Martian Crops

By now you’ve hopefully seen the awesome sight that is Matt Damon trudging around in his own effluvium, growing potatoes as fast as possible to avoid starvation alone on Mars. The fictional astronaut in question, Mark Watney, is marooned on the desolate red planet when his crew flee a deadly sandstorm. When faced with his predicament, he takes the only reasonable course of action to ensure he survives the four years till rescue…To ‘science the shit’ out of the situation.

NASA Mars Plant Growth Module (public domain licensed file from NASA)

As a scientist myself I find this attitude incredibly endearing. I too often attempt to solve problems in daily life scientifically, only trying to make the perfect G&T on a hot summer afternoon is a little less essential to my survival… just. Not only in Mark’s attitude do I find striking similarities. I too would class myself as a ‘Space Botanist’, that is so as to say I grow various plants (ticking the botanist box), in simulated extra-terrestrial soils (and there’s the space box). But more on that later.

Although the story is a futuristic romp of survival in the face of almost certain death, it holds water scientifically in almost all of its twists and turns. Indeed, it should be no surprise that Andy Weir, the author of the book, lives and works down the road from the NASA AMES Research Centre in California. This is NASA’s hub for futuristic research into the colonisation of Mars. One such avenue of research is in sustaining astronauts out in space, both on Mars and indeed on the way there and back in the Mars Transfer Vehicle.

As you the reader might expect, there are no Tesco Metros out in the depths of space. Therefore, any meals and naughty nibbles the astronauts need to survive will have to be taken with them, or indeed grown from scratch. Scientists at NASA and Roscomos (the Russian Federal Space Agency) have been working on growing plants in space since 1982. The first plant to grow and flower in space was a weed known as Arabidopsis aboard the Soviet Salyut 7 orbiting laboratory. Not the recent, albeit very pretty, Zinnia flowers grown by NASA Astronaut Scott Kelly that have been all over the headlines earlier this year.

Arabidopsis (via Wikimedia Commons) and Zinnia (Via Wikimedia Commons)

Since that first vodka-fuelled pioneering plant back in 1982 there have been plenty more species of plants that have been grown in space. Every orbiting laboratory from Skylab and Mir to the International Space Station (ISS) has had botanical passengers aboard. Last august NASA bent the rules and allowed the expedition 44 members on the ISS to munch their way through the first ever ‘Space Salad’ consisting not of quinoa, pomegranate seeds and goji berries, but a big handful of tasty Romaine Lettuce. Yum. After an extensive and over-cautious sterilisation procedure the astronauts said the lettuce tasted…exactly like lettuce. Although this isn’t all that very exciting, it does prove that plants CAN be grown and eaten in space without causing hideous side effects and paranormal psychotic episodes. Despite what Hollywood would lead us to believe.

Until now the majority of research has been split into two main groups. The first, pioneered by Professor Frank B. Salisbury (Utah State Dept. of Agriculture and Food), involved breeding varieties of crops such as dwarf wheat that will grow well in the microgravity and water-limited environment of a space station. The second involved tackling the engineering challenge of growing big, fat wheat ears without soil floating around everywhere and getting into the astronauts’ eyes and goodness knows where else. Professor Ray Wheeler of NASA’s Advanced Life Support Directorate has spent his entire career heading up research into methods for growing large volumes of food in the cramped confines of space habitats. Wheeler has near-perfected the continual growth of crops using repurposed hypobaric chambers from the Mercury Space Program, as well as modern LED lighting units.

Hydroponic culture, the growth of plants not in soil but in nutrient rich water, has been the central technique to NASA’s farming success. However, as you budding astrophysicists may know, there is not all that very much water available on Mars. September 2015 saw the confirmation of liquid water on the thirsty planet’s surface for the first time. Viewed from orbit, liquid water streaks called lineae appear and disappear down the side of Hale Crater depending on the Martian seasons. Much like water freezing and thawing in our own earthly seasons, as the temperature on Mars rises, these super-salty streams melt and run down the crater edges. Despite this discovery, and that of water ice at the polar caps of Mars, water remains a valuable resource on Mars making the use of hydroponic growth unfeasible.

