On Monday, officials from SpaceX and NASA provided an update on the investigation of the anomaly that occurred in April, which destroyed the Crew Dragon spacecraft. In general, they are optimistic with their assessment: “I’m pretty optimistic now, because we have a good way forward,” said Hans Koenigsmann, SpaceX’s vice president of mission assurance.
After nearly three months of work—which included collecting debris from the ground-based incident, analyzing large amounts of data, and numerous tests at SpaceX’s rocket development facility in McGregor, Texas— The company is about 80% complete with its analysis, Koenigsmann said. He characterized the findings discussed Monday as “preliminary.”
The accident occurred during tests of the Crew Dragon thruster systems in Florida. The capsule contains “Draco” arrows used to maneuver in space as well as powerful “SuperDracos”. They will be fired in the event of an emergency with a rocket to safely eject the crew during a launch. Specifically, the April 20 anomaly occurred during the activation phase of the SuperDraco thruster system, when it was pressurized and the valves were opened and closed.
Approximately 100 milliseconds before the fire of the Crew Dragon’s eight SuperDraco thrusters, a leaking component was allowed by a cup of liquid oxidizer — nitrogen tetroxide — or NTO — into the wrong fuel tank Plumbing.
“This slug of NTO was carried through the helium check valve at high speed during the rapid start of the launch escape system, resulting in a structural failure within the check valve,” the company said. in a word. “Failure of the titanium component in the high-pressure NTO region was sufficient to cause the check valve to fire and lead to an explosion.”
Koenigsmann said the company is already taking steps to prevent such a problem from happening again. This includes the use of “burst discs” instead of check valves to eliminate the possibility of any liquid leakage flowing into the gaseous pressure system.
The hardware components needed to mitigate this problem are fairly straightforward, he said. What may take more time is the process of checking other fuel systems in the Crew Dragon for similar weaknesses, as well as demonstrating the basic physics of NTO and titanium that shines in this situation. “The materials are probably the smallest part,” he said.
New schedule uncertain
After flying a flawless Dragon test mission to the International Space Station in February, SpaceX is working on a manned flight (by NASA astronauts Doug Hurley and Bob Behnken) later in this year. That seems unlikely, but Koenigsmann hopes that this case can work in parallel to the many other challenges between the Dragon and that aircraft, such as the qualification of the helicopter’s parachutes.
NASA’s head of the commercial crew program, which pays for and manages the development of Crew Dragon and Boeing’s Starliner vehicles to transport astronauts to and from the International Space Station, expressed satisfaction with the speed and quality of SpaceX’s investigation into the accident .
“In many ways, this is a gift for us,” said Kathy Lueders, NASA administrator. “It is a test on the ground, we have a lot of equipment on board, we have high quality cameras, (and) we are able to get the hardware and the data. Through this process, we will continue to learn things. that will help us fly safely.”
The company also confirmed its plan to use the Crew Dragon spacecraft originally assigned to SpaceX’s first crewed mission to the International Space Station for the In-Flight Abort test—which will test SuperDraco propellants during the ride to space. The first flight assigned to the first mission will now launch Hurley and Behnken on their demonstration flight.
Sources told Ars that SpaceX will likely complete the In-Flight Abort test in 2019, with an operational flight in early 2020, provided all goes well during the abort test. On this schedule, the race between SpaceX and Boeing to launch the first human into orbit from the US home since the 2011 retirement of the space shuttle will be very close.