiS-SzU8UM0 |archive-date=September 19, 2022 |url-status=live |via=YouTube}}</ref>
=== Third orbital flight test (crewed) === [[File:NASA’s Boeing Crew Flight Test Launch (NHQ202406050029).jpg|thumb|{{ComV|CST-100 Starliner|Calypso|full=nolink}} launches on the Crew Flight Test atop an Atlas V rocket.]] [[File:Iss071e265137.jpg|thumb|{{ComV|CST-100 Starliner|Calypso|full=nolink}} docked to the ISS during the Crew Flight Test]] {{Main|Boeing Crew Flight Test}}
Starliner's crewed flight test was intended to be the capsule's final evaluation before entering regular NASA service. The mission plan called for launching two astronauts, commander [[Barry Wilmore]] and pilot [[Sunita Williams]], to dock with the ISS for about a week and return to Earth roughly eight days later.<ref name="sn-20221103">{{Cite news |last=Foust |first=Jeff |author-link=Jeff Foust |date=November 3, 2022 |title=First Starliner crewed flight further delayed |url=https://spacenews.com/first-starliner-crewed-flight-further-delayed/ |url-status=live |archive-url=https://web.archive.org/web/20240606015721/https://spacenews.com/first-starliner-crewed-flight-further-delayed/ |archive-date=June 6, 2024 |access-date=November 3, 2022 |work=[[SpaceNews]]}}</ref>
During approach to the ISS, five of spacecraft's eight aft-facing RCS thrusters failed. After the first two thrusters failed, Wilmore took manual control, noting the vehicle was less responsive than during a test the previous day. NASA waived standard flight rules to allow docking despite the degraded conditions. Eventually, four thrusters failed, resulting in a loss of full [[six degrees of freedom]] (6DOF) attitude control.<ref name="Berger 2025">{{Cite web |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=April 1, 2025 |title=Starliner's flight to the space station was far wilder than most of us thought |url=https://arstechnica.com/space/2025/04/the-harrowing-story-of-what-flying-starliner-was-like-when-its-thrusters-failed/ |access-date=April 3, 2025 |website=Ars Technica |language=en-US}}</ref><ref name="Boeing240802">{{Cite press release |title=Boeing's confidence remains high in Starliner's return with crew |date=August 2, 2024 |publisher=Boeing |url=https://starlinerupdates.com/boeings-confidence-remains-high-in-starliners-return-with-crew/ |quote=1 free-flight hot fire of 5 aft-facing thrusters prior to docking, returning 6-degree of freedom (DOF) axis control}} This statement acknowledges that [[6DoF]] control was lost due to the failures.</ref> The astronauts later described the situation as "very precarious."<ref name="Berger 2025" />
With limited control over the capsule, abandoning the docking attempt was not safe, as the same thrusters were required to orient Starliner for its deorbit burn and reentry. [[NASA Mission Control Center|NASA Mission Control]], which Boeing contracted to operate the spacecraft, attempted a thruster reset. Wilmore stabilized the capsule and called down "Hands off," allowing Mission Control to override the flight software and reactivate the failed jets. Three thrusters were reenabled, but shortly after, a fifth thruster failed. A second reset restored all but one thruster, allowing Starliner to complete its planned autonomous docking.<ref name="Berger 2025" /><ref name="harwood240824">{{Cite news |last=Harwood |first=William |date=August 24, 2024 |title=NASA rules out bringing astronauts home on Boeing's Starliner |url=https://spaceflightnow.com/2024/08/24/nasa-rules-out-bringing-astronauts-home-on-boeings-starliner/ |work=Spaceflight Now |quote=Resetting and firing the thrusters eventually showed that four of the five were again functioning, and the Starliner docked with the ISS after a delay.}}</ref>
A post-mission investigation report released in February 2026 found that the thruster failures were most likely caused by a combination of oxidizer heating and valve seal deformation. Elevated temperatures inside the doghouse containing the thrusters, generated by thruster firings, caused the nitrogen tetroxide oxidizer (NTO) to partially vaporize before reaching the combustion chamber, creating gas bubbles and reducing flow. At the same time, exposure to NTO, heat, and pressure caused the [[Teflon]] seals within the oxidizer valves to deform and expand, further restricting oxidizer flow to the engines.<ref name="nasacftreport" /> A subsequent ground investigation linked the thruster degradation specifically to the Teflon seals.<ref>{{Cite news |last=Harwood |first=William |date=July 26, 2024 |title=Make-or-break tests on tap for Boeing's Starliner capsule |url=https://spaceflightnow.com/2024/07/26/make-or-break-tests-on-tap-for-boeings-starliner-capsule/ |access-date=July 27, 2024 |work=Spaceflight Now |language=en-US}}</ref> While the on-orbit issues were replicated in tests at White Sands using hardware intended for future flights, they could not be reproduced on the in-flight Starliner.<ref name="Chang 2024" /><ref>{{Cite web |title=NASA, Boeing Progress on Testing Starliner with Crew at Space Station |url=https://starlinerupdates.com/nasa-boeing-progress-on-testing-starliner-with-crew-at-space-station/ |website=[[Boeing]]}}</ref>
During the mission, seven of the eight helium manifolds in the service module developed leaks. The investigation determined the most likely cause was incompatibility between the valve materials and NTO, combined with poorly fitting O-rings.<ref name="nasacftreport" />
