A year in space

[Ayahuasca]

Docu on Netflix about Scott Kelly, NASA astronaut who spent almost a year on the ISS as part of research into a trip to Mars.

Put here rather than in TV section for obvious reasons. I don’t have claustrophobia, but that Soyuz capsule would probably induce it! No thank you.

Have any of the conclusions regarding the human effects of spending that long in space been published?

[Eric Mc]

Yes - plenty of papers have been written on the long term effects of Zero G going back to the early 1970s.

[Ayahuasca]

Eric Mc said:

Yes - plenty of papers have been written on the long term effects of Zero G going back to the early 1970s.

No - I meant from that particular experiment. Not sure too many people have spent a year in zero g, even going back to the early 70s. Presumably NASA would not have gone to the expense of putting a man in orbit for a year if they believed that all relevant data was already in published papers.

Edited by Ayahuasca on Wednesday 14th October 17:29

[Beati Dogu]

Scott Kelly's twin brother Mark was also an astronaut, so they were able to do comparative testing on both of them. Dr Mengele styleee (not really).


It's interesting what Scott Kelly said about CO2 levels on the ISS, which are much higher than the 400 ppm trace amount it is on Earth. When a Shuttle crew of 7 rocked up, the CO2 scrubbers couldn't quite cope and he'd get a headache.

Scientist used to think that human tolerance to CO2 was quite high, but it turns out that when it gets above 6600 ppm, it is known to cause symptoms like headaches, mood changes (e.g. short temper, snappiness etc), lethargy, congestion and difficulty concentrating. This is much lower than was previously thought and has led NASA to try to reduce the previous maximum allowable level from 7000 ppm down to 5300 ppm recently.

This doesn't get mentioned much, but keeping CO2 to manageable levels will always be a challenge for deep space / long duration missions.

[Eric Mc]

Read Kelly’s biography. It’s really good. He’s not the only one to spend that length of time in space.

[Ayahuasca]

He looks very un-Hollywood astronaut like... but as a former F14 test pilot must be made of the correct ingredients.

[Ayahuasca]

Beati Dogu said:

Scott Kelly's twin brother Mark was also an astronaut, so they were able to do comparative testing on both of them. Dr Mengele styleee (not really).


It's interesting what Scott Kelly said about CO2 levels on the ISS, which are much higher than the 400 ppm trace amount it is on Earth. When a Shuttle crew of 7 rocked up, the CO2 scrubbers couldn't quite cope and he'd get a headache.

Scientist used to think that human tolerance to CO2 was quite high, but it turns out that when it gets above 6600 ppm, it is known to cause symptoms like headaches, mood changes (e.g. short temper, snappiness etc), lethargy, congestion and difficulty concentrating. This is much lower than was previously thought and has led NASA to try to reduce the previous maximum allowable level from 7000 ppm down to 5300 ppm recently.

This doesn't get mentioned much, but keeping CO2 to manageable levels will always be a challenge for deep space / long duration missions.

Interesting. Apparently 5000ppm is the permitted limit in most workplaces.

[Eric Mc]

Ayahuasca said:

He looks very un-Hollywood astronaut like... but as a former F14 test pilot must be made of the correct ingredients.

They don’t select test pilots based on their looks.

[Ayahuasca]

Eric Mc said:

Ayahuasca said:

He looks very un-Hollywood astronaut like... but as a former F14 test pilot must be made of the correct ingredients.

They don’t select test pilots based on their looks.

Really? Who knew?

[Eric Mc]

It wasn't me who commented on his "un-Hollywood test-pilot" looks.

[Krikkit]

Beati Dogu said:

This doesn't get mentioned much, but keeping CO2 to manageable levels will always be a challenge for deep space / long duration missions.

I suspect there'll be a unit developed which uses electricity to split CO2 into C + O2 - they'll have to use nuclear power for really long duration missions anyway... But it's one of quite a few challenges.

[Beati Dogu]

Krikkit said:

I suspect there'll be a unit developed which uses electricity to split CO2 into C + O2 - they'll have to use nuclear power for really long duration missions anyway... But it's one of quite a few challenges.

On the US section of the ISS they scrub CO2 using a mineral call zeolite (silicon dioxide and aluminum dioxide), which captures it in tiny pores. Heating the mineral bed causes it to release the CO2, which is then vented to space. There are two such units which operate in parallel, so while one is scrubbing, the other will be releasing & venting. The Russian section has a similar scrubber with a 3 bed system using amine as the active ingredient. It used to work very well apparently, but has degraded over time, so the US system does the bulk of the work these day.

For shorter duration missions like Apollo and Shuttle they used lithium hydroxide scrubbers.


Just like a nuclear submarine, they can produce oxygen on the ISS via hydrolysis of water. I believe the ISS currently vents the hydrogen into space for safety reasons.

In the future, that waste hydrogen could be combined with crew exhaled carbon dioxide to reclaim water using the Sabatier process (4H2 + CO2 → 2H2O + CH4).

Starship of course is powered by O2 and CH4 - methane, so that wouldn't be wasted either

It would make sense to use this process on long transits, since they intend to use it generate water and methane on the surface of mars from the 95% CO2 atmosphere anyway.