Settlement of Mars Using Synthetic Biology

By Prakriti Karki 

Will the dreams of those who wish to see humans settle Mars be limited to dreams only or will they turn out to be a reality some day? There are several signs that the latter may come to fruition — some important technologies like those of synthetic biology (SynBio) are even giving more hope to making Mars settlement a reality within our lifetimes. 

Synthetic biology is a new trending engineering approach in biology which has made engineering organisms easier, more efficient, and faster. For instance, the Nobel Prize winning discovery of CRISPR/Cas9 is no longer solely an academic biology lab tool, it has found broader applications in several other sectors. Literally, you will soon likely be able to edit your own DNA simply with an oligonucleotide and an enzyme.

Our world has long been dominated by a myriad of microbes (rather than human population or other living creatures) and, in the present context, the advancement in science and technology has led to several possibilities which were thought to be impossible even just a few years back. Researchers and scientists with a keen interest in having humans explore space have been developing the tools needed for human settlement on Mars, and some are now intrigued at the potential outcome of exploiting terrestrial microbes for various applications on the Red Planet. 

However, we should be clear that microorganisms alone cannot make settlement possible. The easy modification, faster growth, adaptability in variable conditions, and more understanding of their biological mechanisms make them our perfect choice to use. Nevertheless the most important learning from our Mother Earth is that the coordination of physical, chemical, and biological factors and the diversity within them are what makes settlement on the planet possible.

To understand how we can use Earth life to explore Mars, let’s explore a bit more about the Martian physical and chemical environment: the Red Planet’s surface is covered in dust and even has some water in the form of ice; atmospheric gases consist of  primarily CO2 (95%) with some N2 (<2%); and, relative to Earth, Mars has low gravity, low surface pressure and low temperature at the surface, less incident sunlight but higher UV (due to the lack of a magnetic field), and a regolith rich in perchlorates (salts that contain a highly oxidized chlorine atom and which are highly reactive with organic molecules). These factors on the Martian surface are, to some extent, obstacles to human settlement (we are not well-evolved for living in such an environment). However, one research study has indicated that the lower gravity on Mars may not be a major problem for organisms like plants to grow and develop. 

But does this mean physical factors  like gravity do not have a significant effect on survival of living organisms ? Of course not, more research studies are needed to understand the long term effects and also gravity is not the single factor we should tackle for survival on Mars..Studies on plants and other eukaryotes cannot correlate with microorganisms and vice versa. Omics level i.e. data driven synthetic and system biology research can aid in such cause-effect relationship research. 

Similarly, researchers are using shortcuts to make survivability of humans on Mars possible by mimicking Earth conditions there. This is why we often talk about building habitats and greenhouses to sustain a human presence on Mars. But, even then, how will we best adapt our food sources and our building materials and our living spaces to provide for Earth-life like ours while surviving the harsh environment of Mars? Can you imagine the possibility of permanent human settlement on Mars while requiring a continual supply of foods, pharmaceuticals, and other materials from Earth, given that transportation would cost so much (costs could be as high as about $300,000 per kilogram)? Can synbio play its heroic role in solving this problem too? 

Yes. SynBio approaches, related to engineering or reprogramming organisms and integrating genetics and computer science, are directed toward designing biological systems and engineering them to manufacture a variety of products such as polymers, fibers, drugs, food, fuel, and even biological building materials for habitat construction.

Engineering microorganisms to facilitate plant life on Mars. Source: Llorente, Williams, & Goold (2018)

We can even design microbes to be adapted to extreme environmental conditions like those found on Mars — such as a yeast whose whole genome is being re-engineered by the International Consortium. Using the principle of synthetic biology, genes from algae and other plants were cut and pasted into yeast to make substances like omega-3 fatty acids that could prevent bone density loss in astronauts. Engineered yeasts can synthesize rubber hydrocarbons directly from carbohydrates without unwanted side products like proteins, resins, sugars, and other secondary metabolites. Likewise, in the Mars Simulation Laboratory  in 2021, it was reported that lichens and cyanobacteria (which convert N2 to NH3 and CO2 to organic material) show photosynthetic adaptability after 34 days in simulated conditions. Use of these microbes with proper optimization and modification at the genomic level could help us get perfect microorganisms for an evolving environment on Mars and making desired bioproducts.

Similarly, shelter is a basic need of many living organisms. For the establishment of human shelter, microbes can help in the production of building materials — like bricks. It is suggested that bricks could be created through microbially induced calcite precipitation (MICP) with clumping of Martian regolith by microorganisms (like Bacillus pasteurii). Such microorganisms could be engineered to get more effective results by designing them to survive changes in pH, inducing the release of extracellular polysaccharide that helps to bind or adhere soil particles together and prevent dessication. 

In a similar way, martian soil which is rich in hazardous perchlorate, can be treated biologically by engineering CO2-utilizing bacteria to express perchlorate reduction enzymes, thereby enhancing removal of perchlorate. Even biomining, a method of using genetically altered microbes for mining on Mars, could be a great application of synthetic biology. For instance, in a Mars mimic experiment performed on the International Space Station, pieces of basalt soaked in bacterial solutions were used to evaluate the potential of three species of bacteria to extract rare earth elements from the rock. 

There are many applications of SynBio — rather than being limited by looking at physical and chemical barriers, we can play with biological tools to overcome those challenges. Synthetic biology has given that power to play. Interdisciplinary science has given hope. The more we explore, the more we discover. This is the magic of synthetic biology. 

But is not the transport of such microorganisms to Mars a burden? Yes, a little. There is always a tradeoff.  Multitudes of synthetically-altered microorganisms are very little burden to transport to Mars and their proper utilization could be fruitful in making dreams for terraformation of Mars successful. Biofoundries, through automation of robotic facilities, have served to be a boon in the efficient engineering of microorganisms along with providing aid in testing millions of DNA designs in parallel. With the decrease in the cost of DNA synthesis and reading, use of robotics, automation, and AI, this field is sure to show us several ways to explore Mars more efficiently within the next few decades.

Synthetic biology has already broadened the possibilities for human exploration and settlement on Mars. Synthetic biology startups and R&D have been gaining support from several funding agencies and investors. Public agencies like ESA, NASA, and ISRO, along with private organizations like SpaceX, Boeing, and Lockheed Martin, are devoting more resources to future developments of permanent Mars settlement. Our future looks bright. 

Obviously with the clear intersection and collaboration between academia and industries on this topic, we are going to make this dream possible earlier than some have imagined.
Are we ready to travel to Mars? Are we prepared to live on Mars? With the pace of innovation in space science, it seems very nearly a reality. Elon Musk, CEO of SpaceX says, “I think that Mars is gonna be a great place to go. It will be the planet of opportunity.” If everything goes fine, we will be living on two planets. Perhaps, it will be fun to travel to Mars during the winter vacation. 

Won’t it be? Nothing can stop us from dreaming. Thanks to SynBio.

Prakriti Karki is an active member of Media Lab Nepal exploring open science research in Nepal. She also runs a Project GyaNamuna- Connecting Rural Students to the Quality Education.