Dr.Stone

So how long do astronauts commonly stay in space? In the real world, how many astronauts are currently living on satellites in space?

How quickly would an astronaut decide to return once they lost all contact with earth?

I'm hoping there's a missing link here, because if not there's no reason that three millennia down the line civilisation is a bunch of cave men. Astronauts are smart people. The internet may or may not be lost, I don't understand that kind of thing, but books don't vanish. The descendants of the astronauts would inherit a world that had been abandoned for what, a decade or so?
Houses would be dusty, not apocalyptic, they could live in their old homes, read books to understand how things work, and rebuild all the integral bits of society, meanwhile they could study what turned every one to stone and work to undo it. What was it in the end, bat shit and lime water or something?

Weeks to months, the longest stay was 14 months. There are 6 people living on the ISS, they rotate out crews 3 at a time, so there's usually 3 to 6 people up.
They'd probably try to return as soon as they'd run out of food or something irreparably broke.
Space missions work out with the help of thousands of ground crew and millions in infrastructure around the globe. Deorbiting a soyuz isn't like hopping in your truck and driving to walmart, though i bet an experienced cosmonaut who knew what they were doing could probably set it down somewhere not in the middle of the ocean. It wouldn't be pleasant in the least though.
There are supplies on the ISS to last a full crew for several months That is, food, water, air and everything else. It's designed to be as self sustaining as possible.

You wouldn't return immediately if you lose your thousands of ground crew?

Barring something life-threatening happening on the station, you have better odds staying where you are than attempting an improvised return. You sit tight and wait for rescue, for all you know it could be a temporary glitch (it's happened before, but on the order of hours, not months), or any of a number of happenings that wouldn't result in the entire world dying at once. What if contact suddenly resumes and the entire world sees you McGuyvering your way back to earth against protocol?

So it could potentially have been several months before they ran out of food and were forced to return. Either way, not really long enough for things to have gotten too out of hand.

If you see loads of bright flashes coming from earth in the USA and russia regions, and then radio silence, chances are you're not going to be rescued.

Is that how it happens in this manga? In that case no, if i saw bright flashes and radio silence, the first thing that rang a bell would be global thermonuclear war. So probably not coming down at all, rescue or not.
You know, there are people who'd kill or die gladly for a day up there. If i found myself in their situation i'd live out the rest of my 6 months in utter bliss without ground control fucking me around with 8 hours of experiments per day

Is it so great being in a space station, that you'd not return to earth to suss out the situation?

Starvation has gotta be a pretty horrible way to go

I mean, when you think about it, it's the best apocalypse scenario, nothing has been looter there's no external threats but for mother nature, every place you personally haven't already raided is still full of preserved goods.

If earth is glowing glass, stone or dead in some other way, it can wait 6 more months for all i care.
You don't need to starve, there's suicide by airlock, suicide by fiery re-entry, drinking coolant, hydrazine, electrocution, cooked alive, cutting yourself. You probably can't hang but everything else is on the table, be creative

Let's assume that they stay as long as possible hoping for a signal, like one year, you'd get up to 6 people on a mission to recreate humanity with most of the biggest cities already destroyed beyond repair, all power plants out of commission and all the nuclear power plants would already have exploded making the air as carcinogenic as this thread in a few hours. If I remember correctly, a city like Paris would be un-savable after 6 months without any human activities and the Eiffel Tower would fall after 50 to 200 years without maintenance while other buildings would take slightly longer. You see the fall of Rome? Imagine that, worldwide and you only get six people to restart the machine from the beginning of humanity with knowledge but without most of the tools they'd need.

>most of the biggest cities already destroyed beyond repair,
I don't see how, unless it's by the nuclear explosion you mentioned.
>a city like Paris would be un-savable after 6 months without any human activities
Can you explain this to me?
>but without most of the tools they'd need.
All the tools are already there, and there's the knowledge to recreate any tools missing.

I don't think it'd be that bad.

The problem for a city like Paris is getting rid of all the water going through it when you get slightly more rain than usual and it has a pretty darn complex anti flood system with artificial lakes before and after it to ensure it doesn't become Venice every time it rains. All the sewers would be clogged, the aforementioned complex system of flood prevention wouldn't work and without electricity you wouldn't be able to use pumps on a scale large enough to save it either. Remember that powerplants won't last a couple of days without someone able to manage them and they are the things enabling to maintain all that.

A power plant exploding isn't that damaging directly, the issue is the radioactivity, look at the explosions of Chernobyl and Fukushima. A building standing isn't equal to a building functioning, if all your vital infrastructures are destroyed you can consider it destroyed. It's a bit like dying from internal bleeding or an organ failure, you didn't lose a limb but you are still dead.

those are all terrible ways to die

But all the building has to do is provide ready shelter, in this post apocalypse, though I see what you mean about paris and the water, I imagine that could be very damaging to infrastructure, causing collapses.

You know what, I want a spinoff about Senku's dad and how he founded the village after returning to earth mere months after every one got stoned

> Chernobyl and Fukushima
In both cases it was manual human intervention that prevented automatic safety systems from doing their job.

Or suicide by space vacuum

How many automatic safety devices are in place to prevent a city from basically exploding?

>But all the building has to do is provide ready shelter
You aren't going to rebuild humanity with a simple shelter.

Water is a bitch, fire is a bastard and don't get me started on winter.

But the explosions themselves didn't do much damage to other buildings.

That would make my blood boil.

>Water
Even if the plumbing does all just basically explode, there are still dams and reservoirs, and countless survivalist stores full of water cleansing chemicals and shit until you get something more permanent working.
>Fire
You mean making it or putting it out? Making it would be piss easy, and as for putting it out, eh I guess. If lightning strikes a building and lights it up, it'll spread through the city before you can put it out.

Though I can't imagine why all these cities would just start to burn. Even if they did there are towns further in the countryside.

>Winter
Fireplaces.

A city's not supposed to spontaneously explode as soon as nobody's looking in its general direction. Sure it will flood and freeze and maybe burn somewhere, but it won't be completely impossible to survive within one while preserving at least some tools and literacy.
Either something other than stoning happened before emergency landing or at some point survivors decided to do a full reset for some reason.

>survivors decided to do a full reset for some reason.
This is the most likely cause I think. Three millennia is a long time. It's possible for a few centuries technology continued to stagnate, but then some one like the dude who now leads the chad army came along and convinced every one to fuck off into the wilderness. Not likely though seeing as it's senku's own tribe who are now stoneage savages.

You know, it's possible there was some kindo f schism, and there's a hyper technological remnant hidden in a bunker somewhere. That would be interesting.

>implying an emergency spillway failure can't destroy a dam
A dam isn't a magic tool that stops all water, it needs maintenance therefore manpower and it can be destroyed if the flow of water augments past a certain point. Don't underestimate its destructive capacities.

>Fireplaces.
The cold can permanently fuck up modern houses without proper heating.

Or they simply faced the same issue as Senkuu, they had the theory but not the craft. Working copper and bronze is "easy" today, now do it without any electricity and you'll see that it will take ages to get a single decent tool.
My theory is that they managed to have a small conflict after a few generations killing too many useful hands.

The entire manga makes zero sense and you mind about that, of all things?