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posted by hubie on Friday June 17 2022, @01:14AM   Printer-friendly
from the slight-delay-so-just-eat-slower dept.

The propellant leak and ensuing investigation has resulted in a one-month delay to the CRS-25 cargo mission:

A SpaceX cargo mission to the International Space Station has been pushed back to no earlier than July 11 after teams discovered elevated vapor levels of propellant. [...]

Following additional inspections and testing of the Dragon spacecraft, the investigators managed to identify the source of the leak as being a faulty Draco thruster valve inlet joint, which controls the flow of propellant. [...]

This marks the second delay for the cargo resupply mission, the first delay being announced on June 6. The first delay happened after ground teams detected elevated vapor readings of mono-methyl hydrazine while loading the propellant, forcing them to stand down from the launch attempt. [...]

The NASA and SpaceX partnership continues to be a strong one. The space agency recently bought five additional Crew Dragon flights to the ISS after NASA's other commercial partner, Boeing, failed to deliver its own crew vehicle on schedule. The recent glitch with Crew Dragon, it's fair to say, likely won't have much of a bearing on this fruitful working relationship.

Previously: NASA and SpaceX Stand Down on Dragon Launch to Study Hydrazine Issue


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  • (Score: 1, Interesting) by Anonymous Coward on Friday June 17 2022, @04:45AM (4 children)

    by Anonymous Coward on Friday June 17 2022, @04:45AM (#1253906)

    Without information from the people actually working on it we can only guess. Thanks for the picture. Those look like compression seals, so probably mechanical stress during launch/landing, vibration, thermal cycling, or some combination. I don't think torque since this wasn't the first flight for the vehicle and that should have shown up sooner.

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  • (Score: 2) by RS3 on Friday June 17 2022, @06:19AM (3 children)

    by RS3 (6367) on Friday June 17 2022, @06:19AM (#1253924)

    Oh, interesting. So would they recheck torques before relaunch? Like wouldn't that be part of a total check everything procedure?

    • (Score: 0) by Anonymous Coward on Friday June 17 2022, @12:41PM (2 children)

      by Anonymous Coward on Friday June 17 2022, @12:41PM (#1253985)

      Definitely interesting. Thanks for the pict. Some of the actual sealing surfaces might be interesting as well. The answer to this why, raises the next.

      Why did this particular seal fail?

      The fitting on the engine appears drilled for locking wire, but I don't see how that would prevent the fitting from backing off enough for a small leak. Is torque the basic locking mechanism. Any sort of goo or oher mechanicl locking involved? Did they happen to measure the torque required to open the fitting?

      Wonder if they keep video of all the assembly, so they can come back later and see if there was anythng different about how a particular joint was made up after the fact?

      Seems like to properly deform a sealing washer, the how the torque is pulled up is a bit of an art.

      Making rockets requires getting a lot of details just right. Reusable, even more so. These folks really have this down. Interesting to see such a public post mortem. Really bodes well for their attitude of just making stuff that works. Care and pride in workmanship is not something one can create with a burry it in paperwork plan.

      • (Score: 2) by RS3 on Friday June 17 2022, @06:00PM (1 child)

        by RS3 (6367) on Friday June 17 2022, @06:00PM (#1254041)

        You're very welcome. Here's the source article: https://www.teslarati.com/spacex-nasa-cargo-dragon-crs-25-delay-update/ [teslarati.com]

        You pose the correct questions, and we hope they looked into everything. I'm surprised they'd have a problem like this- didn't we (tech world) learn these things long ago?

        Very interesting re: locking wire. They're nice to keep things from coming off, but they don't guarantee proper torque. In fact, if drilled through nut and stud, you can't adjust torque- you have to replace nut and stud and start over.

        "Goo": again, with Loctite or other thread lockers- you can't check / re-torque. You might be able to thoroughly clean threads and start over, but maybe not. And it prevents you from knowing if the the thing relaxed somehow, as would be expected with normal gasket deformation ("cold flow"). Better to replace nut and stud.

        Double-nut might be a better way to go, with the 2nd locking nut being a crimped / locking nut.

        • (Score: 0) by Anonymous Coward on Saturday June 18 2022, @05:59PM

          by Anonymous Coward on Saturday June 18 2022, @05:59PM (#1254243)

          I'm surprised they'd have a problem like this- didn't we (tech world) learn these things long ago?

          Stuff breaks, and rocket launches involve some pretty rough handling. The critical lesson is the necessity of regular inspections and maintenance, such as what found this leak. As long as they find and fix the problems on the ground I'd say they have things well in hand.