Despite NASA and Boeing's public reassurances, Wilmore and Williams later said that on June 6 when they docked they already privately doubted Starliner's ability to return them safely to Earth.<ref name="Berger 2025" /> Boeing, however, continued to express confidence in the capsule's design.<ref name="Chang 2024">{{Cite news |last=Chang |first=Kenneth |date=August 7, 2024 |title=NASA Says Boeing Starliner Astronauts May Fly Home on SpaceX in 2025 |url=https://www.nytimes.com/2024/08/07/science/boeing-starliner-nasa-spacex.html |access-date=August 7, 2024 |work=The New York Times |language=en-US |issn=0362-4331}}</ref><ref name="Boeing240802" /> NASA and Boeing continued to assess the situation, and by late August NASA had concluded that the risks of returning with crew were too high.<ref>{{Cite news |last=Wattles |first=Jackie |date=August 24, 2024 |title=Boeing Starliner's astronauts will return to Earth on Spacex Crew Dragon, NASA says |url=https://www.cnn.com/2024/08/24/science/boeing-starliner-nasa-astronauts-spacex?cid=ios_app |access-date=August 24, 2024 |work=[[CNN]] |language=en}}</ref> The spacecraft returned uncrewed and landed safely at [[White Sands Missile Range]] on 7{{Nbsp}}September at 04:01:35{{nbsp}}UTC (6{{Nbsp}}September, 11:01:35{{Nbsp}}pm{{Nbsp}}[[Mountain Daylight Time|MDT]], local time at the landing site), about six hours after it undocked from the ISS.<ref>{{cite web |date=September 7, 2024 |title=Boeing Starliner capsule lands back on Earth, without astronauts, to end troubled test flight (Video) |url=https://www.space.com/boeing-starliner-lands-earth-crew-flight-test-mission |website=[[Space.com]]}}</ref><ref name="Return plan">{{Cite web |last=Niles-Carnes |first=Elyna |date=August 29, 2024 |title=NASA, Boeing Teams "Go" for Starliner Uncrewed Return – NASA's Boeing Crew Flight Test |url=https://blogs.nasa.gov/boeing-crew-flight-test/2024/08/29/nasa-boeing-teams-go-for-starliner-uncrewed-return/ |access-date=August 29, 2024 |website=[[NASA]] |language=en-US}}</ref>
The mission, originally scheduled for 2017,<ref name="nasa.gov">{{Cite web |date=September 16, 2014 |title=Boeing and SpaceX Selected to Build America's New Crew Space Transportation System |url=https://blogs.nasa.gov/commercialcrew/2014/09/16/boeing-and-spacex-selected-to-build-americas-new-crew-space-transportation-system/ |url-status=live |archive-url=https://web.archive.org/web/20170522164333/https://blogs.nasa.gov/commercialcrew/2014/09/16/boeing-and-spacex-selected-to-build-americas-new-crew-space-transportation-system/ |archive-date=May 22, 2017 |access-date=April 6, 2015 |publisher=NASA}} {{PD-notice}}</ref> had already been plagued by delays due to parachute system issues and wiring concerns.<ref name="sn-20230329">{{Cite news |last=Foust |first=Jeff |author-link=Jeff Foust |date=March 29, 2023 |title=Starliner crewed test flight delayed to July |url=https://spacenews.com/starliner-crewed-test-flight-delayed-to-july/ |url-status=live |archive-url=https://web.archive.org/web/20240606000313/https://spacenews.com/starliner-crewed-test-flight-delayed-to-july/ |archive-date=June 6, 2024 |access-date=March 30, 2023 |work=[[SpaceNews]]}}</ref><ref>{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=June 1, 2023 |title=Boeing finds two serious problems with Starliner just weeks before launch |url=https://arstechnica.com/space/2023/06/boeing-stands-down-from-starliner-launch-to-address-recently-found-problems/ |url-status=live |archive-url=https://web.archive.org/web/20240606015836/https://arstechnica.com/space/2023/06/boeing-stands-down-from-starliner-launch-to-address-recently-found-problems/ |archive-date=June 6, 2024 |access-date=June 2, 2023 |work=Ars Technica |language=en-us}}</ref> A launch attempt on May 6, 2024, was scrubbed due to an oxygen valve problem on the rocket.<ref name="space.com-20240404">{{Cite news |date=April 4, 2024 |title=Boeing's 1st Starliner astronaut launch delayed again, to May 6 |url=https://www.space.com/boeing-starliner-cft-astronaut-launch-delay-may-6 |url-status=live |archive-url=https://web.archive.org/web/20240413130150/https://www.space.com/boeing-starliner-cft-astronaut-launch-delay-may-6 |archive-date=April 13, 2024 |access-date=April 4, 2024 |work=[[Space.com]] |language=en}}</ref> Subsequently, a helium leak in the service module further delayed the mission.<ref name="may_6_scrub">{{Cite news |last=William Harwood |date=May 6, 2024 |title=Starliner launch scrubbed by trouble with a valve in the Atlas 5's Centaur upper stage |url=https://spaceflightnow.com/2024/05/07/starliner-launch-scrubbed-by-trouble-with-a-valve-in-the-atlas-5s-centaur-upper-stage/ |url-status=live |archive-url=https://web.archive.org/web/20240507022259/https://spaceflightnow.com/2024/05/07/starliner-launch-scrubbed-by-trouble-with-a-valve-in-the-atlas-5s-centaur-upper-stage/ |archive-date=May 7, 2024 |access-date=May 6, 2024 |work=Spaceflight Now}}</ref><ref>{{Cite news |last=Harwood |first=William |date=May 22, 2024 |title=Boeing Starliner launch Saturday ruled out as helium leak analysis continues – Spaceflight Now |url=https://spaceflightnow.com/2024/05/22/boeing-starliner-launch-saturday-ruled-out-as-helium-leak-analysis-continues/ |url-status=live |archive-url=https://web.archive.org/web/20240522084103/https://spaceflightnow.com/2024/05/22/boeing-starliner-launch-saturday-ruled-out-as-helium-leak-analysis-continues/ |archive-date=May 22, 2024 |access-date=May 22, 2024 |work=Spaceflight Now |language=en-US}}</ref> Another attempt on June 1 was scrubbed due to a ground computer hardware fault.<ref>{{Cite news |last=Foust |first=Jeff |author-link=Jeff Foust |date=June 1, 2024 |title=Starliner launch attempt scrubbed |url=https://spacenews.com/starliner-launch-attempt-scrubbed/ |url-status=live |archive-url=https://web.archive.org/web/20240606000409/https://spacenews.com/starliner-launch-attempt-scrubbed/ |archive-date=June 6, 2024 |access-date=July 22, 2024 |work=[[SpaceNews]]}}</ref> Starliner launched on June 5 at 14:52 UTC (10:52{{spaces}}am EDT).<ref>{{Cite news |last=Howell |first=Elizabeth |date=June 5, 2024 |title=Boeing's Starliner launches astronauts for 1st time in historic liftoff (photos, video) |url=https://www.space.com/boeing-starliner-crew-flight-test-launch |url-status=live |archive-url=https://web.archive.org/web/20240607234443/https://www.space.com/boeing-starliner-crew-flight-test-launch |archive-date=June 7, 2024 |access-date=June 9, 2024 |work=[[Space.com]]}}</ref>
