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If a rocket fails whether on the launch pad or after the lift-off, how is it determined what component failed?

What are the different methods by which failure is determined?

Amar
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2 Answers2

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This is pretty standard post incident analysis, with extensive data:

  • All live radio telemetry from the rocket is studied.

The telemetry stream is incredible. Data from almost every flow, temperature, speed, angle, pressure sensor etc., is fed live to control.

  • Every component that can be retrieved after an explosion or crash is analysed.

Depending on the type on failure, there may be very little left, or if an explosion happens in space there may be nothing recoverable, however generally there are components and even entire modules that survive in one form or other.

  • All video feeds are analysed frame by frame.

Video is shot from on board, and from hundreds of cameras on and near the launch site, as well as down range. Combined with thousands of public videos from mobile phones etc., there is usually fotage from every angle imaginable.

  • Simulation is carried out using data.

Once information is gathered, simulations provide an insight into triggers for particular behaviour. For example, correct telemetry up until a particular sensor failing, followed closely by ctastrophic failure gives a good indication that something near that sensor may have been to blame, so simulations that can model failure near the sensor are considered.

It's worth looking at the documentaries on the two Shuttle disasters. They go into great detail on all the possible failure modes that match the data they had, used existing samples, ran stress tests and simulations.

Rory Alsop
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  • The telemetry data is an important part that could need more explanation, I think: is data streamed by radio during the whole ascent or is there some kind of black-box? Are there usually sensors that serve no other purpose than to provide additional data in a post-mortem analysis and are not necessary for the normal operation? – DarkDust Sep 14 '18 at 11:50
  • Fault tree analysis is important. – Organic Marble Sep 14 '18 at 12:39
  • @DarkDust Rockets generally don't have black boxes, as it is generally assumed a catastrophic failure will leave them unrecoverable. – Tristan Sep 14 '18 at 15:41
  • NASA still uses film cameras, see this question. But video is used too for TV news feed. Therefore film and video may be used for analysis. – Uwe Sep 16 '18 at 21:54
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See this question and answers there for a bit of information on radio tracking.

There's an excellent video by Paul Shillito (Curious Droid) How did NASA get those great film shots of Apollo and the Shuttle? that describes the evolution of camera systems used to monitor spacecraft on their way up and down. It states that the launch of STS-114 had over 400 cameras for example.

Recording of imagery of launches with catastrophic and near-catastrophic events has been a critical step in the analysis of both actual failures and close calls. Without this, telemetry data alone would be insufficient. It is only one step in the process, but without data, there is no further analysis.

An example of some of the largest ones is shown in the image below, and is discussed further in this question as well as the answers there.

below: Contraves-Goerz Kineto Tracking Mount (KTM), from here.

enter image description here

uhoh
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    This doesn't appear to answer the question, which is not about camera tracking, but about failure mode analysis – Rory Alsop Sep 14 '18 at 12:41
  • @RoryAlsop you can not analyze the images of the failure mode without first capturing the failure mode images. It is an essential step. You can not analyze the telemetry data without receiving the telemetry data. This is also an essential step. You may not think it is the most interesting step, but I do. I'll add a bit more from the video to make this clearer. – uhoh Sep 14 '18 at 12:44
  • Actually I'm not going transcribe the details of the disasters discussed in the video after about 13:15, these are already well documented and covered thoroughly in Wikipedia and elsewhere. – uhoh Sep 14 '18 at 12:56