Dragon 2

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SpaceX Dragon 2
SpaceX Crew Dragon (More cropped).jpg
Artistic rendition of the Dragon 2 approaching the International Space Station (ISS)
Manufacturer SpaceX
Country of origin United States
Operator
Applications ISS crew transfer
Space tourism to lunar orbit
Specifications
Spacecraft type Crewed capsule
Design life
Dry mass about 6,400 kg (14,000 lb)[2]
Payload capacity 3,310 kg (7,300 lb) to ISS
2,500 kg (5,500 lb) return cargo[3] [needs update]
Crew capacity 7
Dimensions
  • Diameter: 3.7 m (12 ft) with trunk[4]
  • Height: 8.1 m (27 ft) with trunk[4]
  • Sidewall angle: 15 degrees
Volume 10 m3 (350 cu ft) pressurized[1]
14 m3 (490 cu ft) unpressurized[1] [needs update]
Regime
Production
Status In development
Built 2 (1 test article, 1 production)
First launch November 2018 (uncrewed),
April 2019 (crewed)[5]

Dragon 2 (also Crew Dragon, Dragon V2, or formerly DragonRider) is the second version of the SpaceX Dragon spacecraft, which will be a human-rated vehicle.[6] It includes a set of four side-mounted thruster pods with two SuperDraco engines each, which can serve as a launch escape system or launch abort system (LAS). It has larger windows, new flight computers and avionics, redesigned solar arrays, and a modified outer mold line from the initial cargo Dragon.[7]

The spacecraft was unveiled on May 29, 2014, during a press event at SpaceX headquarters in Hawthorne, California.[8][9][10] Designed to ferry astronauts to space, the capsule differs considerably from the cargo-carrying Dragon, which has been operational since 2010. As of August 2018, the spacecraft is expected to conduct an automated test mission to the International Space Station (ISS) on November 2018, and to carry its first crew on a demonstration flight on April 2019.[11]

SpaceX completed a launch pad abort test of the spacecraft on 6 May 2015[12] and a hovering test on 24 November 2015.[13]

NASA has signed a contract to procure up to six crewed flights to the International Space Station under the Commercial Crew Development.

Development[edit]

2012 DragonRider mockup, showing the launch escape system engines mounted on the outside of the capsule, when the design was not yet final.
Crewed version of Dragon CRS with powered vertical landing ability

The crewed variant of Dragon was initially called DragonRider.[14] It was intended from the beginning to support a crew of seven or a combination of crew and cargo.[15][16] It was planned to be able to perform fully autonomous rendezvous and docking with manual override ability; and was designed to use the NASA Docking System (NDS) to dock to the ISS.[17][18] For typical missions, DragonRider would remain docked to the ISS for a period of 180 days, but would be designed to be able to do so for 210 days, the same as the Russian Soyuz spacecraft.[19][20][21] From the earliest design concepts which were publicly released in 2010, SpaceX planned to use an integrated pusher launch escape system for the Dragon spacecraft, claiming several advantages over the tractor detachable tower approach used on most prior crewed spacecraft.[22][23][24] These advantages included the provision for crew escape all the way to orbit, reusability of the escape system, improved crew safety due to eliminating a stage separation, and the ability to use the escape engines during landings for a precise solid earth landing of the capsule.[25]

SpaceX originally intended to certify their propulsive landing scheme, in parallel with the parachute-to-water-landing method for Dragon 2, with the goal to hold to the development schedule and "ensure U.S. crew transportation safely and reliably in 2017." SpaceX announced that "land landing will become the baseline for the early post-certification missions" while precision water landing under parachutes was proposed to NASA as "the baseline return and recovery approach for the first few flights of Crew Dragon."[26] Thus the parachute system was initially anticipated to be only a backup system; due to the cancellation of propulsive landing, however, the parachute system will be used for all landings.[25]

As of 2011, the Paragon Space Development Corporation was assisting in developing DragonRider's life support system.[27] In 2012, SpaceX was in talks with Orbital Outfitters about developing space suits to wear during launch and re-entry.[28]

