Jump to content

Recommended Posts

  • Publishers
Posted

4 min read

Unearthly Plumbing Required for Plant Watering in Space

NASA is demonstrating new microgravity fluids technologies to enable advanced “no-moving-parts” plant-watering methods aboard spacecraft.

Two astronauts working at tables with complex systems of tubes, syringes, and other apparatus.
Boeing Astronauts Sunita Williams and Butch Wilmore during operations of Plant Water Management-6 (PWM-6) aboard the International Space Station.
Image: NASA

Crop production in microgravity will be important to provide whole food nutrition, dietary variety, and psychological benefits to astronauts exploring deep space. Unfortunately, even the simplest terrestrial plant watering methods face significant challenges when applied aboard spacecraft due to rogue bubbles, ingested gases, ejected droplets, and myriad unstable liquid jets, rivulets, and interface configurations that arise in microgravity environments.

In the weightlessness of space, bubbles do not rise, and droplets do not fall, resulting in a plethora of unearthly fluid flow challenges. To tackle such complex dynamics, NASA initiated a series of Plant Water Management (PWM) experiments to test capillary hydroponics aboard the International Space Station in 2021. The series of experiments continue to this day, opening the door not only to supporting our astronauts in space with the possibility of fresh vegetables, but also to address a host of challenges in space, such as liquid fuel management, Heating, Ventilation, and Air Conditioning (HVAC), and even urine collection.

The latest PWM hardware (PWM-5 and -6) involves three test units, each consisting of a variable-speed pump, tubing harness, assorted valves and syringes, and either one serial or two parallel hydroponic channels. This latest setup enables a wider range of parameters to be tested—e.g., gas and liquid flow rates, fill levels, inlet/outlet configurations, new bubble separation methods, serial and parallel flows, and new plant root types, numbers, and orders.

Most of the PWM equipment shipped to the space station consists of 3-D printed, flight-certified materials. The crew assembles the various system configurations on a workbench in the open cabin of the station and then executes the experiments, including routine communication with the PWM research team on the ground. All the quantitative data is collected via a single high-definition video camera.

The PWM hardware and procedures are designed to incrementally test the system’s capabilities for hydroponic and ebb and flow, and to repeatedly demonstrate priming, draining, serial/parallel channel operation, passive bubble management, limits of operation, stability during perturbations, start-up, shut-down, and myriad clean plant-insertion, saturation, stable flow, and plant-removal steps.

Both images depict a rectangular structure containing tubes and other devices. The image on the left shows the apparatus with the different parts numbered, while the image on the right shows the same structure with fluid flowing through it.
PWM-5 Hydroponic channel flow on the International Space Station with: (1) packed synthetic plant root model in passive bubble separating hydroponic channel, (2) passive aerator, (3) passive fluid reservoirs for water and nutrient solution balance, (4) passive bubble separator, (5) passive water trap, and (6) passive gas/bubble diverter. The flow is left to right across the channel and the aerated oxygenating bubbly flow is fully separated (no bubbles) by the bubble separator returning only liquid to the ‘root zone.’ The water trap, bubble diverter, root bundle and hydroponic channel dramatically increase the reliability of the plumbing by providing redundant passive bubble separating functions.
Image courtesy of J. Moghbeli/NASA
Four images depicting white strands of string-like material of different lengths.
PWM-5 and -6 Root Models R1 – R4 from smallest to largest: perfectly wetting polymeric strands modelling Asian Mizuna.
Image courtesy of IRPI LLC

The recent results of the PWM-5 and -6 technology demonstrations aboard the space station have significantly advanced the technology used for passive plant watering in space. These quantitative demonstrations established hydroponic and ebb and flow watering processes as functions of serial and parallel channel fill levels, various types of engineered plant root models, and pump flow rates—including single-phase liquid flows and gas-liquid two-phase flows.

Critical PWM plumbing elements perform the role of passive gas-liquid separation (i.e., the elimination of bubbles from liquid and vice versa), which routinely occurs on Earth due to gravitational effects. The PWM-5 and -6 hardware in effect replaces the passive role of gravity with the passive roles of surface tension, wetting, and system geometry. In doing so, highly reliable “no-moving-parts” plumbing devices act to restore the illusive sense of up and down in space. For example,

  • hundreds of thousands of oxygenating bubbles generated by a passive aerator are 100% separated by the PWM bubble separator providing single-phase liquid flow to the hydroponic channel,
  • 100% of the inadvertent liquid carry-over is captured in the passive water trap, and
  • all of the bubbles reaching the bubble diverter are directed to the upper inlet of the hydroponic channel where they are driven ever-upward by the channel geometry, confined by the first plant root, and coalesce leaving the liquid flow as a third, redundant, 100% passive phase-separating mechanism.

