The Challenge of Space Toilets
In November 2016, the American space agency NASA solicited ideas
for space suits that could deal with human waste over several days
of continuous wear.
The Space Poop Challenge was publicized on the
HeroX
crowd-sourcing site.
Inventors had one month to submit their ideas,
in hopes of winning a $30,000 prize.
Astronauts currently wear an absorbent diaper inside their space suit.
That's fine for the 10 hours or so required for
launch and landing to and from the International Space Station.
However, future missions including a possible trip to Mars could require
being sealed inside a space suit for up to a few days.
The Requirements
The 2016 competition called for a system that could be worn for 144 hours,
or six days, handling all urine, feces, and menstrual emissions.
NASA anticipates that adding up every day to up to
a liter of urine,
75 grams or 75 ml of feces,
and 80 ml of menstrual emissions.
Only 75 grams of feces!
The first rule of the Space Poop Challenge is: Do not poop.
Well, OK, sure.
You could get fluid into a sealed space suit for drinking,
but you wouldn't be eating any solid food inside of there.
Still, this suggests that the six-day marathon sessions can be planned
so you can largely clear out your lower digestive tract.
The new plan is clearly for planned use, not emergency situations.
However, NASA wants this system to require no more than 5 minutes out of
the typical 60 minutes to climb in and seal up, so there is some sense
of urgency if not emergency.
Meanwhile, the estate of Frank Herbert will be claiming
prior art
on the Stillsuit concept.
What's Wrong With Current Systems?
Terrestrial toilets rely on gravity to draw waste material away from the body.
Space toilets
must use airflow.
One astronaut described it as voiding your bowels into a vacuum cleaner.
However, this requires relatively high-volume air flow,
something you can't do down inside a space suit.
Also, existing toilet systems in space or on the ground require the
use of your hands.
NASA needs a totally hands-free system to collect waste
and keep it away from the body.
Toilet system on board the U.S. Space Shuttle,
as seen in the National Air and Space Museum in Washington D.C.
The current system of diapers is OK for up to 10 hours
at a time.
However, if you wear diapers without changing them for over a day,
you will get diaper rash.
That could worsen to infection and even sepsis.
As NASA said on the HeroX page:
You don't want any of these solids and fluids stuck to your body for 6 days.
If you have ever taken care of a baby,
you know how easy it is to get diaper rash.
Left untreated, that can turn into a dangerous infection.
You don't want fecal matter getting into the urethra or the vagina,
causing urinary tract or vaginal infections.
Of course, you don't want them to migrate to mouth, nose, ears or cuts.
The point? Your Solution has to keep all of these materials away from
the body, its orifices, and the spacesuit air inlet/outlet orifices.
Astronaut diapers, or "Disposable Absorption Containment Trunk",
as seen in the National Air and Space Museum in Washington D.C.
Further challenges
This is further complicated by the strange behavior of liquids in a
microgravity environment.
They may float around, or they may stick to surfaces because of surface
tension.
Two different liquids may or may not mix when they meet.
And, unlike the cabin or space station atmosphere,
it's 100% oxygen at lower pressure inside a suit.
The Space Poop Challenge was described by
Time
and
Forbes
magazines.
NASA said that they wanted to test the winning ideas by the end of 2017
and deploy a successful system by the end of 2020.
Next article:
"It's nice to have space to defecate" — The winner of NASA's Space Poop Challenge
