Dragon V2

Dragon V2 is the second version of the SpaceX Dragon spacecraft which will be a human-rated vehicle capable of making a terrestrial soft landing.^[7] It will include a set of eight much-larger side-mounted thruster pods which can serve as a Launch Abort System (LAS) or be used for propulsive landings, as well as much larger windows, landing legs which extend from the bottom of the spacecraft, new computers and avionics, and redesigned solar arrays, all packaged in a spacecraft with a changed outer mold line from the initial cargo Dragon that has been flying for several years.^[8]

The spacecraft was unveiled on May 29, 2014—after originally being expected to be unveiled in 2013^[9] —a crew-carrying variant of Dragon that varies considerably from the cargo-carrying Dragon, which has been operational since 2010. Dragon V2 could make its first flight as early as late 2015, with its first flight with people as early as 2016. A launch pad abort test of Dragon V2 was planned for 2014, but has since slipped into early 2015.^{[10][11][12][13]}

NASA has signed a contract to procure up to six crew-carrying flights to the International Space Station under the Commercial Crew Program.

Dragon V2 development history

2012 DragonRider mockup, showing the LES engines mounted on the outside of the capsule, when the design was not yet final.^[14]

Manned version of Dragon CRS with powered vertical landing capability

The crewed variant of Dragon was initially called DragonRider.^[15] It was intended from the beginning to support a crew of seven or a combination of crew and cargo.^[16][17] It was planned to be able to perform fully autonomous rendezvous and docking with manual override capability; and was designed to use the NASA Docking System (NDS) to dock to the ISS.^[18][19] 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.^[20][21][22] 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.^[23][24][25] 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.^[26] An emergency parachute system will be retained as a redundant backup for water landings.^[26]

As of 2011, the Paragon Space Development Corporation was assisting in the development of DragonRider's life support system.^[27] In 2012, SpaceX was in talks with Orbital Outfitters regarding the development of a spacesuit that would be worn during launch and re-entry.^[28]

At a NASA news conference on 18 May 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 launch vehicle for launching Dragon V2.^[31][32]

SpaceX intends to certify their propulsive landing scheme in parallel with the parachute-to-water-landing for Dragon V2, with the goal to hold to the development schedule and "ensure U.S. crew transportation safely and reliably in 2017. 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."^[33]

Technical characteristics

Dragon V2 includes the following features:^[10][11]

• Reuses: fully reusable; capable of being flown multiple times, resulting in a significant reduction in the cost of access to space. SpaceX anticipates on the order of ten flights are possible before significant refurbishment of the space vehicle would be required.
• Capacity: seven astronauts
• Landing: supports both propulsive-landing "almost anywhere in the world" with the accuracy of a helicopter, plus a backup parachute-enabled landing capability. Four extendable landing legs
• 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^[10] 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."^[33]
• the first fully printed 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 in the event of an engine failure.
• Docking: capable of autonomous docking to space stations. Dragon V1 utilized berthing, a non-autonomous method of attachment to the ISS that was completed by use of the Canadarm robotic arm. Pilot capability to park the spacecraft using manual controls if necessary
• Reservoirs: composite-carbon-overwrap titanium spherical tanks for holding the helium used for engine pressurization 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 is capable of being operated in a complete vacuum, and "the crew will wear SpaceX-designed spacesuits to protect them from a rapid cabin depressurization emergency event". However, the spacecraft will also be capable of safe return "in the event of a leak of up to an equivalent orifice of 0.25 inches in diameter."^[33]
• a 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 location.^[33]
• a reusable nose cone—the second structural element of the spacecraft, "which protects the vessel and the docking adaptor during ascent and reentry"^[33]—which pivots on a hinge to enable in-space docking, and returns to the covered position for reentry and future launches^[12]
• a trunk—the third structural element of the spacecraft—which contains the solar arrays, heat-removal radiators, and will provide aerodynamic stability during emergency aborts.^[33]

The landing system is being designed to accommodate three types of landing scenarios:

• propulsive landing
• parachute landing, similar to previous 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]

The parachute system was totally redesigned from the one used in the Dragon V1 capsule, due to the requirement to deploy the parachutes under a variety of launch abort scenarios.^[34]

