SpaceX reveals Dragon V2 Spacecraft for Crewed Missions to ISS
In a highly anticipated event held on Thursday, SpaceX presented its crewed Dragon spacecraft, dubbed Dragon V2. Unveiled by SpaceX Chief Designer and CEO Elon Musk and advertised as 'a 21st century spacecraft', Dragon V2 is capable of carrying a crew of seven into space and incorporates innovative technology to increase reliability and safety while implementing a very high degree of reusability.
SpaceX is planning a first uncrewed flight of the new Dragon as soon as late 2015 and the first crewed mission as early as mid 2016 in preparation for the transfer of crews to and from the International Space Station starting in 2017 should SpaceX be selected to become NASA's Commercial Crew provider.
Building on lesson's learned from the current Dragon design, the Dragon V2 spacecraft features extensive modifications and improvements to make it fit for transporting astronauts. Differences visible at first sight include the gumdrop shape of the spacecraft with a hinged nose cap protecting its docking mechanism, a re-designed trunk section with fins & fixed solar panels and four large engine pods containing eight SuperDraco engines used for a propulsive landing on four deployable landing legs.
Not visible from the outside is Dragon's advanced Life Support System built to support a crew of seven astronauts over a period of several days for the trip to and from ISS. Also hidden to the outside observer is the new Dragon's futuristic interior featuring a glass cockpit with a swing-down control panel consisting of four large touch screens used to control the vehicle at the touch of a fingertip. Only a small set of manual controls are included on the control panel to keep the interior of the spacecraft neat and tidy and make its operation as easy as possible.
The seating arrangement for crews traveling aboard the new Dragon includes two tiers of seats with four and three seats. Sitting in the center, the Commander and Pilot would have access to the swing-down control panel while the two outer seats provide crew members with a view out of two relatively large windows.
The lower tier includes the remaining three seats that could potentially be replaced with cargo should Dragon fly with a crew of four.
To dock with the International Space Station, the Dragon would open up its nose cover to expose a docking system built according to the International Docking System Standard compatible with International Docking Adapters that are to be installed on Pressurized Mating Adapters 2 and 3 to give ISS two docking ports for future visiting vehicles. The rendezvous and docking of the Dragon V2 can be performed automatically or in manual control by the crew using the control panel.
The most radical change from the cargo Dragon to the crewed vehicle is the landing that will utilize eight SuperDraco engines to pin-point a precise landing site at Cape Canaveral for a slow touchdown on four legs that deploy out of the PICA heat shield.
The heat shield itself represents the third generation of the phenolic impregnated carbon ablator heat shield with a lower ablation rate during re-entry to increase the amount of missions it can support.
Coming back from space, Dragon V2 will check its eight SuperDracos before committing to the powered descent procedure that can tolerate the loss of up to two engines and still achieve a successful landing. The parachute system used on the cargo Dragon is also part of Dragon V2 for use as a backup should the SuperDraco test after re-entry fail.
The propulsion system of Dragon V2 unites the Draco thrusters currently featured aboard Dragon with the SuperDraco that will give the spacecraft the ability to conduct ascent aborts and a propulsive landing on land. The engines are fed with hypergolic propellants that are stored in spherical carbon overwrapped titanium tanks installed around the perimeter of the Dragon and pressurized using Helium that is stored in similar tanks.
Operating at a chamber pressures of 69 bar, each SuperDraco provides up to 71,200 Newtons of thrust (7,260 Kilogram-force) with deep throttle capability. Each of the four thruster pods includes two engines, each inside a separate enclosure that protects the other engine in case a SuperDraco fails. Should an engine fail, the neighbor engine would increase its thrust to compensate as Dragon V2 can land safely with just six of its eight SuperDracos working. SuperDraco uses an Inconel superalloy engine chamber manufactured via 3D metal printing, making it the first printed engine in the world.
For a normal landing maneuver, the eight thrusters would be firing four about 25 seconds and throttle down along the way while an ascent abort would utilize the combined axial thrust of 534 Kilonewtons for five seconds to move the vehicle to safety. Since the eight SuperDracos are an integrated part of Dragon, the launch abort system is not jettisoned during ascent and provides abort capability at any point in the flight to orbit.
Landing the Dragon Cape Canaveral is of great importance to SpaceX as part of the rapid reusability plan for Dragon V2, cutting the cost of transporting the vehicle across the country and also eliminating any complex refurbishing operations in between missions. Ideally, the Dragon would only have to be re-fueled and checked briefly before being ready to fly again for a short, low-cost turnaround in between flights.
Coupled with the Falcon 9 that is making its first steps toward reusability, Dragon V2 will build a cost-effective human spaceflight system with a cost per seat of around $20 million which is a bargain compared to the $70-million price tag of a seat aboard a Russian Soyuz spacecraft that is currently the only way to ferry humans to and from the International Space Station.
SpaceX plans a Pad Abort Test using the new Dragon V2 spacecraft later this year followed by an In-Flight Abort Test to demonstrate the SuperDraco's ability to move the craft to safety in the event of a launch vehicle failure. The propulsive landing regime will be demonstrated by a test rig known as DragonFly that is planned to conduct 30 propulsive landing tests at the SpaceX McGregor Facility in Texas once the FAA has granted permission.
When all pieces have fallen into place, SpaceX CEO Elon Musk envisions Dragon assuming a larger role in space exploration, potentially turning to the Moon or Mars.