At a NASA news conference on May 18, 2012, SpaceX confirmed again that their target launch price for crewed Dragon flights is $160,000,000, or $20,000,000 per seat if the maximum crew of 7 is aboard, and if NASA orders at least four DragonRider flights per year.[29] This contrasts with the 2014 Soyuz launch price of $76,000,000 per seat for NASA astronauts.[30]

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.[31][full citation needed][32][33]

Technical specifications[edit]

Dragon 2 includes the following features:[8][9]

  • Reuses: partly reusable; can be flown multiple times, resulting in a significant cut in the cost of access to space. SpaceX anticipates that about ten flights are possible before significant vehicle refurbishing is needed.
  • Capacity: seven astronauts
  • Landing: four main parachutes for water landing; possibility of developing propulsive landing using the SuperDraco engines.
  • Engines: 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[8] Each pod—called a "quad" by SpaceX—contains two SuperDraco engines plus four Draco thrusters. "Nominally, only two quads are used for on-orbit propellant with the Dracos and two quads are reserved for propulsive landing using the SuperDracos."[26]
  • A 3D-printed rocket engine: 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.
  • Docking: able to autonomously dock to space stations. Dragon V1 used berthing, a non-autonomous means to attach to the ISS that was completed by use of the Canadarm2 robotic arm. Pilot ability to park the spacecraft using manual controls if needed
  • Reservoirs: composite-carbon-overwrap titanium spherical tanks to hold the helium used to pressurize engines and also for the SuperDraco fuel and oxidizer
  • Shield: updated third-generation PICA-X heat shield
  • Controls: tablet-like computer that swivels down for optional crew control by the pilot and co-pilot
  • Interior design: tan leather seats
  • 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."[26]
  • Movable ballast sled: to allow 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.[26]
  • Reusable nose cone: the second structural element of the spacecraft, "which protects the vessel and the docking adaptor during ascent and reentry"[26]—which pivots on a hinge to enable in-space docking, and returns to the covered position for reentry and future launches[10]
  • Trunk: the third structural element of the spacecraft, which contains the solar arrays, heat-removal radiators, and will provide aerodynamic stability during emergency aborts.[26]

The landing system was initially designed to accommodate three types of landing scenarios:

  • Propulsive landing, for vertical takeoff, vertical landing (VTVL)
  • Parachute landing, similar to prior American manned space capsules
  • Parachute landing with propulsive assist, similar to that used by the Soyuz (spacecraft): "The whole landing system is designed so that it’s survivable if there’s no propulsive assist at all. So if you come down chutes only with the landing legs, we anticipate no crew injury. It’ll be kind of like landing in the Soyuz."[34]

However, on July 19, 2017, Elon Musk announced that propulsive landing development had been halted and all landings would be under parachute. This also means that the Red Dragon project cannot land on Mars but in absence of confirmation it remains unclear whether those missions are indefinitely postponed, cancelled, or might be reworked to some different objective. The SuperDraco engines would still exist for aborts, but there would be no legs. The effort to qualify propulsive landing for safety as well as the lack of technology commonalities with their ultimate Interplanetary Spaceship was given as a reason.[35]

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.[34]

Planned space transport missions[edit]

Dragon has been designed to fulfill a set of mission 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 such as the planned Bigelow Commercial Space Station. In that use, the full passenger capacity of seven passengers is planned to be used.

