4 ms·

Failure of the tanks would undoubtedly have been catastrophic. Partial failure of a flight control surface proved survivable.

mathsmath 2y ago
It's also worth noting part of the craft flew (intentionally) without heat tiles, and another part with thinner tiles. They're gathering a ton of data to make it robust! Many of these engineers built Falcon 9, and I have a pretty high degree of confidence they'll shake out the issues. SpaceX operates very differently from traditional aerospace, so we'll likely see many more issues come up before Starship is human rated.
- rkagerer 2y ago
  Two tiles were intentionally left out, in a non-critical area (the anticipated damage was still bad for re-usability, but tolerable for re-entry) and instrumented with sensors to collect data like just how hot it gets.
- cubefox 2y ago
  Getting it human rated is likely much harder than reusing the upper stage a couple of times. The difficulty is that Starship has 1) no launch abort system, and 2) the belly flop landing is much more dangerous than conventional and proven capsule based landing. To get the system human rated, they may have to fly tens or even hundreds of flawless cargo missions first.
  - cryptonector 2y ago
    Getting human rated for launching seems feasible. Getting it human rated for landing on Earth seems infeasible.
    - skissane 2y ago
      > Getting it human rated for landing on Earth seems infeasible. Why? For NASA, human-rating - for either Earth launch or Earth re-entry - requires a very detailed engineering analysis of probability of loss-of-crew (LOC), and then NASA has some maximum LOC probability they allow (for NASA Commercial Crew, both launch and landing it is 1-in-500, which is 0.2%-for whole of mission it is 1-in-270). That analysis is based on engineering data, which can include simulations, data collected from actual flights, and data from ground-based testing. If SpaceX can demonstrate N successful uncrewed landings (with maximum G forces within acceptable limits for crew, etc), for sufficiently high N, logically the LOC probability will fall beneath NASA’s threshold, and then NASA will human-rate it. However, they don’t actually have to land it 500 times - all they need is an engineering analysis which calculates the LOC probability as being below threshold, and then NASA’s own engineers review it, and once NASA’s engineers are confident it is correct, the human-rating will be approved
      - theptip 2y ago
        But… why go to all that effort when you can just pop the capsule and land in a thing that is not full of highly explosive fuel? Elon had that idea of using rockets for passenger transport so I’m sure it’s in the plan, but for astronauts I don’t see why you’d rush.
        skissane 2y ago
        > But… why go to all that effort when you can just pop the capsule and land in a thing that is not full of highly explosive fuel? SpaceX wants NASA to human-rate Starship because their long-term plan is to retire Falcon 9 / Dragon. How I expect it will happen: SpaceX will run their own internal analysis of loss-of-crew probability for launch and re-entry. No point going to NASA until they've convinced themselves they are going to meet the standards for human-rating. Once they believe they are, then they'll decide when is the right time to try to convince NASA of it too. Obviously they are already doing this for lunar landing/launch. Some of that is going to be transferrable to Earth landing/launch. Other parts are unique – e.g. probability of surviving re-entry – but they need to estimate that anyway for non-crewed use cases.
      - 2y ago
    - was_a_dev 2y ago
      Absolute worst case, Starship delivers a couple of Dragon capsules to LEO for crew transfer and return
      - cryptonector 2y ago
        This is my expectation.
  - rbanffy 2y ago
    > To get the system human rated, they may have to fly tens or even hundreds of flawless cargo missions first. Each lunar flight implies four launches and three landings on Earth, so the numbers should build up rather quickly.
    - cubefox 2y ago
      It's much more per lunar flight, but there are very few of those flights. About three over the next two decades.
  - philwelch 2y ago
    The Shuttle was human rated (though in retrospect, perhaps wrongly) despite having basically both of those exact same flaws.
    - cubefox 2y ago
      Not just perhaps wrongly, definitely wrongly by NASA's own late security analysis, which led to the early discontinuation of the Shuttle program. The Space Shuttle is a major reason why the security standards for human rating anything is now much higher than for initially human rating the Space Shuttle.
- dragonsky67 2y ago
  I love that they are deliberately tempting failures with the no and thin tiles. In a lot of ways they will learn far more from the heat shield burn through around the flap(s) than they would have if they had been "lucky" and it had all gone perfectly. You during testing you want things to fail, that is the point of testing. If it's all successful you only learn that under those conditions your design works, but if it fails, you learn another way to not do things.
  - GuB-42 2y ago
    That's an often underappreciated aspect of engineering. When parts last longer than expected, it is considered something that needs "fixing". It is a signal that the part can be made cheaper, lighter, etc... If SpaceX had gone with heavy, thick tiles, and they did their job because they were overspecced, it is that much less payload capacity. Even value engineering, which is often criticized when it comes to consumer products is a good thing. Yes, your new dishwasher is not as robust as the one made in the 50s, but it is also 10x cheaper (inflation-adjusted), and it can still wash dishes for maybe 10-15 years without repairs, at which point you may want a new one as technology has improved. Note that I am talking proper engineering, having a single point of failure that prompts a replacement is planned obsolescence and terrible engineering, there should be no single point of failure with good engineering.
    - rbanffy 2y ago
      It'll still be orders of magnitude cheaper than the nearest competitor for many years. They don't need to fix it before gaining very extensive experience flying it.
    - jjk166 2y ago
      As they say, any idiot can make a bridge stand, it takes an engineer to make a bridge barely stand.
rbanffy 2y ago
It's not unheard of planes landing after losing a full wing. You need a lucky and competent pilot to do that.

