Plate Nº 61 · recorded October 2, 2026
Space & AstronomyReported finding
Why Watering Plants on the Moon Won't Work Like on Earth
A suborbital experiment shows surface tension dominates water flow in lunar gravity, complicating irrigation for future Moon bases and lunar farming.
By Elena Vasquez4 min read707 words
In brief
- Lunar gravity is one-sixth of Earth's, making surface tension slow water flow and complicating plant irrigation.
- The experiment flew on Blue Origin's New Shepard 29 in February 2025, providing about two minutes of simulated lunar gravity.
- A 30% glycerol solution flowed better than pure water, suggesting additives could improve water absorption in lunar soil.
Anyone hoping to grow plants on the Moon faces a plumbing problem. A new experiment, carried aboard a Blue Origin suborbital rocket, shows that water does not flow freely under lunar gravity. Instead, surface tension — the same force that lets insects walk on water — becomes the dominant player, and that could force engineers to rethink how future lunar greenhouses are irrigated.
The findings come from a study titled "Assessing Water Dynamics at Lunar Gravity," published in the journal Microgravity Science and Technology. Space biologist John Z. Kiss of Florida Tech, Karl H. Hasenstein of the University of Louisiana at Lafayette, and Christopher P. McKay of NASA Ames Research Center conducted the work together with the company 4SPACE LLC.
Plants matter for any long-term lunar base. They can supply food, oxygen, medicine, water purification, and waste recycling, which makes them indispensable for sustaining life away from Earth. But growing them requires water, and gravity on the Moon's surface is only one-sixth as strong as Earth's. The researchers wanted to find out what that difference means for irrigation.
What the experiment showed
The team tested three liquids: pure water, a 30% glycerol solution, and a salt solution. They watched how each liquid's meniscus — the curved surface a liquid forms inside a container — behaved under simulated lunar gravity.
The results showed clear differences from normal Earth conditions. Surface tension, the cohesive force that makes liquid molecules cling together at a surface, slows water down dramatically in weak 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 serves as 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."
Two minutes of Moon-like conditions
The experiment flew on the Blue Origin New Shepard 29 flight in February 2025. The entire flight lasted about 10 minutes, but the useful window was far shorter: roughly two minutes of simulated lunar gravity, created as the descending rocket rotated like a centrifuge.
This was Kiss's ninth experiment to reach space. 4SPACE approached him with the plans, and Hasenstein played a critical role in the experiment's conception and execution, while McKay contributed to its design.
The hardware itself was a gamble that paid off. The apparatus carried a camera and an accelerometer to record the gravity levels. "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."
A second problem: the soil itself
Even if water moved well, the Moon's surface would still fight against farmers. Lunar soil consists of very fine dust and rock fragments, and it absorbs water poorly. Uneven irrigation can also limit oxygen availability to roots and impair plant growth.
The combination of sluggish water flow and poor soil absorption creates a real challenge for growing plants there, Kiss said. Still, the results contained a hopeful clue: the glycerol solution showed signs of better flow. That opens the door to studying which additives might help water soak into lunar soil and reach plant roots effectively.
A first step, not a final answer
The researchers are careful to frame the work as preliminary. Two minutes of simulated gravity on a suborbital flight cannot capture everything about water behavior on the actual lunar surface. Kiss and his team see the experiment as a starting point.
"We want to verify this surface tension by doing maybe a longer-term experiment and doing a real lunar experiment," Kiss said. "My students and I are very excited about the possibility of future experiments on the moon."
Small-scale studies like this one lay the groundwork for applied research as humanity moves closer to sustaining life beyond Earth. Before astronauts harvest their first lunar lettuce, engineers will need irrigation systems designed for a world where water simply refuses to cooperate.
via Phys.org Space & Astronomy (Source)
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