SpaceX Dragon

Name

SpaceX's CEO, Elon Musk, named the spacecraft after the 1963 song "Puff, the Magic Dragon" by Peter, Paul and Mary, reportedly as a response to critics who considered his spaceflight projects impossible.

History

SpaceX began developing the Dragon spacecraft in late 2004, making a public announcement in 2006 with a plan of entering service in 2009. Also in 2006, SpaceX won a contract to use the Dragon spacecraft for commercially supplied resupply services to the International Space Station for the American federal space agency, NASA.

Commercial Orbital Transportation Services

In 2005, NASA solicited proposals for a commercial ISS resupply cargo vehicle to replace the then-soon-to-be-retired Space Shuttle, through its Commercial Orbital Transportation Services (COTS) development program. The Dragon spacecraft was a part of SpaceX's proposal, submitted to NASA in March 2006. SpaceX's COTS proposal was issued as part of a team, which also included MD Robotics, the Canadian company that had built the ISS's Canadarm2.

On 18 August 2006, NASA announced that SpaceX had been chosen, along with Kistler Aerospace, to develop cargo launch services for the ISS. The initial plan called for three demonstration flights of SpaceX's Dragon spacecraft to be conducted between 2008 and 2010. SpaceX and Kistler were to receive up to $278 million and $207 million respectively, if they met all NASA milestones, but Kistler failed to meet its obligations, and its contract was terminated in 2007. NASA later re-awarded Kistler's contract to Orbital Sciences.

Commercial Resupply Services Phase 1

On 23 December 2008, NASA awarded a $1.6 billion Commercial Resupply Services (CRS) contract to SpaceX, with contract options that could potentially increase the maximum contract value to $3.1 billion. The contract called for 12 flights to the ISS, with a minimum of 20,000 kg (44,000 lb) of cargo carried to the ISS.

On 23 February 2009, SpaceX announced that its chosen phenolic-impregnated carbon ablator heat shield material, PICA-X, had passed heat stress tests in preparation for Dragon's maiden launch. The primary proximity-operations sensor for the Dragon spacecraft, the DragonEye, was tested in early 2009 during the STS-127 mission, when it was mounted near the docking port of the Space Shuttle Endeavour and used while the Shuttle approached the International Space Station. The DragonEye's Lidar and thermography (thermal imaging) abilities were both tested successfully. The COTS UHF Communication Unit (CUCU) and Crew Command Panel (CCP) were delivered to the ISS during the late 2009 STS-129 mission. The CUCU allows the ISS to communicate with Dragon and the CCP allows ISS crew members to issue basic commands to Dragon. In summer 2009, SpaceX hired former NASA astronaut Ken Bowersox as vice president of their new Astronaut Safety and Mission Assurance Department, in preparation for crews using the spacecraft.

As a condition of the NASA CRS contract, SpaceX analyzed the orbital radiation environment on all Dragon systems, and how the spacecraft would respond to spurious radiation events. That analysis and the Dragon design – which uses an overall fault-tolerant triple-redundant computer architecture, rather than individual radiation hardening of each computer processor – was reviewed by independent experts before being approved by NASA for the cargo flights.

During March, 2015, it was disclosed that SpaceX had been awarded an additional three missions under Commercial Resupply Services Phase 1. These additional missions are SpaceX CRS-13, SpaceX CRS-14 and SpaceX CRS-15 and would cover the cargo needs of 2017.

On February 24, 2016, SpaceNews disclosed that SpaceX had been awarded a further five missions under Commercial Resupply Services Phase 1. This additional tranche of missions had SpaceX CRS-16 and SpaceX CRS-17 manifested for FY2017 while SpaceX CRS-18, SpaceX CRS-19 and SpaceX CRS-20 and were notionally manifested for FY2018.

Commercial Resupply Services Phase 2

The Commercial Resupply Services 2 (CRS2) contract definition/solicitation period commenced in 2014 and a result announced on January 14, 2016. The CRS2 launches are expected to commence in 2019, and extend to at least 2024. On January 14, 2016, NASA announced that three companies had been awarded contracts for a minimum of six launches each. SpaceX, Orbital ATK and Sierra Nevada Corporation won contracts. The maximum potential value of all the contracts was indicated to be $14Bn but the minimum requirements would be considerably less. No further financial information was disclosed. The missions involved would be from late 2019 through to 2024.

