Astronauts Flush Chocolates Down the Toilet, For a Good Reason

Astronaut Cady Coleman tosses M&amp;Ms into the space station toilet to show how waste is dealt with.
WATCH How a Toilet Works in Space

This Valentine’s Day, when many on Earth are giving chocolates to their sweethearts, the astronauts on the International Space Station are flushing them down their toilet -- all in the name of science.

ABC News obtained exclusive video of this experiment from orbit.

It's part fun and games on the space station and part science. There's a little kid in every one of us who wants to know how you “go" in space. Astronaut Cady Coleman spent much of her time on orbit honing her plumbing skills –- if the toilet isn’t working, well, Houston, we have a problem.

One day when she finished her repairs, she started playing with candy coated chocolates and the toilet. Coleman said it turned into a giant physics experiment

“In order to make anything work up there we have to have something that either pushes it, or pulls it, so we have a vacuum cleaner," she said. "Trust me you don’t want to try this at home. When I turn on the toilet there is a switch that I throw that pulls everything in.”

The astronauts train extensively at the Johnson Space Center in their high-tech outhouse. Zero gravity means the space station toilet is much more complicated than anything we have at home. The astronauts have to position themselves on the toilet seat, using leg restraints and thigh-bars. And instead of flushing there is a vacuum with fans that suck air and waste into the commode. The waste is disposed of and the liquids recycled into drinking water.

It's part of the quirkiness of living in space. The views are great, the work is challenging, but no hot showers, pizza deliveries or ice cream, or a even a cold beer at the end of the day.

Bartering is big on orbit, since money is useless. Where are you going to spend it? But the astronauts do swap food for more variety.

So how does a highly qualified astronaut feel about being a plumber in orbit? Coleman said she was proud of learning a new skill. “I did spend a lot of time with the toilet, and it made me think it is a very human thing to use the toilet. You need to know that it is going to work right and you won’t be embarrassed if it doesn’t."

ABC News' Clayton Sandell contributed to this story.