Wednesday, March 28, 2012

The Russian ISS Space Toilet

In early March I visited several class rooms, libraries and science museums in the greater San Francisco Bay Area as part of "Destination Station", the traveling exhibit about the International Space Station (coming to North Caroline and then Boston next). There was not one day without somebody asking "How do Astronauts go to the bathroom in Space?". That question was not only asked by kids (mostly though), but by adults as well. With my very unique experiences in that field, I consider myself a good subject to talk a little more about this. But I did get help from people like Astronaut Chris Hadfield and Mike Massimino (see their videos on the bottom).

After learning about the Russian electrical food warmer on the International Space Station, Canadian Astronaut David Saint-Jacques took me to the Russian toilet trainer. Just glancing at this toilet you realize it has no whistles and thrills. Come to realize, neither would really help me anyway! I already have a hard time going to the bathroom as it is without any thrills and since whistling is considered rude here in Russia, I can see why there is none of that going on in the bathroom!

Today in Star City, Russia
September 2010 in Houston, Texas.
There are two toilets on the International Space Station, located in the Zvezda and Tranquility modules. First of all, the principles of space toilets:

There are Liquid and solid wastes (#1 and #2, as they generally get interpreted) and they are trapped separately and processed separately. Air pressure (suction) is used to encourage/directed/wished for (you name it) waste to move in the right direction. Poo really can fly in space.

The primary rule of operation is always to prepare the loo after use, so that it's ready for the next guy. It's a simple rule to remember: After Pee or Poo, quickly prepare the Loo, so the crew doesn't have to wait in queue to let go the dew.

Assuming all systems are functioning, it should be possible to "fire" the toilet up in just a couple of minutes. I think it is an awkward process in the mockup, where gravity keeps everything in place. I don't know if it would be easier or more difficult in zero-G. There is a little seat in a wood finish here on the trainer. A nice touch indeed from the Russians! Below the seat is a disposable tank for solid waste. The hole in the seat should be pre-lined with a single-use packet. Assume the position. Then there is a receptacle with a funnel and hose that will grab liquid waste. It's very important to aim at the funnel from a distance away, rather than trying to get too intimate with it once the suction is under way. This point was stressed repeatedly and I think to remember why. I had an experience on the Space Shuttle potty trainer with Astro Clay...

The first thing that spins up is the urine/air separator motor. This is because we don't want any urine to get sucked into the fan, which would be a mess. So first we have to be sure we can separate urine from the air stream that pulls it along. This is done in a centrifuge. If you spin a mixture of heavy and light fluids together, the heavier stuff goes to the outside. In weightlessness, this is how they separate urine from air.

Once that device is spinning fast enough, a dose of urine preservative (mostly sulphuric acid and chrome trioxide) is flushed into the separator. This is to prevent crystals of urea or other contaminants forming in the plumbing, or in the tanks. This is another complication - we don't want nasty stuff like sulphuric acid to leak into the ISS. Horrible things could happen (far worse than if urine leaked into the compartment). So the tank that stores the preservative has to be triply redundant and extremely robust, and all the pipes have to have double layers and be resistant to acid corrosion.

What's really amazing is how accessible all of these components are. Simply lift up the floor panels around the loo, or open up the wall panel, and you can replace any pump, fan, device or tank. It has to be that way... this is a mission critical system!

And just this week the crew on the ISS had to do some toilet repairs. 

Here are some additional pictures from the Russian space toilet inside the Zvezda module

Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 19/20 flight engineer, performs the daily ambient flush of the potable water dispenser in the waste and hygiene compartment.
ISS toilet and the KTO container in the Russian Zvezda module
The urine collection system panel
A female urine collection cup
A male urine collection cup
The solid waste collection bag. It locks on to a ring under the toilet/commode seat and dangles inside the silver KTO container. When you are finished you just tug on the red tab. That action unseats the bag from the seat lip and airflow pulls the bag inside the KTO container. The red tab is connected to a drawstring encircling the bag’s opening. As the bag is sucked into the KTO you hang on to the red tab and the bag pulls itself shut, when it shuts you let go and it disappears inside the KTO.

Canadian Astronaut and soon to be 
1st Canadian Commander of the ISS Chris Hadfield:

NASA Astronaut Mike Massimino

** some information I got from Mark Shuttleworth who trained in Star City and spent almost 10 days in Space in 2002.