Dutch ecologist Wieger Wamelink couldn’t believe what he was seeing. There, in one of the 840 pots he had been monitoring since April, a mustard plant had sprouted a greenish knob. No, this can’t be, he thought. The plant was flowering in Martian soil.
The mustard plant hadn’t exactly flowered in Martian soil from Mars. Instead, NASA provided Wamelink with substitute Martian soil–stuff collected from the desert, dried out, and zapped of certain nutrients in a way that’s meant to replicate what Martian and lunar soil would be like. Wamelink had ordered more than 100 pounds of each type to his research greenhouse in the Netherlands to see what kinds of plants might prosper in greenhouses on other planets. He and his team planted tomato seeds, stinging nettle, carrots, rye, and a host of other wild species in the soils, then published their results in PLOS One late last month.
“I think we’re really the first to do that,” Wamelink, a self-professed Trekkie who works at the Alterra Institute at the University of Wageningen, says. “We have looked at how plants see what [nutrients are] available in these soils, and it was unknown to NASA. They were very happy when we sent our results.”
Most noteworthy among those results was how well some plants fared on fake Mars. Some seeds germinated after just 24 hours and flowered within 50 days–something Wamelink had never expected. He knew that nitrogen, a key nutrient necessary for plant growth, might not be available in alien soils. But when Wamelink analyzed the Martian soil compared to nutrient-poor sand from the banks of the Rhine, he found that Mars actually had much more going for it than he thought. The Martian atmosphere contains nitrogen, and gusts of gases from the sun charge the nitrogen into a digestible format for plants. The red planet also contains phosphorus, ammonium, and nitrates–all nutrients needed for plant growth. Field mustard and a tough, wild Dutch species called reflexed stone crop produced some of the best results.
Lunar soil, on the other hand, didn’t provide very friendly turf for earthling plant species. Soil on the moon is thin, dusty, and full of aluminum and other heavy metals, Wamelink explains. Both soils, in fact, contain lots of heavy metals, but most plants don’t do well in the presence of aluminum.
Even though Wamelink’s study provided some of the first evidence that earthling species can grow on planets other than Earth, it still doesn’t show how eating those plants might affect humans. Mars contains lots of radiation, and eating radioactive plants full of heavy metals might not be the best idea for the human digestive system.
That said, Wamelink believes that some aspects of the Martian climate might actually be beneficial for plant growth. On a planet with a third of the gravitational pull of Earth, he suspects that plants might be able to grow taller than they ever would on their home planet. Not all scientists agree with him.
“That’s an unresolved issue, but I still think it’s possible,” Wamelink says. In his mind’s eye, he pictures monster sequoias encased in skyscraper Martian greenhouses. “But you’d need to build a dome that’s high enough,” he adds.