NASA may require Artemis astronauts to grow their own crops as they stay permanently on the moon's surface for years to come. Even that should be it. Scientists shared the results of a historic experiment in which they used samples of lunar surface material called regolith to grow plants on Earth. Half a century ago, researchers sowed seeds of the plant Arabidopsis thaliana, related to mustard greens, in small samples of regolith collected on three different Apollo missions.
But while the seeds were sprouting and growing, they were not fully developed.
"Moon soils don't have many of the nutrients needed to support plant growth," Stephen Elardo of the University of Florida said at a news conference Wednesday.
What is Regolith?
The regolith covers almost the entire lunar surface, with bedrock protruding only on very steep-sided crater walls and the occasional lava channel.
The regolith was formed over the last 4.6 billion years from the impact of large and small meteoroids, the constant bombardment of micrometeoroids, and solar and galactic charged particles that shattered the surface rocks. Regolith production by rock erosion can cause fillet build-up around moon rocks.
The impact of micrometeoroids, sometimes traveling faster than 96.000 km/h (60.000 mph), generates enough heat to melt or partially vaporize dust particles. This melting and remelting brings the particles together, welding glassy, jagged-edged agglutinates that resemble tektites found on Earth.
The regolith is generally 4 to 5 m thick in mare areas and 10 to 15 m in old highland areas. Beneath this true regolith is a region of blocky and fractured bedrock created by larger impacts, often referred to as a 'megaregolite'.
The regolith density at the Apollo 15 landing site (26.1322°N 3.6339°E) averages about 30 g/cm1.35 for the upper 3 cm and about 60g/cm1.85 at 3 cm depth.
The term lunar soil is often used interchangeably with "lunar regolith," but it refers to the finer fraction of regolith that typically consists of grains one centimeter in diameter or smaller.
There are some who argue that the term "soil" is not correct for the Moon because the soil is defined as having organic content, whereas lunar soil has no organic content at all.
However, standard usage among researchers is to ignore this distinction.
“Moon dust” generally refers to even finer materials than lunar soil, the fraction less than 30 micrometers in diameter. The mean chemical composition of the regolith can be estimated from the relative concentration of the elements in the lunar soil.
If we go back to our article;
Elardo presented the research, published Thursday in the journal Communications Biology.
As the plants grew to indicate they were stressed, the team found a way relatively quickly with a little help providing them with light, water and nutrients.
"Two days later they started to sprout," said Paul, a professor of horticultural sciences at the University of Florida. “Everything sprouted. I can't tell you how surprised we were.
Each plant looked the same until about day six.”
By the end of their first week, the plants in the regolith showed slower growth, stunted roots and leaves, and some red spots. Subsequent genetic analyzes would confirm that the foliage was under stress.
Lunar regolith is very fine-grained and dusty, but don't be fooled, because these grains are also sharp-edged. Breathing moon dust can damage the lungs, and these things aren't particularly well suited to plant life.
“Ultimately, we want to use the gene expression data to address how we can improve the stress response of plants – crops in particular – where they can grow in lunar soil and have little impact on their health,” Paul added.
Ferl says growing plants on the moon is key to long-term stays on the moon, helping to provide not only food but also clean air and water for astronauts and other visitors.
"When we go somewhere into space, we always take our agriculture with us," said Ferl of the University of Florida.
“Showing that plants will grow in lunar soil is actually a big step in that direction.”