The space race of the 1960s resulted in numerous technological advances. Sending people into such a hostile environment provided myriad physiological challenges.
Famously, urination caught the engineers' attention a little too late.
In Advances in Physiology Education, Hunter Hollins of the National Air and Space Museum reviews Forgotten hardware: how to urinate in a spacesuit. A good chunk of the article deals with the development of the pressurized flight suit, necessary for both high altitude spy planes and the space program. These life-saving devices make urination problematic, even for dudes.
The most obvious solution would seem to be some sort of diaper. However, as anyone who has dealt with a baby knows, moist skin may break down and become uncomfortable. For a few hours this could work, but once flight became measured in days instead of hours, the adult diaper became impractical.
Guess how this works
The engineers looked to another off-the-shelf solution, the condom or Texas catheter. A condom-like sheath rolls over the penis; the opening at the other end connects to some sort of collection bag or bottle. These devices are used medically and for convenience (AKA Bladder Buddy, which the web site assures us makes a great gift). The man urinates and gravity pulls the urine down into the receptacle, away from the urethra.
Oops. No gravity in space. How do we keep the urine from causing trouble?
Up through the Apollo program, astronauts wore pressurized suits throughout their travels, even while in a pressurized cabin. A space-suit valve solved this problem, allowing astronauts to briefly increase the pressure in their suits and force urine into the external receptacle.
So we have dealt with dudes in space. But what about us women? Is this the real reason they grounded us for so long?
Space shuttle and space station missions run longer than those initial Mercury and Apollo missions. In a self-enclosed orbiting world, how can waste be handled? Enter the space toilet.
Click to Enlarge
When we use an earth toilet, we need a single opening. Whatever we excrete, via the power of gravity, falls into the bowl. In most first-world countries, water in the bowl then exits (also via gravity) while more water flushes the bowl and refills it.
Since space has no gravity, we have to do things a bit differently. The diagram shows thigh bars and foot restraints to keep the astronaut on the toilet, something that rarely presents a problem here on earth (unless the user has been drinking a lot).
The space toilet actually has two openings. One appears to be a traditional toilet opening for poop; the other opening is a funnel shaped for the gender of the user. The funnel goes over the urethral opening. Vacuums pull the waste away from the user, making up for the absence of gravity.
The funnel urination system means that in space, women can pee standing up!
This system also allows urine to be processed to recover water. Waste not, want not, when you are miles above the earth!
The lack of gravity also affects urination in other ways. Total body water redistributes, resulting in diuresis shortly after entering weightlessness. The space toilet gets unpacked first! Bladders also get fuller in space. Without gravity, urine does not "pool" in the lower portions of the bladder where most of the sensory neurons lie. We ordinarily feel an urge to void around 1/3 of bladder capacity. In space, the bladder often must get 2/3 full before those nerves get stimulated.
Urine is a fact of our lives, and it must be dealt with, even while we face the final frontier.