During reentry, Starliner experienced a brief navigation glitch and the failure of a crew module orientation thruster, which were unrelated to the earlier RCS issues.<ref name="Clark 2024-09-07">{{Cite news |last=Clark |first=Stephen |date=September 7, 2024 |title=Leaving behind its crew, Starliner departs space station and returns to Earth |url=https://arstechnica.com/space/2024/09/leaving-behind-its-crew-starliner-departs-space-station-and-returns-to-earth/ |access-date=September 7, 2024 |work=[[Ars Technica]]}}</ref> The investigation determined that the orientation thruster likely failed due to corrosion caused by carbazic acid formed from residual propellant and carbon dioxide. The failure of this single thruster reduced the system to zero fault tolerance. The report noted that the crew module orientation system lacked the required two-fault tolerance for deorbit burns, a design limitation that had existed since early development but was not identified until the crewed flight test pre-launch.<ref name="nasacftreport" />
[[Administrator of NASA|NASA administrator]] [[Bill Nelson]] stated that Boeing CEO [[Kelly Ortberg]] committed to continuing the Starliner program despite the setbacks.<ref name="Roulette 2024" /> Boeing, however, drew criticism after abruptly canceling its participation in a post-landing press conference and refusing to answer questions from journalists, opting to release only brief written statements.<ref name="Clark 2024-09-07" />
An investigation report released in February 2026 retroactively classified the mission as a Type A mishap, NASA's most severe failure category, typically reserved for missions involving loss of vehicle or life. The report cited hardware failures, qualification deficiencies, leadership errors, and organizational shortcomings that created risks inconsistent with NASA's human spaceflight safety standards. Administrator [[Jared Isaacman]] said that while the spacecraft has design and engineering deficiencies requiring correction, he was most troubled by the failures in decision-making and leadership at both NASA and Boeing.<ref>{{Cite web |last=Cowing |first=Keith |date=February 19, 2026 |title=A Message From Administrator Jared Isaacman (Starliner) |url=https://nasawatch.com/ask-the-administrator/a-message-from-administrator-jared-isaacman-starliner/ |access-date=February 20, 2026 |website=NASA Watch |language=en-US}}</ref><ref>{{Cite news |last=Roulette |first=Joey |date=February 19, 2026 |title=NASA chief slams Boeing, agency's failures in botched Starliner astronaut mission |url=https://www.reuters.com/business/aerospace-defense/nasa-chief-slams-boeing-agency-failures-botched-starliner-astronaut-mission-2026-02-19/ |access-date=February 19, 2026 |work=Reuters}}</ref><ref name="Berger2026">{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=February 19, 2026 |title=NASA chief classifies Starliner flight as "Type A" mishap, says agency made mistakes |url=https://arstechnica.com/space/2026/02/nasa-chief-classifies-starliner-flight-as-type-a-mishap-says-agency-made-mistakes |access-date=February 19, 2026 |work=[[Ars Technica]]}}</ref>
=== Starliner-1 (uncrewed) === {{main|Boeing Starliner-1}}
Because NASA was unable to certify Starliner based on the crewed flight test, Boeing and NASA agreed that the next flight, Starliner-1, would not carry crew and that it would serve as a test flight for purposes of certification.<ref name="CCP 2025 plan"/><ref name=NASA2025-11-24>{{cite news|title=NASA, Boeing Modify Commercial Crew Contract|publisher=NASA|date=November 24, 2025|access-date=November 24, 2025|url=https://www.nasa.gov/blogs/commercialcrew/2025/11/24/nasa-boeing-modify-commercial-crew-contract/}}</ref> On May 2, 2026, NASA confirmed that Starliner-1 will act as an ISS resupply mission.<ref>{{cite web |last1=Tribou |first1=Richard |title=NASA keeps Boeing Starliner flights in holding pattern in updated space station plan |url=https://www.orlandosentinel.com/2026/05/02/nasa-keeps-boeing-starliner-flights-in-holding-pattern-in-updated-space-station-plan/ |website=[[Orlando Sentinel]] |access-date=2 May 2026}}</ref> {{asof|2026|05}}, teams continue to work through the technical problems, and NASA is considering appropriate launch opportunities for the Starliner-1 mission.<ref name=NASA2026update>{{cite web|title=NASA, Partners Update International Space Station 2026 Flight Plan|url=https://www.nasa.gov/blogs/commercialcrew/2026/05/01/nasa-partners-update-international-space-station-2026-flight-plan|first=Mark A.|last=Garcia|date=May 1, 2026|access-date=May 5, 2026}}</ref>
== Commercial use == [[File:Boeing's CST-100 Starliner spacecraft docking to the ISS.jpg|thumb|Artist's impression of a ''Boeing Starliner'' docking to the ISS]] Under the CCP, Boeing owns and operates the Starliner capsules, allowing the company to offer non-CCP commercial flights if they do not interfere with NASA missions.<ref>{{Cite web |title=Juno: New Origins {{!}} CFT starliner fixed |url=https://www.simplerockets.com/c/cA8OIY/CFT-starliner-fixed |url-status=live |archive-url=https://web.archive.org/web/20240601195723/https://www.simplerockets.com/c/cA8OIY/CFT-starliner-fixed |archive-date=June 1, 2024 |access-date=June 1, 2024 |website=www.simplerockets.com}}</ref> While SpaceX has secured private commercial flights, Boeing has yet to do so.
