Teams | Waste to Base Materials Challenge: Sustainable Reprocessing in Space | HeroX

Original source (on modern site) | Article images: [1]

Imagine you are on a mission to Mars. 

The journey to Mars and back is going to take two to three years, and there may not be any supply ships. To be as efficient and self-sufficient as possible, you will need to be able to recycle, repurpose, or reprocess things and make what you need from base materials. A completely efficient cycle is almost impossible, and some waste will have to be jettisoned to reduce mass and free up space inside the spacecraft. But ideally, you will have little to almost no waste since everything gets broken down and remade into new things.  There are a lot of different kinds of waste on a spacecraft. What are the different ways that those useless waste streams can be repurposed?

This challenge is all about finding ways to convert waste into base materials and other useful things, like propellant or feedstock for 3D printing.  We are looking for your ideas for how to convert different waste streams into useful materials that can then be made into needed things and cycled through multiple times - and we are looking for ideas to convert waste into propellant.  Eventually, we would like to integrate all the different processes into a robust ecosystem that allows a spacecraft to launch from Earth with the lowest possible mass.  For now, we are asking you to share your ideas for waste management/conversion in several specific categories:

1. Trash
2. Fecal waste
3. Foam packaging material
4. Carbon dioxide (CO2) processing

Winning ideas in each category will each receive a prize of $1,000. Additionally, judges will recognize "best in class" ideas, awarding each a prize of $1,000. A total prize purse of $24,000 will be awarded.

NASA's Logistics Reduction Project is developing the future of materials management in next generation spacecraft and also for surface settlements. Winning ideas from this challenge will be included in a white paper that will be part of the roadmap for future technology development work. Go to the Guidelines Tab to learn more details about this challenge.

Background

NASA has already developed a number of systems that process different types of waste, see image below. These are currently in use in spacecraft and at the International Space Station (ISS). For example, scrubbers remove exhaled carbon dioxide (CO2) from the air and, with the addition of hydrogen, convert it into oxygen and other hydrocarbons. But there is always room for improvement, and longer missions will require more efficient, more integrated solutions to waste management.  

For long-term missions, efficient use of space and resources means that very little material is sitting in storage, waiting to be useful. As something becomes waste, systems are needed to process and convert those things into new items or into base materials that can be readily converted into needed items, such as propellant or feedstock for in-space manufacturing. Ideally, a spacecraft will become a perfect, closed, circular economy. For this to occur, the different processes for different types of waste must all be integrated into a single system. But the journey to that complete integration starts with the collection of different ideas for handling different waste streams.  

NASA has identified the waste streams that most urgently need addressing, see category descriptions below. Ideas can be as straightforward as identifying a process to allow a necessary conversion to occur safely on a spacecraft. Or they can be as speculative as proposing a new base material for clothes or foam packaging that can be readily recycled onboard to serve other purposes.   

Although we are interested in ideas at any level of technical maturity, we expect most submissions to contain early stage ideas, or modifications of existing technologies.   There is a preference for approaches that can be implemented within five years, and every attempt should be made to minimize mass and volume.  Additionally, proposed approaches have to be compatible with a number of spacecraft constraints:  

• Solutions should occupy a total volume equivalent to the size of a standard refrigerator or smaller.  The volume can be occupied in any form factor that is appropriate.  (For reference, a standard payload rack on the ISS occupies a volume that is 2 meters high, by 1.05 meters wide, by 0.86 meters deep - with a total usable volume of 1.571 m3, or 55.5 ft3.)
• The mass of a solution should be less than 300kg.  Bear in mind that one criterion of success is the reduction in launch mass achieved.
• Power consumption should be less than 500W continuous, with peak draw of less than 700W.
• Proposed processes have to address concerns around production of or exposure to dangerous by-products. For example, eliminating or providing mitigation measures for situations such as:
  • Outgassing.
  • Production of flammable by-products.
  • Production of toxic or hazardous by-products.
• Proposed processes should consider how to manage waste heat.
• Solutions must be robust to spaceflight and launch loads.
• Ability to work in environments with variable gravity.

Participants can submit ideas to more than one category and can submit multiple ideas to the same category, as long as those ideas are substantially different from one another. NASA will recognize up to 24 winning ideas, and participants are eligible to win multiple awards. These ideas will become part of the roadmap for NASA's future technology development efforts.

