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Dragon spacecraft

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Dragon spacecraft

SpaceX Dragon spacecraft
ISS during the C2+ mission in May 2012.
Description
Role Placing humans and cargo into Low Earth orbit (commercial use)[1]
ISS resupply (governmental use)
Crew None (cargo variant)
7 (DragonRider variant)
Launch vehicle

Falcon 9 v1.0
(Dragon C1Dragon C4)[2]

Falcon 9 v1.1
(Dragon C5–)[2]
Maiden flight 8 December 2010 (launch of first orbital flight)[3]
22 May 2012 (launch of first cargo delivery flight to the ISS)[4]
Dimensions
Height 6.1 meters (20 feet)[5]
Diameter 3.7 meters (12.1 feet)[5]
Sidewall angle 15 degrees
Volume 10 m3 (350 cu ft) pressurized[6]
14 m3 (490 cu ft) unpressurized[6]
34 m3 (1,200 cu ft) unpressurized with extended trunk[6]
Dry mass 4,200 kg (9,300 lb)[5]
Payload to ISS 3,310 kg (7,300 lb), which can be all pressurized, all unpressurized or anywhere in 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 (5,500 lb) of return pressurized cargo[7]
Miscellaneous
Endurance 1 week to 2 years[6]
Re-entry at 3.5 Gs[8][9]
Propellant NTO/MMH[10]

Dragon is a partially reusable spacecraft developed by SpaceX, an American private space transportation company based in Hawthorne, California. Dragon is launched into space by the SpaceX Falcon 9 two-stage-to-orbit launch vehicle, and is capable of both manned and robotic operation.

During its uncrewed maiden flight in December 2010, Dragon became the first commercially built and operated spacecraft to be recovered successfully from orbit.[3] On 25 May 2012, an uncrewed variant of Dragon became the first commercial spacecraft to successfully rendezvous with and be attached to the International Space Station (ISS).[11][12][13] SpaceX is contracted to deliver cargo to the ISS under NASA's Commercial Resupply Services program, and Dragon began regular cargo flights in October 2012.[14][15][16][17]

SpaceX is additionally developing a crewed variant of the Dragon called DragonRider. DragonRider will be able to carry up to seven astronauts, or some combination of crew and cargo, to and from low Earth orbit. SpaceX has received several U.S. Government contracts to develop its 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. The spacecraft's heat shield is furthermore designed to withstand Earth re-entry velocities from potential Lunar and Martian spaceflights.[18]

General characteristics

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.[19] 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 reentry, even at high return velocities from Lunar and Martian missions.[18][20][21] The Dragon capsule is re-usable, and can be flown on multiple missions.[19] The trunk is not recoverable; it separates from the capsule before re-entry and burns up in Earth's atmosphere.[22]

The spacecraft is launched atop a Falcon 9 booster.[23] The Dragon capsule is equipped with 18 Draco thrusters, dual-redun­dant in all axes: any two can fail without compromising the vehicle's control over its pitch, yaw, roll and translation.[20] During its initial cargo and crew flights, the Dragon capsule will land in the Pacific Ocean and be returned to the shore by ship.[24] SpaceX plans to eventually install deployable landing gear and use eight upgraded SuperDraco thrusters to perform a solid earth propulsive landing.[25][26][27]

The trunk section, which carries the spacecraft's solar panels and allows the transport of unpressurized cargo to the ISS, was first utilized for cargo on the SpaceX CRS-2 mission.

