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Omegafanman
·So then that would support the idea of non-sapphire specifications (I suppose?)
It depends what the test criteria are (impact and debris size) as clearly Sapphire has become the watch crystal of choice which does bring some benefits. You also have other objects on the ISS now (cameras, laptops, iPads etc). It would be interesting to know what the test criteria was for the X-33 sapphire watch. It does look like there is no embargo on Sapphire for IVA these days (if there was there are also a lot more screen protector technologies now / again it depends on the failure mode test requirements). @cvalue13 has also noted on another thread the greater risk of damage during EVA and also that when returning and entering a pressurised atmosphere / removing the suit there is more risk to disturb any damaged equipment and release particles. This is covered in a NASA document. That would be a strong reason to only have a plastic crystal watch approved for EVA. Likewise these is I assume more risk (vibration/movement) during launch and landing so again a plastic crystal might make more sense. Of course plastic may have more fire risk potential but materials have moved on a lot I imagine these days (Sapphire and plastic)
