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This answer states parameters were transmitted in real time.

Thus, why was it needed to record them onboard into (perhaps complex) data recorder that are then jettisoned (with a probability of failure for each ejection)?

I think it should have been easier to either only record onboard on data recorder that are then recovered (like in any aircraft crash, technology already widely used and tested) or either only transmit in real time to ground site (like for any telemetry widely used for orbital launch).

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Telemetry can fail, in which case you must recover the recorders:

  1. The capsule simulator was going to hit the water at high velocity, it would have been expensive and an engineering challenge to build recorders that would have survived that impact
  2. The capsule would sink to the bottom of the ocean, perhaps in pieces, requiring sea recovery, which is expensive and slow
  3. Even the most survivable recorders would be damaged by the impact, soft landing the recorders would mean they'd likely be available for future tests, saving taxpayer money
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    $\begingroup$ Could you expand the recorder soft-landing part or give links for further reading? (I didn't know they were designed to soft-land) $\endgroup$ – Manu H Jul 4 '19 at 12:57
  • $\begingroup$ If you look at CourageousPotato's answer to your linked question there's details on the recorders @ManuH $\endgroup$ – GdD Jul 4 '19 at 13:00
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They are trying to get as much test data back as possible in all cases, including (especially) if the capsule suddenly decided to turn into a fireball.

Yes they transmit as much telemetry as they can bandwidth allowing, but the internal recorders will be store a lot more data points at much higher resolution. Ejecting multiple data recorders increases there chances that at least one of them is found, and therefore their chances of getting the full high resolution data that they are unable to transmit live.

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  • $\begingroup$ I fail to how the capsule could turn into fireball. I understand it was basically an inert weight with sensors and data recorder, nothing more. Unless this is an expression to say "loss the capsule in a dramatic unforeseen event such as those the rocket science (KSP-science?) can produce". $\endgroup$ – Manu H Jul 4 '19 at 11:34
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    $\begingroup$ The capsule was inert, but it did have a large solid rocket motor bolted onto it. The point is you always want to be thinking about the worst case scenario, and planning for that. $\endgroup$ – PeteBlackerThe3rd Jul 4 '19 at 12:08
  • $\begingroup$ Even without fireball, there's still a much greater chance of recovering at least one item if they're small and spread out, rather than all slamming into the same large mass. $\endgroup$ – OrangeDog Jul 4 '19 at 17:04

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