Astronauts told to return to ISS after sheltering over air leak repairs

“You crawl around outside and smell for astronaut wizz.”

Thanks

A few years ago a Soyuz was improperly drilled during manufacture. This was patched with a super epoxy... and then began leaking air on orbit. Paint won't seal what a super aerospace epoxy failed to seal.

So, the sealant has to be either a 2-part epoxy (harder to mix and apply), or a UV-cured epoxy. It has to adhere to a vast array of surfaces, since we cannot predict if the next leak will be in aluminum, cracked ceramic, silicone gasket, rubber gasket, plastic.... Anything it outgasses must be extremely inert, so that it doesn't cause a new problem when it reacts with a different surface (the gas on the ISS is never diluted by a giant planetwide reservoir).

Paint is obviously not a two-part epoxy nor a UV-curing epoxy; nor is it guaranteed to have fully inert outgases; finally it is not likely to be adherent to all the possible surfaces.

It's as if the situation requires a robotic diamond drill, and you propose we hit it with a big rock. The big rock won't do.

In college, we'd use toothpaste for the holes left from nails in the walls we hung up our posters with.

Quoting an ISS astronaut: Today's coffee is tomorrow's coffee.

Paint that would fall to the ground if it didn't stick to anything on Earth, would just be floating around in microgravity. Any dissolved gasses or moisture can usually passively sort themselves out due to their differing masses, but again, not in microgravity.

wait, do they have to have matched CTE and k to the existing material... hmm

It works out to be more efficient, at least in terms of mass, to send up large tanks of compressed gas instead.

Why the difference? It's a question of what risks you were most afraid of. Even today, every single spacewalk is done at 0.4atm pure O2- trying to do a spacewalk at 100kPa even the strongest man in the world would have trouble bending his arms- so before a spacewalk the astronauts need to spend several hours pre-breathing pure O2 to get all the nitrogen out of their bloodstream before they can do a spacewalk. The Apollo program thought it was safer if the astronauts could do a spacewalk at literally any point in the mission, so that's what the spacecraft was designed around.

On the other hand, for long duration spaceflight, introducing a different pressure and atmosphere is just another potential source of health problems. Even today, the largest source of information on how human bodies last under 0.4atm pure O2 is the three Skylab missions from 1973-1974. And so the Soviets- who were always more interested in space stations than the moon- and NASA during the Shuttle era went with the atmosphere that seemed like it offered less health risks for people staying on a space station.

Okay, so what about the Apollo 1 fire? To speed up testing, Apollo 1 did two tests at the same time: the Plugs-Out Test, where the astronauts were in the spacecraft with everything running and practicing their countdown, and the Overpressure test where they pressurized the spacecraft to 1.4 atm (to mimic the pressure differential in outer space). And they did it with pure O2. So you had all of these electronics running in an environment at 1.4atm pure O2. And that was incredibly dangerous, in a way that actual spaceflight, a mere 0.4atm O2, was not. But it was just a test, another in a long string of them, and no one involved ever really analyzed it as a potential hazard.

After Apollo 1 a few things were changed: one was that they did the Plugs Out test and the Overpressure test at different times, and a lot of stuff was turned off for the Overpressure test. Another was that the Apollo capsule at takeoff was 1atm 80/20 until a couple of minutes into flight, when it dumped the cabin atmosphere overboard and replaced it with pure O2 at 0.4atm. That's why the astronauts carried little packs in their arms in all the pictures of them getting into the spacecraft, that's the pure O2 tank that they were breathing off of until they could switch to the atmosphere in the cabin after it was replaced.

Just convincing them that their problem boiled down to a single incorrect bit was difficult enough but then having to, in a day, build and successfully operate a test harness to prove the fix worked was the real stress.

I do not miss embedded engineering.

Generally firmware can't be updated by the end user because there is physically no way to do so without returning the hardware. (Unless an update mechanism is specifically implemented in hardware, obv)

Pucker factor goes way up because if you ship a bug, there's no way back. If you aren't careful, you can break physical devices which can have consequences anywhere from thousands of RMAs to burning down a user's house depending on the hardware and how bad you fucked up.

The deployment process itself is about the same. Tests and more tests, including testing on prototype and/or pre-production units. Hardware testing can get wild depending on application, but I don't think any SWE would find it too surprising. Then you email a binary to your manufacturer and pray

So in a cylindrical ship you'd want to have one end pointing at the Sun most of the trip. This is, of course, very different in effect on the hull compared to the repeated expansion and contraction of heating cycles.

You don't get the AtOx going to mars but you have everything else which will utterly take its toll on a traveling craft.

[1]: https://youtu.be/ksn5yrsC3Wg

Anything larger, say a lost screw driver, would punch thru the ISS like it wasn't even there leading to some ugly consequences.

The ISS can dodge debris by adjusting the height of its orbit.

> Otherwise please use the original title, unless it is misleading or linkbait; don't editorialize.

So, even if you use original title, once "Live Update" article changes, it might seem that submission did not use original title.

Fry: How many atmospheres can the ship withstand?

Professor Hubert Farnsworth: Well, it's a space ship, so I'd say anywhere between zero and one.