space

NASA Space Poop Challenge: Finding Relief in Space

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.

BACKGROUND

A spacesuit is much more than a set of clothes astronauts wear on spacewalks. A fully equipped spacesuit is really a one-person spacecraft. The formal name for the spacesuit used on the space shuttle and International Space Station is the Extravehicular Mobility Unit, or EMU. “Extravehicular” means outside of the vehicle or spacecraft. “Mobility” means that the astronaut can move around in the suit. The spacesuit protects the astronaut from the dangers of being outside in space.

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.

Minimum Requirements

  • 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”).

 

Solution Criteria

Soundness and Technical Readiness of the Design
Likelihood that the Solution will work as described to satisfy the minimum requirements with a minimum of risk.  This includes the technical readiness level (TLR) of the design.  

Gas Conservation

Effectiveness at ensuring the conservation of gas in the crew member’s suit

Health and Safety

Level of health and safety the Solution will provide to the crew member including dryness and prevention of pain, infection and permanent injury

Suit Integrity

Effectiveness ensuring the integrity of the crew member’s suit, including the number of entry/exit points required

Speed

Ease and feasibility of integrating the Solution with the body and the suit within 5 minutes.  

Ease of Use/ Constraints

Ease of use given the constraints required for using (e.g., clean shaven, limitations on timing of waste elimination, requirement to be near a specific technology, etc.)

Comfort

Level of physical, emotional, and psychological comfort the crew member will experience using the Solution, including while donning, moving around, and seated and strapped in

Ease of Incorporation

Ease of incorporating into existing suits and vehicle,

Other Benefits

Other benefits that the judges identify or the competitor points out that do not fall into the above categories.  Could also include judge preferences, such as for simplicity.

Constraints & Limitations

The crew member will have less than 60 minutes to get into and seal their spacesuit.  To ensure the crew member’s safety, the Solution needs to take no more than 5 minutes of that time.

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

Facts About Poop
Human feces ranges from 55% to 75% water. Much of the 25% to 45% that remains 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. Unlike coal, of course, this is a fuel that hardly needs to be sought or mined, but like coal, it can have a lot of value.
Facts About Urine

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.

Calculation for Total Storage of Fluid & Solid Waste

Urine: 6 L

Fecal matter: 450 mL
Menstruation: 80 mL

Feces Water

Feces: 55% – 75% water
(450 mL x .55 = 247.5 mL water)
(450 mL x .75 = 337.5 mL water)

Range: 247.5 mL – 337.5 mL

Opt for higher range for extra capacity

Feces Solid

(450 mL – 247.5 mL = 202.5 mL)
(450 mL – 337.5 mL = 112.5 mL)

Range: 112.5 mL – 202.5 mL

Opt for higher range for extra capacity

All Fluid

Urine + Fecal water + Menstruation
6 L (6,000 mL) + 337.5 mL + 80 mL = 6,417.5 mL or 6.4175 L

All Solid

Fecal solid
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.

 

METHODOLOGY

In order to examine breakthrough possibilities with the Space Poop Challenge, we employed the following methodology:

  1. Collection.
  2. Storage.
  3. Disposal.

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.  

ANALYSIS

Collection Phase

Material Science

The material science of the seal and collection system has to take into account comfort, movement, elasticity, antibacterial property, allergy, lightness, strength and durability. This requires further research into coatings, adhesives, speciality chemicals and advanced materials to meet the requirements. For elasticity, lightweight and compactness, it has to have properties like a balloon made from materials such as rubber, latex, silicone, polychloroprene or nylon fabric that meets the health and safety standards.

Feces

A unisex design for human solid waste collection provides an airtight seal around the anus. The component that touches the skin has to be seal tight to maintain pressure-demand suction without compromising leakage. In addition to the seal, an elastic strap system made be needed as secondary precaution and backup system.

Male Urine

Gender specific fluid seal component has to be developed. A male collection component would closely resembles an elastic condom mechanism that is tightly sealed at the end to prevent fluid leakage.

Female Urine & Menstruation

For a woman, similar to the solid waste collection system, a separate seal would securely collect the female’s’ urine and menstrual fluid. It’s plausible that a custom urine, menstrual and feces seal and valve system may be needed to miniaturize for comfort. It should be noted that though it could be a unified seal and value system, the tubing would separate the solid from the fluid for proper storage and analysis.   

Modification to LCVG Inner Suit

The Liquid Cooling and Ventilation Garment (LCVG) would need to be modified to create openings for the human waste. The openings should be minimal to support the collection system without adversely impacting the core cooling and ventilation function of the inner suit.

Demand Pressurized Valves

Most modern demand valves use a downstream rather than an upstream valve mechanism. In a downstream valve, the moving part of the valve opens in the same direction as the flow of liquid or gas and is kept closed by a spring. The usual form of downstream valve is a spring-loaded poppet with a hard elastomer seat sealing against an adjustable metal “crown” around the inlet orifice. The poppet is lifted away from the crown by a lever operated by the diaphragm.

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.

Universal Motor

To support the low pressure suction, a universal or suction DC motor can be used to operate the removal of the feces, urine and menstrual fluid. The motors must meet torque, low and high speed, lightweight, miniature, and low-energy requirements to support six days of operation.  

Storage Phase

Outer Layer Over the Inner Suit

The spacesuit leaves very little room for additional storage capacity. A 2” inch space between the astronaut’s body and the suit must be maintained for proper oxygen circulation. A storage solution for inside the suit would have to be incredibly thin to maintain the 2” inch gap yet through a larger surface area provide additional storage capacity. Think a layer on top of the inner tight 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 more plausible storage is likely the Primary Life Support Subsystem (PLSS) backpack that already serves as a storage and power source. Moreover, placing the storage inside the PLSS moves it away from the near vicinity of the body into a separate unit which increases safety and health.

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.

Disposal Phase

In the case of the legging storage approach, removal is as easy as taking off the outer layer to dispose the human waste through an outflow valve mechanism.

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.  

BRAINSTORMING

Jettison into Space
The topic of human waste can make most people feel queasy. Hence, it’s not an unnatural response to want to get this stuff out of the suit.

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 Dry
Freeze-drying or also referred to as lyophilisation, lyophilization, or cryodesiccation is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport. Freeze-drying works by freezing the material and then reducing the surrounding pressure to allow the frozen water in the material to sublimate directly from the solid phase to the gas phase.

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.

Recycle & Reuse

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.

RECOMMENDATION

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.

This approach would likely require substantial design changes to the PLSS and therefore would be a more costly investment and time required to implement the solution. However, we believe that in order to support the astronaut in space for the six day duration, this is the recommendation that we would provide to NASA.
 
Tune in for my next experiment!
 
Keep learning.
– Christian
 


This blog is moderated by Christian’s parents: https://medium.com/@ScottAmyx/ All comments will be reviewed and approved before publishing.

 

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