155
votes
Accepted
Could we breathe an atmosphere that is not nitrogen based?
We can breathe pure oxygen for unlimited time if the pressure is not too high; about 0.4 bar is okay. Breathing pure oxygen at 1 bar is possible for some hours, but a longer time may damage the lungs. ...
- 49.5k
44
votes
Accepted
How did humans grow plants on the Moon despite the harsh conditions?
While it's still cool, it's not as tricky as it may sound at first:
The seeds, including water, are stored in a sealed, heated and shielded container. The container also includes fruit flies and ...
- 12.6k
43
votes
Are there types of animals that can't make the trip to space? (physiologically)
To keep an animal alive, a spacecraft needs to create conditions (e.g. temperature, pressure, concentrations of gases or electrolytes) within the animal's normal physiological range. We can recreate ...
- 48.4k
43
votes
Accepted
Was the Apollo 13 CO2 problem a matter of capacity, or of rate?
From this NASA page about Apollo 13:
There were four cartridges from the LM and four from the backpacks,
counting backups. However, the LM was designed to support two men for
two days and was being ...
- 49.5k
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 ...
- 25k
29
votes
Is there any reason that we have not sent a small mammal to Mars?
Mice probably are too short-lived, you want something larger (unless you are building a generation ship!)
Domestic mice have a lifespan of up to about 30 months. This is not very long for Mars ...
- 9,517
28
votes
Accepted
Astronauts make a lot of CH₄ and some H₂ as well; do space capsules and space stations have systems to remove these?
For the ISS, the relevant bit of kit would be the Trace Contaminant Control System, which is part of the Air Revitalisation System.
A Trace Contaminant Control System ensures that over 200 various ...
- 8,188
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 ...
26
votes
Where exactly are the Apollo space suit sublimators venting steam into space? is there a photo of an astronaut in space that shows the opening?
It can be hard to see because it's on the front of the PLSS behind the astronaut's helmet.
(NASA photo of Irwin on Apollo 15, I cropped it and added the arrow)
Here's an exploded view showing the ...
- 189k
24
votes
What typically gets sent to the ISS?
If you want an example manifest for one logistics flight, that's available.
Search terms...suggest "ISS Cargo Manifest"
From SpaceX 2 Cargo Manifest
(see link for details)
81 kg of crew ...
- 189k
23
votes
How does SpaceX plan to supply or recycle respiratory gasses?
How does SpaceX plan to supply or recycle respiratory gasses?
As with most questions about SpaceX, the answer to this question is essentially that SpaceX is a private company, and unless either ...
- 20.7k
22
votes
What did the Apollo missions do with old LiOH canisters & the water they produced?
What happened to the old canisters after they were used up? Were they manually replaced? Were they tossed behind the seats?
@OrganicMarble's answer covers this with reliable sources quoted.
I only ...
- 6,462
20
votes
Could we breathe an atmosphere that is not nitrogen based?
Yes, we don't require nitrogen to breathe. For example, NASA astronauts used to use a pure oxygen environment. The complication with this environment was the risk of fire.
For more information:
Why ...
- 23.8k
20
votes
Are there types of animals that can't make the trip to space? (physiologically)
The two extremes are the most-likely sources of death for creatures in space - weightlessness and the g-force of takeoff.
Weightlessness could be a critical issue for any creature which relies ...
- 301
20
votes
Accepted
What did the Apollo missions do with old LiOH canisters & the water they produced?
The canisters were manually replaced. Here is the appropriate checklist section.
From CSM Operations Checklist Section 10 Systems Management
Used canisters were stowed in the container that the ...
- 189k
20
votes
Accepted
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
...
- 189k
18
votes
Accepted
Cyanobacteria as Life Support?
Why this wouldn't work? It works for the Earth; the reason why it is not implemented in space is purely in the engineering limitations.
Cyanobacteria live in water, humans live in air.
Gravity is ...
- 2,529
17
votes
Accepted
How many times has there been 13 people inside the ISS and is it hard on the station?
The only 3 missions that had 13 people in the ISS at one time are STS-131 (as listed in the question), STS-127, and STS-128. Here are the analogous crew photos from those missions.
STS-127
STS-128
...
- 189k
17
votes
Accepted
Why did Apollo 13 need to scrub the air in the LM?
They needed to remove carbon dioxide from the air. As the astronauts exhaled, the carbon dioxide accumulated and if left unchecked, would reach a high enough partial pressure that they would no longer ...
- 587
16
votes
How many times has there been 13 people inside the ISS and is it hard on the station?
To answer the part 'is is hard on the station':
The air conditioning system can cope with at least 12 people on board continuously. There are 3 systems for removal of carbon dioxide: 2 Carbon ...
- 130k
15
votes
Icy Hot Astronauts
Common wisdom says that space is cold. I wouldn't go so far as to call that a misconception, but it's certainly a bit of a misunderstood fact.
See, space is not cold in the way your fridge or a block ...
- 3,771
14
votes
Could we breathe an atmosphere that is not nitrogen based?
Yes, provided that the inert gas is not toxic and contains the requisite proportions and pressures of oxygen, humans should have no trouble breathing a gas mixture comprised of helium or other gasses. ...
- 2,325
14
votes
Accepted
Any potential downside to throwing personal life support out the door on the Moon?
They threw out the PLSS, but that didn't leave them without the use of those space suits entirely. The space suits could be coupled via umbilicals to the LEM ECLSS or to the CM life support system (...
- 130k
14
votes
Accepted
How does air circulate between modules on the ISS?
The Intermodule Ventilation (IMV) system
A final component of the atmospheric
control system is the Intermodular
Ventilation (IMV) shown in
Figure 4 for Node 2. The IMV
system is basically a bunch of ...
- 189k
12
votes
Are there types of animals that can't make the trip to space? (physiologically)
Lugworms living in the sand below tidal sea waters. They need gravity to burrow in and feed from the tiny animals living between sand particles. They would survive some weeks without food.
Starfish, ...
- 49.5k
12
votes
What typically gets sent to the ISS?
Based on @Martin Schroeder comment. I found out a cargo with water supply:
https://spaceflight101.com/progress-ms-03/cargo-manifest/
420kg of water out of a 2405kg payload.
Presumably, There are ...
- 221
12
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 ...
- 189k
11
votes
Cyanobacteria as Life Support?
Another engineering aspect is controllability. Most electrical/mechanical/chemical life support systems can be throttled to anywhere between 0% and 100% of production capacity within minutes, if not ...
- 449
10
votes
Accepted
How much algae would you need to fully support a person?
I was recently involved in a feasibility study for using Chlorella vulgaris algae for generating medical oxygen using solar energy in off-grid medical facilities.
Bottom line: it requires one cubic ...
- 27.9k
9
votes
Accepted
Is the silica gel used in the ISS recycled?
The author of that answer was confused by a poorly written NASA PR document.
The majority of the humidity control on the US part of the ISS is not done using silica gel. It is done using condensing ...
- 189k
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