As humanity looks toward future bases on the moon, plant cultivation will be critical for sustaining life there. Plants can provide food, oxygen, medicine, water purification and waste recycling, making them indispensable for lunar development.
A recent study, “Assessing Water Dynamics at Lunar Gravity,” from space biologist John Z. Kiss, Karl H. Hasenstein and Christopher P. McKay, working with 4SPACE, LLC., aimed to understand how water behaves in lunar gravity. Gravity on the Moon’s surface is only one-sixth as strong as Earth’s gravity, and the researchers wanted to know what that means for plant irrigation.
What the researchers found were clear differences in the behaviors of the liquids they were testing under lunar gravity.
“The surface tension is more of a factor in how water flows. In essence, it doesn’t flow as freely (in lunar gravity) because of the surface tension,” said Kiss, who is Florida Tech’s provost and senior vice president for academic affairs. “If you’re going to water plants on the moon, you might have to design the whole system a little bit differently than you would on Earth.”
4SPACE approached Kiss with the plans for the experiment, his ninth to go to space. The experiment was designed with Hasenstein, from University of Louisiana at Lafayette, whose contributions were critical to its conception and execution. McKay from NASA Ames Research Center was also involved in the experiment design.
The research, conducted during the Blue Origin New Shepard 29 flight in February 2025, tested three different liquids — pure water, a 30% glycerol solution and a salt solution — to see how the meniscus of the liquid – its curved surface inside a container – would react to simulated lunar gravity. The flight was only about 10 minutes and generated simulated lunar gravity for around two minutes by rotating like a centrifuge as it descended.
Understanding the flow of water on the lunar surface is very important to the survival of plants on the moon, since uneven irrigation can limit oxygen availability and impair plant growth. Lunar soil is made up of very fine dust and rock fragments, which makes it ineffective at absorbing water.
The combination of the lack of water flow on the moon and the poor absorption of water into the lunar soil creates a challenge for propagating plants, Kiss said. The researchers found that the glycerol solution showed signs of better water flow, opening the door for research on what additives could be useful in promoting water absorption for plants in lunar soil.
Kiss explained that the success of this research was not a certainty when it was being sent to space.
“This was new hardware, there’s a camera in there, there’s an accelerometer so we would know what the gravity levels were — it worked,” Kiss said. “I can’t emphasize that enough, because a lot of people design these things for years and then something goes wrong.”
Kiss and his team were able to avoid those pitfalls and produce an experiment with valuable results, but they want to use this as a starting point for further research.
“We want to verify this surface tension by doing maybe a longer-term experiment and doing a real lunar experiment. My students and I are very excited about the possibility of future experiments on the Moon,” Kiss said.
Smaller scale research like this opens the door for more applied research later on, as humanity works closer to the ability to sustain life outside of Earth.