The CCP agreement permits Boeing to sell seats for space tourists on ISS flights. While initially proposed, the extended length of typical ISS missions makes this unlikely.<ref>{{Cite news |last=Klotz |first=Irene |date=September 17, 2014 |title=Boeing's 'space taxi' includes seat for a tourist |url=https://www.reuters.com/article/boeing-space-idUSL1N0RI2XY20140917 |url-status=live |archive-url=https://web.archive.org/web/20150924204556/http://www.reuters.com/article/2014/09/17/boeing-space-idUSL1N0RI2XY20140917 |archive-date=September 24, 2015 |access-date=August 6, 2015 |work=Reuters}}</ref>
In October 2021, [[Blue Origin]], Boeing, and [[Sierra Nevada Corporation]] announced plans for a commercial space station called [[Orbital Reef]]. This "mixed-use business park" could be serviced by both Starliner and Sierra Nevada's [[Dream Chaser]] spacecraft.<ref>{{Cite news |last=Davenport |first=Justin |date=October 27, 2021 |title=Blue Origin, Sierra Space, and Boeing announce Orbital Reef |url=https://www.nasaspaceflight.com/2021/10/announce-orbital-reef/ |url-status=live |archive-url=https://web.archive.org/web/20211130060908/https://www.nasaspaceflight.com/2021/10/announce-orbital-reef/ |archive-date=November 30, 2021 |access-date=November 30, 2021 |work=nasaspaceflight.com |language=en}}</ref><ref>{{Cite news |last=Chappell |first=Bill |date=October 25, 2021 |title=Blue Origin says it will build an orbiting mixed-use business park in space |url=https://www.npr.org/2021/10/25/1049077333/blue-origin-space-station-business-park-space-orbital-reef-bezos |url-status=live |archive-url=https://web.archive.org/web/20211129160341/https://www.npr.org/2021/10/25/1049077333/blue-origin-space-station-business-park-space-orbital-reef-bezos |archive-date=November 29, 2021 |access-date=November 30, 2021 |work=NPR |language=en}}</ref><ref>{{Cite news |last=Grush |first=Loren |date=October 25, 2021 |title=Blue Origin reveals plans for future commercial space station called Orbital Reef |url=https://www.theverge.com/2021/10/25/22744526/blue-origin-space-station-orbital-reef-announcement |url-status=live |archive-url=https://web.archive.org/web/20211129160340/https://www.theverge.com/2021/10/25/22744526/blue-origin-space-station-orbital-reef-announcement |archive-date=November 29, 2021 |access-date=November 29, 2021 |work=[[The Verge]] |language=en}}</ref>
== Launch vehicle == Starliner was designed to be compatible with multiple launch vehicles, including the Atlas V, [[Delta IV]], [[Falcon 9]], and [[Vulcan Centaur]].<ref name="sdc20180803">{{Cite news |last=Wall |first=Mike |date=August 3, 2018 |title=Crew Dragon and Starliner: A Look at the Upcoming Astronaut Taxis |url=https://www.space.com/41367-commercial-crew-spacecraft-starliner-dragon.html |url-status=live |archive-url=https://web.archive.org/web/20190821180355/https://www.space.com/41367-commercial-crew-spacecraft-starliner-dragon.html |archive-date=August 21, 2019 |access-date=August 29, 2020 |publisher=SPACE.com}}</ref>
For the three completed test flights and up to six further missions, Starliner is expected to fly atop the Atlas V. However, United Launch Alliance, the operator of the Atlas V, ceased production of the rocket in 2024 after producing vehicles for all remaining contracted launches.<ref name="Verge">{{Cite news |last=Roulette |first=Joey |date=August 26, 2021 |title=ULA stops selling its centerpiece Atlas V, setting path for the rocket's retirement |url=https://www.theverge.com/2021/8/26/22641048/ula-boeing-lockheed-end-sales-atlas-v-rocket-russia-rd180 |url-status=live |archive-url=https://web.archive.org/web/20211228153058/https://www.theverge.com/2021/8/26/22641048/ula-boeing-lockheed-end-sales-atlas-v-rocket-russia-rd180 |archive-date=December 28, 2021 |access-date=September 1, 2021 |publisher=The Verge}}</ref><ref>{{Cite tweet |number=1800818621247008910 |user=torybruno |title=Bitter sweet. The final Atlas V is making its way through the factory. There are 16 AV missions to go. They will all be built this year, making more room for #Vulcan rate production |first=Tory |last=Bruno |author-link=Tory Bruno |date=June 12, 2024 |access-date=June 14, 2024}}</ref> The vehicles have been allocated to customers, including the six needed for the remaining Starliner flights.