Dragon 2 is a class of reusable spacecraft developed and manufactured by U.S. aerospace manufacturer SpaceX, intended as the successor to the Dragon cargo spacecraft. The spacecraft launches atop a Falcon 9 Block 5 rocket and returns via ocean splashdown. When compared to Dragon, Crew Dragon has larger windows, new flight computers and avionics, redesigned solar arrays, and a modified outer mold line. The spacecraft has two planned variants – Crew Dragon, a human-rated capsule capable of carrying up to seven astronauts, and Cargo Dragon, an updated replacement for the original Dragon. Crew Dragon is equipped with an integrated launch escape system in a set of four side-mounted thruster pods with two SuperDraco engines each. Crew Dragon has been contracted to supply the International Space Station (ISS) with crew under the Commercial Crew Program, with the initial award occurring in October 2014 alongside Boeing CST-100 Starliner. Crew Dragon's first non-piloted test flight to the ISS launched in March 2019. Cargo Dragon will supply the ISS with cargo under the Commercial Resupply Services-2 (CRS-2) after a January 2016 selection alongside Northrop Grumman Innovation Systems' Cygnus and Sierra Nevada Corporation's Dream Chaser. SpaceX's first CRS-2 mission with the Cargo Dragon is slated to occur in August 2020 after SpaceX's final CRS-20 mission with the original Dragon spacecraft. The Crew Dragon capsule that flew in the first test flight was scheduled to be used in a flight abort test before it unexpectedly exploded during a test of its SuperDraco engines on 20 April 2019. An investigation into the explosion was completed on 15 July 2019 and resulted in changes to vehicle plumbing. The in-flight abort test was conducted on 19 January 2020 at 15:30 UTC. The first crewed launch is scheduled for April 2020.
There are two variants: Crew Dragon and Cargo Dragon. Crew Dragon was initially called DragonRider and it was intended from the beginning to support a crew of seven or a combination of crew and cargo. It is able to perform fully autonomous rendezvous and docking with manual override ability using the NASA Docking System (NDS). For typical missions, Crew Dragon will remain docked to the ISS for a period of 180 days, but is designed to remain on the station for up to 210 days, matching the Russian Soyuz spacecraft. From the beginning of the development process, SpaceX planned to use an integrated pusher launch escape system for the Dragon spacecraft.
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. (As of 2011), the Paragon Space Development Corporation was assisting 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 (IVA type suit), 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 SpX-DM1 test, 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 $160 million, or about $20 million per seat if the maximum crew of 7 is aboard and NASA orders at least four Crew Dragon flights per year. This contrasts with the 2014 Soyuz launch price of $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 plans to use the Falcon 9 Block 5 launch vehicle for launching Dragon 2.
Dragon 2 includes the following features: Dragon 2 is partially reusable, potentially resulting in a significant cost reduction. SpaceX plans to use new capsules for every crewed flight for NASA. Cargo Dragon can carry 3,307 kilograms (7,291 lb) to the ISS; Crew Dragon has a capacity of seven astronauts (only four seats are used for NASA missions). Above the seats, there is a three-screen control panel, a toilet (with privacy curtain) and the docking hatch. Ocean landings are accomplished with four main parachutes in both variants. The parachute system was fully redesigned from the one used in the prior Dragon capsule, due to the need to deploy the parachutes under a variety of launch abort scenarios.
Crew Dragon has eight side-mounted SuperDraco engines, clustered in redundant pairs in four engine pods, with each engine able to produce 71 kilonewtons (16,000 lbf) of thrust to be used for launch aborts. Each pod also contains four Draco thrusters that can be used for attitude control and orbital maneuvers. The SuperDraco engine combustion chamber is printed of Inconel, an alloy of nickel and iron, using a process of direct metal laser sintering. Engines are contained in a protective nacelle to prevent fault propagation if an engine fails.
Once on orbit, Dragon 2 is able to autonomously dock to the ISS. Dragon used berthing, a non-autonomous means to attach to the ISS that was completed by use of the Canadarm2 robotic arm. Pilots of Crew Dragon retain the ability to dock the spacecraft using manual controls interfaced with a static tablet-like computer. The spacecraft can be operated in full vacuum, and "the crew will wear SpaceX-designed space suits to protect them from a rapid cabin depressurization emergency event". Also, the spacecraft will be able to return safely if a leak occurs "of up to an equivalent orifice of 0.25 inches [6.35 mm] in diameter."
Propellant and helium pressurant for both launch aborts and on-orbit maneuvering is contained in composite-carbon-overwrap titanium spherical tanks. A PICA-X heat shield protects the capsule during reentry, while a movable ballast sled allows more precise attitude control of the spacecraft during the atmospheric entry phase of the return to Earth and more accurate control of the landing ellipse location. A reusable nose cone "protects the vessel and the docking adaptor during ascent and reentry", pivoting on a hinge to enable in-space docking and returning to the covered position for reentry and future launches
The trunk is the third structural element of the spacecraft, containing solar panels, heat-removal radiators, and fins to provide aerodynamic stability during emergency aborts.
The previous Cargo Dragon’s deployable solar arrays have been eliminated and are now built into the trunk itself. This increases volume space, reduces the number of mechanisms on the vehicle and further increases reliability.
