138

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. A mix of oxygen and helium is also breathable and is used for deep diving. Xenon cannot be used due to its narcotic effect on the body. Argon is less ...


69

Am I not considering something? Yes. You are not considering Mir, Soyuz, and the Space Shuttle. The International Space Station is a multinational program, jointly led by the US and Russia. While the US and Russia had to compromise on many design decisions, the makeup of the breathing atmosphere was not one of them. The decision to pressurize the ISS to ...


67

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 theoretically be a lot more reliable and well characterized than a new CO2 or H2 storage system. If you polled ISS astronauts past and present - basically anyone ...


48

Methods of cleaning Current washing technologies are mostly solvent based. Most normal "soiling" of clothing is a mixture of oils and salts (Both of which are products of sweat), and sloughed skin cells, often bound by those same oils. When one finds clothing irritable from extended wear, it's usually due to the effects of accumulated sweat and ...


43

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 nearly any environment; however, the resources necessary to do this may be prohibitive. Thus, the answer to the question is that it may be possible, yet ...


41

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 asked to care for three men for about four days. After a day and a half in the LM, a warning light showed that the carbon dioxide had built up to a dangerous ...


40

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 yeast. So the plants are not grown in the lunar soil (which would be the interesting and challenging next step) but in a portable, sealed ecosystem. (See for ...


30

There are two kinds of depressurization alarm: ΔP/ΔT (rapid depressurization) ATM PRESS (slow leak, or pressure hitting the thresholds) Main steps that are taken: Record incident and contact mission control Take pressure gauge Evacuate into the Soyuz Check if Soyuz descent module is leaking If time remaining (T.res) is less than X minutes, say "Bye-...


27

A hole in the LEM during lunar operations would likely have been grounds to abort, and return to the CSM. For the flight up, it's known that duct tape was carried in the LEM; Apollo 17 made use of it repairing their rover, and proved it's ability to hold in high quality vacuum. It's thus very likely that they'd have patched a single small hole or pair of ...


26

Yes. Lunar regolith contains oxygen -- about 50% by weight. Specifically, you can heat (perhaps with solar energy) Ilmenite and liberate oxygen. The reaction requires hydrogen, but the hydrogen is not consumed by the process. Specifically, the reaction is: FeTiO3 + H2 → FeTiO2 + H2O → H2 + ½O2 Engineering a reliable system on the moon to do this is, of ...


24

Temperature and Humidity Control (THC) system is a part of the International Space Station's (ISS) Environmental Control and Life Support System (ECLSS). Thermal Control System (TCS) is a component part of the THC system and subdivides into the Active Thermal Control System (ATCS, PDF document) and Passive Thermal Control System (PTCS). From a PDF document ...


22

I decided to search through NTRS and found this: http://hdl.handle.net/2060/20130012684 Waterless Clothes-Cleaning Machine This machine can be used wherever water is at a premium, or to minimize washing with water. Lyndon B. Johnson Space Center, Houston, Texas A waterless clothes-cleaning machine has been developed that removes loose particulates and ...


22

Rory mentions oxygenation rate which is an excellent point but there's additional reasons why not keep ISS atmosphere at a lower pressure - thermal convection and air cycling. Pressure at roughly one atmosphere means that the ventilation system on the station works better and no pockets of carbon dioxide or even carbon monoxide build up, which would be ...


22

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 supplies (food, clothes, paperwork) 25 kg of international partner experiments 323 kg of NASA experiments 3 kg of EVA tools 135 kg of ISS hardware 8 kg of PC parts ...


21

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 wish to add (after going through Apollo-7 to Apollo-11 flight journals), the exact mentioned in communication compartment numbers with (square type Command Module)...


20

Several approaches are taken. Cargo vehicles bring up Oxygen and other atmospheric components (Nitrogen, etc). The Russian segments life support system works different and independant of the US side, which is a nice redundancy model. The Russian side has a system that recycles water from urine and moisture that needs to be removed to electrolyze to oxygen ...


20

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 totally on gravity for swallowing - it's likely that some bird species would not be able to properly eat or drink in space. In the long-term, it's likely that a few ...


19

Quoth Robert Frost, self-described as "instructor/engineer in the NASA Mission Operations Directorate": If the object is in LEO and larger than around 10 cm, the ISS can be warned and moved, a few orbits in advance of the potential impact. For smaller objects, they just accept the risk. The ISS has shields called Whipple bumpers. They are multi-...


19

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 unused canister was removed from. The CO2-odor absorber filter change sequence involves numerically identified filters and alphabetically identified filter ...


16

Chances: Murphy's law - bad things eventually happen. Reasons: Besides (micro-)meteorites, as mentioned by @TildalWave, the risk is with the astronauts themselves. EVAs are for repairing stuff, 'plumbing', handling tools and equipment etc. It is natural to break stuff while you work. In terms of numbers, although there were plenty of EVAs in history, ...


16

No, the scrubber design was not modified. The Apollo 14 press kit has a list of the changes made after Apollo 13: The major changes to the command/service modules include adding a third cryogenic oxygen tank installed in a heretofore empty bay of the service module, addition of an auxilliary [sic] battery in the service module as a backup in case ...


16

The higher plants are less efficient, so the entity will probably be not a bush, but a jar of algae. 30-40 liters of Сhlorella suspension could provide for a gaseous exchange of a single person. Grishin Yu. I. "Artificial Space Ecosystems" Cosmonautics, Astronomy 7/1989


16

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 Did NASA Still Use Pure Oxygen After the Apollo 1 Fire? - Amy Teitel


14

There are certain plants that are more efficient in removing and adding Oxygen to the surrounding environment, but the main disadvantage is that they need soil with comfortable acidity otherwise the roots of the plants would die. That prevents them from being used on other planets where the acidic contents in the soil is more (but there are a few exceptions)....


14

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 be able to eliminate carbon dioxide from their bodies and take in oxygen. The Apollo spacecraft (both the CM and the LM) used lithium hydroxide canisters for ...


13

I can see four major factors that determine where a spacesuit can be used: Temperature issues. The temperature on Titan is much lower than on the Moon or Mars, so you'll need more insulation or heating. conversely, closer to the sun you need to reflect the sunlight more to prevent overheating. If you use the suit in a vacuum, you need to get rid of excess ...


13

The ISS has a number of thermal management systems. The most visible part are the radiators attached to the main truss (they are the two sets of 3 white panels just to the left and right of middle, and yes, there's a tear towards the end of the first one on the right side) Those panels are part of the External Thermal Control System (ETCS), if I'm not ...


13

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 (this was used on Apollo 15-17 for EVAs to retrieve material from the Service Module during the flight back to Earth). The PLSS could store consumables for 4 hours ...


13

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. In fact, many scuba divers will use helium based trimix specifically to reduce the nitrogen content of their breathable gas mixture.


12

Good question, and this is not really an answer to your question I know, but it's too long for a comment. My reaction to reading it was (perhaps strangely) to wonder about even the necessity of clothes in space. It seems to me that on Earth, we wear clothes for a number of reasons (some practical, others more cultural and traditional than any purely ...


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