Demonstration flights

The first flight of the Falcon 9, a private flight, occurred in June 2010 and launched a stripped-down version of the Dragon capsule. This Dragon Spacecraft Qualification Unit had initially been used as a ground test bed to validate several of the capsule's systems. During the flight, the unit's primary mission was to relay aerodynamic data captured during the ascent. It was not designed to survive re-entry, and did not.

NASA contracted for three test flights from SpaceX, but later reduced that number to two. The first Dragon spacecraft launched on its first mission – contracted to NASA as COTS Demo Flight 1 – on 8 December 2010, and was successfully recovered following re-entry to Earth's atmosphere. The mission also marked the second flight of the Falcon 9 launch vehicle. The DragonEye sensor flew again on STS-133 in February 2011 for further on-orbit testing. In November 2010, the Federal Aviation Administration (FAA) had issued a re-entry license for the Dragon capsule, the first such license ever awarded to a commercial vehicle.

The second Dragon flight, also contracted to NASA as a demonstration mission, launched successfully on 22 May 2012, after NASA had approved SpaceX's proposal to combine the COTS 2 and 3 mission objectives into a single Falcon 9/Dragon flight, renamed COTS 2+. Dragon conducted orbital tests of its navigation systems and abort procedures, before being grappled by the ISS' Canadarm2 and successfully berthing with the station on 25 May to offload its cargo. Dragon returned to Earth on 31 May 2012, landing as scheduled in the Pacific Ocean, and was again successfully recovered.

On 23 August 2012, NASA Administrator Charles Bolden announced that SpaceX had completed all required milestones under the COTS contract, and was cleared to begin operational resupply missions to the ISS.

Operational flights

Dragon was launched on its first operational CRS-contract mission on 8 October 2012, and completed the mission successfully on 28 October.

SpaceX CRS-2, the second CRS mission from SpaceX, was successfully launched on 1 March 2013. SpaceX CRS-3, SpaceX's third CRS mission, was launched on 18 April 2014 and was berthed with the ISS from 20 April 2014 through 18 May 2014. SpaceX CRS-4 successfully launched on Sunday, 21 September 2014 and berthed with the ISS on Tuesday, 23 September. It splashed down in the Pacific Ocean carrying 3,276 pounds of cargo and science samples.

Crewed development program

In 2006, Elon Musk stated that SpaceX had built "a prototype flight crew capsule, including a thoroughly tested 30-man-day life-support system". A video simulation of this escape system's operation was released in January 2011. Musk stated in 2010 that the developmental cost of a crewed Dragon and Falcon 9 would be between $800 million and $1 billion. In 2009 and 2010, Musk suggested on several occasions that plans for a crewed variant of the Dragon were proceeding and had a two-to-three-year timeline to completion. SpaceX submitted a bid for the third phase of CCDev, CCiCap.

NASA Commercial Crew Development program

SpaceX was not awarded funding during the first phase of NASA's Commercial Crew Development (CCDev) milestone-based program. However, the company was selected on 18 April 2011, during the second phase of the program, to receive an award valued at $75 million to help develop its crew system.

Their CCDev2 milestones involved the further advancement of the Falcon 9/Dragon crew transportation design, the advancement of the Launch Abort System propulsion design, completion of two crew accommodations demos, full-duration test firings of the launch abort engines, and demonstrations of their throttle capability.

SpaceX's launch abort system received preliminary design approval from NASA in October 2011. In December 2011, SpaceX performed its first crew accommodations test; the second such test is expected to involve spacesuit simulators and a higher-fidelity crewed Dragon mock-up. In January 2012, SpaceX successfully conducted full-duration tests of its SuperDraco landing/escape rocket engine at its Rocket Development Facility in McGregor, Texas.

