how is oxygen level maintained in international space station?
605258
Recycling. Electrolyse of water. Plants give O2.\nCompressed and deep cooled liquid O2.
580216
The first step is to figure out how much Δv it takes to reach the space station's orbit (and make sure you add a decent reserve on top of it just in case the unexpected happens).  For a station in Earth orbit something higher than 9 km/s seems reasonable, less for lower inclination orbits.\n\nOnce you've got that you then need the exhaust velocity of your rocket, it would depend on what you are using but you can get some rough values from the first source.\n\nWith that the mass ratio is the exhaust velocity times the natural log (ln key on scientific calculators) of the Δv.\n\nThe mass ratio is the difference between the starting and ending mass of the rocket so the amount of fuel will be the (mass ratio minus one) times the mass of the rocket structure + payload.\n\nYou'll probably get something absurdly large (it's very hard to exceed 10 in the real world) and if so then you've got to use staging which makes it a lot more complicated.\n\nThe Soyuz FG which launches the Soyuz and Progress spacecraft to the ISS has about 280 tonnes of propellant at launch over all three stages for a spacecraft lighter than 8 tonnes.  Of course the Soyuz FG uses LOX/Kerosene, more efficient propellants like LOX/H2 would need less propellant for the same payload but it isn't going to be an order of magnitude reduction.
315284
hydrogen sulfide, carbon monoxide, and carbon dioxide.  Plus, you have to be concerned that there might be no oxygen in the air.\n\nEntering a sewer should be left for people trained in doing "confined space" entries.
782454
No, they have a special bathroom\nI looked it up for you on the web\n\n4. HOW DO ASTRONAUTS GO TO THE BATHROOM AND TAKE CARE OF OTHER PERSONAL HYGIENE? \nEach Space Shuttle has a toilet that can be used by both men and women. Designed to be as much as possible like those on Earth, the units use flowing air instead of water to move waste through the system. \n\nSolid wastes are compressed and stored on-board, and then removed after landing. Waste water is vented to space, although future systems may recycle it. The air is filtered to remove odor and bacteria and then returned to the cabin. \n\nAstronauts brush their teeth just like they do on Earth. There is no shower on the Shuttle, so astronauts must make do with sponge baths until they return home. \n\nThe toilet that was first flown aboard STS-54 is completely new in design and offers new and improved features: \n\nThe new toilet features better hygiene, larger storage capacity, greater dependability, and an overall cost savings in maintenance. \n\n-The previous model had a 14-day capacity for storage of waste material. The new model has an unlimited storage capacity. \n\n-The new model features a cylinder system where a plastic bag is placed in the toilet before use. The bag is then sealed and is forced to the bottom of the cylinder after each use by a plunger attached to a lever. A new bag is then placed in the toilet for the next astronaut. When the cylinder is filled, it is replaced by a new cylinder. \n\n-The previous model relied on air flow to pull the waste to a holding tank. None of the waste was separated as it is now. The new system provides better hygiene conditions. There was no way to empty the old system. When it was full, it simply could hold no more waste materials. It had a 14 day capacity. \n\n-The new toilet also provides an odor-free environment. The old model did not. \n\n-The opening in the lid of the toilet was increased from 4" to 8", allowing for easier handling of the plastic storage bags. \n\n-The urine collection system was also improved. A newer type of fan system is being used to force the urine to a holding tank where it is periodically ejected into space, where it vaporizes. \n\n-The previous system had trouble with corrosion in the fan system. \n\n-The new toilet can be cleaned without removal from the orbiter at the completion of the mission, reducing the cost of servicing. \n\n-The previous system must be removed and sent to a company in Houston, Texas for servicing.
51283
Shuttles bring oxygen with them, because they have to burn their fuel to propel themselves through space.  It is because they carry liquid oxygen that they are so incredibly dangerous.\n\nBut really, fire is just an oxidation/reduction reaction.  All you really need are an oxidizer, a reducer, and heat.  Oxygen gas in the air serves as the oxidizer for most fires, and carbohydrates (lignin, cellulose, oil, petroleum, coal, etc) serve as the reducer in most fires you see.  But some rockets use nitrogen dioxide as the oxidizer instead of oxygen.  You could, theoretically, use hydrogen gas and chlorine gas to make a flame in the absense of oxygen--but oxygen is the only common and abundant oxidizer, since it is created as a byproduct of photosynthesis in plants and cyanobacteria.
336478
I'm pretty sure they have oxygen tanks on board or they might have an intake valve somewhere outside the plane for the few oxygen atoms floating around up there but the oxygen already in the cabin from take-off should be enough for the flight itself.
118751
its where the blood picks up the oxygen.
122472
I believe they act as a catalyst for the reaction: 2(O3) -> 3(O2)\n\nNote that because they act as catalysts they are not consumed in the reaction, so the CFCs that are already in the atmosphere are there to stay.