SpaceX competed for a contract with NASA to deliver some number of specific crew-transport missions to the ISS under the third phase of the Commercial Crew Development program.[8]

In an August 2014 presentation, SpaceX revealed that if NASA chooses to use the Dragon 2 space capsule under a Commercial Crew Transportation Capability (CCtCap, Commercial Crew Development) contract, then only four of the seven possible seats would be used for carrying NASA-designated passengers to the ISS, as NASA would like to use the added payload mass and volume ability to carry pressurized cargo. Also, all NASA landings of Dragon 2 are planned to initially use the propulsive deceleration ability of the Super Draco engines only for a propulsive assist right before final touchdown, and would otherwise use parachutes "all the way down."[34]

On 16 September 2014, NASA announced that SpaceX, together with Boeing, has been selected to provide crew transport ability to ISS. SpaceX will receive $2.6 billion under this contract.[36] NASA considers Dragon to be the least expensive proposal.[32]

In a departure from prior NASA practice during the first five decades of the space age, where NASA contracted with commercial firms to build spaceflight equipment and then NASA operated the spacecraft directly, NASA is purchasing space transport services from SpaceX with the Dragon 2 contract, and will leave the launch, transit, and operation of the spacecraft to SpaceX.[37]

According to Elon Musk in a question and answer session on 29 May 2014 unveiling of the Dragon 2, the older version of Dragon will be used in tandem with Dragon 2 as a cargo ferry for coming years.

Following the Dragon 2 pad abort test in early May 2015, Musk revealed plans to use a variant of the Dragon 2 spacecraft—in conjunction with the Falcon Heavy launch vehicle—to transport science cargos across much of the solar system, in cislunar and inner solar system regions such as Mars in 2020 with the Red Dragon but also to outer solar system destinations such as Jupiter's moon Europa. Details include that SpaceX expects to be able to transport 2,000–4,000 kg (4,400–8,800 lb) to the surface of Mars, including a soft retropropulsive landing using SuperDraco thrusters following a limited atmospheric deceleration. For destinations with no atmosphere, the Dragon variant would omit the parachute and heat shield, and add propellant.[38] However, these plans were indefinitely postponed following the cancellation of propulsive landing development for the Dragon vehicle in mid-2017.[35]

Crewed circumlunar flight[edit]

On February 27, 2017, SpaceX CEO Elon Musk announced that the company will attempt to fly two private citizens on a free return trajectory around the moon in late 2018.[39] The Dragon 2 spacecraft would launch on the Falcon Heavy booster. The two private citizens, who have not yet been named, approached SpaceX about taking a trip around the Moon, and have "already paid a significant deposit" for the cost of the mission, according to a statement from the company. The names of the two individuals will be announced later, pending the result of initial health tests to ensure their fitness for the mission, the statement said.[40] The two passengers would be the only people on board what SpaceX expects to be about a week-long trip around the Moon, according to Musk, who spoke with reporters during a phone conference. "This would be a long loop around the moon. . . . It would skim the surface of the moon, go quite a bit further out into deep space and then loop back to Earth," Musk said during the teleconference. "So I'm guessing, distance-wise, maybe [about 500,000 to 650,000 kilometers].[41] The Dragon spacecraft would operate, in large part, autonomously, but the passengers would have to train for emergency procedures. The Dragon 2 capsule will require some upgrades for the deep-space flight, but Musk said those would be limited mainly to installing a long-range communications system.

On 5 February 2018 Elon Musk announced the Falcon Heavy rocket would not be used for crewed missions.[42][43] Elon Musk indicated on 6 February 2018 that the BFR will likely be used for the flight instead, indicating that SpaceX is moving forward with space tourism plans.[44]

Flight testing[edit]

SpaceX is planning a program of four tests for the Dragon 2 that will include both a "pad abort" test, and an in-flight abort test, plus both an uncrewed robotic orbital flight to the ISS, and finally a 14-day crewed demonstration mission to the ISS in 2019.[45][46]

Pad abort test[edit]

Crew Dragon Pad Abort Test Launch
An infographic of the SpaceX Dragon 2 Pad Abort Test for the May 2015 test, produced by SpaceX

In August 2014, it was announced that the pad abort test would occur in Florida, at SpaceX's leased pad at SLC 40. 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.[34][37][47] The test objective was to demonstrate sufficient total impulse, thrust and controllability to conduct a safe pad abort.

