(SpaceX) has unveiled the human-rated version of its Dragon spacecraft with which it is competing for ’s Commercial Crew Program to ferry astronauts to the International Space Station (ISS).
The "V2" version, revealed by SpaceX CEO Elon Musk at the company’s Hawthorne, Calif, facility on May 29, is designed to carry a crew of seven and differs considerably from the cargo variant currently flown to the ISS. “We wanted to take a big step in technology – a step change in space travel,” Musk says. “It really takes things to the next level,” he adds.
Configured with eight side-mounted SuperDraco thruster engines clustered in pairs, and supported on extendable landing legs protruding through the heat shield, the vehicle is designed to be able to land under its own power “anywhere on Earth with the accuracy of a helicopter. That’s something I think a modern spaceship should be able to do,” Musk says.
The vehicle will also be able to dock directly to the ISS autonomously without needing the large Canadarm 2 robotic arm that is used to maneuver the cargo Dragon into place. Dragon V2 also retains the ‘Version 1” parachute system as a safety back up in case of an engine anomaly, Musk says. “So when it reaches a certain altitude just before landing it will test the engines, and verify they are all working and proceed to a propulsive landing. But if any anomaly is detected it will then deploy the parachutes even in the event of the propulsion system not working.”
The vehicle can lose up to two engines and still make a safe landing, according to Musk, who considers the development of the 16,000-lb.-thrust SuperDraco thruster as the most significant technical challenge involved in the development of the Dragon V2. “That’s an engine that has to produce a tremendous amount of thrust and yet be very light. It’s also got to throttle over a wide range, and it’s got to react very quickly. It was quite a tricky thing to develop.”
SpaceX completed qualification testing of the thruster earlier this week at its McGregor, Texas, test site. The engine system is also designed to power the Dragon’s launch escape system as well as provide a propulsive landing capability. The regeneratively cooled engine is not only capable of deep-throttling but is designed for multiple restarts, and is produced from inconel using an additive manufacturing, direct metal laser sintering process. “This will be the first fully printed rocket engine to see flight,” Musk says. Each one is contained in a protected nacelle “in case anything goes wrong.”
“The reason this is important is it enables rapid reusability of the spacecraft," Musk says. "You can just reload propellant and fly again." He envisages up to 10 flights per vehicle before significant refurbishment. Other highlights noted by Musk included the composite overwrapped titanium spheres containing the pressurized helium for the propulsion tanks for the SuperDraco engine. The engines operate at a chamber pressure of around 1,000 psi and are fed from propellant tanks located around the base of the vehicle.
The new Dragon also features the third generation of the SpaceX-specific phenolic impregnated carbon ablator (PICA-X) heat shield technology. “It ablates less as it enters the atmosphere” Musk says. Inside the vehicle are flat panel display and control screens, with mechanical switches and knobs for key functions.
The first key milestone for the Dragon V2 is a launch pad abort test in which the vehicle will be positioned at pad height and then launched to simulate an emergency. “Next year we expect to do the highaltitude abort test at Max Q [max dynamic pressure] and execute an abort. These are tests, so they could go wrong,” Musk says. “Conceivably we could do the first flight to orbit at the end of 2015, and the first flight with people in 2016." Musk adds that SpaceX will attempt to continue development of the enhanced Dragon even if it loses the contest for thecontract. “We will do our best to continue development,” he says.