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posted by hubie on Friday June 17, @01:14AM   Printer-friendly [Skip to comment(s)]
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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NASA and SpaceX Stand Down on Dragon Launch to Study Hydrazine Issue 13 comments

NASA and SpaceX stand down on Dragon launch to study hydrazine issue:

NASA and SpaceX have delayed the launch of a Cargo Dragon spacecraft for at least a couple of weeks due to an issue during the prelaunch loading of hypergolic propellants.

The space agency had been planning to launch the spacecraft on June 12 but announced the delay in an email on Monday evening to reporters.

"During propellant loading of the Cargo Dragon spacecraft, elevated vapor readings of mono-methyl hydrazine were measured in an isolated region of the Draco thruster propulsion system," the space agency's statement said. "The propellant and oxidizer have been offloaded from that region to support further inspections and testing."

Draco thrusters provide on-orbit maneuvering propulsion for the Dragon spacecraft. NASA said that it is working with SpaceX to identify the source of the elevated readings and take any corrective actions. On Tuesday morning, astronauts on board the International Space Station were told by Mission Control in Houston that the launch date would slip until at least June 28.

This is not a new Dragon vehicle. Designated Dragon "C208," this vehicle has previously flown two supply missions, both in 2021. It is an upgraded version of the original Cargo Dragon spacecraft, known as "Cargo Dragon 2."

See also: Dragon Mission on Hold as Astronauts Conduct Eye Exams, Spacesuit Work


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  • (Score: 2, Informative) by Anonymous Coward on Friday June 17, @02:08AM (13 children)

    by Anonymous Coward on Friday June 17, @02:08AM (#1253874)

    Replace the seals and re-torque the fittings involved. I have an amazing ability to detect Hydrazine and N204 leaks down to 2ppm with my nose. I worked on Delta II and IV and the safety people were always amazed when I discovered a leak no one else had detected. N2O4 smells like bleach and A50 (Aerozine 50) smells like old fish. Have you ever smelled a bleach like odor when a vehicle passes on the street? That is Oxides of nitrogen (NOX) and that is exactly what N2O4 smells like. Dammit, can't find my login at the moment so Anonymous Coward it is. Have a good day Soylentills, you never know when it might be your last.

    • (Score: 4, Interesting) by RS3 on Friday June 17, @04:16AM (5 children)

      by RS3 (6367) on Friday June 17, @04:16AM (#1253899)

      Pic of thruster and possible problem location:

      https://www.teslarati.com/wp-content/uploads/2022/06/flight-proven-Cargo-Dragon-Dracos-Pauline-Acalin-4-crop-1536x699.jpg [teslarati.com]

      Question: what made the problem in the first place? Incorrect torque? Seal / metal "cold flow"? Maybe go back and re-torque them a few times after some thermal cycling?

      Natural gas and propane vehicles and stationary engines (generators) often smell somewhat like chlorine to me. Maybe a hotter, more pungent version. I thought methane and propane burned cooler and you'd have less NOx?

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

        by Anonymous Coward on Friday June 17, @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.

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

          by RS3 (6367) on Friday June 17, @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, @12:41PM (2 children)

            by Anonymous Coward on Friday June 17, @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, @06:00PM (1 child)

              by RS3 (6367) on Friday June 17, @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, @05:59PM

                by Anonymous Coward on Saturday June 18, @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.

    • (Score: 0) by Anonymous Coward on Friday June 17, @05:25AM (5 children)

      by Anonymous Coward on Friday June 17, @05:25AM (#1253911)

      Oh wow, that's fascinating. What does it mean when a car has a sweet smell when you first start it? Mine does that.

      • (Score: 0) by Anonymous Coward on Friday June 17, @06:02AM (3 children)

        by Anonymous Coward on Friday June 17, @06:02AM (#1253919)

        Coolant leak. (not OP)

        • (Score: 2) by RS3 on Friday June 17, @06:23AM (2 children)

          by RS3 (6367) on Friday June 17, @06:23AM (#1253925)

          I think parent refers to the exhaust smell, especially in cold weather, when first starting an engine.

          • (Score: 2) by Runaway1956 on Friday June 17, @09:44AM (1 child)

            by Runaway1956 (2926) Subscriber Badge on Friday June 17, @09:44AM (#1253952) Homepage Journal

            If the exhaust smells sweet, I'd question whether the head gasket was blown. Coolant being pumped through a cylinder and out the exhaust is going to produce that odor. Time for a compression test, I think.

            --
            Our first six presidents were educated men. Then, along came a Democrat.
            • (Score: 2) by RS3 on Friday June 17, @06:09PM

              by RS3 (6367) on Friday June 17, @06:09PM (#1254042)

              All good points, but I'm talking about a smell I notice when a brand new car is first started. Cold weather being the operative.

              To me, antifreeze has a very distinct odor, and the smell I'm referring to is not that at all. It's not all that sweet, but that's a good approximation.

              It just dawned on me: different USA states have different fuel additives, including ethanol content. They even reformulate it based on the season and temperatures. So it may be more of a thing depending on where you live, time of year, etc.

              I buy gasoline in various places, not caring about the brand, and mostly from independent places that buy gasoline from several different source refineries. So that might also be a factor. I notice the smell of the gasoline varies depending on the brand, and again, can vary even when I go to the same independent retailer. Sometimes it's almost sweet smelling. Some brands flat out stink bad.

      • (Score: 2) by ElizabethGreene on Friday June 17, @04:24PM

        by ElizabethGreene (6748) on Friday June 17, @04:24PM (#1254025)

        The only fluid that smells kool-aid sweet in a car is the engine coolant. If you smell it in the exhaust, that could be a head gasket or other coolant leak. If you smell it under the hood, it could be a leak or a hose going soft. If you smell it inside your car it could be your heater core has a small leak. Usually in the latter case you'll also notice a light film on the inside of your windshield.

    • (Score: 2) by DeathMonkey on Friday June 17, @03:17PM

      by DeathMonkey (1380) on Friday June 17, @03:17PM (#1254010) Journal

      Replace the seals and re-torque the fittings involved.

      The people responsible for that have been sacked.
      Mynd you, møøse bites Kan be pretti nasti... We apologise again for the fault in the subtitles.
      Those responsible for sacking the people who have just been sacked have been sacked.

      The directors of the firm hired to continue the credits after the other people had been sacked, wish it to be known that they have just been sacked. The credits have been completed in an entirely different style at great expense and at the last minute. Executive Producer ELON MUSK

  • (Score: 0) by Anonymous Coward on Friday June 17, @12:14PM (1 child)

    by Anonymous Coward on Friday June 17, @12:14PM (#1253977)

    "The NASA and SpaceX partnership continues to be a strong one"

    Holy fucking captain obvious.
    Gee I thought after this the realationship would be down hill from here.
    Thank you for the retard clarification.

    • (Score: 3, Insightful) by ElizabethGreene on Friday June 17, @04:21PM

      by ElizabethGreene (6748) on Friday June 17, @04:21PM (#1254023)

      I don't think it's unreasonable to offer this assurance. SpaceX upset the "big aerospace" apple cart, flipped it over, and lit it on fire. Those companies are now spending piles of money lobbying for their survival. I'd be shocked if they weren't trying to leverage this problem as a wedge issue.

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