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SpaceX Falcon 9 launch
A SpaceX Falcon 9 rocket launches Iridium telecommunication satellites from Vandenberg Air Force Base in California on Jan. 14. (SpaceX Photo)

Investigators are raising concerns about persistent cracking in the turbine blades in SpaceX’s rocket engines, and adding to doubts about the schedule for flying NASA astronauts to the International Space Station.

The concerns are contained in a draft report being prepared by the Government Accountability Office, according to The Wall Street Journal. The Journal said its information came from government and industry officials familiar with the GAO’s study of SpaceX’s Falcon 9 rocket and its Merlin engines.

In response to today’s Journal article, SpaceX said it was working to resolve the turbine blade issue in cooperation with NASA.

“We have qualified our engines to be robust to turbine wheel cracks,” SpaceX spokesman John Taylor told GeekWire in an email. “However, we are modifying the design to avoid them altogether.  This will be part of the final design iteration on Falcon 9. SpaceX has established a plan in partnership with NASA to qualify engines for manned spaceflight.”

The Journal quoted NASA’s acting administrator, Robert Lightfoot, as saying he thinks “we know how to fix” the issues relating to SpaceX’s turbopumps.

In a follow-up email, NASA spokeswoman Tabatha Thompson noted that the concerns about the turbopump cracks aren’t exactly new. “NASA previously identified concerns raised in the article, and briefed the Aerospace Safety Advisory Panel and other independent reviewers,” she said.

For example, a report issued by NASA’s Office of Inspector General last September said SpaceX was experiencing “ongoing issues with stress fractures in turbopumps that must be resolved” before it begins launching astronauts.

The draft report from the GAO, which is Congress’ investigative arm, also concluded that neither SpaceX nor the Boeing Co. is likely to conduct regular space taxi flights to the space station by 2018.

That echoes assessments from other analysts, including officials at NASA. In a procurement document issued last month, NASA said the two companies are “not expected to begin fully operational flights to the ISS until 2019.” The current schedule calls for crewed test flights to begin next year, but that timeline could slip.

The Journal said its sources pointed to frequent modifications in Falcon 9 boosters as a potential source of delays in NASA certification. The draft report also is said to raise questions about the status of parachute tests for Boeing’s CST-100 Starliner space taxi.

SpaceX’s turbopump issues are unrelated to the fuel tank problems that led to the loss of Falcon 9 rockets and their payloads in June 2015 and September 2016. Those setbacks forced a significant reshuffling of SpaceX’s launch schedule. The company executed its first successful liftoff in five months on Jan. 14, and it’s due to send an uncrewed Dragon cargo capsule to the space station in mid-February.

The Dragon resupply mission would mark the first space launch from Kennedy Space Center’s historic Launch Complex 39A since the end of the space shuttle era in 2011. Another Falcon 9 rocket is expected to put the EchoStar 23 communication satellite into orbit from Pad 39A later this month, but Taylor said SpaceX is still waiting for a launch license from the Federal Aviation Administration.

Check out the full report from The Wall Street Journal. This posting was updated at 10:12 a.m. PT Feb. 3 with further reaction from NASA.

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