ABOUT THE NASA SPACE POOP CHALLENGE
The U.S. National Aeronautics and Space Administration (NASA) seeks proposed solutions for urine, fecal and menstrual management systems to be used in the crew’s launch and entry suits over a continuous duration of up to 144 hours. An in-suit waste management system would be beneficial for contingency scenarios or for any long duration tasks.
Waste management systems should address fecal, urine, and/or menstrual waste management in a pressurized survival suit environment for six days while protecting the safety and health of crew members.
Three types of spacesuits exist for different purposes: IVA (intravehicular activity), EVA (extravehicular activity), and IEVA (intra/extravehicular activity). For our purpose, we will assume IEVA.
The spacesuit consists of several pieces. The Hard Upper Torso covers the astronaut’s chest. The arm assembly covers the arms and connects to the gloves. The helmet and Extravehicular Visor Assembly are designed to protect the astronaut’s head while still allowing him or her to see as much as possible. The Lower Torso Assembly covers the astronaut’s legs and feet. The flexible parts of the suit are made from several layers of material. The layers perform different functions, from keeping oxygen within the spacesuit to protecting from space dust impacts.
Underneath the spacesuit, astronauts wear a Liquid Cooling and Ventilation Garment (LCVG) in contact with the astronaut’s skin. Tubes are woven into this tight-fitting piece of clothing that covers the entire body except for the head, hands and feet. Water flows through these tubes to keep the astronaut cool during the spacewalk.
On the back of the spacesuit is a backpack called the Primary Life Support Subsystem. This backpack contains the oxygen that astronauts breathe during a spacewalk. It also removes carbon dioxide that astronauts exhale. The backpack also provides electricity for the suit. A fan moves the oxygen through the spacesuit and life support systems, and a water tank holds the cooling water that flows through the Liquid Cooling and Ventilation Garment.
Also attached to the back of the suit is a device called the Simplified Aid for Extravehicular Activity Rescue, or SAFER. SAFER has several small thruster jets. If an astronaut became separated from the space station, he or she could use SAFER to fly back.
Skintight suits, also known as mechanical counterpressure suits or space activity suits, are a proposed design which would use a heavy elastic body stocking to compress the body. The head is in a pressurized helmet, but the rest of the body is pressurized only by the elastic effect of the suit. This eliminates the constant volume problem, reduces the possibility of a space suit depressurization and gives a very lightweight suit. When not worn, the elastic garments’ may appear to be that of clothing for a small child. These suits may be very difficult to put on and face problems with providing a uniform pressure. Most proposals use the body’s natural perspiration to keep cool. Sweat evaporates readily in vacuum and may desublime or deposit on objects nearby: optics, sensors, the astronaut’s visor, and other surfaces. The icy film and sweat residue may contaminate sensitive surfaces and affect optical performance.
The whole suit, including the gloves, is pressurized to 4.3 PSID to enable the body to function properly. Without pressure the body swells, loses most of its circulation, and of course, causes extreme pain. The gloves are attached by metal bearings to the sleeves to ensure a proper seal. Once the suit is sealed, it must remain sealed until the astronaut enters another pressurized environment. While sealed, it is impossible for an astronaut to access their own body, even to scratch their nose.
Gas (100% oxygen) enters at 4.5 cubic feet per minute through a waist level connector to fill the 2” space between the astronaut’s body and the suit, and circulates out through another waist level connector to be cleaned and brought back to the suit. A mesh cover protects against particles getting into the air connectors. If they did get inside, they could easily block the flow of air.
This gas supply is clearly a very precious commodity. While a very small amount is lost to leakage, the Solution must not add to this leakage. However, careful use of 1000 cubic centimeters per minute (0.01 cubic feet per minute) over a period of 3 minutes per use would not jeopardize the integrity of the suit.
The suit allows the astronauts to move around, get into tight spaces, and sit down and buckle up for long periods of time. Your Solution should be comfortable in all of these situations.
Finally, a small power sources of up to 28V with current below 100mA could be provided inside or outside of the suit.
WHAT A BREAKTHROUGH LOOKS LIKE
What’s needed is a system inside a spacesuit that collects human waste for up to 144 hours and routes it away from the body, without the use of hands. The system has to operate in the conditions of space – where solids, fluids, and gases float around in microgravity (what most of us think of as “zero gravity”) and don’t necessarily mix or act the way they would on earth. This system will help keep astronauts alive and healthy over 6 days, or 144 hrs.
You will design a solution that can be incorporated into the orange Modified Advanced Crew Escape Suit (MACES). MACES has been adapted for missions of longer duration than the original Advanced Crew Escape Suit (ACES) was designed for.
