SpaceX Dragon 2
Dragon 2 is a class of partially reusable spacecraft developed, manufactured, and operated by the American space company SpaceX for flights to the International Space Station and private spaceflight missions. The spacecraft, which consists of a reusable space capsule and an expendable trunk module, has two variants: the 4-person Crew Dragon and Cargo Dragon, a replacement for the Dragon 1 cargo capsule. The spacecraft launches atop a Falcon 9 Block 5 rocket, and the capsule returns to Earth through splashdown.
Crew Dragon's primary role is to transport crews to and from the ISS under NASA's Commercial Crew Program, a task handled by the Space Shuttle until it was retired in 2011. It will be joined by Boeing's Starliner in this role when NASA certifies it. Crew Dragon is also used for commercial flights to ISS and other destinations and is expected to be used to transport people to and from Axiom Space's planned space station.
Cargo Dragon brings cargo to the ISS under a Commercial Resupply Services-2 contract with NASA, a duty it shares with Northrop Grumman's Cygnus spacecraft. As of January 2025, it is the only reusable orbital cargo spacecraft in operation, though it may eventually be joined by the under-development Sierra Space Dream Chaser spaceplane.
Development and variants
There are two variants of Dragon 2: 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. Earlier spacecraft had a berthing port and were berthed to ISS by ISS personnel. Dragon 2 instead has an IDSS-compatible docking port to dock to the International Docking Adapter ports on ISS. It is able to perform fully autonomous rendezvous and docking with manual override ability. For typical missions, Crew Dragon remains docked to the ISS for a nominal period of 180 days, but is designed to remain on the station for up to 210 days, matching the Russian Soyuz spacecraft.Crew Dragon
Crew Dragon is capable of autonomous operation. SpaceX and NASA state that it is capable of carrying seven astronauts, but in normal operations, it carries two to four crew members, and as of 2025, has never carried more than four.Crew Dragon includes an integrated pusher launch escape system whose eight SuperDraco engines can separate the capsule away from the launch vehicle in an emergency. SpaceX originally intended to use the SuperDraco engines to land Crew Dragon on land; parachutes and an ocean splashdown were envisioned for use only 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. However, propulsive landing was later cancelled, leaving ocean splashdown under parachutes as the only option.
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-fitted space suit that provides cooling inside the Dragon but can also protect its wearer in a rapid cabin depressurization. For the Demo-1 mission, a test dummy was fitted with the spacesuit and sensors. The spacesuit is made from Nomex, a fire-retardant fabric similar to Kevlar.
The spacecraft's design was unveiled on May 29, 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. In March 2022, SpaceX President Gwynne Shotwell told Reuters that "We are finishing our final, but we still are manufacturing components, because we'll be refurbishing". SpaceX later decided to build a fifth Crew Dragon capsule, to be available by 2024. SpaceX also manufactures a new expendable trunk for each flight.
SpaceX's Commercial Crew Transportation Capabilities contract values each seat on a Crew Dragon flight to be around US$88 million, while the face value of each seat has been estimated by NASA's Office of Inspector General to be around US$55 million. This contrasts with the 2014 Soyuz launch price of US$76 million per seat for NASA astronauts.
Cargo Dragon
Dragon 2 was intended from the earliest design concept to carry crew, or with fewer seats, both crew and cargo.The cargo version, dubbed Cargo Dragon, became a reality after 2014, when NASA sought bids on a second round of multi-year contracts to bring cargo to the ISS in 2020 through 2024. In January 2016, SpaceX won contracts for six of these flights, dubbed CRS-2., Cargo Dragon had completed ten missions to and from the ISS with the eleventh mission in progress and more missions planned.
Cargo Dragons lack several features of the crewed variant, including seats, cockpit controls, astronaut life support systems, and SuperDraco abort engines. Cargo Dragon improves on many aspects of the original Dragon design, including the recovery and refurbishment process.
Since 2021, Cargo Dragon has been able to provide power to some payloads, saving space in the ISS and eliminating the time needed to move the payloads and set them up inside. This feature, announced on August 29, 2021, during the CRS-23 launch, is called Extend-the-Lab. "For CRS-23 there are 3 Extend-the-Lab payloads launching with the mission, and once docked, a 4th which is currently already on the space station will be added to Dragon". For the first time, Dragon performed test reboost of the ISS via its aft-facing Draco thrusters on November 8, 2024, at 17:50 UTC.
