Packing for Mars: The Curious Science of Life in the Void

by Mary Roach

Gravity is why there are suns and planets in the first place. It is practically God. In the beginning, the cosmos was nothing but empty space and vast clouds of gases. Eventually the gases cooled to the point where tiny grains coalesced. These grains would have spent eternity moving through space, ignoring each other, had gravitational attraction not brought them together. Gravitation is the lust of the cosmos.

The anonymous researchers…discovered that this is the way dolphins do it. A third dolphin is always present during the mating process. This led to the creation of the space-going equivalent of aviation’s Mile High Club known as the Three Dolphin Club.

Zero-gravity excretion is not entirely a joking matter. The simple act of urination can, without gravity, become a medical emergency requiring catheterization and embarrassing radio consults with flight surgeons. “The urge to go is different in space,” says Weinstein. There is no early warning system as there is on Earth. Gravity causes liquid waste to accumulate on the floor of the bladder. As the bladder fills, stretch receptors are stimulated, alerting the bladder’s owner to the growing volume and delivering an incrementally more insistent signal to go. In zero gravity, the urine doesn’t collect at the bottom of the bladder. Surface tension causes it to adhere to the walls all around the organ. Only when the bladder is almost completely full do the sides begin to stretch and trigger the urge. And by then the bladder may be so full that it’s pressing the urethra shut.

He said he’d known women who, while out hiking or backpacking, are “able to take their pants down to their ankles and kind of lean back against a tree and just by moving things around a little bit, getting some room there, be able to fire away and direct it.” There was a silence while I contemplated this new and life-changing information. Chase went on. “I’m telling you, women can pee harder than men.