How does the ISS get more oxygen? Do they have a device that can create more, or do they simply send shipments of O2?
In: Physics
Here’s a [good article on the ISS oxygen generation](https://www.cnet.com/news/breathe-deep-how-the-iss-keeps-astronauts-alive/).
You can get oxygen from breaking down water (electrolysis). All you need is electricity, which is convenient in space, because electricity doesn’t have to be shipped from Earth; you can get electricity from solar panels.
Water’s H2O, so breaking down water also gives you hydrogen. You can use the hydrogen to turn CO2 into H2O and CH4 (the Sabatier reaction). This is convenient because the astronauts are all breathing out CO2.
So with the Sabatier reaction, you’re turning two waste products (hydrogen and CO2) into a valuable resource (water) and one waste product (CH4, also known as methane).
About 80% of the oxygen on the ISS is recycled, the remaining amount has to be replenished by supply ships.
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