On 3 August 2012, NASA announced the award of $440 million to SpaceX for the continuation of work on the Dragon under CCiCap. On 20 December 2013, SpaceX completed a parachute drop test to validate the new parachute design. This involved carrying a 5,400 kilograms (12,000 lb) Dragon test article by helicopter to an altitude of 2,400 meters (8,000 ft) above the Pacific Ocean. The test article was released and intentionally forced into a tumble. Dragon then released its two drogue parachutes, followed by its three main parachutes and splashed down into the ocean. The test article was then retrieved by helicopter and returned to shore.

On 6 May 2015, SpaceX completed a pad abort test for the Dragon 2. During this test, the Dragon used its abort engines to launch away from a test stand at Launch Complex 40. It traveled to an altitude of 1,187 meters (3,894 ft), separated from its trunk, deployed its drogue parachutes and then the main parachutes. It splashed down into the ocean and was recovered. The vehicle was planned to reach an altitude of 1,500 meters (5,000 ft) but one of the engines underperformed due to an abnormal fuel mixture ratio. The Dragon flown is planned to be refurbished for the in-flight abort test.

In a planned in-flight abort test, Dragon will use its launch abort engines to escape from a modified Falcon 9 that is already in flight. The launch is planned to occur from SLC-4E. This test would occur at the point of worst-case dynamic loads, which is also when Dragon has the smallest performance margin for separation from its launch vehicle. The Falcon 9 planned to be used would only have three engines on the first stage and would have no second stage.

An uncrewed test mission to the ISS, SpX-DM1, is planned to be launched in May 2017. It would be 30-day mission that would spend the majority of its time docked to the space station. It would then land in the ocean and be retrieved. A crewed test mission to the ISS, SpX-DM2, is planned to be launched in December 2017 and last for 14 days.

Development funding

In 2014, SpaceX released the total combined development costs for both the Falcon 9 launch vehicle and the Dragon capsule. NASA provided US$396 million while SpaceX provided over US$450 million to fund both development efforts.

Production

In December 2010, the SpaceX production line was reported to be manufacturing one new Dragon spacecraft and Falcon 9 rocket every three months. Elon Musk stated in a 2010 interview that he planned to increase production turnover to one Dragon every six weeks by 2012. Composite materials are extensively used in the spacecraft's manufacture to reduce weight and improve structural strength.

By September 2013, SpaceX total manufacturing space had increased to nearly 1,000,000 square feet (93,000 m²) and the factory had six Dragons in various stages of production. SpaceX published a photograph showing the six, including the next four NASA Commercial Resupply Services (CRS) mission Dragons (CRS-3, CRS-4, CRS-5, CRS-6) plus the drop-test Dragon, and the pad-abort Dragon weldment for commercial crew.

Dragon CRS

The Dragon spacecraft consists of a nose-cone cap that jettisons after launch, a conventional blunt-cone ballistic capsule, and an unpressurized cargo-carrier trunk equipped with two solar arrays. The capsule uses a PICA-X heat shield, based on a proprietary variant of NASA's Phenolic impregnated carbon ablator (PICA) material, designed to protect the capsule during Earth atmospheric entry, even at high return velocities from Lunar and Martian missions. The Dragon capsule is re-usable, and can fly multiple missions. The trunk is not recoverable; it separates from the capsule before re-entry and burns up in Earth's atmosphere. The trunk section, which carries the spacecraft's solar panels and allows the transport of unpressurized cargo to the ISS, was first used for cargo on the SpaceX CRS-2 mission.

The spacecraft is launched atop a Falcon 9 booster. The Dragon capsule is equipped with 18 Draco thrusters, dual-redundant in all axes: any two can fail without compromising control over vehicle pitch, yaw, roll and translation. During its initial cargo and crew flights, the Dragon capsule will land in the Pacific Ocean and be returned to the shore by ship.

For the ISS Dragon cargo flights, the ISS's Canadarm2 grapples its Flight-Releasable Grapple Fixture and berths Dragon to the station's US Orbital Segment using a Common Berthing Mechanism. The CRS Dragon does not have an independent means of maintaining a breathable atmosphere for astronauts and instead circulates in fresh air from the ISS. For typical missions, Dragon is planned to remain berthed to the ISS for about 30 days.

