But now, by mixing in some of the organic materials that give Earth's dirt its edge, they've managed to make 10 species including peas and tomatoes yield produce. Mixing in organic matter from Earth made the soil hold water better (the "moon" soil in particular is very hydrophobic) and provided nutrients for the growing plants.
In theory, their results — which have to be taken with a big grain of salt, as they have not yet been peer reviewed and published — suggest that future settlers on Mars or the moon could bring along packets of soil-boosting organics from Earth, plop everything into a growing tray and grow happy plants onboard their spacecraft without sacrificing space and fuel to heavy loads of Earth soil.
There are a few potential hiccups, however: While the "lunar" soil is almost certainly a good match for the real thing, given the fact that humans have brought home samples of moon dust before, the pseudo Martian soil is more of a guess. It's made by NASA and based on chemical analyses by orbiters and landers, so it's not a total shot in the dark. But we don't actually know how soil from Mars behaves.
And then there's the fact that the plants might be toxic to humans.
Wieger Wamelink, an ecologist working on the plant-growth experiments, explained that Martian and lunar soils both have lots of heavy metals. On Earth, some plants are able to avoid taking up heavy metals — and even if they can't avoid them, it's usually not a problem. Not for the plants, anyway.
"As soon as we start to eat them, those heavy metals can pose a problem for us," Wamelink said.
The researchers are crowdfunding to supplement the budget for their next experiment, which will focus on analyzing the plants grown from these "alien" soils for safety and nutrition.
Wamelink, who writes a blog for the Dutch nonprofit Mars One — a group that intends to make a one-way trip to Mars in 2024 that many scientists say is unrealistic — obviously hopes that he and his colleagues' techniques will be used in space one day. He says Mars One would "definitely" attempt to use his soil findings to grow crops on Mars, and he hopes that NASA would as well. But in his day-to-day research, Wamelink's primary focus is studying the relationship between plants and different soils on Earth, and he thinks his spacey experiments could have great applications on our own planet.
"There are over 7 billion people on the planet, and they have to be fed," Wamelink said. "One solution is to grow crops in places where it's now basically impossible."
Figuring out how to create happy, healthy plants in relatively small growth trays, and using poor soil, is knowledge that could be used just about anywhere. In their next round of experiments, he and his colleagues will start working with sand from the Sahara as a new "alien" growth medium.
"It's quite an important spin-off of the Mars work, I think, to learn how to cultivate plants out in the desert," he said.