Waste Stream Categories

Trash 

Trash consists of food, drink pouches, wet wipes, cotton clothes and towels, hygiene products, plastics and ziplock bags, velcro, and nitrile gloves. These items are primarily composed of carbon, hydrogen, oxygen, and small amounts of nitrogen. Water is also often present and its recovery is valuable. In fact water is already recovered from humidity condensate and urine on the International Space Station.

We are interested in processes that can recover water. We are also interested in ways to convert dry trash into materials that can become the base material for making new things, like feedstock for 3D printing of broken or needed components, such as

gears, elastomers, gaskets, storage containers, tools, etc. Keep in mind that a spacecraft has limited volume and no gravity, so any process that converts dry trash into reusable base materials must meet constraints around volume, mass, power consumption, waste heat, and the avoidance of highly reactive or hazardous reagents.  Outgassing is a particular concern. Common recycling approaches that shred mixed waste and then separate different components for material-specific reprocessing are not currently practical onboard, but process modifications might change that. Novel approaches to recycling are of interest, as are approaches that might start with a new base material for clothing and packaging. In the case of proposing new base materials, remember that the required performance properties of a polymer used to make gears or tools are likely very different from those used to make clothes or storage containers.

Fecal Waste 

Fecal waste needs to be made biologically safe, is composed generally of the same elements as trash, and has significant amounts of water. 

In addition to water, fecal waste is rich in microbes. We want to recover the water, and we are also interested in processes that can harness the microbial activity inherent in this waste stream. Urine falls in this waste category too. What are the possible uses for the brine and salts left after water removal?

Foam Packing 

Foam packing is used to protect items from the force of high acceleration during launch. After launch the foam is not needed, and it takes up valuable open volume in the spacecraft. Most foam used for this purpose is ZOTEK, Plastazote, or a similar highly-crosslinked material, which can be difficult to reprocess.  These are lightweight, high performance materials that are easily fabricated into complex shapes. They are made without chemical blowing agents and are top-rated for both flame and outgassing performance.

Although space missions currently use ZOTEK or Plastazote, other new foams can be proposed if they meet the needed performance specifications (launch, landing, and fire resistance requirements), and if a compelling case can be made for how they contribute to the spacecraft's integrated materials lifecycle. For example, if a foam can be processed into feedstock for 3D printers, that would be a tremendous advantage since the feedstock would occupy significantly less volume than the foam, and feedstock for 3D printers wouldn't need to be carried onboard separately. Another approach would be to consider the lifecycle of foam usage in a mission. For example, after launch, foam is then compacted into radiation shields and stored for use on storm shelters during Mars transit. Upon arrival at Mars, foam is re-transformed into packing foam to protect delicate instruments sent to the Mars surface, and foam is also converted into propellant for the Mars descent vehicle. On the return trip to Earth, the remaining foam is used as propellant for ion thrusters and as gas for resisto-jet thrusters for spacecraft maneuvering.

Carbon Dioxide (CO2) Processing 

CO2 is exhaled by astronauts and then extracted from the air. The Environmental Control and Life Support System then processes the CO2, with the addition of hydrogen, to recover  oxygen while producing by-product hydrocarbons like methane, ethylene, and acetylene. These hydrocarbons are currently vented to space, but they also are potential resources. 

How can we extract value from those hydrocarbons? We are interested in processes that convert them into propellants, usable materials, or starting materials for other onboard processes.

Prize

NASA will recognize up to 24 winning ideas, and participants are eligible to win multiple awards. Although the same idea may be submitted to multiple categories, responsive submissions will make a strong case for why the idea is relevant and applicable to the selected category. At least two and up to 14 prizes will be awarded in each category, with 20 awards total across all categories. Additionally, judges will recognize four ideas as "best in class". This category will allow judges to recognize inventive and creative approaches that don't necessarily fit into a specific waste category but nonetheless hold great potential for overall waste management. Things that might fall into this category include (but are not limited to): greatest impact on launch mass, best physical process, or best chemical process.

In addition to the cash awards, winners will be cited in a NASA white paper that is expected to serve as a roadmap for future technology development efforts. Select winners may be contacted for additional insight into proposed ideas.