Ever since NASA began sending shuttles into space, you`ve wondered, haven`t you, how do the astronauts . . . how do they . . . well, let`s put it this way: When you`ve gotta go, you just find a bathroom, a lavatory or a stand of bushes at the side of the road and go. But what do the astronauts do? It`s a good question, because in an orbiting shuttle the astronauts are weightless. As you`ve seen on television, they can walk up walls and across the ceiling; they can float in midair. There`s no gravity to keep them in the seats, no gravity to keep their feet on the floor. That`s the easy part of the astronauts` gotta-go problem. The hard part: There`s no gravity to keep anything from floating about the cabin.
So NASA contracted with General Electric to build a Space Age water closet that defies zero-gravity. The result is the shuttle`s extraordinary waste collection system (WCS): ”an integrated, multifunctional system used primarily to collect and process biological wastes from crew members in a zero-gravity environment.”
The description is from NASA`S 1,001-page ”National Space Transportation System Reference: Volume 1, Systems and Facilities,” which goes on to explain that ”the WCS is located in the middeck of the orbiter crew compartment in a 29-inch-wide area immediately aft of the crew ingress and egress deck side hatch.” The commode itself is 27 by 27 by 29 inches and, according to NASA,
”is used like a standard toilet.” Not quite.
”The system collects, stores and dries fecal wastes and associated tissues; processes urine and transfers it to the waste-water tank; processes EMU (extravehicular mobility unit) condensate water from the airlock and transfers it to the waste-water tank if an extravehicular activity is required on a mission; provides an interface for venting trash container gases overboard; provides an interface for dumping ARS (air revitalization system)
waste water overboard in a contingency situation; and transfers ARS waste water to the waste-water tank.”
To put it another way, the WCS collects and disposes of the same stuff as a standard water closet but also collects and disposes of wastes from elsewhere in the shuttle, sometimes.
To make personal use of the WCS, the astronaut enters the ”waste management compartment” and not only shuts the door but also draws the
”waste management system privacy curtains,” one of which is ”attached to the top of the door and interfaces with the edge of the interdeck access.”
The other curtain also is attached to the door but ”interfaces with the galley, if installed.” The compartment door also serves as an ”ingress platform during prelaunch (vertical) operations.”
Once inside, the astronaut may wish to sit on the commode, in which case he or she had best not be in a great hurry because there is much to do before the main event:
”The commode contains a single multilayer hydrophobic porous bag liner for collecting and storing solid waste.” (No, the bag does not have rabies;
it simply refuses to collect water; the water passes right through on its way to a waste water tank.)
”When the commode is in use, it is pressurized, and transport air flow is provided by (one of two) fan separator(s). When the commode is not in use, it is depressurized for solid waste drying and deactivation. The urinal is essentially a funnel attached to a hose and provides the capability to collect and transport liquid waste to the waste water tank.
”The fan separator provides transport air flow for the liquid. The fan separators separate waste liquid from the air flow. The liquid is drawn off to the waste water tank, and the air returns to the crew cabin through the odor and bacteria filter,” which, as the name suggests, ”removes odors and bacteria from the air that returns to the cabin.”
To make sure the aforementioned ”biological wastes and associated tissues” enter the WCS, the astronaut must be seated firmly on the seat of the commode or, if standing, be firmly rooted to the floor. Were the astronaut to begin floating at this point, he would be joined by what he had hoped to leave in the commode.
As NASA explains it, ”the system employs various restraints and adjustments to enable the user to achieve the proper body positioning to urinate or defecate in a zero-gravity environment. Two foot restraints are provided. A toe bar is located at the commode base and is used to urinate standing.
”A footrest restrains the feet of a crew member sitting on the commode. It consists of an adjustable platform with detachable Velcro straps for securing the feet. . . .