<ref name="Berger 2022-06-02">{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=June 2, 2022 |title=NASA just bought the rest of the space station crew flights from SpaceX |url=https://arstechnica.com/science/2022/06/nasa-just-bought-all-the-seats-needed-for-space-station-crews-into-2030/ |url-status=live |archive-url=https://web.archive.org/web/20221006171726/https://arstechnica.com/science/2022/06/nasa-just-bought-all-the-seats-needed-for-space-station-crews-into-2030/ |archive-date=October 6, 2022 |access-date=May 9, 2024 |work=[[Ars Technica]] |language=en-us}}</ref>
The Starliner faces an uncertain future after that. Delta IV is retired and no more are available,<ref>{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=August 22, 2019 |title=The last single-stick Delta rocket launched Thursday, and it put on a show |url=https://arstechnica.com/science/2019/08/the-last-single-stick-delta-rocket-launched-thursday-and-it-put-on-a-show/ |url-status=live |archive-url=https://web.archive.org/web/20201107224032/https://arstechnica.com/science/2019/08/the-last-single-stick-delta-rocket-launched-thursday-and-it-put-on-a-show/ |archive-date=November 7, 2020 |access-date=August 6, 2020 |work=[[Ars Technica]]}}</ref> the Falcon 9 is owned by crewed launch competitor SpaceX, and the Vulcan Centaur has not yet been human-rated, testing Boeing would have to pay for.<ref name="Berger 2022-06-02" />
=== Configuration === For Starliner launches, ULA uses the Atlas N22 configuration. All other Atlas V launches use a payload fairing and the single-engine version of the Centaur upper stage. N22 is configured with no payload fairing, two solid rocket boosters (SRBs), and a [[Centaur (rocket stage)#Dual Engine Centaur (DEC)|Dual Engine Centaur]] second stage. Starliner is the only crewed payload for Atlas V.
While most Atlas V launches since 2021 have used the newer Northrop Grumman [[Graphite-Epoxy Motor|GEM63]] SRBs, these boosters are not rated for human spaceflight. Therefore, crewed missions employ the older Aerojet Rocketdyne [[AJ-60A]] SRBs.<ref>{{Cite news |last=Clark |first=Stephen |date=May 15, 2021 |title=Billion-dollar missile defense satellite ready for launch Monday in Florida |url=https://spaceflightnow.com/2021/05/15/billion-dollar-missile-defense-satellite-ready-for-launch-monday-at-cape-canaveral/ |access-date=September 16, 2024 |work=Spaceflight Now}}</ref>
Although the Dual Engine Centaur had not been used since 2000 after the introduction of the more powerful Atlas V, it was brought back into service for Starliner missions. Two engines allow the rocket to fly a gentler and flatter trajectory to minimize the G-forces experienced by the astronauts and ensures the capsule can abort at any time, returning the crew to Earth in case of a problem.<ref>{{Cite web |title=OFT-2: Dual Engine Centaur returns to service for Starliner launches |url=https://blog.ulalaunch.com/blog/oft-2-dual-engine-centaur-returns-to-service-for-starliner-launches |access-date=August 27, 2024 |website=ULA |language=en}}</ref>
== Launch profile == After passing through the stages of [[max q|max ''q'']], SRB jettison, booster separation, Centaur ignition, nosecone and aeroskirt jettison, it releases the Starliner spacecraft at stage separation, nearly 15 minutes after lift-off on a {{cvt|181 × 72|km|mi|order=flip|adj=mid|-high}} suborbital trajectory, just below the [[orbital speed|orbital velocity]] needed to enter a stable orbit around Earth. After separating from the Dual Engine Centaur, the Starliner's own thrusters, mounted on its service module, boost the spacecraft into orbit to continue its journey to the International Space Station.
