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The Question

(Submitted April 11, 1997)

My first graders want to know, How do astronauts go to the bathroom in space? I think the potty chair is in place. Is this correct?

The Answer

We have come up with a number of answers to your question. We will let you, as the professional teacher, decide which is appropriate for your classroom and what is best left to the teachers lounge.

I. The Official NASA pages:

A. There is a nice space shuttle web page at: Digging in there I found a Q&A Web page. Here's what it says:

6. How do you take a bath, brush your teeth, and go to the bathroom in space?

We do not have a bath or shower on the Shuttle, so we just wash off with wet washcloths, using soaps that you don't have to rinse off. When we brush our teeth, we can either swallow the toothpaste or spit it into a washcloth. Designing a toilet for zero-gravity is tougher. We use air flow to make the urine or feces go where we want, since gravity will not do it for us. You have to be more careful and think about what you are doing with the toilet in the Shuttle.

B. Another colleague pointed out that Johnson Space Center is the home of the astronauts, and they have some web pages dealing with this issue too. (We really know little more than you do about the astronaut program -- but they do.)

Their home page at: has links for KIDS, EDUCATORS, and more.

I went to their page: and this is what I found:

This used to be under the old FAQ at Spacelink. It has since been removed.


Each 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.

Solid 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.

Astronauts 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.

The toilet that was first flown aboard STS-54 is completely new in design and offers new and improved features:

The new toilet features better hygiene, larger storage capacity, greater dependability, and an overall cost savings in maintenance.

-The previous model had a 14-day capacity for storage of waste material. The new model has an unlimited storage capacity.

-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.

-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.

-The new toilet also provides an odor-free environment. The old model did not.

-The opening in the lid of the toilet was increased from 4" to 8", allowing for easier handling of the plastic storage bags.

-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.

-The previous system had trouble with corrosion in the fan system.

-The new toilet can be cleaned without removal from the orbiter at the completion of the mission, reducing the cost of servicing.

-The previous system must be removed and sent to a company in Houston, Texas for servicing.

I hope this helps.


Jonathan Keohane and most all of the Ask an Astrophysicist Team
-- for Imagine the Universe!

Questions on this topic are no longer responded to by the "Ask an Astrophysicist" service. See for help on other astronomy Q&A services.

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