”Two body restraints are provided for use when crew members are seated on the commode. The primary restraint is a thigh bar that the crew member lifts up out of the detent position, rotates over the thigh and releases. It exerts a preloaded force on each thigh of approximately 10 pounds. The second restraint is a backup method. It consists of four Velcro fabric thigh straps with a spring hook on one end. Two of the straps are attached to the top front commode surface mating attach points, and the other two are installed on a bracket with five holes on the upper sides of the commode, below and outboard of the thigh bars. The crew member is secured in position by wrapping two straps over each thigh and attaching the mating Velcro surfaces.
Once strapped in, the astronaut must tell the WCS exactly what it`s supposed to do by operating its controls:
”The controls on the waste collection system are the vacuum valve, fan separator select switch, mode switch, fan separator bypass switches and commode control handle. The system uses dc power to control the fan separators and ac power for fan separator operations. The mode switch and the commode control handle are mechanically interlocked to prevent undesirable system configurations. The remaining controls operate independently. The fan separator bypass switches allow the crew member to manually override a fan separator limit switch failure.
”For launch and entry the vacuum valve is closed. During on-orbit operations when the WCS is not in use, the vacuum valve is opened. This exposes the commode (overboard) via the vacuum vent system, and any solid wastes in the commode are dried. The hydrophobic bag liner in the commode allows gas from the commode to vent overboard, but does not allow the passage of free waste.
”In the urine collection mode, the vacuum valve remains in open. The fan sep select switch is positioned 1 or 2. When positioned to 1, main bus A dc power is supplied to the mode switch; and when positioned to 2, MNB dc power is supplied to the mode switch. The mode switch positioned to WCS/EMU energizes a relay for a fan separator (dependent on fan sep 1 or 2 position). In either the ”urine collection mode” or ”urine and feces collection mode,” it is the job of the fan separator to create a gentle suction, necessary to keep those biological wastes and associated tissues moving in the right direction-down.
”The liquid and air mixture from the urinal line enters the fan separator axially and is carried to a rotating chamber. The mixture first contacts a rotating impact separator that throws the liquid to the outer walls of the rotating fluid reservoir. Centrifugal force separates the liquid and draws it into a stationary pitot tube in a reservoir and directs the liquid to the waste water tank. Air is drawn out of the rotating chamber by a blower that passes the air through the odor and bacteria filter, where it mixes with cabin air and re-enters the crew cabin.
”In the urine and feces collection mode, the commode control handle is pulled up, and the commode is pressurized with cabin air through the debris screen and flow restrictor in approximately 20 seconds. . . .
”The commode seat is made of a contoured, compliant, semisoft material that provides proper positioning of the user and is sealed to minimize air leakage. Feces enter the commode through the 4-inch-diameter seat opening and are drawn in by cabin air flowing through holes under the seat at 30 cubic feet per minute. Fecal mater and tissues are deposited on the porous bag liner, and air is drawn through the hydrophobic liner material to the fan separator.
”The hydrophobic liner material prevents free liquid and bacteria from leaving the collector. (Toilet tissue is the only paper item permitted to be disposed of in the commode.) Urine is processed as in the urine collection mode. The off/down position closes the sliding gate valve and depressurizes the commode for deactivation and solid waste drying. If the handle is left partially up, it would cause loss of cabin air through the vacuum vent.”
But what if it doesn`t work?
”If both fan separators in the waste collection system fail, feces are collected by the Apollo fecal bag. . . . (If) it is not possible to dump urine overboard, urine may be collected using a contingency urine collection device.”
However sophisticated this marvel of Space Age technology, those primitive Apollo fecal bags do come in handy.
”They`ve had some problems with the system,” says Craig Kovault, spaceflight expert for Aviation Week. ”When they first flew it, it ground up and dried the feces so fine that it turned into a powder and came floating out. There`s a famous story about how Sally Ride was starting to eat a cracker and one of the other crewmen on Mission 7 noticed the black flecks on it and said, `Don`t eat that.` ”