The suborbital trajectory is unusual for a satellite launch, but it is [[Space Shuttle#Launch|similar to the technique]] used by the [[Space Shuttle]] and [[Space Launch System]]. It ensures that, if the spacecraft fails to make the orbital insertion burn, it will re-enter the atmosphere in a controlled way.<ref>{{cite news |last=Clark |first=Stephen |date=December 19, 2019 |title=Starliner test flight to use special Atlas 5 configuration, unusual launch trajectory |journal=Spaceflight Now |url=https://spaceflightnow.com/2019/12/19/starliner-test-flight-to-use-special-atlas-5-configuration-unusual-launch-trajectory/ |quote=The 44-mile-high perigee, or low point, of the suborbital trajectory is inside Earth's atmosphere, meaning the Starliner would re-enter the atmosphere and come back to Earth without an additional propulsive maneuver.}}</ref> The Starliner's orbit insertion burn begins about 31 minutes into the mission and lasts 45 seconds.<ref>{{Cite news |last=Clark |first=Stephen |date=May 19, 2022 |title=Boeing's Starliner crew capsule takes off on long-awaited test flight |url=https://spaceflightnow.com/2022/05/19/boeings-starliner-crew-capsule-takes-off-on-long-awaited-test-flight/ |url-status=live |archive-url=https://web.archive.org/web/20220520180402/https://spaceflightnow.com/2022/05/19/boeings-starliner-crew-capsule-takes-off-on-long-awaited-test-flight/ |archive-date=May 20, 2022 |access-date=May 20, 2022 |work=Spaceflight Now}}</ref>
== List of spacecraft == {{As of|2020|1}}, Boeing planned to have three Boeing Starliner capsules in service to fulfill the needs of the Commercial Crew Program with each capsule expected to be capable of being reused up to ten times with a six-month refurbishment time.<ref>{{Cite web |last=Krebs, Gunter |title=Starliner (CST-100) |url=https://space.skyrocket.de/doc_sdat/starliner.htm |url-status=live |archive-url=https://web.archive.org/web/20230608182241/https://space.skyrocket.de/doc_sdat/starliner.htm |archive-date=June 8, 2023 |access-date=August 29, 2020 |publisher=Gunter's Space Page}}</ref><ref>{{Cite web |title=CST-100 Starliner |url=https://www.boeing.com/space/starliner/ |url-status=live |archive-url=https://web.archive.org/web/20210719145445/https://www.boeing.com/space/starliner/ |archive-date=July 19, 2021 |access-date=January 19, 2020 |publisher=Boeing}}</ref> On August 25, 2020, Boeing announced it would alternate between just two capsules for all planned Starliner missions instead of three.<ref name="SFN20200825" />
{| class="wikitable" ! {{nowrap|{{Abbr|S/N|Serial number}}}} ! Name ! Type ! Status ! Flights ! Flight time ! Total flight time ! Notes<ref name="starlinerlist-1" /><ref name="starlinernotebook" /> ! {{abbr|Cat.|Commons category and Wikidata page}} |- | {{abbr|S1|Spacecraft 1}} | {{color|grey|None}} | Prototype | {{Draw|Retired}} | 1 | {{Time interval|November 4, 2019, 14:15:00|4 November 2019, 14:16:19|show=dhms|abbr=on}} ([[Boeing Pad Abort Test|PAT]]) | {{Time interval|November 4, 2019, 14:15:00|4 November 2019, 14:16:19|show=dhms|abbr=on}} | Prototype used only for pad abort test. | [[File:Commons-logo.svg|15px|link=c:Category:Boeing Starliner Spacecraft 1]] |- | [[Boeing Starliner Spacecraft 2|S2]] | {{color|grey|TBA}} | Crew | {{Active}} | 1 | {{Time interval|May 19, 2022, 22:54:47|25 May 2022, 22:49|show=dhm|abbr=on}} ([[Boeing Orbital Flight Test 2|OFT-2]]) | {{Time interval|May 19, 2022, 22:54:47|25 May 2022, 22:49|show=dhm|abbr=on}} | Completed the [[Boe-OFT-2|OFT-2]] flight. | [[File:Commons-logo.svg|15px|link=c:Category:Boeing Starliner Spacecraft 2]] [[File:Wikidata-logo.svg|20px|link=d:Q104881693]] |- | [[Boeing Starliner Calypso|S3]] | ''[[Boeing Starliner Calypso|Calypso]]'' | Crew | {{Active|Active}} | 2 | {{Plainlist| * {{Time interval|December 20, 2019, 11:36:43|22 December 2019, 12:58:53|show=dhm|abbr=on}} ([[Boeing Orbital Flight Test|OFT]]) * {{Time interval|5 June 2024 14:52:15|7 September 2024 04:01:35|show=dhm|abbr=on}} ([[Boeing Crew Flight Test|CFT]]) }} | 95d 14h 31m | Named after [[Jacques Cousteau]]'s ship {{ship|RV|Calypso}}. First Starliner to orbit during [[Boe-OFT|OFT]], first to carry crew to space during [[Boeing Crew Flight Test|CFT]]. | [[File:Commons-logo.svg|15px|link=c:Category:Boeing Starliner Calypso]] [[File:Wikidata-logo.svg|20px|link=d:Q87412988]] |}
== List of flights == List includes only completed or currently manifested missions. Dates are listed in [[Coordinated Universal Time|UTC]], and for future events, they are the earliest possible opportunities (also known as {{Abbr|NET|no earlier than}} dates) and may change. {| class="wikitable sticky-header" ! Mission and [[Mission patch|Patch]] ! Capsule ! Launch date ! Landing date ! Remarks ! Crew ! Outcome |- | [[Boeing Pad Abort Test|Pad Abort Test]]<br />([[:File:Boeing Pad Abort Test.png|patch]])<!--Please do not insert any non-free images as visible images--> | {{abbr|S1|Spacecraft 1}} | colspan="2" style="text-align:center" | November 4, 2019 | Simulating an escape from a failing rocket, Starliner's RS-88 engines lifted the capsule from a pad at [[White Sands Missile Range|White Sands]]. Only two of three parachutes opened, but was declared a success. | {{N/A}} | {{success}} |- | [[Boeing Orbital Flight Test|Orbital Flight Test]]<br />([[:File:Boeing Orbital Flight Test.png|patch]])<!