Nanobubbles in Variable Gravity

Reducing resupply on long-duration space missions by using closed-loop life support requires a different approach to mass transfer than buoyancy-based sparging, a common degassing method used on Earth, that is challenging in microgravity. Metastable nanobubbles may provide gravity-independent, sustained mass transfer with higher transfer rates, closing the life support loop. Also, these nanobubbles have biocidal effects, potentially streamlining spaceflight water purification processes. The Characterizing Production and Stability of Nanobubbles in Variable Gravity experiment aims to advance the state-of-the-art and increase confidence in integrating nanobubble technology into life support systems requiring gas-liquid contacting. 

Problem Statement Tomato plants, wastewater processing, carbon dioxide scrubbing, and propellent all have something in common – they require multiphase mass transfer (gas into liquid) to effectively function. Typical terrestrial methods for mass transfer include macro- and microbubble sparging (bubbling gases into liquid). These gas-liquid contacting systems are limited to terrestrial use because they are not mass/power/volume-efficient enough for spaceflight. The current standard for reduced/microgravity environments are rate-limited, diffusion-dominated membranes. Due to this mass transfer gap, current life support systems are partially open loop and require frequent resupply missions. This is not sustainable for missions beyond low Earth orbit (LEO). Attaining loop closure for carbon, oxygen, and water is the only way long-duration spaceflight can be Earth-independent, minimize resupply missions, and thrive on other planetary surfaces (i.e., lunar, Martian). 

Technology Maturation Currently, experiments have only used nanobubbles terrestrially and have not studied their production or sustainment in reduced gravity or the survivability of launch loads. Parabolic flight tests are expected to help researchers capture the ability for a ground-validated nanobubble generator to produce nanobubbles in brief periods of microgravity. The subsequent >1-g maneuvers to reset from a parabola will be used to study the survivability of these produced or contained bubbles by using a laser-based bubble tracker. Multiple flights will be used to investigate nanobubble characteristics for various spaceflight-pertinent gases, such as carbon dioxide and oxygen (air). The production of nanobubbles in a spaceflight-relevant environment is expected to advance the system’s technology readiness level (TRL) to TRL 5. 

Summary of Flight Testing 
5/4/2025: The experiments from this flight campaign demonstrated that nanobubble generation technology enhances gas delivery under microgravity conditions. This represents a significant advancement for gas-limited systems in space exploration, with potential applications for in-situ resource generation, autonomous food production, and improved fuel efficiency.

10/28/2025: During this campaign, we successfully demonstrated that nanobubbles generated on Earth maintain stability even under extreme gravity changes, including zero gravity. Our experiments further revealed that nanobubbles can be generated in zero gravity conditions, enabling highly efficient gas-liquid contact processes.

This capability could significantly enhance the performance of systems that depend on gas exchange, reducing both the operational footprint and resource requirements for implementation in space-based applications.

These findings open new possibilities for optimizing life-support and fuel systems in space environments.

- Improved life support: Replaces membranes and increases efficiency Minimize resupply: - - Closed-loop systems can reduce resupply needs 

Future Customers 
- Potential applications for closed-loop life support systems in space include: 
- Aquaculture/food production 
- Oxygen recovery from carbon dioxide 
- Wastewater processing 
- Enhanced terrestrial water treatment, aquaculture, and horticulture

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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