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.[28]

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.[29] Composite materials are extensively used in the spacecraft's manufacture to reduce weight and improve structural strength.[30]

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.[31]

History

SpaceX began developing the Dragon spacecraft in late 2004.[32] In 2006, SpaceX won a contract to utilize the Dragon spacecraft for commercially supplied resupply services to the International Space Station for the American federal space agency, NASA.[33]

NASA ISS resupply contract

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.[33] The initial plan called for three demonstration flights of SpaceX's Dragon spacecraft to be conducted between 2008 and 2010.[34][35] SpaceX and Kistler were to receive up to $278 million and $207 million respectively,[35] if they met all NASA milestones, but Kistler failed to meet its obligations, and its contract was terminated in 2007.[36] NASA later re-awarded Kistler's contract to Orbital Sciences.[36][37]

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.[38] 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.[38]

On 23 February 2009, SpaceX announced that its chosen heat shield material, PICA-X, had passed heat stress tests in preparation for Dragon's maiden launch.[39] PICA-X is reportedly ten times cheaper to manufacture than NASA's PICA heat shield material.[40]

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 thermal imaging capabilities were both tested successfully.[41][42] The COTS UHF Communication Unit (CUCU) and Crew Command Panel (CCP) were delivered to the ISS during the late 2009 STS-129 mission.[43] The CUCU allows the ISS to communicate with Dragon and the CCP allows ISS crew members to issue basic commands to Dragon.[43] 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.[44]

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 utililizes 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.[45]

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.[46][47] 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 reentry to Earth's atmosphere; the mission furthermore marked the second flight of the Falcon 9 launch vehicle.[48] The DragonEye sensor flew again on STS-133 in February 2011 for further on-orbit testing.[49] In November 2010, the Federal Aviation Administration (FAA) had issued a reentry license for the Dragon capsule, the first such license ever awarded to a commercial vehicle.[50]

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+.[4][51] 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.[11][52][53][54][55] Dragon returned to Earth on 31 May 2012, landing as scheduled in the Pacific Ocean, and was again successfully recovered.[56][57]

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 re-supply missions to the ISS.[58]

Operational flights

Dragon was launched on its first operational CRS-contract mission on 8 October 2012,[14] and completed the mission successfully on 28 October.[59]

SpaceX CRS-2, the second CRS mission from SpaceX, was successfully launched on March 1, 2013. SpaceX CRS-3, SpaceX's third CRS mission, is scheduled for early 2014.

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".[32] A video simulation of this escape system's operation was released in January 2011.[26] Musk stated in 2010 that the developmental cost of a crewed Dragon and Falcon 9 would be between $800 million and $1 billion.[60] 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.[61][62] SpaceX submitted a bid for the third phase of CCDev, CCiCap.[63][64]

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.[65][66]

Their CCDev2 milestones involve 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.[67]

SpaceX's launch abort system received preliminary design approval from NASA in October 2011.[68] 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.[69][70] In January 2012, SpaceX successfully conducted full-duration tests of its SuperDraco landing/escape rocket engine at its Rocket Development Facility in McGregor, Texas.[71]

On 3 August 2012, NASA announced the award of $440 million to SpaceX for the continuation of work on the Dragon under CCiCap.[72] In November 2012, following the success of Dragon's first operational resupply mission, NASA declared SpaceX to have completed its first three CCiCap milestones.[73]

In July 2013, SpaceX stated that a pad abort test is planned to occur no sooner than December 2013.[74] During this test, the Dragon capsule will use its abort engines to launch away from a test stand at Launch Complex 40.[75][76] It will travel to an altitude of 5,000 feet (1,500 m), deploy its parachutes, splashdown into the ocean and be recovered.[75][76] An in-flight abort is planned for no sooner than April 2014, which would see Dragon using its launch abort engines to escape from a Falcon 9 that is already in flight.[75][77] 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.[77]

As part of an optional milestone of CCiCap, the first crewed Dragon flight would occur no sooner than mid-2015.[77] This orbital flight would see Dragon being launched into a 200-nautical-mile (370-km) orbit. The first crewed mission is planned to last at least three days and be performed with a crew of three non-NASA personnel.[77] As part of another optional milestone, the first crewed Dragon flight to the ISS is planned to be launched no sooner than December 2015; this mission will also carry a non-NASA crew.[77]

Red Dragon

Main article: Red Dragon (spacecraft)

