When the Apollo program sent astronauts on moon missions that lasted a week or more, every 12-year-old wondered the same thing- how do you poop in space? We didn't get much in the way of answers, as NASA was fully aware of the public sensibilities of the time. But they had to deal with human body functions along with all the other technicalities of space travel. The system they worked out was difficult, time-consuming, and unpleasant. NASA's history site explains.
The fecal collection system presented am even more distasteful set of problems. The collection process required a great dead of skill to preclude escape of feces from the collection bag and consequent soiling of the crew, their clothing, or cabin surfaces. The fecal collection process was, moreover, extremely time consuming because of the level of difficulty involved with use of the system. An Apollo 7 astronaut estimated the time required to correctly accomplish the process at 45 minutes. Good placement of fecal bags was difficult to attain; this was further complicated by the fact that the flap at the back of the constant wear garment created an opening that was too small for easy placement of the bags.
How bad could it be? Jason Torchinsky decided to find out. Unable to attain an original collection bag, he built one to specifications and tested it out himself. You can read the review at Jalopnik, but be aware the language is graphic, and the description is not for the faint of heart. -via Digg