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[ music ]

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>> Hey there.

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I'm Tom Marshburn,

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an astronaut living

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and working aboard

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the International Space Station,

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the sole space-based

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proving ground

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and stepping stone

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for NASA's Artemis Program.

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Have you ever wondered

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how astronauts up here

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get fresh, breathable oxygen?

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The answer might surprise you.

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Come on, follow me,

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and let's check it out.

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The oxygen we breathe

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comes from recycled water.

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The Water Recovery System

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recycles waste water

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that takes the form of urine,

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sweat, and condensation,

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and pumps it into

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the Oxygen Generator System,

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or OGS.

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When the water reaches the OGS,

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it goes through a process

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called electrolysis.

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Electrolysis is the process

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of creating a chemical reaction

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by passing an electric current

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through an electrolyte,

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which is a solution

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containing ions.

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This means to decompose water,

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an energy source,

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like a battery,

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is necessary.

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We're taking water

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and breaking it down

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into its two components,

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Hydrogen Gas and Oxygen Gas.

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The law of Conservation of Mass

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states that matter is neither

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created nor destroyed

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in a chemical reaction.

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This means that the number

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of atoms in the reactant side

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must be equal to

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the same number of atoms

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on the product side

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of the equation.

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Notice how, once balanced,

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the number of atoms

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and their reactants is equal

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to the number of atoms

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in the products.

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The oxygen produced from

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this chemical reaction

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is vented back to us

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in the main cabin

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so we can breathe

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and continue our work up here.

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The hydrogen gas produced

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from the chemical reaction

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is combined with

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the carbon dioxide

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we exhale to generate

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water and methane.

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The methane produced

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from this chemical reaction

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is vented into space,

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and the water feeds

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back into the OGS,

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completing a regenerative

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life support cycle.

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So being able to recycle water

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is absolutely essential for us

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living aboard the space station.

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Turns out water is very heavy.

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You don't want to have to

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carry it up every time

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you deliver a crew

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to the space station.

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So what we do is

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we recycle our water,

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up to 93% of the water here,

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and using the technology

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we have now.

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To spend a lot of time

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in orbit around the moon

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and on the lunar surface,

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and to go to Mars,

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we need to be able to

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recycle 98% of the water,

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which is what we are doing

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right now, investigating

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new technologies in order

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to be able to accomplish

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98% recycle rate.

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So in the air right now

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around us is, uh, moisture.

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It comes off of our bodies.

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And that is captured

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in the air conditioning systems,

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over here to my right,

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and to my left.

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You can probably hear

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the air conditioning system.

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And that captures

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the moisture coming

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from our bodies,

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and from some flu--

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free fluids we might

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have floating around.

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That goes to

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the water recovery system,

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along with our urine,

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and then, through a process

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of, uh, electrolysis,

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we're able to create oxygen.

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Not only do we save

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on the water,

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but we're able to produce

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that vital constituent

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that's important for--

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essential for us to live.

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I hope you learned

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a little bit more

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about chemical reactions

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and the law of

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Conservation of Mass today.

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Now it's your turn to practice

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what you've learned,

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using the corresponding

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classroom connection.

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As you can see,

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Conservation of Mass

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is pretty important on Earth

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and in space.

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See you next time.