Commercial Crew Program

The Commercial Crew Program (CCP) is a human spaceflight program operated by NASA, in association with American aerospace manufacturers Boeing and SpaceX. The program conducts rotations between the expeditions of the International Space Station program, transporting crews to and from the International Space Station (ISS) aboard Boeing Starliner and SpaceX Crew Dragon capsules, in the first crewed orbital spaceflights operated by private companies. The program succeeds NASA's involvement in the Soyuz program, upon which it was dependent to transport its astronauts to the ISS following the retirement of the Space Shuttle program in 2011. Each mission in the Commercial Crew Program will send up to four astronauts to the ISS aboard either a Crew Dragon or Starliner, with options for a fifth passenger being available to NASA. Crew Dragon spacecraft are launched to space atop a Falcon 9 Block 5 launch vehicle and return to Earth via splashdown in the Atlantic Ocean. Starliner spacecraft are launched atop an Atlas V N22 launch vehicle and return on land with airbags on one of four designated sites in the western United States. SpaceX's first operational mission in the program launched on 15 November 2020, while Boeing's first mission is due to launch in 2021.

Development of the Commercial Crew Program began in 2011 through a rescope of the Commercial Crew Development (CCDev) program, a Recovery Act initiative originally aimed at funding development of various human spaceflight technologies in the private sector. While NASA had previously envisioned internally-developed crewed vehicles to perform ISS crew rotation, such as the Orbital Space Plane in the early 2000s and the Orion spacecraft in the late 2000s, the agency looked instead to commercial industry to provide transport to the ISS, following cancellation of the Constellation program in 2010 and a refocusing of Orion for crewed deep space exploration only. A series of open competitions over the following two years saw successful bids from Boeing, Blue Origin, Sierra Nevada, and SpaceX to develop proposals for ISS crew transport vehicles.

Boeing and SpaceX were ultimately selected by NASA in September 2014 to fly astronauts to the ISS, though the decision was met with an unsuccessful legal challenge from Sierra Nevada. While the first operational missions in the program were initially planned for 2017, numerous issues during design, testing, and operation of the spacecraft and launch vehicles pushed first operational flights to 2020 and 2021, with additional occupations on Soyuz spacecraft up to Soyuz MS-17 being bought by NASA to compensate for the delays. The final test flight of Crew Dragon was launched in May 2020, while the final test flight of Starliner is planned for launch in 2021, prior to the companies' first operational missions.

Background
In 2004, the Aldridge Commission – established by President George W. Bush following the Space Shuttle Columbia disaster – called for crewed flights to the Moon with a Crew Exploration Vehicle in its final report. Following the NASA Authorization Act of 2005, the Constellation program was established, which envisioned a revised Crew Exploration Vehicle named Orion conducting crew rotation flights to the International Space Station (ISS) in addition to its lunar exploration goals. Orion superseded the Orbital Space Plane, which was specifically designed for ISS crew rotation. In 2009, the Augustine Commission appointed by President Barack Obama found that the program's funding and resources were insufficient to execute its goals without significant delays to its schedule and an increase of US$3 billion in funding, which prompted NASA to start considering alternatives to the program. The Constellation program was officially cancelled in 2010, with NASA repurposing Orion for exploration beyond Earth, and collaborating with commercial partners for ISS crew rotation and other crewed activities in low Earth orbit following the retirement of the Space Shuttle program in 2011. The new arrangement would additionally end NASA's dependency on Roscosmos' Soyuz program to deliver its astronauts to the ISS.

CCDev awards


The NASA Authorization Act of 2010 allocated US$1.3 billion for an expansion of the existing Commercial Crew Development (CCDev) program over three years. While the program's first round of competition in 2010 focused on funding development of various human spaceflight technologies in the private sector as part of the American Recovery and Reinvestment Act, its second round, CCDev 2, focused on proposals for spacecraft capable of shuttling astronauts to and from the ISS. The competition for CCDev 2 funding concluded in April 2011, with Blue Origin receiving US$22 million to develop its biconic nose cone capsule concept, SpaceX receiving US$75 million to develop the a crewed version of their Dragon spacecraft and a human-rated Falcon 9 launch vehicle, the Sierra Nevada Corporation receiving US$80 million to develop the Dream Chaser, and Boeing receiving US$92.3 million to develop the CST-100 Starliner. SpaceX had previously been contracted by NASA to operate ISS resupply flights with their Dragon spacecraft, as part of NASA's Commercial Resupply Services. The program's third round, Commercial Crew integrated Capability (CCiCap), aimed to financially support the development of winning proposals over 21 months through to May 2014, in preparation for crewed missions to the ISS within five years. Despite winning awards in CCDev 1 and CCDev 2, Blue Origin decided against competing in CCiCap, opting instead to rely on private investment from their owner, Jeff Bezos, to continue development on crewed spaceflight. The competition for CCiCap funding ended in August 2012, with US$212.5 million allocated to Sierra Nevada's Dream Chaser, US$440 million allocated to SpaceX's Crew Dragon, and US$460 million allocated to Boeing's Starliner. While Alliant Techsystems's integrated Liberty launch vehicle and spacecraft was a finalist, it was rejected due to concerns about the lack of detail in Alliant Techsystems's proposal.

