Science

The Air Up There: What Space Stations Smell Like

In Leroy Chiao’s five-day stint as astronaut guest blogger, he’s striving to illuminate the everyday aspects of life aboard the International Space Station, stuff that isn’t in press releases. Today’s topic? The air they breathe.


OK, so someone wanted to know what the International Space Station smells like. After we opened the hatch, I noticed a moderate smell of plastics, not unlike that new car smell. That’s from the various synthetic materials onboard, outgassing. It’s not too bad, and after an hour, I stopped noticing it.

We do scrub the atmosphere, though. We have carbon dioxide removal systems, as well as a micro-impurities removal device. Oxygen is added of course, as it is consumed. We use an electrolysis device to crack water, dumping the hydrogen overboard. (See gallery for all the air-processing machinery described here.)

That device is a bit cantankerous, so we also have oxygen candles, which we “burn” periodically. These are the same kinds of systems that are onboard nuclear submarines, which face similar technical requirements.

One interesting fact is that nitrogen is not replaced, except to compensate for leakage. The human body does not really utilise the inhaled nitrogen, so it is recycled.

What else? What is the temperature onboard? The temperature was set by the mission commander—me. I live in Houston, so I like air conditioning. The cabin was set to about 70 degrees Fahrenheit. (21ÂșC)

Follow astronaut Leroy Chiao in his guest column, as we celebrate human life in space with our “Get Me Off This Rock” week. You can check out tons of great shots from Leroy’s ISS mission in his NASA gallery.

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