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Comment by gwbas1c | Hacker News Reader

Maybe someone who knows more about the ISS than I do can answer this:

Naively, I would assume that there are airlocks between the different sections of the ISS. I would also assume that they would close these airlocks while doing the kind of work they are doing to repair the leaks.

So, assuming I'm right (and my assumptions might be wrong,) why do the astronauts need to shelter?

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There aren’t even doors between sections. Airlocks are serious things, there is one or two for station for EVA. There are multiple hatches for docking spacecraft.

One of the innovations of ISS is larger docking adapter with bulkhead that is removed after docking. Russian section still uses hatches. All of the cables go through the docking adapter or hatch which makes impossible to close door or quickly disconnect.

There are doors (called hatches) between the segments. Each segment flew up separately and pressurized. So there are actually two hatches between each segment, since there’s one on each.

If things go wrong, they're already in the vehicle supposed to bring them back. It might be upsetting to be 3 locked doors away from your best way to come back home

This is the right answer - if it goes wrong they are already placed in the escape vehicle, sitting in their space suits.

Well, I won't claim to know the answer, but "please do not move between different airlocked sections while this work is underway" sounds a lot like the definition of "shelter" to me

In this case, per the article, "shelter" meant "shelter in a capsule capable of returning to earth and put on the spacesuits that you wear during return to earth".

I.e. leaving the actual ISS structure entirely.

I would guess they're worried about breaking something, but thanks for the clarification (and apologies for not having RTFA)

Repairing a leak with an uncertain cause could be at high risk of catastrophic decompression if it was caused by certain types of corrosion or stress.

There are normally-open air-tight hatches between modules. Various utility connections and air ducts are normally run through the open hatches so it would take a bit of work to disconnect these connections before they could be closed.

Not exactly something you want to be doing under time pressure.

What’s the reason against separate conduit for utilities?

Just a guess: Harder to build and operate with more failure modes and less opportunity for intervention.

Those would need to be connected during docking and sealed separately anyway if you wanted to seal the hatch. More failure points.

You'd still need to pull out the utilities and close a now second hatch in the conduit to seal the thing. What would be the point?

If such a conduit would connect two sections that the hatch is meant to isolate, you would have to make the conduit and everything running through it airtight, even under a catastrophic loss of air. If the conduit didn't seal as well as the hatch, which is meant to withstand hard vacuum on the other side of it, it would defeat the purpose of the hatch.

Most stuff runs outside of the capsule including power and dangerous ammonia. They use connectors that fit to the hull and have plugs on each side. Gases/liquids can be controlled with valves. And parts can fit tightly together to make a seal. The stuff running through the hatches is designed to be quickly disconnected in an emergency.

I guess the main question about this kind of routing is if things are safer kept on the unpressurized side or not. And that the risk of a small hole on the hull is offset by reducing the risk of leaks in the pressurised area.

They just didn't have enough of reserved general purpose connections for future use. I guess this woild be especially the case with the Russian modules, which were literally surplus Soviet manned space army outposts(such a thing do not make a lot of sense, they did it anyway).

This one

https://en.wikipedia.org/wiki/Salyut_3

had a machine gun!

What was the gun for?

Shooting American spacecraft. What else would it be for?

If it made pew-pew sounds (inside the station, obv), mission accomplished regardless of it actually being able to shoot anything down, up or everywhere.

The story that I read somewhere was that it was tested once but the recoil either damaged the station or it would have affected its orbit so they never tried it again.

There was also Polyus which was going to be an entire battle station designed to counter Reagan's SDI satellites[0], but it never made it into orbit. It had lasers, though.

[0]https://nationalinterest.org/feature/the-rise-fall-the-sovie...

If that test round of bullets came out at 1000m/s, I wonder where are they now?

They'd cover around 1.5 billion km (<1 billion miles), and be past Saturn's orbit if fired away from the Sun. But it would not achieve escape velocity on its own, and the station was obviously moving relative to Sun and Earth, so we'd have to account for it too.

I think the service module is both structurally and functionally critical. If it is failing and you do not know why, catastrophic failure is presumably possible, not just some air loss. A hole or crack in the module is now apparently double the size it was until recently, that is a trend that presumably could continue to rapid unscheduled disassembly.

> Naively, I would assume that there are airlocks between the different sections of the ISS.

There are not. The airlocks on the ISS are either docking modules for spacecraft, for spacewalks, or for deploying satellites.

The crew shelters in the vehicles so that in case of an emergency they can evacuate immediately.

Compression loss can lead to a decompression of sorts if I had to guess... it is a vaccum out there. The force from a decompression can yield a chain reaction or strongly disrupt the entire station.

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