lb3 said:
DCS is a different kind of risk altogether and is not as uncommon as you might think. The atmospheres and suit pressures planned for Artemis are very challenging from a DCS perspective and there is a strong push to reduce prebreathe times so the crew can spend more time outside. The docs you think would go ballistic have accepted that DCS is inevitable during the Artemis campaign.
Life would be much simpler if they would use a 70% O2 atmosphere like on Skylab.
I was thinking of ISS EVAs, not Artemis EVAs. What I should have said was that if the crew was regularly experiencing DCS symptoms during ISS EVAs in the EMU, the docs and Safety would have a problem.
I'm aware of the Exploration Atmosphere Prebreathe Protocol test campaign for Artemis, where the objective of the testing is to determine a vehicle cabin (or in this case, a test chamber) gas mix and suit prebreathe duration that will result in a statistically acceptable number of DCS events, such that the likelihood of any single EVA has a low risk of DCS. The goal is not to get zero events. If a test series completes its simulated EVAs and none of the subjects experiences DCS symptoms, then the question has to be asked, "Was that particular protocol too conservative? Can the prebreathe duration be shortened? If so, by how much? Should the cabin's gas mix/pressure be changed, and if so, to what?"
I'm also aware of the concept of a walking prebreathe, where the crew begins the EVA at a higher suit pressure and the suit pressure slowly decreases to the operational pressure, which is a good idea from an ops standpoint, but it is challenging from a suit design/mobility perspective.
(Based on your history on this thread, it's evident you know all that. I guess I was typing all that out for the benefit(?) of everyone else.)
I agree with you about the 70% O2 cabin atmosphere. A zero-prebreathe suit would be optimal from an EVA timeline perspective.