Planned space transport missions

Dragon has been designed to fulfill a set of mission requirements that will make the capsule useful to both commercial and governmental customers. SpaceX and Bigelow Aerospace are working together to support round-trip carrying of commercial passengers to low-Earth orbit (LEO) destinations such as the planned Bigelow Commercial Space Station. In that use, the full passenger-carrying 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.^[10]

In an August 2014 presentation, SpaceX revealed that if NASA chooses to use the Dragon V2 space capsule under a Commercial Crew Transportation Capability 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 utilize the additional payload mass and volume capability to carry pressurized cargo. In addition, all NASA landings of Dragon V2 are planned to initially use the propulsive deceleration capability 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 September 16, 2014, NASA announced that SpaceX, together with Boeing, has been selected to provide crew transportation capability to ISS. SpaceX will receive $2.6 billion under this contract.^[35] NASA considers the Dragon as the cheapest proposal.^[32]

In a departure from previous NASA practices during the first five decades of the space age—where NASA contracted to commercial companies to build spaceflight equipment and then NASA operated the spacecraft directly—NASA is purchasing space transport services from SpaceX with the Dragon V2 contract, and will leave the launch, transit, and operation of the spacecraft to SpaceX.^[36]

According to Elon Musk in a question and answer session at the May 29, 2014 unveiling of the Dragon V2, Dragon V1 will be used in tandem with Dragon V2 as a cargo ferry for coming years.

Flight testing

SpaceX is planning a program of four tests for the Dragon V2 that will include both a "pad abort" test, and an in-flight abort test, followed by an uncrewed robotic orbital flight to the ISS, and finally a 14-day crewed demonstration mission to the ISS in 2017.

SpaceX Dragon V2 Pad Abort Vehicle, assembled and stacked on the Dragon trunk in a test chamber, January 2015.

Pad abort test

In August 2014, it was announced that the pad abort test would take place in Florida, at SpaceX's leased pad at SLC 40. The test will take place no earlier than May 5, 2015.^{[37][36][38][39]} While a flight-like Dragon V2 and trunk will be used for the pad abort test, they will rest atop a truss structure for the test rather than a full Falcon 9 rocket. A crash test dummy will be placed inside the test vehicle to record acceleration loads and forces at the crew seat. The test objective will be to demonstrate sufficient total impulse, thrust and controllability to conduct a safe pad abort. One of the seven seats on-board will be loaded with an anthropomorphic test device embedded with a suite of sensors, while the remaining six seats will be loaded with weights to simulate full-passenger-load weight.^[37][36][34]

In-flight abort test

An in-flight abort test was, as of January 2015, planned to take place no earlier than March 2015 at SpaceX's California leased launch pad at Vandenberg AFB Space Launch Complex 4E. The test will utilize a Falcon 9 launch vehicle to ascend and accelerate the capsule into the troposphere where the abort will occur in the transonic velocity region at the point of maximum drag.^[40] The test objective is to demonstrate the ability to safely get away from the ascending rocket under the most difficult atmospheric conditions of the flight trajectory.^[34][41] SpaceX brought the three-engine Falcon 9 that will be used for the in-flight abort test to the launch pad at Vandenberg for the first time in April 2015 in order to conduct a tanking test. It was erected on the revised and rebuilt Transporter/Erector/Launcher (TEL) and fully loaded with propellants to test both the vehicle and ground support equipment on 9 April 2015.^[40]

Two orbital flight tests

Following the pad abort test and in-flight abort tests, SpaceX plans to launch an uncrewed orbital test flight (designated "SpX-DM1") using the company's Falcon 9 rocket no earlier than December 2016, with its first crewed mission ("SpX-DM2") using the launch system coming shortly after that, tentatively manifested for April 2017.^[13][36]

See also

• CST-100, a capsule crew-carrying spacecraft being developed by Boeing
• Prospective Piloted Transport System - a new-generation, reusable capsule, manned spacecraft proposal in Russia in the late 2000s.
• Dream Chaser, a spaceplane being developed in the early 2010s by Sierra Nevada Corporation
• Blue Origin orbital spacecraft – an American private biconic nose cone design vehicle
• Orion (spacecraft), a spacecraft being built for NASA by Lockheed Martin
• Automated Transfer Vehicle – a single-use, expendable cargo vehicle that was in use by the ESA from 2008 until retirement in February 2015.
• Crew Exploration Vehicle
• Private spaceflight

References

External links

• Media related to Dragon V2 at Wikimedia Commons