A system to route and collect human waste away from the body without the use of hands
Keep urine and/or fecal waste away from a crew member’s body for a minimum of 144 hours while in a space suit
Operate in a microgravity scenario
Operate within a full launch and entry suit at an internal pressure of 4.3 PSID and 100% oxygen environment which cannot be opened for manual access within the 144 hour time period
Operate while a crew member is moving, bending, and/or seated and strapped into a chair
Manage at least one of the three following human wastes for up to 6 days
Manage up to 1L (4 cups) per day of urine per crew member (based on planned liquid intake during mission)
Manage up to 75 grams (⅓ cup) of fecal mass and 75mL fecal volume per crew member (based on planned food intake during mission). Fecal matter may range from liquid to solid, but the Solution is not required to handle uncontrollable, ongoing diarrhea.
Manage up to 80 mL of menstrual fluid over 6 days
Require less than five minutes for a crew member to, on their own, set up and secure the Solution to their body, prior to, or along with, getting into their launch and entry suit.
Operate effectively for both men and women of varying size and weight within the range of 1% to 99% on the Airforce ANSUR anthropometric database.
Relevant measurements for your solution, which might include, but not be limited to: waist circumference (24.2 to 43.5”), Buttock circumference (33.1 to 45.2”), Hip breadth, sitting (31.5 to 46.5”), Waist back (15.4 to 22”) and Waist depth (5.9” to 11.8”).
Health and Safety
Ease of Use/ Constraints
Ease of Incorporation
Constraints & Limitations
Gas (100% oxygen) enters at 4.5 cubic feet per minute through a waist level connector to fill the 2” inch space between the astronaut’s body and the suit, and circulates out through another waist level connector to be cleaned and brought back to the suit.
THE SMELLY FACTS
The energy-generating part of this equation involves solid waste only, but all that urine humans produce every year has a role too. According to a Swedish study, every 1,000 liters (264 gal.) of urine contains 600 g (.66 lbs) apiece of phosphorous and potassium and 900 g (1 lb.) of sulphur. Combining both solid and liquid waste, a single human produces 4.5 kg (9.9 lbs) of nitrogen per year, according to the World Health Organization. All of this could be recycled as nutrients for crops, increasing yields and helping to bring down both poverty and hunger.
Urine: 6 L
Range: 247.5 mL – 337.5 mL
Range: 112.5 mL – 202.5 mL
Current Available Solutions
Current commercial products that provide urine waste management utilize gravity to route and collect urine away from the body.
Some require the use of hands, and most are not meant to be used for 144 hours.
No commercial products have been found that provide fecal waste management for a 144-hour period with or without the use of hands.
While the implemented Solution can be discarded after each mission, it does have to function well for 6 days and multiple bowel and bladder evacuations.
Prior to that, men wore Urine Collection and Transfer Assembly (UCTA) and Fecal Collection Systems (FCS).
Women have never had anything besides the adult diaper while wearing a suit. When not wearing a suit, but within the vehicle, women had a choice of 3 versions of cup-type urine collection systems that used air flow to effectively cause urine to swirl away from a woman’s body.
A Urine Collection Device (UCD) is used during spaceflight to collect and contain urine. A UCD consists of a storage bag, adapter tubing, and disconnect hardware for both the male and female adapters. Each UCD bag can store approximately 1 quart of urine. The bags are either disposed of in the spacecraft waste management system (WMS) or returned to earth for further research. UCDs are also used outside the spacecraft during Extravehicular Activity (EVA) operations.
In order to examine breakthrough possibilities with the Space Poop Challenge, we employed the following methodology:
In the Collection phase, we are interested in exploring possible solutions to collect human waste and route it away from the body without the use of hands.
In the Storage phase, we are examine different methods to store the urine, fecal matter and menstrual fluid.
In the Disposal phase, we evaluate the methods to remove the human waste from the spacesuit.
Female Urine & Menstruation
Modification to LCVG Inner Suit
Demand Pressurized Valves
The value system should ensure no reverse flow of fluid or solid back to the body.
Tightly sealed diluter-demand and pressure-demand suction system operates only when there is a discharge. Due to microgravity, a powered vacuum suction system is needed to ensure that the fluid and especially solid is moved away from the body into the storage chamber. For minimal power consumption, it should maintain a constant low air pressure. When the system detects fluid or solid discharge (through change in pressure, computer vision or sensors), the suction power should increase proportional to the type, size, hardness and duration to properly dispose of the matter quickly away from the body.
Outer Layer Over the Inner Suit
Not knowing the detailed specifications of the inner suit, tubing, wires, and other sensitive equipment inside the suit, it’s difficult to gauge the available surface area for storage. Assuming that an outer storage layer over the entire body is not feasible, a partial storage solution up to the waist or pelvis area through a legging system that can be pulled over the inner suit. The surface area may not be large enough to meet all the storage requirements but it would be significantly improved from today’s astronaut single-use diapers.
