154 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. ...
Uwe's user avatar
  • 49k
68 votes
Accepted

Why vent $CO_2$ and $H_2$ waste products to space on ISS?

Added complexity is never welcome in a situation where lives are on the line and help isn't a phone call away. There have been a number of ammonia-related events and those are in systems that should ...
uhoh's user avatar
  • 149k
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 ...
DarkDust's user avatar
  • 12.5k
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 ...
DrSheldon's user avatar
  • 48k
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 ...
Uwe's user avatar
  • 49k
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 ...
GremlinWranger's user avatar
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 ...
ikrase's user avatar
  • 8,874
29 votes
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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 ...
Anthony Khodanian's user avatar
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 ...
Starfish Prime's user avatar
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 ...
Organic Marble's user avatar
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 ...
Organic Marble's user avatar
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 ...
Jörg W Mittag's user avatar
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 ...
Sergiy Lenzion's user avatar
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 ...
called2voyage's user avatar
  • 23.7k
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 ...
Jeutnarg's user avatar
  • 301
20 votes
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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 ...
Organic Marble's user avatar
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 ...
fraxinus's user avatar
  • 2,249
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 ...
Fred Larson's user avatar
17 votes
Accepted

How many times has there been 13 people inside the ISS and is it hard on the station?

The only 2 missions I am aware of that had 13 people in the ISS at one time are STS-131 (as listed in the question) and STS-127. Here is the analogous crew photo from that mission. Which crewperson ...
Organic Marble's user avatar
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 ...
Hobbes's user avatar
  • 128k
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 ...
leftaroundabout's user avatar
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. ...
Justin Braun's user avatar
  • 2,275
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 (...
Hobbes's user avatar
  • 128k
14 votes
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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 ...
Organic Marble's user avatar
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, ...
Uwe's user avatar
  • 49k
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 ...
Koenig Lear's user avatar
11 votes
Accepted

How have space suits dissipated the heat removed from astronauts?

For Apollo, space suits used the Primary/Portable/Personal Life Support System during EVAs. This is a schematic of the PLSS: The PLSS used sublimation cooling. Water was run over a heat exchanger, ...
Hobbes's user avatar
  • 128k
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 ...
mlk's user avatar
  • 449
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 ...
Organic Marble's user avatar
9 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 ...
Woody's user avatar
  • 21.6k

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