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There is a big difference in the consequences, but the fact that it was a test does not, of course, mean one can dismiss the question of whether, and how, a sig

There is a big difference in the consequences, but the fact that it was a test does not, of course, mean one can dismiss the question of whether, and how, a significant problem had escaped all efforts to eliminate unnecessary risks up to that point. Once something has reached the point where it is considered nominally ready for use (or has actually been put in service), the failure of a test conducted within operational parameters should be treated as seriously as a failure in actual use.

gpm 7y ago
Not that it shouldn't be, or wasn't, treated seriously. But it was very far from operational parameters. It was a previously flown capsule that had been dunked in sea water. Crew capsules are not re-used.
- ceejayoz 7y ago
  There's no indication in the post-mortem that the issue had anything to do with reuse or immersion. > "We believe that we had a liquid slug of the (NTO) in the pressurization system," Koenigsmann said. "When we opened the valves and pressurized the propellant system, we think that this slug was driven back into the check valve. ... That basically destroyed the check valve and caused an explosion." Hence the redesign. There's also been discussion of reusing Crew Dragon on unmanned CRS missions. https://www.teslarati.com/spacex-no-crew-dragon-spaceship-reuse-nasa-astronaut-launches/ https://www.teslarati.com/spacex-no-crew-dragon-spaceship-re... > Although the OIG report in question never specifically states it, some of the language used to describe Dragon 2’s cargo configuration does seem to imply that Cargo Dragon 2s will predominately (if not exclusively) be derived as slightly-modified Crew Dragon capsules, seemingly indicating that SpaceX’s CRS-2 missions may only ever launch flight-proven Crew Dragon capsules.
- mannykannot 7y ago
  That might or might not have been relevant, and the fact that something was changed as a consquence of the investigation argues strongly for the latter. I do not understand the effort being put into arguing that this failure was largely inconsequential because it was a test. Clearly - and rightly - neither SpaceX nor NASA took it that way.
  - gpm 7y ago
    > I do not understand the effort being put into arguing that this failure was largely inconsequential because it was a test. That's not what I'm attempting to argue... and why my post starts with a disclaimer that I'm not trying to argue that. I just think it's important to keep the facts straight.
    - mannykannot 7y ago
      It is also important to identify which facts are relevant.
      - gpm 7y ago
        And yet it's still important to not misstate facts regardless of whether or not they are relevant, because other people will take those supposed facts and apply them in other ways then you did.
        mannykannot 7y ago
        And yet it's still important to not merely present facts regardless of whether or not they are relevant, because other people will take those facts and suppose they are relevant. Note the issue that unites these two statements - it is relevance. A test does not have to be a simulation of actual use to be relevant.
        deleted 7y ago
        [deleted]
        gpm 7y ago
        Let me say this in a different way. As soon as you misstate a fact in a public forum where people might not know the truth of the matter, that misstatement becomes relevant to many readers. Because otherwise people will read your supposed fact, assume it is true, and apply it elsewhere. That doesn't make it necessarily relevant to the original point of whether or not it was an issue that needed to be taken seriously, but that's why I explicitly started my post by stating so. I honestly can't believe that you're defending a serious misstatement of the conditions of the test on the internet by saying "well it doesn't matter that the premise of my post was wrong". Of course it matters, even if I agree with your conclusion anyways.
shkkmo 7y ago
> significant problem had escaped all efforts to eliminate unnecessary risks up to that point. This test was part of the process of identifying and eliminating those risks. There is no difference between a failure during a test and a failure during operation, in terms of identifying needed changes in space craft design. There is a difference when it comes to evaluating the design and testing process of the company. SpaceX seems to be very good at balancing moving quickly with design, then testing safely, using those test to find weaknesses and learning from their failures to iterate rapidly. Despite some early failures, it seems SpaceX is rapidly on its way to having the best launch safety record in the industry.
- mannykannot 7y ago
  All I am saying is that by the time you are flying the thing, you should have high confidence in it. A failure at that point should lead to a serious reevaluation of that confidence, regardless of whether the failure occurs on a test or an operation (the exception being those tests that are to destruction, or at least well outside the operational envelope, and only then if the failure occurs at about the point you expect, or beyond it.) I agree that SpaceX is looking very competent.
  - shkkmo 7y ago
    > All I am saying is that by the time you are flying the thing, you should have high confidence in it. It seems like there is a balance between the level of confidence you achieve prior to a flight test, the costs of a failed test, and the speed at which you can implement and iterate designs. > A failure at that point should lead to a serious reevaluation of that confidence, If, as in this case, the failure is due to non-considered risk, you certainly want to make changes to the assumptions you make during the design process in the future (in additional to the changes you make in your current design.) I don't think you need to generally question your confidence in your components that have not only passed all their operational tests, but have been used successfully to complete operational missions.