The pad abort test was conducted successfully on 6 May 2015 at approximately 09:00 Eastern Daylight Time (EDT). The vehicle splashed down safely in the ocean to the east of the launchpad 99 seconds later.[12] A fuel mixture ratio issue was detected after the flight in one of the eight SuperDraco engines, but did not materially affect the flight.[48] More detailed test results were to be subsequently analyzed by both SpaceX and NASA engineers.[49]

Hovering test[edit]

Dragon 2 spacecraft conducting a propulsive hover test

On November 24, 2015, SpaceX conducted a test of Dragon 2's hovering abilities at the firm’s rocket development facility in McGregor, Texas. In a video published by the firm,[13] the spacecraft is shown suspended by a hoisting cable and igniting its SuperDraco engines. The capsule hovers in equilibrium for about 5 seconds, kept in balance by its 8 engines firing at reduced thrust to compensate exactly for gravity.

This video shows the second test of the two-part milestone under NASA’s Commercial Crew Development program. The first test, a short firing of the engines intended to verify a healthy propulsion system, was completed two days earlier on November 22.

The test vehicle was the same capsule that performed the pad abort test earlier; it was nicknamed DragonFly.[50]

Uncrewed orbital test flight[edit]

The first orbital test of Dragon 2 will be an uncrewed mission, designated SpX-DM1[37] and scheduled, as of August 2018, for November 2018.[11] The spacecraft will test the approach and automated docking procedures with the ISS, remain docked for a few weeks, then conduct the full re-entry, splashdown and recovery steps to qualify for a crewed mission. Life support systems will be monitored all along the test flight. The same capsule will be re-used later for an in-flight abort test.[51]

In-flight abort test[edit]

SpaceX plans to conduct an in-flight abort test from Kennedy Space Center Launch Complex 39A in Florida after the first uncrewed orbital test flight and prior to the first crewed test flight.[52] The test is planned to be conducted on March 2019[53] with the refurbished capsule from the uncrewed test flight.[54]

Earlier, this test had been scheduled before the uncrewed orbital test,[51] however, SpaceX and NASA consider it safer to use the more recently designed capsule rather than the older test article from the pad abort test.[54]

The Dragon 2 test capsule will be launched in a sub-orbital flight to conduct a separation and abort scenario in the troposphere at transonic velocities, at max. Q, where the vehicle experiences maximum aerodynamic pressure.[55] The test objective is 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.[34] The capsule will then splash down in the ocean with traditional parachutes, possibly with assistance of its integrated thrusters to smooth the final moments of the descent.

The in-flight abort capsule was originally planned to launch on F9R Dev2 before the Falcon 9 Full Thrust vehicle (and its densified propellants) made F9R Dev2 incompatible with both of SpaceX's active orbital launch pads. Then a special version of the Falcon 9 first stage with just three engines was prepared for this test and carried to the launch pad at Vandenberg in April 2015 to conduct a tanking test. It was erected on the revised and rebuilt transporter erector (TE) and fully loaded with propellants on 9 April 2015 to test both the vehicle and ground support equipment.[55] Those plans were later scrapped, and the abort test will be performed using an entire Falcon 9 Block 5 rocket and will be used as a test of the fueling procedure in order to human-rate the Falcon 9 rocket for NASA's Commercial Crew Program.

Crewed orbital test flight[edit]

Dragon 2 mockup and the astronauts selected for the first two missions, from left to right: Douglas Hurley, Robert Behnken, Michael Hopkins and Victor Glover.

As of August 2018, Dragon 2 is scheduled to carry its first crew of two NASA astronauts on a 14-day test flight mission to the ISS in April 2019.[11] They could well be the first people to ride a post-Shuttle American spacecraft into orbit, since the orbital test flight of the Boeing CST-100 Starliner is currently scheduled for the middle of 2019.[11] 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.[56] The SpX-DM2 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.[37][57]

On August 3, 2018 NASA announced the crew for the DM-2 mission.[58] 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.

See also[edit]

References[edit]

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  5. ^ https://spacexnow.com/upcoming.php SpX DM 1, SpX DM 2
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External links[edit]