Red Dragon is a concept for a low-cost uncrewed Mars lander that would utilize a SpaceX Falcon Heavy launch vehicle and a modified Dragon capsule to enter the Martian atmosphere. The concept will be proposed for funding in 2013 as a NASA Discovery mission, for launch in 2018.[78][79] The mission would search for the biosignatures of past or present life on Mars. Red Dragon would drill about 1 metre (3.3 ft) underground in an effort to sample reservoirs of water ice known to exist in the shallow Martian subsurface.[78][79]

A Dragon capsule is capable of performing all the entry, descent and landing (EDL) functions required 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 sufficiently for the final stage of its descent to be within the capabilities of its SuperDraco retro-propulsion thrusters.[78][79]

Mars One Dragon

The private Mars One colonization project has proposed to use a 5-metre (16 ft)-diameter variant of Dragon, launched on a SpaceX Falcon Heavy rocket, to transport crew and cargo to the Martian surface.[80][81] The Mars One variant would have a volume of around 25 m3 (880 cu ft).[80] According to the Mars One timetable, the first launch, with a cargo payload of 2,500 kg (5,500 lb), is due to occur in January 2016, in preparation for the projected arrival of human colonists in 2023.[82] As of May 2013, they have no relationship with SpaceX.[83]

Design

Dragon CRS

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.[84] 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.[85] For typical missions, Dragon is planned to remain berthed to the ISS for about 30 days.[86]

The CRS Dragon's capsule can transport 3,310 kg (7,300 lb) of cargo, which can be all pressurized, all unpressurized or anywhere in 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).[7] The trunk was first used operationally on the Dragon's CRS-2 mission in March 2013.[87] Its solar arrays produce a peak power of 4 kW.[10]

DragonLab

When used for non-NASA, non-ISS commercial flights, the uncrewed version of the Dragon spacecraft is called DragonLab.[19] It is reusable, free-flying, and capable of carrying both 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.[6] 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.[6] As of August 2013, there are two DragonLab missions listed on the SpaceX launch manifest: one in 2016 and another in 2018.[88] The same two missions were listed on the SpaceX manifest in November 2011.[89] The Russian Bion satellites and the American Biosatellites once performed similar uncrewed payload-delivery functions.

DragonRider

DragonRider, the crewed variant of Dragon, will support a crew of seven or a combination of crew and cargo.[91][92] It is planned to be able to perform fully autonomous rendezvous and docking with manual override capability; and will use the NASA Docking System (NDS) to dock to the ISS.[19][93] For typical missions, DragonRider would remain docked to the ISS for a period of 180 days; it is required to be able to do so for 210 days, the same as the Russian Soyuz spacecraft.[94][95][96] SpaceX plans to use an integrated pusher launch escape system for the Dragon spacecraft, with several claimed advantages over the tractor detachable tower approach used on most prior crewed spacecraft.[97][98][99] These advantages include the provision for crew escape all the way to orbit, reusability of the escape system, improved crew safety due to the elimination of a stage separation, and the ability to use the escape engines during the landing phase for a precise solid earth landing of the Dragon capsule.[100] An emergency parachute will be retained as a redundant backup for water landings.[100]

The Paragon Space Development Corporation is assisting in the development of DragonRider's life support system.[101] SpaceX is also in talks with Orbital Outfitters regarding the development of a spacesuit that would be worn during launch and re-entry.[102]

At a NASA news conference on 18 May 2012, SpaceX confirmed again that their target launch price for crewed Dragon flights is $140,000,000, or $20,000,000 per seat if the maximum crew of 7 is aboard. This contrasts with the 2012 Soyuz launch cost of $63,000,000 per seat for NASA astronauts.[103]

Dragon version 2

The version 2 Dragon spacecraft will be capable of land touchdowns. It will include side-mounted thruster pods as well as much larger windows, and landing legs which pop out at the bottom of the spacecraft. The design is expected to be unveiled later in 2013.[104]

List of Dragon missions

List includes only completed or currently manifested missions. All NASA CRS missions are currently scheduled to launch from Cape Canaveral Launch Complex 40. Launch dates are listed in UTC.

