Microbes on Mars
Jack discusses the challenges of colonising Mars by humans
“Mars however presents a challenge that requires novel ideas and technologies, ideas which will come from disciplines not normally associated with space travel.”
It seems inevitable that humans will venture to Mars in the near future; SpaceX CEO Elon Musk recently announced plans for manned missions to Mars as early as 2022. Boeing CEO Dennis Muilenburg responded with claims that they would be first to bring humans to the Red Planet. This journey to Mars, however, will not be simple. It needs more than public enthusiasm and charismatic billionaires dreaming of space colonies — it demands scientific innovation. Space travel solutions have traditionally come from teams of aeronautical engineers and physicists; Mars however presents a challenge that requires novel ideas and technologies, ideas which will come from disciplines not normally associated with space travel.
Microbes on Mars
A round trip to Mars will demand scientific and engineering innovation; it is more than an extension of the lessons learned from trips to space stations or the Moon. Armstrong, Aldrin and Collins travelled to the Moon in just under 52 hours. A journey to Mars however, could take 6 to 7 months. Astronauts aboard these gruelling missions will be confined to cramped quarters and bombarded by radiation. Their reward for such journeys will be a lifeless, inhospitable destination. Safety while travelling to and living on the Red Planet is not guaranteed. It will depend upon the development of a suite of life-support technologies. As Mark Watney said in ‘The Martian’, we’re “gonna need to science the sh*t out of this” if we’re to make it on Mars.
Some of this science may come from the field of synthetic biology. Synthetic biology is the convergence of biology and engineering, which treats DNA, genes and cells as tools to create novel ‘biological machines’. The early researchers in synthetic biology assembled rudimentary biological memory units and oscillatory networks (clocks) as proofs of concept. This work demonstrated that the logic of computer engineering could be applied to living cells, that we can construct biological circuitry and machinery. Synthetic biology research has become, in recent years, more sophisticated. Some have developed, for example, tiny chips lined with human cells, Organs-On-Chips for testing drugs. ‘Living therapeutics’ have been devised, microbes programmed to recognise and treat human diseases. These devices, as well as biofuels, biomaterials and biocomputing demonstrate the potential in building with biology. Biological machines could help to make life on Mars a reality.
A number of Mars mission profiles are being considered at the moment. There are short-stay (opposition-class), long-stay (conjunction-class) and intermediate length missions. Short-stay missions would see a crew on the surface of Mars for 30-90 days, while a long-stay could go on for 500 days. Long missions attract the attention of synthetic biology researchers, as mission resources will need to be generated on Mars.
The resources required to sustain humans on Mars for this long is more than can be sent in one shipment. The crew on the Red Planet would need to be supported with more food and water, medicines and the fuels necessary for a journey back to Earth than could be sent on their rockets, making supplying these missions with the required resources costly. This cost is mitigated however, with ‘in situ resource utilization’ or IRSU. IRSU solutions harness the materials that we find at a destination, rather than carry everything from Earth. ISRU missions carrying humans to Mars could be much lighter and faster, while also reducing the cost. The resources that we could manipulate include gases in the atmosphere, soil, loose surface stones and human waste. This can then be used to produce Mission Consumables, propellants, food and life-support stocks. If our destination on Mars is well researched, if we know that it can provide resources, ISRU will help us to get there and back again.
Some researchers are combining synthetic biology with ISRU. Synthetic biology has a critical advantage over traditional electromechanical ISRU systems in that they are much cheaper. Sending heavy cargo into space is prohibitively expensive; every unit of mass that is sent on these journeys requires an additional 99 units of support mass. Electromechanical life-support systems which supply oxygen, food or fuel are bulky and increase the cost of these trips.
Speculate the future
Electromechanical ISRU systems, such as hydrogen reduction chambers for oxygen production or water purifying membrane sheets, perform fantastically here on Earth, but sending these hefty machines to Mars will not be feasible for many missions. Bacterial cells don’t weigh nearly as much and they can, if engineered with the right genes, replace the classical systems. Various teams at NASA, such as the Ames Bioengineering Branch address this problem with synthetic biology alternatives to these bulky systems. Prototype concepts such as Water-Walls from NASA store organic waste generated by the crew in polyethylene bags which contain biological and chemical solutions capable of removing carbon dioxide. They then metabolise this waste to produce oxygen or purify water. Another NASA prototype, Microbial Fuel Cells, are designed to produce renewable electricity or biofuels from crew wastes.
If we speculate for a moment and imagine that these first voyages testing synthetic biology technologies succeed. Crews survive the long stays on Mars with microbial oxygen production, waste disposal and water purification.
Scientists could then decide to return as colonisers, not visitors. This would be stage three of NASA’s Journey to Mars strategy. The first, ‘Earth Reliant’ stage, where we are right now, is followed by the second ‘Proving Ground’ stage and finally the ‘Earth Independent’ stage. If we are to progress fully to Earth ‘Independence’ and become resident on the planet, we would need not only ISRU, but planetary engineering. This could mean terraforming Mars, in other words transforming it to support life.
Although commonplace in science fiction films, the complete transformation of another planet would be near-impossible. True-terraforming involves initially seeding a planet with hardy, extremophile organisms and anaerobic bacteria that could supply the planet with oxygen. The temperature of the entire planet, the pressure exerted by the atmosphere and its gaseous composition would all have to be altered. Given that these processes took hundreds of millions of years on Earth, a colonisation of Mars seems infeasible and overly ambitious. This is not the aim of synthetic biology; instead the process of para-terraforming — creating enclosed, self-sustaining and Earth-like environments — is being discussed. Synthetic geomicrobiology uses engineered microbes to mine minerals such as iron, nickel or copper, which could be used in biocement as well as soil formation. Synthetic biology could provide the materials and the environment needed to establish settlements. Microbes will also break down and recycle human waste generated in the settlement. Biomining companies are already using some of these species here on Earth — all we need to do is modify them so as to work with the geology of Mars.
The design of these artificial, habitable settlements may then seem straightforward. This couldn’t be further from the truth – we have trouble doing it even here on Earth. In the desert of Oracle, Arizona during the late ‘80s, the Biosphere vivarium was built. Its designers imagined that it would develop into a self-sustained, closed ecological system capable of supporting life. It had miniature rainforest, grassland and ‘ocean’ environments. The life in this artificial set-up regulated the oxygen supply and its energy was provided by small natural-gas enclosures. After everything had been assembled, a human crew moved in for a two year stay. These were to be biological engineering’s utopian domes in the desert.
However, the project eventually encountered some serious problems. The oxygen in the Biosphere dropped below the level needed to support the crew. Oxygen depletion is, to say the least, a serious problem and it could only be resolved by pumping more into the enclosure. Water supplies, another necessity, were difficult to keep clean. They became polluted with excessive nutrients and needed treatment before it could be used by the crew. These problems, tensions within the crew and a range of other problems led to the ultimate failure of the project.
In light of these results, talk of establishing colonies may seem like far-fetched. Scepticism is understandable, but the experiments at Biosphere were only baby steps. Later projects, such as Russia’s Mars500 simulation saw crew members isolated for 520 days or the HI-SEAS have made progress after Biosphere’s failures. Crews of astronauts and cosmonauts have spent months (as well as one year-long stay) aboard the International Space Station. We are making progress. The rapid acceleration of synthetic biology promises to address the technical issues, water and oxygen supply. Space is hard and synthetic biology won’t be the solution to every problem we face on Mars, but part of a multidisciplinary approach. The dream of Mars will take time and it will encounter setbacks. We won’t find life on Mars — engineered life, however, may help us to survive there.