--Please do not insert any non-free images as visible images--> | [[Boeing Starliner Calypso|S3.1<br />''Calypso'']] | December 19, 2019 | December 22, 2019 | First uncrewed orbital flight test. Orbited but failed to rendezvous with ISS. Landed successfully. | {{N/A}} | {{Partial failure}} |- | [[Boeing Orbital Flight Test 2|Orbital Flight Test 2]]<br />([[:File:Boeing OFT 2 patch.png|patch]])<!--Please do not insert any non-free images as visible images--> | [[Boeing Starliner Spacecraft 2|S2.1]] | May 19, 2022 | May 25, 2022 | Second uncrewed orbital flight test. Experienced {{abbr|OMAC|Orbital Maneuvering and Attitude Control}} and {{abbr|RCS|Reaction Control System}} thruster malfunctions, but successfully docked to ISS. | {{N/A}} | {{Partial failure}}{{efn|1=Retroactively classified in February 2026 as a partial failure.<ref name="Berger2026"/>}} |- | [[Boeing Crew Flight Test|Crew Flight Test]]<br />([[:File:Boeing CFT patch.png|patch]])<!--Please do not insert any non-free images as visible images--> | [[Boeing Starliner Calypso|S3.2<br />''Calypso'']] | June 5, 2024 | September 7, 2024 | Crewed flight test to ISS. Landed uncrewed due to malfunctioning RCS thrusters. | {{plainlist| * [[Barry Wilmore]] * [[Sunita Williams]] }} | {{Failure}}{{efn|1=Retroactively classified in February 2026 as a Type A mishap, the most serious failure category, typically reserved for missions involving loss of vehicle or life.<ref name="Berger2026"/><ref name="nasacftreport"/>}} |- | [[Boeing Starliner-1|Starliner-1]] | [[Boeing Starliner Spacecraft 2|S2.2]] | TBD<ref name="Berger2026"/> | {{abbr|TBD|to be determined}} | Uncrewed cargo flight to ISS | {{N/A}} | {{Planned}} |- | Starliner-2 | {{abbr|TBD|to be determined}} | {{abbr|TBD|to be determined}} | {{abbr|TBD|to be determined}} | | {{abbr|TBA|to be announced}} | {{Planned}} |- | Starliner-3 | {{abbr|TBD|to be determined}} | {{abbr|TBD|to be determined}} | {{abbr|TBD|to be determined}} | | {{abbr|TBA|to be announced}} | {{Planned}} |- | Starliner-4 | {{abbr|TBD|to be determined}} | {{abbr|TBD|to be determined}} | {{abbr|TBD|to be determined}} | | {{abbr|TBA|to be announced}} | {{Planned}} |}
In November 2025, NASA and Boeing modified the initial contract. The modified contract calls for three crewed flights after successful completion of the uncrewed Starliner-1 flight.<ref name=NASA2025-11-24>{{cite news|title=NASA, Boeing Modify Commercial Crew Contract|publisher=NASA|date=November 24, 2025|access-date=November 24, 2025|url=https://www.nasa.gov/blogs/commercialcrew/2025/11/24/nasa-boeing-modify-commercial-crew-contract/}}</ref>
== Technology partners == {{div col}} * [[Aerojet Rocketdyne]], reaction control system and retrorockets<ref>{{Cite news |date=December 12, 2019 |title=Aerojet Rocketdyne gears up for first flight of Boeing's Starliner Spacecraft |url=https://www.rocket.com/article/aerojet-rocketdyne-gears-first-flight-boeing%E2%80%99s-starliner-spacecraft |url-status=live |archive-url=https://web.archive.org/web/20230506184709/https://www.rocket.com/article/aerojet-rocketdyne-gears-first-flight-boeing%E2%80%99s-starliner-spacecraft |archive-date=May 6, 2023 |access-date=May 6, 2023 |publisher=Aerojet Rocketdyne}}</ref> * Airborne Systems, parachutes<ref>{{Cite web |date=May 4, 2012 |title=Boeing Tests Parachute System for CST-100 Spacecraft |url=https://www.nasa.gov/exploration/commercial/crew/boeingdroptest.html |url-status=dead |archive-url=https://web.archive.org/web/20230531222513/https://www.nasa.gov/exploration/commercial/crew/boeingdroptest.html |archive-date=May 31, 2023 |access-date=May 6, 2023 |publisher=NASA}}</ref> * [[Bigelow Aerospace]], elements of crew capsule<ref name="bigelow" /> * [[Collins Aerospace]], life support systems<ref>{{Cite news |date=April 8, 2019 |title=Collins Aerospace to provide Earth-like atmosphere on Boeing's new 'space taxi' for NASA |url=https://spaceref.com/press-release/collins-aerospace-to-provide-earth-like-atmosphere-on-boeings-new-space-taxi-for-nasa/ |access-date=May 6, 2023 |work=spaceref.com}}</ref> * [[David Clark Company]], spacesuits<ref>{{Cite news |last=Howell |first=Elizabeth |date=April 17, 2024 |title='I really like these suits.' Boeing's snazzy (and flexible) Starliner spacesuits have astronauts buzzing (exclusive) |url=https://www.space.com/boeing-starliner-astronaut-spacesuit-fashion-safety |access-date=June 20, 2024 |language=en}}</ref> * [[ILC Dover]], airbags<ref>{{Cite news |date=May 31, 2022 |title=ILC Dover becomes a provider of spacesuits for Boeing's Starliner |url=https://www.spacedaily.com/reports/ILC_Dover_becomes_a_provider_of_spacesuits_for_Boeings_Starliner_999.html |url-status=live |archive-url=https://web.archive.org/web/20230506192634/https://www.spacedaily.com/reports/ILC_Dover_becomes_a_provider_of_spacesuits_for_Boeings_Starliner_999.html |archive-date=May 6, 2023 |access-date=May 6, 2023 |work=spacedaily.com}}</ref> * [[Samsung]], mobile communications technology<ref>{{Cite news |last=Leon Spencer |date=May 22, 2014 |title=Samsung and Boeing collaborate on mobile tech in space |url=https://www.zdnet.com/article/samsung-and-boeing-collaborate-on-mobile-tech-in-space/ |url-status=live |archive-url=https://web.archive.org/web/20230506184711/https://www.zdnet.com/article/samsung-and-boeing-collaborate-on-mobile-tech-in-space/ |archive-date=May 6, 2023 |access-date=May 6, 2023 |work=[[ZDNet]]}}</ref> * Spincraft, crew module pressure shell spin-form work<ref>{{Cite news |last=Richardson |first=Mike |date=July 20, 2018 |title=Building a better spaceship |url=https://www.aero-mag.com/boeing-starliner-international-space-station |url-status=live |archive-url=https://web.archive.org/web/20230506184716/https://www.aero-mag.com/boeing-starliner-international-space-station |archive-date=May 6, 2023 |access-date=May 6, 2023 |work=Aerospace Manufacturing}}</ref> {{div col end}}