Mission name Launch date (UTC) Remarks Outcome
SpX-C1 (COTS 1) 8 December 2010[105] First Dragon mission, second Falcon 9 launch Success[3]
SpX-C2+ (COTS 2) 22 May 2012[4] First Dragon mission with complete spacecraft, first rendezvous mission, first berthing with ISS Success[56]
SpaceX CRS-1 8 October 2012[15][16][106] First Commercial Resupply Services (CRS) mission for NASA, first non-demo mission. Falcon 9 rocket suffered a partial engine failure during launch but was able to deliver Dragon into orbit.[14] However, a secondary payload did not reach its correct orbit.[107] Mission success; launch anomaly[59]
SpaceX CRS-2 1 March 2013[108][109] First launch of Dragon using trunk section to carry cargo.[87] Launch was successful, but anomalies occurred with the spacecraft's thrusters shortly after liftoff. Thruster function was later restored and orbit corrections were made,[108] but the spacecraft's rendezvous with the ISS was delayed from its planned date of 2 March until 3 March, when it was successfully berthed with the Harmony module.[110][111] Dragon splashed down safely in the Pacific Ocean on 26 March.[112] Mission success; spacecraft anomaly[108]
SpaceX CRS-3 11 February 2014 (not earlier)[113] Second of two ISS cargo resupply flights scheduled by NASA for 2013[114]
DragonRider abort test Spring 2014[115] Pad abort test
SpaceX CRS-4 6 April 2014[114][116][117]
DragonRider abort test Summer 2014 In-flight abort test; no earlier than April 2014[77]
SpaceX CRS-5 2014[118]
SpaceX CRS-6 TBA Hardware scheduled to arrive at launch site in 2014[119]
SpaceX CRS-7 TBA Hardware scheduled to arrive at launch site in 2014[119]
SpaceX CRS-8 2015[120] Hardware scheduled to arrive at launch site in 2015.[119] As of January 2013, will deliver the Bigelow BEAM module in the unpressurized cargo trunk.[120]
DragonLab-1 2016[88]
SpX CRS-9 TBA Hardware scheduled to arrive at launch site in 2015[119]
SpX CRS-10 TBA Hardware scheduled to arrive at launch site in 2015[119]
SpX CRS-11 TBA Hardware scheduled to arrive at launch site in 2015[119]
SpX CRS-12 TBA Hardware scheduled to arrive at launch site in 2015[119]
DragonLab-2 2018[88]

Specifications


Uncrewed version

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.[6]

Pressure vessel
  • 10 m3 (350 cu ft) interior pressurized, environmentally controlled, payload volume.[6]
  • Onboard environment: 10–46 °C (50–115 °F); relative humidity 25~75%; 13.9~14.9 psia air pressure (958.4~1027 hPa).[6]
Unpressurized sensor bay (recoverable payload)
Unpressurized trunk (non-recoverable)
  • 14 m3 (490 cu ft) payload volume in the 2.3 m (7 ft 7 in) trunk, aft of the pressure vessel heat shield, with optional trunk extension to 4.3 m (14 ft 1 in) total length, payload volume increases to 34 m3 (1,200 cu ft).[6]
  • Supports sensors and space apertures up to 3.5 m (11 ft 6 in) in diameter.[6]
Power, telemetry and command systems

Radiation tolerance

Dragon utilizes a "radiation-tolerant" design in the electronic hardware and software that make up its flight computers. The system utilizes 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.[45] Including the six computers that make up the main flight computers, Dragon employs a total of 18 triple-processor computers.[45]

See also

Comparable vehicles

References

External links

  • Dragon Spacecraft overview on SpaceX official website
  • SpaceX CCDev2 Agreement with NASA
  • SpaceX CCDev2 bi-monthly progress reports
  • Dragon cargo delivery to ISS (COTS 2 highlight reel)
  • Dragon crew transport to ISS (CG rendering)
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