WASHINGTON: Scientists working to cultivate the field of extraterrestrial agriculture have grown chickpeas in dirt made mostly of simulated lunar soil, a step towards enabling astronauts on long-term moon missions to produce their own food.
Researchers said harvestable chickpeas were grown in soil mixtures composed primarily of "moon dirt" modelled after lunar samples retrieved during Nasa's Apollo missions more than half a century ago.
Chickpeas of a variety called "Myles" were raised in a climate-controlled growth chamber at Texas A&M University. Seeds were coated with beneficial fungi and planted in a mix of the simulated lunar soil, made by Florida-based company Space Resource Technologies and a nutrient-rich substance called vermicompost produced when earthworms break down organic waste.
Harvestable chickpeas grew in soil mixtures of up to 75 per cent lunar simulant. As the percentage of simulated moon soil — known as regolith — increased, the number of harvestable chickpeas decreased, though the size of the chickpeas remained stable. Seeds planted in 100% lunar simulant failed to produce flowers and seeds, experiencing early death.
The United States and China have plans to send astronauts back to the lunar surface in the coming years, with an eye towards long-term bases on the moon.
"Chickpeas are high in protein and other essential nutrients, making them a strong candidate for space crop production", said Jessica Atkin, a doctoral candidate and Nasa fellow at Texas A&M's Department of Soil and Crop Sciences, lead author of the research published on Thursday in the journal Scientific Reports.
A local food source is considered vital to sustaining people staffing moon bases because of the impracticality of transporting all needed food from Earth.
"In our goal towards establishing a lunar presence — or one on Mars — we will need to learn how to grow food on the moon, since it will not be sustainable to ship food in spaceships. This is because it is still quite expensive to ship things to space, so weight is a factor and also because the survival of astronauts on the moon can't be dependent on the timely shipment of supplies", said study co-author Sara Oliveira Santos, a postdoctoral researcher at the University of Texas Institute for Geophysics.
"Plants would also help produce oxygen and enhance life-support systems for future human settlements", said astrobiologist Jyothi Basapathi Raghavendra of Northumbria University in England, lead author of a second study published on Thursday that examined growing conditions for microbes in simulated Martian soil.
Moon soil is basically crushed rock and dust, often sharp and glass-like, formed over billions of years by meteorite impacts. While it contains essential nutrients and minerals for plants to grow, it is inorganic and inhospitable, unlike the nutrient-rich and organic Earth soil.
"Previous studies have shown plants can germinate in authentic lunar samples or grow in regolith simulants, often by adding compost or other types of organic matter", Atkin said. "In this study, we focused on microorganisms. Instead of only adding organic material, we tested whether plant-microbe partnerships could help condition regolith, improve its structure and reduce plant stress".
HOW DO THEY TASTE?
So what did these chickpeas taste like? We do not know yet.
"The chickpeas are currently being tested for metal accumulation, which is why we haven't eaten them just yet", Atkin said.
Lunar regolith and the simulant used by the researchers contain high levels of metals such as aluminium and iron. Iron is an essential nutrient for plants. Aluminium is not and can be toxic when consumed. — Reuters
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