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 are working together to support round-trip transport of commercial passengers to low Earth orbit (LEO) destinations, using the full capacity of seven passengers. 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 $2.6 billion under this contract. Dragon was the least expensive proposal, but NASA's William H. Gerstenmaier considers 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 (ISS) on 2 March 2019.
In June 2019, Bigelow Space Operations announced it had reserved with SpaceX up to 4 missions of 4 passengers each to ISS as early as 2020 and plans to sell them for around $52 million per seat. These plans were canceled by September 2019.
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 January 2020 at the earliest.
The pad abort test was conducted successfully on 6 May 2015 at SpaceX's leased SLC-40. Dragon landed safely in the ocean to the east of the launchpad 99 seconds after ignition of the SuperDraco engines. While a flight-like Dragon 2 and trunk were used for the pad abort test, they rested atop a truss structure for the test rather than a full Falcon 9 rocket. A crash test dummy embedded with a suite of sensors was placed inside the test vehicle to record acceleration loads and forces at the crew seat, while the remaining six seats were loaded with weights to simulate full-passenger-load weight. The test objective was to demonstrate sufficient total impulse, thrust and controllability to conduct a safe pad abort. A fuel mixture ratio issue was detected after the flight in one of the eight SuperDraco engines, but did not materially affect the flight.
On 24 November 2015, SpaceX conducted a test of Dragon 2's hovering abilities at the firm's rocket development facility in McGregor, Texas. In a video, the spacecraft is shown suspended by a hoisting cable and igniting its SuperDraco engines to hover for about 5 seconds, balancing on its 8 engines firing at reduced thrust to compensate exactly for gravity. The test vehicle was the same capsule that performed the pad abort test earlier in 2015; it was nicknamed DragonFly.
In 2015, NASA named its first Commercial Crew astronaut cadre of four veteran astronauts to work with SpaceX and Boeing – Robert Behnken, Eric Boe, Sunita Williams, and Douglas Hurley. The Crew Dragon Demo-1 mission will complete the last milestone of the Commercial Crew Development program, paving the way to starting commercial services under an upcoming ISS Crew Transportation Services contract. On 3 August 2018, NASA announced the crew for the DM-2 mission. The crew of two will be formed by NASA astronauts Bob Behnken and Doug Hurley. Behnken previously flew as mission specialist on the STS-123 and the STS-130 missions. Hurley previously flew as a pilot on the STS-127 mission and on the final Space Shuttle mission, the STS-135 mission.
The first orbital test of Crew Dragon was an uncrewed mission, designated Crew Dragon Demo-1 and launched on 2 March 2019. The spacecraft tested the approach and automated docking procedures with the ISS, remained docked until 8 March 2019, then conducted the full re-entry, splashdown and recovery steps to qualify for a crewed mission. Life-support systems were monitored all along the test flight. The same capsule was planned to be re-used in June for an in-flight abort test before it exploded on 20 April 2019.
On 20 April 2019, the Crew Dragon capsule used in the Crew Dragon 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 accident 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 nitrogen 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 were successful. The vehicle used for this ground test will also be used for the following in-flight abort test.
Some of the modifications are :
SpaceX conducted an in-flight abort test from Kennedy Space Center Launch Complex 39A in Florida on 19 January 2020 at 15:30 UTC. The Crew Dragon test capsule was launched in an atmospheric flight to conduct a separation and abort scenario in the troposphere at transonic velocities, at max Q, where the vehicle experiences maximum aerodynamic pressure. 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 regular Falcon 9 Block 5 rocket.
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.
Currently targeting April 2020, Demo-2 will be the first launch carrying crew.
Crew Dragon units and mission assignments after the 20 April 2019 explosion that destroyed C201.
|C201||Crew Dragon Demo-1 and, destroyed during preliminary testing for IFAT|
|C202, C203, C204||Test articles|
|C205||used in in-flight abort test|
|C206||Crew Dragon Demo-2|
|C208-212 (?)||CCtCap-2 - CCtCap-6 (?)|
List includes only completed or currently manifested missions. Launch dates are listed in UTC.
|Mission||Capsule №||Launch date (UTC)||Remarks||Time at ISS
|Dragon 2 pad abort test||DragonFly||6 May 2015||Pad abort test, Cape Canaveral Air Force Station, Florida||N/A||Success|
|Crew Dragon Demo-1||C204||2 March 2019||Uncrewed test flight of the Crew Dragon capsule; docked 3 March 2019, 08:51 UTC; departed 8 March 2019, 05:32 UTC||04:21:17||Success|
|Crew Dragon in-flight abort test||C205||19 January 2020||Used the capsule originally planned for Crew Dragon Demo-2.||N/A||Success|
|Crew Dragon Demo-2||C206||April 2020 ||Crewed test flight with two astronauts for two weeks. Will use the capsule planned for the first operational crew mission.||TBA||Planned|
|USCV-1||C207||July 2020||Pending success of Demo-2, NASA has contracted six operational crewed flights.
First one will deliver ISS Expedition 64/65 crew consisting of Mike Hopkins, Victor Glover, and Japanese Soichi Noguchi.
|CCtCap missions 2–6||After 2020||NASA has contracted six operational flights to carry up to four astronauts and 220 pounds of cargo to the ISS.||Planned|
|CRS-2 missions 1–6||2020–2024||Six more Cargo Dragon launches under the CRS-2 contract.||Planned|