There was a certain strategy to it, which involved aiming for the minimum of pain when using the device. If she opened the valve too soon, the suction would grab at her. And when it resealed itself it was liable to trap a little piece of her inside it. The way round that was to start pissing a split second before opening the valve. But there was a danger that the funnel would just slip off, and off would float her piss in little golden globules.

It took her a few seconds to be able to let go.

Now that she’d gotten set up there, she considered whether to try taking a dump. That was actually easier, mechanically, than peeing. She’d have to start up the slinger, a spinning drum under the commode. The shit would stick to the walls of the drum, and later she would turn a switch to expose the drum to vacuum, and the shit would be frozen and dried out.

But, though she felt a pressure in her lower gut, there was nothing doing; she suspected it was going to take her a few days to relax enough to unclench. And besides, there was no gravity to help her, as the guys had informed her with glee; she wasn’t looking forward to the experience.

She took a couple of wet wipes and cleaned out the inside of the funnel. The wipes might have come out of any drugstore back home, except for the strong stink of disinfectant about them.

She unlocked herself from the john seat. She pushed her hands into the washbasin, a plastic globe which sprayed water across her skin and out into a waste tank. One or two droplets escaped the basin and went oscillating around the john, but she swatted them out of the air easily. There was a row of towel holders on the wall, little color-coded rubber diaphragms: towels, their corners shoved into the holders, hung out in the air like flags. She dried her hands.

She heard a noise; she turned.

Ralph Gershon was in the wardroom, wearing a T-shirt and shorts. He was just floating, with a plastic can of Coke in one hand and a silver-gray lithium hydroxide canister in the other. The lith canisters were used to scrub carbon dioxide out of the recycled air, and they had to be checked and changed regularly. The familiar red-and-white Coke can was pretty much the normal size and shape, except for a baby-style microgravity dispenser at the top.

Gershon held a finger up to his lips — evidently Stone was still asleep — and he held the can out toward her.

She shook her head. “Too gassy.”