In December 2012, the three CCiCap winners were each given an additional USD$10 million in funding as the first of two series of "certification products contracts" (CPC) to allow for further testing, engineering standards, and design analysis to meet NASA's safety requirements for crewed spaceflight. The second CPC series manifested as Commercial Crew Transportation Capability (CCtCap), the final phase of the CCDev program, where NASA would certify an operator to run crewed flights to the ISS through an open competition. The window for proposal submissions was closed on 22 January 2014. Sierra Nevada announced a week later that a privately-funded orbital test flight of a Dream Chaser spacecraft, using an Atlas V launch vehicle intended to be purchased by Sierra Nevada, was planned to occur on 1 November 2016. On 16 September 2014, CCtCap concluded with SpaceX's Crew Dragon and Boeing's Starliner being the sole winners, each receiving US$2.6 billion and US$4.2 billion in funding respectively. Sierra Nevada filed a protest with the Government Accountability Office (GAO) in response, citing "serious questions and inconsistencies in the source selection process." The United States Court of Federal Claims held up a decision to proceed with development of the Crew Dragon and Starliner during the protest, citing concerns for crewed operations of the ISS in the event of a delay to the Commercial Crew Program. The GAO declined Sierra Nevada's protest in January 2015, stating that evidence gathered by the GAO discredited Sierra Nevada's claims against NASA; Sierra Nevada accepted the decision. The company laid off 90 staff members working on the Dream Chaser following the CCtCap result, and repurposed the spacecraft as a for-hire vehicle for commercial spaceflight. A cargo variant of the Dream Chaser would later be developed and selected by NASA to fly uncrewed resupply missions to the ISS under a Commercial Resupply Services 2 contract.

Post-selection


While the first flights of Commercial Crew Program were originally intended to be launched by the end of 2017, Boeing announced in May 2016 that their first crewed flight would be delayed to 2018 due to issues related to Starliner's Atlas V N22 launch vehicle. In December 2016, SpaceX announced their first crewed flights would also be delayed to 2018, following the loss of Amos-6 in an accidental launch pad explosion of a Falcon 9, the Crew Dragon's launch vehicle. With no further flights in the Soyuz program for American astronauts past 2018, the delays caused concern with the GAO, who recommended in February 2017 that NASA develop a plan for crew rotation in the event of further delays. Following the settlement of a lawsuit against Russian aerospace manufacturer Energia over Sea Launch, Boeing received options for up to five seats on Soyuz flights, which NASA purchased from Boeing. NASA announced the astronauts chosen to pilot the Crew Dragon and Starliner vehicles in August 2018,  and two months later penned the launch of demonstration missions for the Crew Dragon and Starliner for dates in 2019. The uncrewed SpaceX Demo-1 mission was launched on 2 March 2019, in which a Crew Dragon successfully docked with the ISS and returned to Earth six days after launch. The capsule used in the mission, however, was accidentally destroyed in a static fire test of its SuperDraco engines in April 2019,  causing further delays to launch of future Crew Dragon flights. The Boeing Orbital Flight Test and Boeing Crew Flight Test, which had both been delayed due to a failed test of Starliner's abort system, were further pushed from dates in early-to-mid 2019 to late 2019 due to undisclosed reasons.

The Boeing Pad Abort Test and Orbital Flight Test were eventually conducted in November and December 2019,  though were both mired in technical failures such as the partial deployment of Starliner's parachutes during the Pad Abort Test, and major malfunctions of Starliner's software during the Orbital Flight Test, which precluded an intended docking with the ISS and prompted a truncation of the mission. The Orbital Flight Test was declared a "high-visibility close call" by NASA following an independent review, and a second Orbital Flight Test is currently scheduled for late 2020, with Boeing covering the cost of the flight in lieu of additional CCDev funding. Amid further uncertainties about the Commercial Crew Program's progress, NASA purchased a seat on the Soyuz MS-17 mission to ensure participation in Expedition 64 in the event that operational missions in the program are further delayed, with the purchase of additional Soyuz seats beyond MS-17 being described as a possibility. The SpaceX In-Flight Abort Test was successfully conducted in January 2020,  setting the stage for the final, crewed test flight of Crew Dragon – SpaceX Demo-2 – which launched astronauts Bob Behnken and Doug Hurley to the ISS in May 2020. Following delays caused by the Boeing Orbital Flight Test, the Crew Flight Test is due to launch astronauts Christopher Ferguson, Mike Fincke, and Nicole Aunapu Mann to the ISS in early 2021.