461537
Before launch, the shuttle crew activates the the ship's rockets. At t=0, the Solid Rocket Boosters or SRBs are activated to provide the initial lift. As the name implies, the SRBs run on solid fuel in order to maximize thrust, but the design has a major drawback. Combustion of the solid fuel cannot be controlled in any way, and it will continue to burn the rest of the way until the fuel runs out 5 minutes later. So, the ship is stabilized before ignition.  After 5 minutes, the SRBs are jettisoned to lessen weight and the SRBs parachute back to earth. The shuttle continues on with the fuel in the external tank (the orange cone) attatched to its belly until the fuel it contains is used up 30 minutes later. That is then it is also jettisoned, but unlike the SRBs, the external tanks remain in space, for good. The shuttle then maneuvers itself around using its own fuel and thrusters to do the job it came up for. It may dock with the ISS, do some repairs, release its sattelite cargo or do whatever it came up to do.\n\nWhen it's time to head home, the shuttle again uses its thrusters and boosters to maneuver itself into low orbit and heads into the atmosphere for re-entry. As the shuttle heads deeper into Earth's atmosphere, friction between the shuttle and the air increases. The space shuttle is purposely built to utilize this effect for re-entry. Its design incorporates a flat base on the underside. That part and some others are generously covered with special ceramic tiles that can withstand temperatures up to 5000 degrees, depending on the thickness. So, the shuttle maximizes friction during re-entry by facing its underside to the direction it is travelling to, using the red-hot ceramic tiles to absorb the heat while slowing itself down. It is a dangerous procedure. If only one of the tiles cracked, went loose or dropped, the shuttle will disintegrate like shuttle Columbia. If the shuttle survives, it heads to its planned destination - a commercial runway. It slowly shifts its flying position back to aircraft-style and lands using landing gears and brake parachute.
149295
carbon, hydrogen and oxygen.
699839
carries oxygen around the body
82741
The astronauts do indeed take water with them into space.  It is always kept in a sealed container to keep it from getting into everything by drifting around.  They have to take water with them...nobody can survive without water.  Even when they are outside their shuttle or space station or capsule, there is a water container inside their space suit and use a straw like fixture inside their suit to sip on when they are doing an EVA (extravehicular activtiy)
570305
yes! liquid oxygen and liquid hydrogen.  mix them together, light a match and stand back.
106668
The external tank on the space shuttle uses liquid Hydrogen and liquid Oxygen.  I hope that helps.
491647
They carry their own.\nEither in the form of liquid oxygen, or they use a fuel that  will liberate oxygen as part of the combustion reaction, like hydrogen peroxide.\n\nNote that these are very inefficient, because you have to haul large masses of oxidizers up out of the gravity well...  This is going to put an effective stop to long-haul space travel until a better form of propulsion is well established.\n\n(For extra points...)\nIon drives, mass reaction drives and things like hydrogen "ramjets" are being worked on as alternatives -  and, my favourite concept, the solar sail, is in the wings...  :-)\nI've sailed the oceans, I would really love to sail space, but I doubt I'll live that long.
259470
It is quite possible to recycle oxygen and water for a station like the ISS. Great progress is being done in water recycling, they reuse the water we exhale and are working on reusing the water in urine. \n\nThe oxygen is trickier. The actual process is well known but the reactors needed are too energy hungry and may also be dangerous: they produce methane gas as an intermediate product. Using the moon and doing the work there would make more sense. There isn´t a lot of water there but oxygen is plentyful. It is the main component of lunar soil. Shipping all the waste from the ISS to the moon instead of dumping it and shipping oxygen and fresh water back makes more economic sense than permanently launch it from earth. \n\nThe waste would basically be sewage, CO2 (bound to lithiumhydroxide) and various wastes like plastic containers and food waste. As much water as possible would have been extracted from the waste. Water is mostly oxygen by weight and since there is plenty of oxygen it is a waste of energy. On the moon the plastic containers are cracked, turned into carbon and hydrogen as far as possible. Then you take lunar minerals like ilmenite (a slightly ferromagnetic iron-titanium oxide) and run a stream of hydrogen through it. Water is the result as the hydrogen reacts with oxygen in the mineral. You split the water into pure oxygen and hydrogen. You run the hydrogen through the mineral to get more water while you use the pure oxygen to incinerate all the other waste. You get even more co2 and water from this, which you use to extract more oxygen, and eventually you will end up with lots of oxygen and also metals like steel and titanium. (Biological processes aren´t used in the beginning as they are less reliant and predictable in space. All exhaust and ashes from the incineration is kept and stored as it will be used when biological waste digestors and food production are ready to be put into use.) You ship the oxygen to the ISS (along with fresh lithiumhydroxide canisters) to be turned into more carbon dioxide. We don´t want to ship CO2 (the oxygen) so a process where is reacts with hydrogen can be used. You get methane and water. The water is used aboard while the methane is shipped to the moon along with the other waste. By doing this the moon will become enriched with the volatiles (hydrogen, nitrogen, carbon) that are missing today.
311828
O2 is always more stable