NASA Research Announcement: Urine and Air Separation – Two Phase Fluid Separator Technology

This is Modification 1 to the NASA Research Announcement (NRA) entitled "Urine and Air Separation – Two Phase Fluid Separator Technology", which was posted on 4/8/2025.The due date for submissions has not been extended. 

Posting update:

NASA is seeking proposals under a new Focus Area of Notice ID 80JSC025ISSNRA Research Opportunities for International Space Station (ISS) Utilization. This opportunity is made available through the ISS NASA Research Announcement (NRA) NNJ13BG001N, Focus Area 5 “Urine and Air Separation – Two Phase Fluid Separator Technology."  Focus Area 5 seeks to advance the state-of-the-art (SOTA) of urine/air separator technology with the ability to integrate the technology demonstration into a contingency toilet should an unrecoverable failure occur.  Details including submission instructions and due dates are included in the focus area posted on NSPIRES.

NRA Link: https://nspires.nasaprs.com/external/solicitations/summary!init.do?solId=%7b21E0270C-BC1F-EFC4-3D87-30713B5FF373%7d&path=open

Base:

Focus Area 5: Urine and Air Separation – Two Phase Fluid Separator Technology

Scope and Objectives

NASA is seeking proposals under this focus area to advance the state-of-the-art (SOTA) of urine/air separator technology with the ability to integrate the technology demonstration into a contingency toilet should an unrecoverable failure occur. The contingency toilet architecture will use a urine collection interface with airflow for waste separation from the body, odor control, and a gas-liquid separator to allow the collected urine to be processed with the on-board urine processor. The entire system will be efficiently packaged to minimize the onboard volume but allow for maintenance by crew on ISS. 

To sufficiently advance the SOTA, a proposed separator must be able to reliably and robustly provide sufficient separation over a variable flow rate and duration of urine. If needed, airflow may be provided by an external blower or fan. It must be efficient, minimize system power and cooling requirements, and be small enough in size to fit within the spacecraft. It must be robust and have a long life to minimize the crew system maintenance and the spares mass needed for a human space exploration mission.

Additionally, an advancement on the SOTA would meet or exceed the following:

1. Fluid interfaces: The Separator should provide degassed urine to a filtered line leading to an external container (ambient) or the ISS urine processing systems (~3 psi back pressure)
2. Pretreat compatibility: The separator should accept air and urine mixed with approximately 3-5 mL of alternate pretreat concentrate (APC) made of 85% aqueous phosphoric acid and 6.2% chromium trioxide by mass as an oxidizer. Reference US Patent No. 9,878,928,B1 for more information.
3. Airflow: Urine is collected from a funnel with an airflow of up to 250 (+-50) SLPM. Crew may throttle the airflow rate. An external separate blower may provide airflow. The proposed separator technology should minimize pressure drop at the specified flow rate.
4. Urine Rate: Separator should be able to accept micturition rates up to 55 mL/sec (including flush water and pretreat). Nominal rate is 30 mL/sec.
5. Liquid volume: Separator should be able to accommodate 1.5 L of liquid per flush
6. Separator Volume & Dimensional Envelope: Volumetrically smaller solutions are desired. Separator should aim to fit into a 10” x 10” x 10” volume
7. Performance with Varying liquid to air ratios: The separator should perform well with inlet pretreated urine rates between 0 and 55 mL/sec. Urine donation averages about 0.3 liters of urine, but the urine separator can see significantly larger flushes up to and including 1.5 L per flush.  ISS adds 50 mL of flush water with about 3-5 mL of concentrated pretreat per flush. The pretreat is added during the urine donation and the separator should have sufficient liquid volume to allow mixing of the pretreatment chemicals with the urine as it is separated from the intake air.
8. Urine outlet gas content: the separated urine should have less than 1% free gas by volume. It should be assumed the liquid is at gas saturation at body temperature 98.6 F  The gas outlet should be less than 1% by volume of liquid carry over. Water vapor/humidity in the outlet gas is excluded from this value. Liquid carryover applies to a full over, including startup and shut down after a urination cycle (e.g., residual liquid in the separator must appropriately managed and not allowed to migrate to where it will leave the separator on the subsequent cycle).
9. Vehicle Power Interfaces: Separator and controller power source can be 28 VDC or 120 VDC
10. Separator life: An ideal operational life would be 3 years to support reusable habitats and would support >20,000 cycles before repair or replacement. The shelf life of the separator is desired to be 15 years. An exploration goal is to design hardware for crew repair / maintenance at and individual component level.
11. Control and telemetry: The separator controller shall allow for remote operation. Telemetry reported should include current used and speed (in RPM’s) of the device. Liquid flow, airflow and outlet pressure is desired.
12. Survive launch loads & vibration: Robust to survive up to 6 g, variable frequencies. The hardware will be launched as a payload and installed on ISS on-orbit. It is expected to be soft stowed, and not operate during launch.
13. Acoustics: The separator should minimize noise produced. An integrated system goal is for the separator (and blower if needed) should be <70 dB.
14. Materials & Lubricants: Materials used in NASA spacecraft must meet requirements for flammability, off-gassing, and system compatibility per NASA-STD-6001 (Rev B). The output from the separator is expected to be returned to the cabin through an odor filter. All wetted surfaces must be compatible with APC described in section B above.
15. EMI and Magnetic Fields: The integrated separator must comply with NASA SSP 30237: Space Station Electromagnetic Emission and Susceptibility Requirements.
16. Robust:

• Survive periods of deadheads (temporary blocking of air flow at the funnel entrance and allowing ~100 ml of liquid to accumulate before it enters the separator as a slug) and suction
• Tolerate particulate ingested by air-intake. Expect air / urine mixture will be screened near inlet of the system to capture large particulate > 0.04”
• Describe accommodations needed to keep separator viable for non-continuous use

     17. Safe to use in the rest of the system:

• Not generate excessive pressure during nominal operation, including deadhead periods
• Fracture containment for safety
• Not generate excessive particulate/FOD in urine or exhaust

Submission and Evaluation Instructions:

This focus area is following the two step procedures outlined in the NASA Grant and Cooperative Agreements Manual (GCAM). NASA is currently accepting white papers through April 18, 2025 at 11:59pm central time. The format for the white paper shall follow the instructions set forth in this NRA in section IV.3.1 White Paper Format. NASA will review the submissions and issue invitations to submit proposals to the most advantageous white papers. The following will be considered by NASA when reviewing white papers:

1. The proposal shows a clear need for the use of the ISS and its unique capabilities and demonstrates relevance to the scope and objectives of focus area 5 – compliance check only (i.e. pass/fail).
2. Technical capability
3. Cost
4. Schedule

Technical Q&A will occur after invitations to submit proposals are issued. Process questions can be submitted directly to the NRA manager (colleen.corbett@nasa.gov) and the Focus Area 5 Manager Christopher Brown (christopher.a.brown@nasa.gov) at any time and will be answered individually until close of business the day white papers are due.

White paper submission is required through the NSPIRES system. White papers submitted through any other means (email, physical mail, fax, etc.) will not be considered for evaluation. Use of NSPIRES requires user registration and can be problematic for first time users. NASA recommends that white papers be submitted early to avoid delays impacting the eligibility of the submission. White papers received after the due date and time as defined in this solicitation are considered late and will only be reviewed at NASA’s discretion.