Spacecraft
The Commercial Crew Program utilizes the SpaceX Crew Dragon and the Boeing Starliner to shuttle astronauts to and from the ISS. Both spacecraft are automated capsules that can be manually controlled by their crew via touch screens in case of an emergency. The crew cabins of both spacecraft feature 11 m3 of pressurised volume, and can carry up to seven crew each, though NASA will only send as many as four crew on each mission in the program; an extension to occupy a fifth seat is available to NASA. The NASA Docking System is also used by both spacecraft to dock with the ISS, replacing the Common Berthing Mechanism used by previous Commercial Orbital Transportation Services spacecraft such as the first-generation Dragon, and can both last up to 210 days in space docked to the ISS. In addition, the spacecraft were designed to meet NASA's safety standard of a 1-in-270 chance of catastrophic failure, which is higher than the 1-in-90 chance of the Space Shuttle.

SpaceX's Crew Dragon is a variant of the company's Dragon 2 class of spacecraft, which is an upgraded version of the first-generation Dragon. It measures 3.7 m wide, 4.4 m tall without its trunk, and 7.2 m with its trunk. While trunks are discarded at the end of each flight, crew cabins are designed to be reusable, with reflights of flown capsules being considered by NASA and SpaceX. Alternatively, Crew Dragon spacecraft can be repurposed as uncrewed Cargo Dragon spacecraft for use in SpaceX's Commercial Resupply Services 2 missions, with each capsule capable of being flown up to five times. Crew Dragon spacecraft can spend up to a week in free flight without being docked to the ISS. Each Crew Dragon capsule is equipped with a launch escape system consisting eight of SpaceX's SuperDraco engines, which provide 71000 newtons of thrust each. While these engines were originally intended to perform a propulsive landing upon return to Earth, with the first test vehicle having been equipped for such capabilities, these plans were ultimately abandoned in favour of a traditional splashdown return on the Atlantic Ocean. SpaceX's CCtCap contract values each seat on a Crew Dragon flight to be between US$60–67 million, while the face value of each seat has been estimated by NASA's Office of Inspector General (OIG) to be around US$55 million.

Boeing's CST-100 Starliner – "CST" being an acronymn for "Crew Space Transportation" – measures 4.6 m in diameter and 5.1 m in height. The crew module of Starliner can be reused for up to ten flights, while the service module is expended during each flight. Various engines manufactured by Aerojet Rocketdyne for orbital maneuvering, attitude control, reaction control, and launch escape, are utilized by Starliner. Eight reaction control engines on the spacecraft's crew module and 28 reaction control engines on the spacecraft's service module provide 380 newtons and 445 newtons each, respectively. Also located on the service module, 20 custom-made Orbital Maneuvering and Attitude Control (OMAC) engines provide 6700 newtons of thrust each,  while four RS-88 engines provide 178000 newtons of thrust each in a launch abort scenario. During a nominal flight without a launch abort, Starliner can use unspent fuel reserved for its RS-88 engines to help its OMAC engines perform the orbital insertion burn, following separation from the Centaur upper stage during launch. Once in space, Starliner spacecraft can survive up to 60 hours in free flight. Unlike Crew Dragon, Starliner is designed to return to Earth on land instead of ocean, using airbags to cushion the vehicle's impact with the ground. Four sites in the western contiguous United States – the Dugway Proving Ground in Utah, Edwards Air Force Base in California, White Sands Missile Range in New Mexico, and Willcox Playa in Arizona – will serve as landing ranges for returning Starliner spacecraft, though in an emergency scenario, it is also equipped to perform a splashdown return. Boeing's CCtCap contract values each seat on a CST-100 flight to be between US$91–99 million, while the face value of each seat has been estimated by NASA's OIG to be around US$90 million.

Missions
Both Boeing and SpaceX are contracted for six operational flights each, launching on an average of every six months. The Commercial Crew Program's first operational mission, SpaceX Crew-1, carried astronauts Victor Glover, Mike Hopkins, Soichi Noguchi, and Shannon Walker to the ISS on 16 November 2020 aboard Crew Dragon Resilience. C207 was originally planned to be used in SpaceX Crew-2, but was reassigned following a scheduling change that occurred following the destruction of C201. With Chris Cassidy having arrived at the ISS during Soyuz MS-16, the arrival of the astronauts aboard C207 marked the first time since the Space Shuttle program in which the US Orbital Segment of the ISS is completely staffed with four crew. While NASA astronauts were given assignments to either Crew Dragon or Starliner flights, Noguchi – a JAXA astronaut – was open for assignment to whichever spacecraft would launch the first operational mission. Boeing's first operational mission in the program, Boeing Starliner-1, will ferry astronauts Josh Cassada and Sunita Williams to the ISS in 2021 aboard Calypso. SpaceX Crew-2 is planned for launch in 2021, with NASA approving the use of a previously-flown Falcon 9 first-stage booster and a refurbished Crew Dragon Endeavour for the mission. In July 2020, Shane Kimbrough, Megan McArthur, Akihiko Hoshide and Thomas Pesquet were assigned to SpaceX Crew-2 to fly to the ISS in early 2021. SpaceX's third operational Crew Dragon flight is scheduled to launch in September 2021 carrying Thomas Marshburn, Raja Chari, and Matthias Maurer, with a fourth member to be announced.