Enhanced Primary Life Support Subsystem
The PLSS already has a motor for removing carbon dioxide but it’s possible that a dedicated motor for human waste removal is needed. This would also require increase in battery requirement of the PLSS.
Though the PLSS is the more logical choice, it may result in a greater design change to the entire spacesuit and PLSS to accommodate the increased need for solid and fluid storage, power, additional motors and other technology requirements.
For storage in the enhanced PLSS, outflow valves for solids and fluid can expunge the human waste from the PLSS system.
For cleaning and reuse, some components inside the suit could be disposable or reusable. The proper disinfecting and cleaning protocols that NASA requires can be applied to ensure safe and clean operation of the entire system for continual reuse. For the PLSS system, the human waste compartments may have to be removable for cleaning.
The problem, of course, how do you safely jettison this stuff into space so that it’s does not compromise your suit? Any miscalculation of gases, suit pressure or the possibility of the spacesuit becoming vulnerable to space’s hostile environment when opening it to dispose the waste can lead to disastrous consequences.
One of the biggest dangers in space and reentry into Earth’s atmosphere is space debris, including junk, waste, trash, litter, and defunct man-made objects in space – old satellites, spent rocket stages, and fragments from disintegration, erosion, and collisions. Space debris is incredibly dangerous to astronauts and their safety. Therefore, jettisoning human waste would be adding to the space debris that could increase the likely of accidents and deaths.
Freeze drying on a small scale can be achieved by mechanical refrigeration, dry ice in aqueous methanol, or liquid nitrogen.
Nitrogen is an inert gas that does not readily burn or support combustion. At elevated temperatures and pressures, nitrogen reacts with oxygen to form various nitrogen oxides (usually NO and NO2). If the nitrogen is in liquid form, it is not more reactive to combustion, but would be a bit less reactive in the sense the temperature is lower.
However, nitrogen atoms are often found in many explosive compounds, such as TNT, nitroglycerin or hydrogen cyanide. Yes, the activation energy is high but certainly not the most prudent idea to introduce to a spacesuit designed for life-preservation in space.
Methanol is a flammable and combustible liquids at a flashpoint of <73° F. So definitely, not a good idea to have it inside a spacesuit.
Mechanical refrigeration system would add unnecessary bulk and increased electric use.
Freeze dry, regardless of the method, does not help alleviate the collection, storage and disposal issues.
Survival in space requires recycling, including body fluids and feces. Human feces serve as fertilizer or biosolids, which is necessary to grow food in space or on an inhospitable planet. It contains essential plant nutrients such as nitrogen, phosphorus and potassium. Urine also contains nitrogen, phosphorus and potassium.
The value doesn’t stop there. Human feces ranges from 55% to 75% water. That can be separated and recycled into drinkable water. The remaining 25% to 45% consists of gaseous methane—produced by bacterial breakdown—and a solid residue which, if dried and concentrated, has an energy content similar to that of coal. It provides energy.
The technology to convert poop, urine or menstrual fluid into safe, drinkable water exists. For instance, a few years ago Bill Gates drank poop water processed through the Omni Processor. The question is can the technology and process be miniaturized enough to fit inside a spacesuit or the PLSS? Certainly, if astronauts were required to live in their spacesuits for months, the design would be drastically changed to account for recycling but for a six day storage of human waste, the added bulk of a recycling system may not prove sagacious in investment.
After the disposal phase, of course, the human waste can be recycled in the space station or shuttle, assuming that it’s not needed for research.
Minimum Viable Product with Minimal Change: Poopy Pants
The simplest solution with the least change impact would involve a thin pants-like garment that the astronaut can wear over the LCVG inner suit. To minimize obstruction with tubes and electrical connections, the human waste garment would take up the lower portion of the body, resembling long leggings that can expand to contain human waste without jeopardizing the space needed for oxygen circulation inside the suit. The current LCVG would need to be modified to have openings for suction cups and tubes to capture the urine, fecal matter, and menstruation fluid into this new garment. It would contain separate compartments for liquid and solid. The poopy pants solution would need to meet elastic, non-flammable, antibacterial, leak-proof and other material science requirements to ensure total safety for the astronaut.
The biggest drawback with this approach is that, depending on the expandability capacity, it may not be sufficient to meet all the human waste collection and storage requirements. Nonetheless, it would be an improvement from today’s astronaut diapers.
Complete Solution with Potentially Substantial Change to Spacesuit and the Primary Life Support Subsystem
For a solution that can holistically meet the NASA Space Poop Challenge requirements, it would require a more permanent design change to the PLSS. Rather than partially meeting the requirements through a garment approach inside the already tight space suit, it’s more logical to expand the capability of the PLSS to accommodate the human waste storage and added battery and electronic components without jeopardizing the safety and health of the astronaut. There are still some changes needed to the LCVG to integrate into the PLSS for transfer of human waste but it presents the most elegant solution.
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