The CRS Dragon's capsule can transport 3,310 kg (7,300 lb) of cargo, which can be all pressurized, all unpressurized, or anywhere between. It can return to Earth 3,310 kg (7,300 lb), which can be all unpressurized disposal mass or up to 2,500 kg of return pressurized cargo, driven by parachute limitations. There is a volume constraint of 14 m³ (490 cu ft) trunk unpressurized cargo and 11.2 m³ (400 cu ft) of pressurized cargo (up or down). The trunk was first used operationally on the Dragon's CRS-2 mission in March 2013. Its solar arrays produce a peak power of 4 kW.

The CRS Dragon design was modified beginning with the fifth Dragon flight on the SpaceX CRS-3 mission to the ISS in March 2014. While the outer mold line of the Dragon was unchanged, the avionics and cargo racks were redesigned to supply substantially more electrical power to powered cargo devices, including the GLACIER and MERLIN freezer modules for transporting critical science payloads.

DragonLab

When used for non-NASA, non-ISS commercial flights, the uncrewed version of the Dragon spacecraft is called DragonLab. It is reusable and free-flying and can carry pressurized and unpressurized payloads. Its subsystems include propulsion, power, thermal and environmental control, avionics, communications, thermal protection, flight software, guidance and navigation systems, and entry, descent, landing, and recovery gear. It has a total combined upmass of 6,000 kilograms (13,000 lb) upon launch, and a maximum downmass of 3,000 kilograms (6,600 lb) when returning to Earth. As of November 2014, there were two DragonLab missions listed on the SpaceX launch manifest: one in 2016 and another in 2018. The same two missions are listed on the SpaceX manifest in December 2015 but no dates are shown. The American Biosatellites once performed similar uncrewed payload-delivery functions, and the Russian Bion satellites still continue to do so.

Dragon 2

A successor of Dragon called Dragon 2 is under development by SpaceX, designed to support crewed missions. It will be able to carry up to seven astronauts, or some mix of crew and cargo, to and from low Earth orbit. The Dragon 2 heat shield is designed to withstand Earth re-entry velocities from Lunar and Martian spaceflights. SpaceX has received several U.S. Government contracts to develop the Dragon 2 crewed variant, including a Commercial Crew Development 2 (CCDev 2)-funded Space Act Agreement in April 2011, and a Commercial Crew integrated Capability (CCiCap)-funded space act agreement in August 2012.

Red Dragon

In addition to SpaceX's privately funded plans for an eventual Mars mission, NASA Ames Research Center had developed a concept called Red Dragon: a low-cost Mars mission that would use Falcon Heavy as the launch vehicle and trans-Martian injection vehicle, and the Dragon 2-based capsule to enter the atmosphere of Mars. The concept was originally envisioned for launch in 2018 as a NASA Discovery mission, then alternatively for 2022, but as of September 2015 it has not been yet formally submitted for funding within NASA. The objectives of the mission would be return the samples from Mars to Earth at a fraction of the cost of the NASA own return-sample mission now projected at 6 billion dollars. On 27 April 2016, SpaceX announced its plan to go ahead and launch a modified Dragon lander to Mars in 2018.

A Dragon capsule can perform all entry, descent and landing (EDL) functions needed to deliver payloads of 1 tonne (2,200 lb) or more to the Martian surface without using a parachute. Preliminary analysis shows that the capsule's atmospheric drag will slow it enough for the final stage of its descent to be within the abilities of its SuperDraco retro-propulsion thrusters.

List of Dragon missions

List includes only completed or currently manifested missions. Launch dates are listed in UTC.

DragonLab

The following specifications are published by SpaceX for the non-NASA, non-ISS commercial flights of the refurbished Dragon capsules, listed as "DragonLab" flights on the SpaceX manifest. The specifications for the NASA-contracted Dragon Cargo were not included in the 2009 DragonLab datasheet.

Radiation tolerance

Dragon uses a "radiation-tolerant" design in the electronic hardware and software that make up its flight computers. The system uses three pairs of computers, each constantly checking on the others, to instantiate a fault-tolerant design. In the event of a radiation upset or soft error, one of the computer pairs will perform a soft reboot. Including the six computers that make up the main flight computers, Dragon employs a total of 18 triple-processor computers.