This will be the first crewed launch of astronauts from the U.S. since the end of the Space Shuttle era in 2011. Since then, NASA has been relying on the Russian space program Roscosmos to ferry astronauts back and forth to the International Space Station.
The lucky first crew will be Doug Hurley and Bob Behnken aboard the SpaceX Crew Dragon capsule. The spacecraft carrying the astronauts will launch to the ISS atop a Falcon 9 rocket.
Both Hurley and Behnken are veterans of the Space Shuttle program and will launch from Pad 39A, which was used during the last shuttle flight. And, the two are married to other astronauts and are former military test pilots.
Liftoff for the May 27 launch is expected after 4:30 p.m. EST. That's when the Earth's rotation will bring the launch complex under the orbital plane of the International Space Station. Then, if the launch goes as planned, Crew Dragon and the two astronauts will dock at the ISS around 11:30 a.m. May 28.
SpaceX originally intended to land Crew Dragon on land using the LES engines, with parachutes and an ocean splashdown available in the case of an aborted launch. Precision water landing under parachutes was proposed to NASA as 'the baseline return and recovery approach for the first few flights' of Crew Dragon. Propulsive landing was later cancelled, leaving ocean splashdown under parachutes as the only option. Paragon Space Development Corporation assisted in developing Crew Dragon's life-support system. In 2012, SpaceX was in talks with Orbital Outfitters about developing space suits to wear during launch and re-entry. Each crew member wears a custom space suit fitted for them. The suit is primarily designed for use inside the Dragon : however, in the case of a rapid cabin depressurization, the suit can protect the crew members. The suit can also provide cooling for astronauts during normal flight. For the Demo-1 mission, a test dummy nicknamed Ripley was fitted with the spacesuit and sensors. The spacesuit is made from Nomex, a fire retardant fabric similar to Kevlar.
At a NASA news conference on 18 May 2012, SpaceX confirmed their target launch price for crewed Dragon flights of US$160 million, or about US$23 million per seat if the maximum crew of seven is aboard and NASA orders at least four Crew Dragon flights per year. This contrasts with the 2014 Soyuz launch price of US$76 million per seat for NASA astronauts. The spacecraft's design was unveiled on 29 May 2014, during a press event at SpaceX headquarters in Hawthorne, California. In October 2014, NASA selected the Dragon spacecraft as one of the candidates to fly American astronauts to the International Space Station, under the Commercial Crew Program. SpaceX is using the Falcon 9 Block 5 launch vehicle to launch Dragon 2.
Crew Dragon is equipped with an integrated launch escape system consisting of eight SuperDraco engines, capable of accelerating the vehicle away from the rocket in an emergency. The spacecraft features redesigned solar arrays and a modified outer mold line compared to the original Dragon, and possesses new flight computers and avionics. As of March 2020, four operational Dragon 2 spacecraft have been manufactured, as well as several unflown test articles.
Crew Dragon serves as one of two spacecraft types that are expected to transport crews to and from the ISS under NASA's Commercial Crew Program, the other being the Boeing CST-100 Starliner; both craft succeeding the crew orbital transportation capabilities of the Space Shuttle which retired from service in 2011. It is also expected to be used in flights by American space tourism company Space Adventures and to shuttle tourists to and from Axiom Space's planned space station. Crew Dragon's first uncrewed test flight occurred in March 2019, and its first crewed test flight – with astronauts Robert Behnken and Douglas Hurley – occurred in May 2020. This marked the first time a private company launched a crewed orbital spacecraft. Cargo Dragon is expected to supply cargo to the ISS under a Commercial Resupply Services-2 contract with NASA, along with Northrop Grumman Innovation Systems' Cygnus spacecraft and Sierra Nevada Corporation's Dream Chaser spacecraft. The first flight of Dragon 2 in a cargo configuration launched in December 2020. On 10 November 2020, the Crew Dragon, as well as the Falcon 9 rocket and associated ground systems, were fully certified by NASA as the first commercial launch system in history capable of transporting humans to and from the ISS. As of May 2021, the Crew Dragon spacecraft that carried four astronauts to the International Space Station in November 2020 broke the record for the longest spaceflight by a U.S. crew vehicle, surpassing the 84-day mark set by an Apollo capsule on the final flight to the Skylab space station on 8 February 1974.