== See also == {{Portal|Spaceflight}} {{Div col}} * [[List of crewed spacecraft]] * [[Dream Chaser]], a spaceplane under development * [[Mengzhou (spacecraft)|Mengzhou]], a human-rated spacecraft being developed in [[China]] * [[Orel (spacecraft)|Orel]], a human-rated spacecraft being developed in [[Russia]] {{Div col end}}
== Notes == {{notelist}}
== References == {{Reflist|refs=
<ref name="sfn20210118">{{Cite news |last=Clark |first=Stephen |date=January 18, 2021 |title=Boeing making progress on Starliner software for test flight in March |url=https://spaceflightnow.com/2021/01/18/boeing-making-progress-on-starliner-software-for-test-flight-in-march/ |url-status=live |archive-url=https://web.archive.org/web/20220517123307/https://spaceflightnow.com/2021/01/18/boeing-making-progress-on-starliner-software-for-test-flight-in-march/ |archive-date=May 17, 2022 |access-date=January 18, 2021 |work=Spaceflight Now}}</ref>
<ref name="space20210121">{{Cite news |last=Howell |first=Elizabeth |date=January 21, 2021 |title=Boeing's Starliner spacecraft software passes qualification review for next NASA test flight |url=https://www.space.com/boeing-starliner-software-approved-oft-2-test-flight |url-status=live |archive-url=https://web.archive.org/web/20210121204136/https://www.space.com/boeing-starliner-software-approved-oft-2-test-flight |archive-date=January 21, 2021 |access-date=January 21, 2021 |work=[[Space.com]]}}</ref>
<ref name="starlinerlist-1">{{Cite news |last=Clark |first=Stephen |date=December 22, 2019 |title=Boeing's first commercial crew capsule christened "Calypso" |url=https://spaceflightnow.com/2019/12/22/boeings-first-crew-capsule-christened-calypso/ |url-status=live |archive-url=https://web.archive.org/web/20200309230903/https://spaceflightnow.com/2019/12/22/boeings-first-crew-capsule-christened-calypso/ |archive-date=March 9, 2020 |access-date=March 9, 2020 |work=Spaceflight Now |quote=The Starliner vehicle that landed Sunday in New Mexico, designated Spacecraft 3 [...] Spacecraft 1 was built for Boeing's pad abort test and is not intended to fly in space. [...] she has named the Starliner vehicle that returned Sunday "Calypso" in an ode to the research vessel used by French explorer Jacques Cousteau}}</ref>
<ref name="starlinernotebook">{{Cite web |date=2019 |title=Reporter's Starliner Notebook |url=https://www.boeing.com/space/starliner/launch/documents/Starliner_Notebook.pdf |url-status=live |archive-url=https://web.archive.org/web/20230824233443/https://www.boeing.com/space/starliner/launch/documents/Starliner_Notebook.pdf |archive-date=August 24, 2023 |access-date=March 9, 2020 |publisher=Boeing |page=9 |quote=Spacecraft 1 was used for testing the launch abort system during the program's Pad Abort Test in New Mexico. Spacecraft 2 [is] being prepared to fly the first people on Starliner's Crew Flight Test. Spacecraft 3 [is] slated for the uncrewed Orbital Flight Test...}}</ref>
<ref name="nasacftreport">{{Cite web |date=February 5, 2026 |title=Starliner Propulsion System Anomalies during the Crewed Flight Test - Investigation Report |url=https://www.nasa.gov/wp-content/uploads/2026/02/nasa-report-with-redactions-021926.pdf?emrc=76e561 |url-status=live |archive-url=https://web.archive.org/web/20260221210551/https://www.nasa.gov/wp-content/uploads/2026/02/nasa-report-with-redactions-021926.pdf?emrc=76e561 |archive-date=February 21, 2026 |access-date=February 22, 2026 |publisher=NASA |pages=3, 21, 25, 33, 71}}</ref> }}
== External links == {{Commons}} * {{YouTube|Mn_gXEK5XmQ|Boeing/Bigelow Crew Space Transport Vehicle}} by Boeing (2010) * {{YouTube|6VYIUi9H3vM|Boeing Unveils America's First Space Taxi, Unlocks Possibilities for Future}} by Boeing (2014) * [https://www.boeing.com/space/starliner/launch/documents/Starliner_Notebook.pdf Reporter's Starliner Notebook] * [https://www.youtube.com/watch?v=6LKMS6xKuuA Astronaut Doug Hines enters the Boeing Starliner for the first time during OFT-2] * [https://www.nasa.gov/wp-content/uploads/2019/08/cctcap_boeing_508.pdf?emrc=a8de2c Boeing Commercial Crew Transportation Capability Contract (CCtCap)] - the fixed price contract with NASA for the Starliner program
{{Boeing Starliner}} {{Crewed spacecraft}} {{Crewed ISS flights}}
[[Category:Boeing Starliner| ]] [[Category:American spacecraft]] [[Category:Bigelow Aerospace]] [[Category:Boeing spacecraft and space launch systems|Starliner]] [[Category:Commercial spaceflight]] [[Category:Crewed spacecraft]] [[Category:Reusable spacecraft]] [[Category:Supply vehicles for the International Space Station]]