SANTA FE, N.M. — SpaceX said Dec. 23 that it completed the tenth successful consecutive test of the new parachute design for its Crew Dragon spacecraft, a milestone that NASA previously said was critical before the agency would allow astronauts to fly on the vehicle.

The company said in a tweet that the successful test took place Dec. 22, making the tenth consecutive multi-parachute test of the design the company calls Mark 3. That test, the company said, brings it “one step closer to safely launching and landing NASA astronauts.”

Yesterday the team completed the 10th successful multi-chute test in a row of Crew Dragon’s upgraded Mark 3 parachute design – one step closer to safely launching and landing @NASA astronauts pic.twitter.com/nfFjnKygB4 — SpaceX (@SpaceX) December 23, 2019

SpaceX moved to the Mark 3 design in the fall after problems with the Mark 2 design, including a failed test in April. “We think the Mark 2 parachutes are safe, but the Mark 3 parachutes are possibly 10 times safer,” Elon Musk, founder and chief executive of SpaceX, said at an Oct. 10 event with NASA Administrator Jim Bridenstine at the company’s Hawthorne, California, headquarters. “I think that the Mark 3 parachutes, in my opinion, are the best parachutes ever, by a lot.”

The company started with a series of single-parachute tests, including performing 12 such tests over a week in October. “We’ve been working through different chute testing. SpaceX guys did 12 chute tests in week as we’re working to perfecting the Mark 3 design,” Kathy Lueders, manager of NASA’s commercial crew program, said at a meeting of the NASA Advisory Council’s human exploration and operations committee in late October.

Bridenstine said at the October event with Musk that the agency and SpaceX would review the performance of the Mark 3 parachutes after completing 10 tests. “We are committed as a team, SpaceX and NASA, to the Mark 3 parachute, which is superior to the Mark 2,” he said. “We need to get with the Mark 3 now consistent, repeatable performance.”

“Given where we are and the resources being deployed on that particular effort, we talked even today that we could see as many as 10 drop tests between now and the end of the year,” he said then. Those tests, he said, would be compared to the earlier Mark 2 parachutes, possibly using earlier Mark 2 tests to qualify the Mark 3 parachutes “as long as we see consistent, repeatable performance.”

“Depending on how the next 10 drop tests go, we will know how many more drop tests we will need,” Bridenstine said.

The agency hasn’t recently commented on how the parachute tests will feed into decisions about approving those parachutes for use on the Demo-2 crewed test flight of the spacecraft, with NASA astronauts Bob Behnken and Doug Hurley on board. However, Bridenstine tweeted “Great news!” in response to SpaceX’s announcement of the latest parachute test.

“Absolutely amazing!” responded Hurley. He said he and Behnken “can’t thank you all enough for your tireless efforts to get us ready to fly Demo-2.”

Absolutely amazing! A special Congratulations to the @SpaceX parachute team. @AstroBehnken and I can’t thank you all enough for your tireless efforts to get us ready to fly Demo-2. https://t.co/kghcM0Vuk1 — Col. Doug Hurley (@Astro_Doug) December 23, 2019

Parachutes have been one of the key issues with development of Crew Dragon, in particular with what’s known as “asymmetric loading” of the parachutes. “The problem that Dragon has really enlightened the community and basically forced us to go out and understand what this problem is,” said Robert Sinclair, chief engineer with Airborne Systems, which is working on SpaceX’s parachutes as well as those for spacecraft like Boeing’s CST-100 Starliner and NASA’s Orion.

Sinclair, in a Dec. 19 interview, said there are many factors that go into how a parachute can inflate asymmetrically, which has made it a challenge for designers. “We’ve had a number of what we’ve called ‘asymmetry summits’ where I’ve had all the world’s experts come to my facility to sit down and discuss this,” he said. Work has included instrumenting parachutes with sensors to measure the loading and developing improved models of parachute systems.

“That one thing that SpaceX found when they had that problem has enormously helped the entire recovery system community,” he said.