Dragon is intended to fulfill a set of requirements that will make the capsule useful to both commercial and government customers. SpaceX and Bigelow Aerospace were working together to support round-trip transport of commercial passengers to low Earth orbit destinations, but the plan was canceled. Instead Axiom plans to launch tourists to the Space Station and eventually their own private space station. NASA flights to the ISS will only have four astronauts, with the added payload mass and volume used to carry pressurized cargo.
On 16 September 2014, NASA announced that SpaceX and Boeing had been selected to provide crew transportation to the ISS. SpaceX will receive US$2.6 billion under this contract. Dragon was the less expensive proposal, but NASA's William H. Gerstenmaier considered the CST-100 proposal the stronger of the two.
In a departure from the prior NASA practice, where construction contracts with commercial firms led to direct NASA operation of the spacecraft, NASA is purchasing space transport services from SpaceX, including construction, launch, and operation of the Dragon 2.
In August 2018, NASA and SpaceX agreed on the loading procedures for propellants, vehicle fluids and crew. High-pressure helium will be loaded first, followed by the passengers approximately two hours prior to scheduled launch; the ground crew will then depart the launch pad and move to a safe distance. The launch escape system will be activated approximately 40 minutes prior to launch, with propellant loading commencing several minutes later. The first automated test mission launched to the International Space Station on 2 March 2019.
In early 2019, crewed flights were expected to begin no earlier than July 2019. They were later planned to begin no earlier than on 30 May 2020. The first crewed flight launched on 30 May 2020 with the launch of the Demo-2 mission.
In June 2019, Bigelow Space Operations announced it had reserved with SpaceX up to four missions of four passengers each to ISS as early as 2020 and planned to sell them for around US$52 million per seat. These plans were canceled by September 2019.
On 18 February 2020, building on development for NASA's commercial crew program, Space Adventures announced an agreement with SpaceX to fly up to four paying space tourists on a standalone mission aboard a Crew Dragon spacecraft in late 2021 or 2022 that could reach an altitude two-to-three times higher than the International Space Station.
SpaceX planned a series of four flight tests for the Crew Dragon: a 'pad abort' test, an uncrewed orbital flight to the ISS, an in-flight abort test, and finally a 14-day crewed demonstration mission to the ISS, which was initially planned for July 2019, but after a Dragon capsule explosion, was delayed to May 2020.
On 20 April 2019, the Crew Dragon capsule used in the Demo-1 mission was destroyed in an explosion during static fire testing at the Landing Zone 1 facility. On the day of the explosion, the initial testing of the Crew Dragon's Draco thrusters was successful, with the anomaly occurring during the test of the SuperDraco abort system. Telemetry, high-speed camera footage, and analysis of recovered debris indicate the problem occurred when a small amount of dinitrogen tetroxide leaked into a helium line used to pressurize the propellant tanks. The leakage apparently occurred during pre-test processing. As a result, the pressurization of the system 100 ms before firing damaged a check valve and resulted in the explosion.
Since the destroyed capsule had been slated for use in the upcoming in-flight abort test, the explosion and investigation delayed that test and the subsequent crewed orbital test.
The SuperDraco engine test that failed on 20 April 2019 was repeated successfully on 13 November 2019. The full duration static fire test of Crew Dragon's launch escape system took place at Cape Canaveral Air Force Station at SpaceX's Landing Zone 1 at 20:08 UTC. The test was successful, showing that the modifications made to the vehicle to prevent a failure like the one that happened 20 April 2019 were successful. The vehicle used for this ground test would also be used for the following in-flight abort test.
