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Watermeal may become an essential food for astronauts

Watermeal, Earth’s tiniest flowering plant, may become an essential astronaut food source and an efficient oxygen generator for space missions, according to a recent report from the European Space Agency (ESA).

Mahidol University researchers in Thailand have tested watermeal’s space potential by subjecting the minuscule plant to 20 times Earth’s normal gravity on the Large Diameter Centrifuge (LDC).


The LDC, located at ESA’s ESTEC technical center in the Netherlands, is a four-arm centrifuge which allows researchers to expose materials to hypergravity for extended periods. 

The project, facilitated through HyperGES, is a collaboration under the Access to Space for All initiative, backed by both the ESA and the United Nations Office of Outer Space Affairs (UNOOSA).

The centrifuge, capable of reaching up to 67 revolutions per minute, houses six gondolas along its arms, which are each able to hold 80 kilograms. 

Focus of the study 

The Mahidol University team, led by Tatpong Tulyananda, placed samples of watermeal in boxes equipped with LED lights simulating natural sunlight, within these gondolas. 

Watermeal, a tiny plant floating on Thai and Asian water bodies, does not possess roots, stems, or leaves, and has been under study using clinostats to observe its reaction to microgravity.

“We became interested in watermeal because we wanted to model how plants respond to changing gravity levels. Because watermeal doesn’t have any roots, stems or leaves, it is basically just a sphere floating on a body of water. That means we can focus directly on the effects that gravity shifts will have on its growth and development,” said Tulyananda.

“In addition, it produces a lot of oxygen through photosynthesis. And watermeal is also a good protein source, which has been consumed in our country for a long time – used with fried egg to soup, or eaten as part of a salad. You consume 100% of the plant when you eat it, so it holds promise in terms of space-based agriculture.”

Valuable insights 

The research team observed minimal differences in the plant’s growth between 1g and simulated microgravity. The short-lived nature of watermeal, with a life cycle ranging between five to ten days, allows for the examination of its entire life cycle in a short span. 

The experiment yielded two generations of watermeal, the analysis of which Tulyananda believes will provide valuable insights into the plant’s hypergravity response.

“So far, we have seen little to no difference between plant growth at 1g and simulated microgravity, but we want to extend our observations to get an idea of how the plants react and adapt across the whole range of gravity environments,” explained Tulyananda.

“Another advantage of watermeal is that it is quite a short-lived plant, so we can study its entire life cycle within five to 10 days.”

“Our two weeks of experimentation give us access to two generations of watermeal overall. What we do next is examine the plants directly, then render extracts into a solid pellet form that we will take home to study. Then we can put these samples through detailed chemical analysis to gain insights into the broad spectrum of watermeal’s hypergravity response.”

More about watermeal 

Watermeal, scientifically known as Wolffia, is recognized as the smallest flowering plant on Earth. Belonging to the duckweed family (Lemnaceae), this tiny plant is aquatic, predominantly floating on the surface of water bodies. 

Size and appearance 

Each individual watermeal plant is extremely small, roughly the size of a pinhead. It has a simple, globular, and rootless structure, often appearing like minute green grains on the water. Unlike typical plants, watermeal lacks stems, leaves, and roots.


Watermeal thrives in quiet, nutrient-rich freshwater environments like ponds, lakes, and marshes.

The plant is found globally, with a significant presence in Asia and Thailand.

Nutritional value

Watermeal is known to be a rich source of protein, making it a nutritious foodstuff. It has been a part of the diet in some countries, consumed in various forms like in soups, salads, or with fried eggs.

Because you consume 100% of the plant when you eat it, it offers maximum nutritional benefits per serving.

Image Credit: ESA

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