31
votes
Why is it so hard to build a closed-loop ecological life support system?
It is not so much 'hard' as it is an expensive area of research that is challenging to justify funding for. Biosphere 2 proved a number of things, some of them about humans but but most significantly ...
- 23.4k
28
votes
Accepted
Why is it so hard to build a closed-loop ecological life support system?
To answer another facet of your question that others have looked over, is the question of why it is so easy to do with much smaller "ecosystems in a jar". You would think a larger system ...
20
votes
What (if any) pre-breathes were "attempted" on the ISS, and why?
There is always a prebreathe prior to an EVA from the US side of the ISS.
Prior to each EVA, an oxygen
prebreathe is conducted to prevent
the crew from getting the bends
after depressurization of the
...
- 187k
11
votes
How will the Polaris Dawn cabin pressure and oxygen partial pressure dovetail with that of their EVA suits? (100% oxygen?)
Partial answer to
Is this a fire safety issue? Does the lower total pressure decrease the danger?
I have no detailed (or even sketchy) knowledge about how SpaceX does it but...
There are definite ...
- 187k
6
votes
Accepted
Why is the breathing atmosphere of the ISS a standard atmosphere (at 1 atm containing nitrogen)?
Answer: To prevent absorptive atelectasis (Hunter lung) due to breathing pure oxygen long term.
Not the reasons below:
Oxygen toxicity (correlates with O2 partial pressure, not O2 concentration)
...
- 24.8k
4
votes
Cyanobacteria as Life Support?
Answer: O2 generation by algae has been implemented. It does work, but it is very challenging to scale the process. And it has a significant mass and power consumption penalty over stored oxygen.
I ...
- 24.8k
4
votes
Why is it so hard to build a closed-loop ecological life support system?
I suspect that the main problem is lack of knowledge concerning all of the possible feed back loops that might occur under different circumstances and all of the possible interactions and competitions ...
- 10.1k
3
votes
Why is it so hard to build a closed-loop ecological life support system?
Answer: Because the biochemistry of life is really, REALLY complicated.
Spacecraft engineering, by comparison, is really easy. Engineers can design systems which are isolated from each other and are ...
- 24.8k
3
votes
How will the Polaris Dawn cabin pressure and oxygen partial pressure dovetail with that of their EVA suits? (100% oxygen?)
Wow, 3 Questions in one... but all nice ones!
Let's begin with the first one:
The last crewed vehicle with a 100% oxygen atmosphere was the Apollo Spacecraft during the Apollo Soyuz Test Project in ...
- 3,765
2
votes
Why will the Polaris Dawn "pre-breathe" be so long (45 hours) and gradual? What are the proposed advantages over a short one?
It may be due to the difficulties in navigating the atmospheric composition and pressure from mostly high pressure nitrogen with 21% oxygen to low pressure oxygen with no nitrogen whilst avoiding too ...
- 10.1k
1
vote
Could we breathe an atmosphere that is not nitrogen based?
Answer: Yes, there are a range of atmospheric compositions which could be breathable but do not contain nitrogen.
The requirements for long-term breathing gas is
Near “normal” ( = Earth atmospheric) ...
- 24.8k
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