Safely exiting zero-tau capsule

Question

Setting is 20 minutes into future - everything is as we know it, or as we can reasonably predict, except the zero-tau capsules.

Capsule is a thin mesh of Unobtanium connected to a portable Handwavium reactor. When turned on, time inside does not flow. Details "by the numbers":

1. It is unclear if time inside actually stopped or is just extremely slowed down. A [insert reasonable time here]-long experiment did not show any measurable time inside (in other words, you may adjust this).
2. Starting field up and shutting it down can be instantaneous, or take as long as 10 seconds during which time inside slows down or speeds up.
3. Field border is sharp, around 1ℓ_P. We put it in the middle of metal plates that are casing for capsule, to prevent anything from interacting directly with such border (or in near-vacuum between plates, if interactions with metal would be a problem - again this is adjustable).
4. Unobtanium mesh is supposed to be something that creates the field, but has no other uses or effects - it does not shield anything from anything, does not get old, nothing. Thus, it shouldn't matter if it's in or out. Probably out, because getting it destroyed would be a good story element, but that's something for another question. Similarly with Handwavium reactor. Please ignore them where possible, their only meaningful effect should be existence of the zero-tau field.

That way, trip to Mars can be as short as 30 seconds, from the passenger point of view.

The problem is: How to safely exit?

Metal walls of the capsule can stop anything bigger than hydrogen atoms, and slow down other things. But that is still around seven months of cosmic radiation, atoms leaking in thorough the seal etc, released in a very, very short time. Sudden gravity change would not help, and probably there are things that I haven't thought of, too.

So, how would we make it safe for our travelers? I want them to survive and I do not want any neural or perception damages. Other than that I can live with, as long as it heals, at least in early stages when we are only setting up Mars operations. We need to get passengers healthy when we go to commercial flights, but if it is too difficult, it can wait.

Answer 1

Your zero-tau capsules are the ideal solution for their own problem:

You state that all radiation and particles that hit an active capsule are slowed down and released in a burst when the capsule is shut off. That means not only is the inside shielded while the capsule is active, but anything behind the capsule as well. These capsules are now a perfect shield that can stop even neutrinos or gamma radiation.

So, surround each passenger-capsule on all sides with other capsules, that are empty or contain cargo; then no radiation can hit the capsules in the middle. Just make sure to take the outer capsules far away before switching them of.

Or better yet: surround your whole spaceship with shield capsules. Perhaps multiple layers, in case anything goes wrong.

Answer 2

Who says you have to have the field in unbroken operation for the whole trip?

Sensors near the "event horizon" monitor the exposure of the capsule to external radiation. When a pre-set safety threshold is approached, the capsule switches off for a small amount of time (whatever the minimum cycle time for the field - power off and back on - is, plus a small delay to allow the passenger to properly absorb/emit/adjust to the radiation), allowing the particles to strike the occupant while they are still at a safe level, and allowing gravity (and other fields) to adjust in smaller increments.

This might increase the length of the trip from the occupant's perspective, but as the shielding gets better, these interruptions can be reduced, perhaps to the point that you only need five or ten per trip, each lasting 20 seconds or so (10 second spin-down and 10 second spin-up in your extreme case). Even with modern day shielding the number of cycles would probably only be on the order of 5 or so a day, making a 300 day trip take 100 minutes from the passenger's point of view. Rounding, we can call it two hours, and the best thing to do would be to render the passenger unconscious for the journey anyway, so that two hours would be a pleasant nap.

If the cycle time was near instant (the lower bound of your power on/off range), then a conscious passenger simply gets a time lapse view of the trip lasting a few dozen seconds, which could be seen as a feature.

In either case, some form of anti-radiation treatment and a shielded suit would be recommended to shorten the duration needed in real-time to adjust to the radiation dump.

Answer 3

I'd go with "time slows down" interpretation. If radiation particle hits the capsule, it is slowed down at its boundary, and will be released once the field is turned off.

This obviously creates a problem as passenger will be bombarded by all the particles accumulated during their voyage.

I would recommend shielding the capsule from radiation and light during the voyage. Space stations are shielded anyway, and while capsule will require more shielding, there is also smaller area to shield. Or you can keep large number of capsules in a vault (less surface area than individual capsules).

Gravity change is inevitable, but effect is just a (near-)fall from standing position. Can't be that bad.

I hope you realize passenger cannot "exit" the capsule on their own accord. Somebody (or something) would have to shut down the field generator.