On SpaceX CRS-33, Dragon included "boost kit" propulsion module in Dragon's hollow unpressurized trunk, which is typically used to carry larger experiments that are robotically attached to the outside of the ISS. The kit comprises six dedicated propellant tanks containing hydrazine and nitrogen tetroxide, a helium pressurant tank, and two Draco thrusters aligned with the station's velocity vector. The boost kit is based on, but operates independently from Dragon's primary propulsion system. When activated, the system can add about to the ISS's orbital velocity, equivalent to the total reboost impulse of roughly one-and-a-half Russian Progress cargo vehicles, which are normally responsible for orbit maintenance. The kit carries enough propellant to provide about one-third to one-fourth of the ISS's annual reboost needs.
The US Deorbit Vehicle is a planned Cargo Dragon variant that will be used to deorbit the ISS and direct any remnants into the "spacecraft cemetery", a remote area of the southern Pacific Ocean. The vehicle will attach to the ISS using one of the Cargo Dragon vehicles, which will be paired with a longer trunk module equipped with 30 additional Draco thrusters and will carry of propellant, nearly six times the normal load. NASA plans to launch the deorbit vehicle in 2030 where it will remain attached, dormant, for about a year as the station's orbit naturally decays to. The spacecraft is to then conduct one or more orientation burns to lower the perigee to, followed by a final deorbiting burn to push the station into the ocean. In June 2024, NASA awarded a contract worth up to $843 million to SpaceX to build the deorbit vehicle as it works to secure funding.
Design
SpaceX, which aims to dramatically lower space transportation costs, designed Dragon 2 to be reused, not discarded as is typical of spacecraft. It is composed of a reusable capsule and a disposable trunk.SpaceX and NASA initially certified the capsule to be used for five missions., they are working to certify it for up to fifteen missions.
To maximize cost-effectiveness, SpaceX incorporated several innovative design choices. The Crew Dragon employs eight side-mounted SuperDraco engines for its emergency escape system, eliminating the need for a traditional, disposable escape tower. Furthermore, instead of housing the critical and expensive life support, thruster, and propellant storage systems in a disposable service module, Dragon 2 integrates them within the capsule for reuse.
The trunk serves as an adapter between the capsule and the Falcon 9 rocket's second stage and also includes solar panels, a heat-dissipation radiator, and fins to provide aerodynamic stability during emergency aborts. Dragon 2 integrates solar arrays directly into the trunk's structure, replacing the deployable panels of its predecessor, Dragon 1. On Cargo Dragon missions, the trunk can also be used to transport unpressurized payloads, such as the Roll Out Solar Array, or it can be fitted with a "boost kit" to perform reboosts of the ISS. The trunk is connected to the capsule using a fitting known as "the claw".
The typical Crew Dragon mission includes four astronauts: a commander who leads the mission and has primary responsibility for operating the spacecraft, a pilot who serves as backup for both command and operations, and two mission specialists who may have specific duties assigned depending on the mission. However, the Crew Dragon can fly missions with just two astronauts as needed, and in an emergency, up to seven astronauts could return to Earth from the ISS on Dragon.
On the Crew Dragon, above the two center seats, there is a three-screen control panel. Below the seats is the cargo pallet, where around of items can be stowed. On the ground, crews enter the capsule through a side hatch. The capsule’s ceiling includes a small space toilet, and an International Docking System Standard port. For private spaceflight missions not requiring ISS docking, the IDSS port can be replaced with a domed plexiglass window offering panoramic views, similar to the ISS Cupola. Additionally, SpaceX has developed a "Skywalker" hatch for missions involving extravehicular activities.
The Cargo Dragon is loaded from the side hatch as well as through the IDSS port on the ceiling. It lacks the control panels, life support, windows, and seats of the Crew Dragon.
The spacecraft can be operated in full vacuum, and crew wears SpaceX-designed space suits to protect them from a rapid cabin depressurization emergency event. The spacecraft has also been designed to be able to land safely with a leak "of up to an equivalent orifice of in diameter".
The spacecraft's nose cone protects the docking port and four forward-facing thrusters during ascent and reentry. This component pivots open for in-space operations. Dragon 2's propellant and helium pressurant for emergency abort and orbital maneuvers are stored in composite-carbon-overwrap titanium spherical tanks at the capsule's base in an area known as the service section.
For launch aborts, the capsule relies on eight SuperDraco engines arranged in four redundant pairs. Each engine generates of thrust. Sixteen smaller Draco thrusters placed around the spacecraft control its attitude and perform orbital maneuvers.
When the capsule returns to Earth, a PICA-3 heat shield safeguards the capsule during reentry. Dragon 2 uses a total of six parachutes to decelerate after atmospheric entry and before splashdown, compared to the five used by Dragon 1. The additional parachute was required by NASA as a safety measure after a Dragon 1 suffered a parachute malfunction. The company also went through two rounds of parachute development before being certified to fly with crew. In 2024, the use of the SuperDraco thrusters for propulsive landing was enabled again, but only as a backup for parachute emergencies.