Hale Crater on Mars (Credit: NASA/JPL-Caltech/Univ. of Arizona)

As those of you who have already watched the Martian will be smugly pointing out to your fellow readers in the coffee-shop: ‘Actually, Mark the astronaut grows his potatoes in the Martian soil and everything is hunky-dory!’. This is in fact the exact angle of NASA’s and my own research. The Martian soil, known to us botanical boffins as ‘regolith’ is composed mostly of a mixture of different rusts. It is this rusty composition that gives our beloved Mars its distinctive red hue. However, in this planet’s particular case most of that rust is from aluminium and magnesium oxides, not iron. Another major difference between the Martian regolith and our own brown muck is the abundance of organic compounds. Unfortunately, I’m not referring to the organic multi-coloured carrots and soya milk down at the Wholefoods market, rather the compounds from which all life is built. Compounds such as thiamin (vitamin B1) and organic phosphates, are vital for the growth of plants in any circumstance.

The Mars Curiosity Rover has been trundling around the planets surface for the better part of 4 years and in that time has been zapping the surface with its laser-vision (I’m not kidding, google it) looking for signs that life could once have survived on Mars. With this information scientists have found that among the total composition of the regolith, organic compounds are at very low levels. The essential building-blocks that plants would require to grow are essentially ‘locked away’ in inorganic and insoluble forms.

Mars Curiosity Rover, 2011 (via Wikimedia Commons)

With information on the regolith’s composition from its many Mars probes, NASA has been able to simulate Martian regolith in large quantities for researchers such as myself and other researchers to examine and test. With this Martian regolith simulant in hand, I have been busily trying to get various different crop plants to grow from high-protein soy beans to pak choi and spinach. However, I am not the only team members in my march to farming on Mars, I have enlisted the help of many millions of bacteria and fungi in my experiments. These micro-organisms are the key to our soil on Earth being able to support such large amounts and varieties of plants. They sit in the soil and constantly generate essential organic compounds both from old plant and animal matter but also from the metal oxide minerals found in the soil particles themselves. By harnessing the mechanisms that these bacteria and fungi use to mine soil particles, I am creating pioneering ‘Bacterionauts’ that have been modified to grow within the Martian regolith and convert inaccessible nutrients into accessible forms such as phosphates required for plant energy and ammonia required for protein synthesis.

Soybean grown in Martian Regolith for the first time

In the future when we do first send astronauts to Mars, the lucky sods will only have to spray a little ‘Bacterionaut solution’ on the regolith and hey presto, instant-soil! Well not quite, but in our experiments so far the bacteria appear to be essential to the plants long-term survival. Plants with no bacterial counterparts in the regolith do indeed germinate and grow a little but do not survive long, and certainly not to the key point where they produce fruit and seeds. The test plants with my customised bacterial counterparts grow larger, and more importantly produce seeds (especially in the case of the soy beans).

Soybean in Martian Regolith Simulant

Not only is my research important off this planet, but more importantly it applies to the parts of our planet that are rapidly becoming more and more difficult to farm. The Earth has lost 30% of its arable farmland in the past 40 years due in part to global warming. Regions in Australia, the USA and in much of Europe have been massively eroded and many of the nutrients in the soil have been stripped out due to pollution and drying. The research I undertake could help in these regions by providing a foothold for plants to grow again by extracting and providing nutrients. Over time the constant growth and decomposition of plants can regenerate the soil for intensive farming.

Written by Kyle C. Grant, a Doctoral Student in the Synthetic Biology Centre for Doctoral Training at the University of Oxford, working on next-generation synthetic bio-circuitry and related topics. He is a Wadham College Postgraduate Scholar and NASA Astrobiology Ambassador. I have worked within the interface between Astrophysics and Microbiology since midway through my undergraduate studies and continue to do so within my DPhil training.

Kyle Grant, the author