Some of the modifications are:
Replacement of the valves with burst discs: Unlike valves, burst discs are designed for single use. Addition of flaps on each SuperDraco in order to reseal the thrusters prior to splashdown in the ocean, preventing water intrusion.
In-flight abort test
The Crew Dragon in-flight abort test was launched on 19 January 2020 at 15:30 UTC from LC-39A on a suborbital trajectory to conduct a separation and abort scenario in the troposphere at transonic velocities shortly after passing through max Q, where the vehicle experiences maximum aerodynamic pressure. The Dragon 2 used its SuperDraco abort engines to push itself away from the Falcon 9 after an intentional premature engine cutoff. Ten seconds after Dragon 2 was jettisoned, the Falcon 9 exploded and was destroyed. The spacecraft followed its suborbital trajectory to apogee, at which point the spacecraft's trunk was jettisoned. The smaller Draco engines were then used to orient the vehicle for the descent. All major functions were executed, including separation, engine firings, parachute deployment, and landing. Dragon 2 splashed down at 15:38:54 UTC just off the Florida coast in the Atlantic Ocean. The test objective was to demonstrate the ability to safely move away from the ascending rocket under the most challenging atmospheric conditions of the flight trajectory, imposing the worst structural stress of a real flight on the rocket and spacecraft. The abort test was performed using a Falcon 9 Block 5 rocket with a fully fueled second stage with a mass simulator replacing the Merlin engine.
Earlier, this test had been scheduled before the uncrewed orbital test, however, SpaceX and NASA considered it safer to use a flight representative capsule rather than the test article from the pad abort test.
This test was previously planned to use the capsule C204 from Demo-1, however, C204 was destroyed in an explosion during a static fire testing on 20 April 2019. Capsule C205, originally planned for Demo-2 was used for the In-Flight Abort Test with C206 being planned for use during Demo-2. This was the final flight test of the spacecraft before it began carrying astronauts to the International Space Station under NASA's Commercial Crew Program.
Prior to the flight test, teams completed launch day procedures for the first crewed flight test, from suit-up to launch pad operations. The joint teams conducted full data reviews that needed to be completed prior to NASA astronauts flying on the system during SpaceX's Demo-2 mission.
Demo-2: crewed orbital flight test
On 17 April 2020, NASA Administrator Jim Bridenstine announced the first crewed Crew Dragon Demo-2 to the International Space Station would launch on 27 May 2020. Astronauts Bob Behnken and Doug Hurley crewed the mission, marking the first crewed launch to the International Space Station from U.S. soil since STS-135 in July 2011. The original launch was postponed to 30 May 2020 due to weather conditions at the launch site. The second launch attempt was successful, with capsule C206, later named Endeavour by the crew, launching on 30 May 2020 19:22 UTC. The capsule successfully docked with the International Space Station on 31 May 2020 at 14:27 UTC. On 2 August 2020, Crew Dragon undocked and splashed-down successfully in the ocean.
Launching in the Dragon 2 spacecraft was described by astronaut Bob Behnken as 'smooth off the pad' but 'we were definitely driving and riding a dragon all the way up ... a little bit less g's but more 'alive' is probably the best way I would describe it'.
Regarding descent in the spacecraft, Behnken stated, 'Once we descended a little bit into the atmosphere, Dragon really came alive. It started to fire thrusters and keep us pointed in the appropriate direction. The atmosphere starts to make noise—you can hear that rumble outside the vehicle. And as the vehicle tries to control, you feel a little bit of that shimmy in your body. ... We could feel those small rolls and pitches and yaws—all those little motions were things we picked up on inside the vehicle. ... All the separation events, from the trunk separation through the parachute firings, were very much like getting hit in the back of the chair with a baseball bat ... pretty light for the trunk separation but with the parachutes it was a pretty significant jolt.'