The demonstrated successes of PWM-5 and -6 offer a variety of ready plug-and-play solutions for effective plant watering in low- and variable-gravity environments, despite the challenging wetting properties of the water-based nutrient solutions used to water plants. Though a variety of root models are demonstrated by PWM-5 and -6, the remaining unknown is the role that real growing plants will play in such systems. Acquiring such knowledge may only be a matter of time.

Five images depicting devices consisting of tubes, white clips, and other structures; red liquid containing bubbles traverses through the various devices.
100% Passive bubbly flow separations in microgravity demonstrated for PWM ‘devices’: a. bubble separator, b. bubble diverter, c. hydroponic channel and root model, and d. water trap. Liquid flows denoted by red arrows, air flows denoted by white arrows.
Images courtesy of NASA

Project Lead: Dr. Mark Weislogel, IRPI LLC

Sponsoring Organization: Biological and Physical Sciences Division

View the full article

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By NASA
      NASA’s SpaceX Crew-10 Farewell and International Space Station Change of Command
    • By Space Force
      Set to take place Dec. 8-9 at Patrick SFB, the third annual Guardian Arena will bring together 35 elite three-person teams from Space Force units across the country.

      View the full article
    • By European Space Agency
      Image: This summer, a team of robots explored a simulated martian landscape in Germany, remotely guided by an astronaut aboard the International Space Station. This marked the fourth and final session of the Surface Avatar experiment, a collaboration between ESA and the German Aerospace Center (DLR) to develop how astronauts can control robotic teams to perform complex tasks on the Moon and Mars.
      The session introduced new levels of autonomy and complexity. NASA astronaut Jonny Kim operated two robots – ESA’s four-legged Spot and DLR’s humanoid Rollin’ Justin – to retrieve scattered sample containers and deliver them to a lander. Spot navigated the terrain autonomously, while Justin was guided through a mix of direct control and pre-set commands. This setup allowed Jonny to delegate tasks and focus on higher-level decisions, building on other sessions where robots required full teleoperation.
      In a second scenario, ESA’s Interact rover transported DLR’s robot dog Bert to a cave entrance. After removing a boulder, Jonny deployed Bert, which then simulated a malfunction in one of its legs. Jonny had to retrain Bert’s walking algorithm in real time before it continued into the cave and detected signs of martian ice. This tested how operators respond to unexpected challenges and adapt robotic systems on the fly.
      The robots are controlled from the International Space Station using a custom-built interface developed by ESA and DLR, combining a joystick and a haptic-feedback device. The interface allows switching between first-person view for immersive teleoperation and a top-down map for broader mission oversight. This flexibility lets the astronaut manage multiple robots efficiently, balancing direct control with strategic delegation.
      Over four sessions, the Surface Avatar team has refined its approach to human-robot interaction, improving both teleoperation and task delegation to autonomous systems. The experiment has also helped to identify which tasks astronauts prefer to control directly and which can be safely handed over to robotic systems, offering valuable insight for future mission planning.
      Read our blog to find out more.
      View the full article
    • By Amazing Space
      🔴 LIVE: Real Video Of Earth From Space RIGHT NOW - ISS HD Camera Views | 24/7 Space Station Feed
    • By NASA
      NASA/Aubrey Gemignani A SpaceX Falcon 9 rocket carrying the SpaceX Dragon spacecraft Endeavour lifts off from Launch Complex 39A at NASA’s Kennedy Space Center in Florida on Aug. 1, 2025. NASA astronauts Zena Cardman and Mike Fincke, JAXA (Japan Aerospace Exploration Agency) astronaut Kimiya Yui, and Roscosmos cosmonaut Oleg Platonov are aboard the spacecraft. After the crew arrives at the International Space Station, they will perform research, technology demonstrations, and maintenance activities aboard the orbiting laboratory. Crew-11 will also contribute to NASA’s Artemis campaign by simulating Moon landing scenarios that astronauts may encounter near the lunar South Pole, showing how the space station helps prepare crews for deep space human exploration.
      The flight is the 11th crew rotation mission with SpaceX to the space station as part of NASA’s Commercial Crew Program.
      Image credit: NASA/Aubrey Gemignani
      View the full article
  • Check out these Videos

×
×
  • Create New...