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A Primer on Long-Duration Life Support

mceglowski.substack.com

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Re: A Primer on Long-Duration Life Support

#11

Post by birdsongs »

oersted wrote: post #7

Curious that both average inputs and outputs match to exactly 5.74 kg. I had intuitively assumed there would be a significant difference, but I suppose that even if a lot of energy is extracted, the mass difference will be negligible, mc2 and all. I'm also surprised that the vast majority of the output carbon is in the form of CO2 rather than feces. It's all rather obvious in retrospect, it was just nice to see cryst…

> I'm also surprised that the vast majority of the output carbon is in the form of CO2 rather than feces.

Not sure if you know, but in the same vein, I was shocked when I learned ~50% of the biomass of trees is carbon (right, we knew that), but also that the carbon came from CO2 the tree respirated. Also makes total sense in hindsight, but still think it's so cool.

The trees literally build their mass from the air and sunlight (and yes, obviously also water and trace minerals from the roots).

Re: A Primer on Long-Duration Life Support

#12

Post by malfist »

isoprophlex wrote: post #5

On water reclamation: > On the Mir space station, this used to happen organically. Collecting water was a grubby job that involved chasing beach-ball sized spheres of condensate around the colder parts of the spacecraft with trash bags before they could climb into the walls and cause mayhem. Crew members spent three to four hours a day on this dirty and difficult task. That sounds, frankly, horrible. It made me think…

Mir famously stank. Though you'd be glad to know without gravity your nose doesn't work as well

Re: A Primer on Long-Duration Life Support

#13

Post by adolph »

birdsongs wrote: post #11
oersted wrote: post #7

Curious that both average inputs and outputs match to exactly 5.74 kg. I had intuitively assumed there would be a significant difference, but I suppose that even if a lot of energy is extracted, the mass difference will be negligible, mc2 and all. I'm also surprised that the vast majority of the output carbon is in the form of CO2 rather than feces. It's all rather obvious in retrospect, it was just nice to see cryst…

> I'm also surprised that the vast majority of the output carbon is in the form of CO2 rather than feces. Not sure if you know, but in the same vein, I was shocked when I learned ~50% of the biomass of trees is carbon (right, we knew that), but also that the carbon came from CO2 the tree respirated. Also makes total sense in hindsight, but still think it's so cool. The trees literally build their mass from the air an…

There is a nice Feynman children's lecture about this [0] from the series "Fun to Imagine" [1]

0. https://www.youtube.com/watch?v=ITpDrdtGAmo

1. https://www.bbc.co.uk/programmes/p0198zc1

Re: A Primer on Long-Duration Life Support

#14

Post by mordechai9000 »

billfor wrote: post #8

The most interesting thing I learned is that we let people who need Zoloft on the ISS. The FAA will disqualify you for that unless you jump through hoops.

My guess is they stock it in case someone needs it during the mission. Not that they are sending people who are already taking it.

Re: A Primer on Long-Duration Life Support

#15

Post by jp57 »

Haven't many of the non-zero-g challenges been at least partly solved on nuclear submarines, that carry large crews and stay submerged for months at time? Of course there are more challenges, but you do have people living in a pressure canister for long periods.

Re: A Primer on Long-Duration Life Support

#16

Post by siruwastaken »

jp57 wrote: post #15

Haven't many of the non-zero-g challenges been at least partly solved on nuclear submarines, that carry large crews and stay submerged for months at time? Of course there are more challenges, but you do have people living in a pressure canister for long periods.

I think the difference is largely due to the fact that bringing a bit of extra weight isn't as problematic in a submarine as it is in a spacecraft. For example, you always have a water source that can give you oxygen and you don't have to worry about discarding the byproducts.

Re: A Primer on Long-Duration Life Support

#18

Post by sans_souse »

emptybits wrote: post #4

"The limiting factor in urine distillation is actually the high level of calcium from disintegrating astronaut bone, a nice example of how problems in space find ways to compound one another." Sobering. One of the many long term effects of life away from Earth.[1] With humanity's future probably (?) driving more of us to leave the planet, I'm glad these things are being studied. Where there's a will, there's a way. […

> With humanity's future probably (?) driving more of us to leave the planet, I'm

I'm seeing it's becoming ever-clearer that our best and possibly only real "option" is here on Earth. That means not fixing our mess = no future.

Re: A Primer on Long-Duration Life Support

#19

Post by billfor »

mordechai9000 wrote: post #14
billfor wrote: post #8

The most interesting thing I learned is that we let people who need Zoloft on the ISS. The FAA will disqualify you for that unless you jump through hoops.

My guess is they stock it in case someone needs it during the mission. Not that they are sending people who are already taking it.

If somebody needed it during a mission it would take at least 2 weeks to take effect. Those drugs are not usually prescribed for acute mental issues.

Re: A Primer on Long-Duration Life Support

#20

Post by DennisP »

billfor wrote: post #19
mordechai9000 wrote: post #14

Earlier quoted context omitted.

My guess is they stock it in case someone needs it during the mission. Not that they are sending people who are already taking it.

If somebody needed it during a mission it would take at least 2 weeks to take effect. Those drugs are not usually prescribed for acute mental issues.

People typically stay on the ISS for six months.
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