The Mars Gardens: a comparison of the viability of plants grown in Martian simulant regolith and in a hydroponics system

Over the next few decades NASA and private enterprise missions, such as SpaceX-Mars, plan to send human missions to Mars with the ultimate goal of establishing a permanent human presence on this nearby planet. For a colony on Mars to be self-sustaining, it will be necessary to provide food by growing plants in sheltered and heated greenhouses. Due to the huge cost of transporting materials into space, it will be too expensive to transport growing medium from Earth to Mars. Therefore, the growing medium must already be abundant on the red planet. Research at Villanova University as part of the Mars Gardens Project has shown that it is possible to successfully cultivate plants in simulant Martian regolith. However there are many issues with the simulant soil that need to be remedied before it is suitable for agricultural applications. The Martian regolith must be stripped of perchlorates, which are harmful to humans. Also, organic materials, such as worm castings, must be added to the regolith to provide nutrients for the plants, as Martian regolith is inherently sterile. From our past experience, the clay-like properties of the simulant-regolith exacerbate problems such as root-rot, wilting, and root-growth deficiency. Because using regolith as the growing medium presents significant challenges, this study explores the use of hydroponics systems as an alternative to regolith-based agriculture. In a hydroponic system no soil is used and the plant roots are placed directly in a nutrient solution. Due to the ease of nutrient-absorption, the test plants grow larger and more quickly than their soil-based counterparts. A comparison of plants grown in Martian simulant regolith and a hydroponics system indicates hydroponics may be preferable for Martian agriculture. Future work will investigate methods of further optimization of the hydroponics system.