Thinking about farming in space? Choose Mars over the moon

If humans form a colony on Mars, their survival will depend on developing a steady source of food. That could take the form of buildings filled with plants growing hydroponically or aeroponically. Otherwise, a recent study by three Dutch research institutes found that it may actually be possible to grow crops directly in the soil found on Mars and the moon.

The Dutch study covered many different types of crops from tomatoes to wheat to mustard. The team planted seeds in two types of Earth-made soil that mimicked the kinds found on the moon and Mars. It also placed seeds in low-quality Earth soil.

Over 50 days, the researchers observed how many seeds germinated, how many flowers and leaves they grew and if they were alive by the end. They found that the synthetic Martian soil supported plant growth as well as, and often better than, the dirt from Earth. The lunar soil performed poorly, though plants were able to grow in it.

Chart courtesy of the authors.

Chart courtesy of the authors.

That’s a bit surprising because both bodies have more heavy metals in their soil than Earth. Moon soil is also much poorer in nutrients and has a much higher pH than the other two soil types. But nevertheless, neither the synthetic Martian nor lunar dirt was toxic to plants.

But don’t run off and plant crops just anywhere in space. Any plants growing there would need to take place in a climate-controlled habitat, as temperatures are nowhere near as nice on Earth. A day on Mars can range from -207 to 80 degrees Fahrenheit because there is little atmosphere. Any space plants would require a regular source of heat and watering.

The Dutch team pointed out some bigger questions about its study as well. For example, real Martian and lunar soil could be worse at holding onto water than the synthetic variety. Astronaut farmers also might not have access to naturally occurring nitrogen — an incredibly important ingredient for plant growth — requiring it to be added to the soil. Oh, and there’s that whole minimal gravity thing.

No matter what the challenges, growing crops and other plants in actual soil will remain of interest to human space explorers. Not all plants are great at growing in an aeroponic or hydroponic environment. And there’s just something about that Martian dirt that makes vegetables taste delicious.