gpm 7y ago

Not that it shouldn't be, or wasn't, treated seriously. But it was very far from operational parameters. It was a previously flown capsule that had been dunked in sea water. Crew capsules are not re-used.

ceejayoz 7y ago
There's no indication in the post-mortem that the issue had anything to do with reuse or immersion. > "We believe that we had a liquid slug of the (NTO) in the pressurization system," Koenigsmann said. "When we opened the valves and pressurized the propellant system, we think that this slug was driven back into the check valve. ... That basically destroyed the check valve and caused an explosion." Hence the redesign. There's also been discussion of reusing Crew Dragon on unmanned CRS missions. https://www.teslarati.com/spacex-no-crew-dragon-spaceship-reuse-nasa-astronaut-launches/ https://www.teslarati.com/spacex-no-crew-dragon-spaceship-re... > Although the OIG report in question never specifically states it, some of the language used to describe Dragon 2’s cargo configuration does seem to imply that Cargo Dragon 2s will predominately (if not exclusively) be derived as slightly-modified Crew Dragon capsules, seemingly indicating that SpaceX’s CRS-2 missions may only ever launch flight-proven Crew Dragon capsules.
mannykannot 7y ago
That might or might not have been relevant, and the fact that something was changed as a consquence of the investigation argues strongly for the latter. I do not understand the effort being put into arguing that this failure was largely inconsequential because it was a test. Clearly - and rightly - neither SpaceX nor NASA took it that way.
- gpm 7y ago
  > I do not understand the effort being put into arguing that this failure was largely inconsequential because it was a test. That's not what I'm attempting to argue... and why my post starts with a disclaimer that I'm not trying to argue that. I just think it's important to keep the facts straight.
  - mannykannot 7y ago
    It is also important to identify which facts are relevant.
    - gpm 7y ago
      And yet it's still important to not misstate facts regardless of whether or not they are relevant, because other people will take those supposed facts and apply them in other ways then you did.
      - mannykannot 7y ago
        And yet it's still important to not merely present facts regardless of whether or not they are relevant, because other people will take those facts and suppose they are relevant. Note the issue that unites these two statements - it is relevance. A test does not have to be a simulation of actual use to be relevant.
        deleted 7y ago
        [deleted]
        gpm 7y ago
        Let me say this in a different way. As soon as you misstate a fact in a public forum where people might not know the truth of the matter, that misstatement becomes relevant to many readers. Because otherwise people will read your supposed fact, assume it is true, and apply it elsewhere. That doesn't make it necessarily relevant to the original point of whether or not it was an issue that needed to be taken seriously, but that's why I explicitly started my post by stating so. I honestly can't believe that you're defending a serious misstatement of the conditions of the test on the internet by saying "well it doesn't matter that the premise of my post was wrong". Of course it matters, even if I agree with your conclusion anyways.

shkkmo 7y ago

> significant problem had escaped all efforts to eliminate unnecessary risks up to that point. This test was part of the process of identifying and eliminating those risks. There is no difference between a failure during a test and a failure during operation, in terms of identifying needed changes in space craft design. There is a difference when it comes to evaluating the design and testing process of the company. SpaceX seems to be very good at balancing moving quickly with design, then testing safely, using those test to find weaknesses and learning from their failures to iterate rapidly. Despite some early failures, it seems SpaceX is rapidly on its way to having the best launch safety record in the industry.

mannykannot 7y ago
All I am saying is that by the time you are flying the thing, you should have high confidence in it. A failure at that point should lead to a serious reevaluation of that confidence, regardless of whether the failure occurs on a test or an operation (the exception being those tests that are to destruction, or at least well outside the operational envelope, and only then if the failure occurs at about the point you expect, or beyond it.) I agree that SpaceX is looking very competent.
- shkkmo 7y ago
  > All I am saying is that by the time you are flying the thing, you should have high confidence in it. It seems like there is a balance between the level of confidence you achieve prior to a flight test, the costs of a failed test, and the speed at which you can implement and iterate designs. > A failure at that point should lead to a serious reevaluation of that confidence, If, as in this case, the failure is due to non-considered risk, you certainly want to make changes to the assumptions you make during the design process in the future (in additional to the changes you make in your current design.) I don't think you need to generally question your confidence in your components that have not only passed all their operational tests, but have been used successfully to complete operational missions.