Thursday, July 20, 2017
SpaceX drops plans for powered Dragon landings
SpaceX Chief Executive Elon Musk, speaking at the International Space Station Research and Development Conference here July 19, confirmed recent rumors that the version of the Dragon spacecraft under development for NASA’s commercial crew program will not have the ability to land on land using SuperDraco thrusters that will be incorporated into the spacecraft primarily as a launch abort system.
“It was a tough decision,” he said when asked about propulsive landing capability during a question-and-answer session. “Technically it still is, although you’d have to land it on some pretty soft landing pad because we’ve deleted the little legs that pop out of the heat shield.”
SpaceX planned to transition from splashdowns, which is how the current cargo version of the Dragon returns to Earth, to “propulsive” landings at a pad at some point after the vehicle’s introduction. Certification issues, he said, for propulsive landings led him to cancel those plans.
“It would have taken a tremendous amount of effort to qualify that for safety, particularly for crew transport,” he said.
Another reason for the change, he said, is that SpaceX had reconsidered what is the best way to land large spacecraft on the surface of Mars in support of the company’s long-term goals to establish a human presence there.
“There was a time that I thought the Dragon approach to landing Mars, where you’ve got a base heat shield and side-mounted thrusters, would be the right way to land on Mars,” he said. “Now I’m pretty confident that is not the right way and there’s a far better approach.”
He didn’t describe that alternative approach, but said that “the next generation of SpaceX rockets and spacecraft” will use that different landing technique. In a later tweet, though, Musk clarified that the alternative approach will also use a version of propulsive landing.
“It doesn’t seem like the right way of applying resources right now,” he said of the original propulsive landing technique.
Abandoning that propulsion landing technique would also appear to put into jeopardy SpaceX’s planned Red Dragon spacecraft, which would have landed a Dragon 2 spacecraft on the Martian surface. SpaceX announced plans for Red Dragon last year for launch in 2018, but SpaceX President Gwynne Shotwell said in February that the launch had slipped to 2020 as the company focused on its commercial crew program and a return to flight of the Falcon 9 after a September 2016 pad explosion.
More recently, there were rumors that SpaceX had either further delayed that first Red Dragon mission or cancelled it entirely. Musk did not directly address the status of Red Dragon in his talk, but the lack of propulsion landing systems, particularly legs, would appear to rule out such missions.
Musk also confirmed in the interview that SpaceX is developing a revised version of the overall Mars exploration architecture that he unveiled at the International Astronautical Congress (IAC) in Guadalajara, Mexico, in September 2016. That plan involved the development of giant reusable launch vehicles, called the Interplanetary Transport System, for sending spacecraft to the surface of Mars or elsewhere in the solar system.
“It’s evolved quite a bit since the last talk,” Musk said of the Mars architecture. “The key thing that I’ve figured out is how to pay for this whole system to go to Mars. It’s super expensive.”
That alternative approach, he said, involves decreasing the size of the vehicles somewhat. “You make it capable of doing Earth orbit activity as well as Mars activity,” he said. “Maybe we can pay for it by using it for Earth orbit activity. That’s one of the key elements of the new architecture.”
“I think this one’s got a shot of being real on the economic front,” he said. That update, he said, may be presented at this year’s IAC in September in Adelaide, Australia.
Falcon Heavy and commercial crew
In the near term, though, Musk said SpaceX is primarily focused on completing development of the crewed version of the Dragon spacecraft. “Overall I think it’s going really well,” he said, with plans in place to start test flights of the vehicle around the middle of 2018.
That timeline is well behind the original schedule for the program, which called for the vehicle to be certified by NASA by the end of 2017. “It’s been way more difficult than cargo, to be sure,” he said of commercial crew development. “As soon as people enter the picture, it’s really giant step up in making sure things go right.”
Musk said NASA oversight was “much tougher” than on the commercial cargo program, but that disagreements were limited to “small technical bones of contention” with the agency. He didn’t given examples of those issues, beyond calling them “esoteric.”
“Overall, I’m confident that it’s going to be a system that NASA feels good about and SpaceX feels good about,” he said.
Also coming up is the first flight of the long-delayed Falcon Heavy rocket, now planned for late this year. Musk repeated earlier comments that development of the rocket, years behind schedule, was much more difficult than originally anticipated.
Musk also appeared to lower expectations about the success of that first launch. He said that liftoff requires the simultaneous ignition of 27 engines: nine engines in each of the three booster cores. “There’s a lot that could go wrong there,” he said, also citing the dynamical environment of the Falcon Heavy in flight that is difficult to test on the ground.
“There’s a lot of risk associated with the Falcon Heavy,” he said. “There’s a real good chance that vehicle does not make it to orbit. I want to make sure and set expectations accordingly.”
“I encourage people to come down to the Cape to see the first Falcon Heavy mission,” Musk said. “It’s guaranteed to be exciting.”