mathsmath 2y ago

It's also worth noting part of the craft flew (intentionally) without heat tiles, and another part with thinner tiles. They're gathering a ton of data to make it robust! Many of these engineers built Falcon 9, and I have a pretty high degree of confidence they'll shake out the issues. SpaceX operates very differently from traditional aerospace, so we'll likely see many more issues come up before Starship is human rated.

rkagerer 2y ago
Two tiles were intentionally left out, in a non-critical area (the anticipated damage was still bad for re-usability, but tolerable for re-entry) and instrumented with sensors to collect data like just how hot it gets.
cubefox 2y ago
Getting it human rated is likely much harder than reusing the upper stage a couple of times. The difficulty is that Starship has 1) no launch abort system, and 2) the belly flop landing is much more dangerous than conventional and proven capsule based landing. To get the system human rated, they may have to fly tens or even hundreds of flawless cargo missions first.
- cryptonector 2y ago
  Getting human rated for launching seems feasible. Getting it human rated for landing on Earth seems infeasible.
  - skissane 2y ago
    > Getting it human rated for landing on Earth seems infeasible. Why? For NASA, human-rating - for either Earth launch or Earth re-entry - requires a very detailed engineering analysis of probability of loss-of-crew (LOC), and then NASA has some maximum LOC probability they allow (for NASA Commercial Crew, both launch and landing it is 1-in-500, which is 0.2%-for whole of mission it is 1-in-270). That analysis is based on engineering data, which can include simulations, data collected from actual flights, and data from ground-based testing. If SpaceX can demonstrate N successful uncrewed landings (with maximum G forces within acceptable limits for crew, etc), for sufficiently high N, logically the LOC probability will fall beneath NASA’s threshold, and then NASA will human-rate it. However, they don’t actually have to land it 500 times - all they need is an engineering analysis which calculates the LOC probability as being below threshold, and then NASA’s own engineers review it, and once NASA’s engineers are confident it is correct, the human-rating will be approved
    - theptip 2y ago
      But… why go to all that effort when you can just pop the capsule and land in a thing that is not full of highly explosive fuel? Elon had that idea of using rockets for passenger transport so I’m sure it’s in the plan, but for astronauts I don’t see why you’d rush.
      - skissane 2y ago
        > But… why go to all that effort when you can just pop the capsule and land in a thing that is not full of highly explosive fuel? SpaceX wants NASA to human-rate Starship because their long-term plan is to retire Falcon 9 / Dragon. How I expect it will happen: SpaceX will run their own internal analysis of loss-of-crew probability for launch and re-entry. No point going to NASA until they've convinced themselves they are going to meet the standards for human-rating. Once they believe they are, then they'll decide when is the right time to try to convince NASA of it too. Obviously they are already doing this for lunar landing/launch. Some of that is going to be transferrable to Earth landing/launch. Other parts are unique – e.g. probability of surviving re-entry – but they need to estimate that anyway for non-crewed use cases.
    - 2y ago
  - was_a_dev 2y ago
    Absolute worst case, Starship delivers a couple of Dragon capsules to LEO for crew transfer and return
    - cryptonector 2y ago
      This is my expectation.
- rbanffy 2y ago
  > To get the system human rated, they may have to fly tens or even hundreds of flawless cargo missions first. Each lunar flight implies four launches and three landings on Earth, so the numbers should build up rather quickly.
  - cubefox 2y ago
    It's much more per lunar flight, but there are very few of those flights. About three over the next two decades.
- philwelch 2y ago
  The Shuttle was human rated (though in retrospect, perhaps wrongly) despite having basically both of those exact same flaws.
  - cubefox 2y ago
    Not just perhaps wrongly, definitely wrongly by NASA's own late security analysis, which led to the early discontinuation of the Shuttle program. The Space Shuttle is a major reason why the security standards for human rating anything is now much higher than for initially human rating the Space Shuttle.
dragonsky67 2y ago
I love that they are deliberately tempting failures with the no and thin tiles. In a lot of ways they will learn far more from the heat shield burn through around the flap(s) than they would have if they had been "lucky" and it had all gone perfectly. You during testing you want things to fail, that is the point of testing. If it's all successful you only learn that under those conditions your design works, but if it fails, you learn another way to not do things.
- GuB-42 2y ago
  That's an often underappreciated aspect of engineering. When parts last longer than expected, it is considered something that needs "fixing". It is a signal that the part can be made cheaper, lighter, etc... If SpaceX had gone with heavy, thick tiles, and they did their job because they were overspecced, it is that much less payload capacity. Even value engineering, which is often criticized when it comes to consumer products is a good thing. Yes, your new dishwasher is not as robust as the one made in the 50s, but it is also 10x cheaper (inflation-adjusted), and it can still wash dishes for maybe 10-15 years without repairs, at which point you may want a new one as technology has improved. Note that I am talking proper engineering, having a single point of failure that prompts a replacement is planned obsolescence and terrible engineering, there should be no single point of failure with good engineering.
  - rbanffy 2y ago
    It'll still be orders of magnitude cheaper than the nearest competitor for many years. They don't need to fix it before gaining very extensive experience flying it.
  - jjk166 2y ago
    As they say, any idiot can make a bridge stand, it takes an engineer to make a bridge barely stand.

rbanffy 2y ago

It's not unheard of planes landing after losing a full wing. You need a lucky and competent pilot to do that.