Before humankind can explore strange new worlds and seek out new life and new civilizations, it will have to deal with a weighty down-to-earth constraint: launchpad economics. Every unit of mass of payload that launched into space requires the support of an additional 99 units of mass, with “support” encompassing everything from fuel to oxygen to food and medicine for the astronauts. But mass-efficient payloads should be possible, insist researchers at the University of California, provided space explorers make use of nontraditional biological techniques. In particular, these researchers say synthetic biology should give space missions a boost.
The researchers published a techno-economic analysis that appeared online in the Journal of the Royal Society Interface. The analysis—“Towards synthetic biological approaches to resource utilization on space missions”—makes the case that synthetic biology “is capable of processing volatiles and waste resources readily available on lunar and Martian space missions in a way that, when compared with anticipated nonbiological approaches, reduces the launch mass of propellants, food, and raw material for three-dimensional printing, and also overcomes the decreased product shelf-life of a common therapeutic.”
Envisioning a 916-day mission to Mars, the authors of the study considered the ways synthetic biology could trim the cargo manifest: “It is determined that 205 days of high-quality methane and oxygen Mars bioproduction with Methanobacterium thermoautotrophicum can reduce the mass of a Martian fuel-manufacture plant by 56%; 496 days of biomass generation with Arthrospira platensis and Arthrospira maxima on Mars can decrease the shipped wet-food mixed-menu mass for a Mars stay and a one-way voyage by 38%; 202 days of Mars polyhydroxybutyrate synthesis with Cupriavidus necator can lower the shipped mass to three-dimensional print a 120 m3 six-person habitat by 85%.
In addition, microbes could also completely replenish expired or irradiated stocks of pharmaceuticals, which would provide independence from unmanned resupply spacecraft that take up to 210 days to arrive.
“Space has always provided a wonderful test of whether technology can meet strict engineering standards for both effect and safety,” said Adam Arkin, Ph.D., senior author of the study and director of Berkeley Lab’s Physical Biosciences Division. “NASA has worked decades to ensure that the specifications that new technologies must meet are rigorous and realistic, which allowed us to perform up-front techno-economic analysis.”
At Berkeley, Dr. Arkin’s research brief includes developing a framework to effectively combine comparative functional genomics, quantitative measurement of cellular dynamics, biophysical modeling of cellular networks, and cellular circuit design. Dr. Arkin’s group is also committed to leveraging these technologies to facilitate biological manufacturing applications in health, the environment, and bioenergy—on Earth and, now, in outer space.
The advantage biological manufacturing holds over abiotic manufacturing is the remarkable ability of natural and engineered microbes to transform very simple starting substrates, such as carbon dioxide, water biomass, or minerals, into materials that astronauts on long-term missions will need. This capability should prove especially useful for future extraterrestrial settlements.
“The mineral and carbon composition of other celestial bodies is different from the bulk of Earth, but the earth is diverse with many extreme environments that have some relationship to those that might be found at possible bases on the Moon or Mars,” adds Dr. Arkin. “Microbes could be used to greatly augment the materials available at a landing site, enable the biomanufacturing of food and pharmaceuticals, and possibly even modify and enrich local soils for agriculture in controlled environments.”
The authors acknowledge that much of their analysis is speculative and that their calculations show a number of significant challenges to making biomanufacturing a feasible augmentation and replacement for abiotic technologies. However, they argue that the investment to overcome these barriers offers dramatic potential payoff for future space programs.
The authors also have ideas about how to proceed next. “The results suggest that future synthetic biology and technological efforts should focus on improving bioreactor nutrient recycling percentages, enhancing bioproduction of alternative nitrous oxide fuels, bettering flavors of Spirulina, testing interlocking three-dimensional printed PHB blocks in habitat and furniture construction, and increasing biosynthesis efficiencies of desired outputs, including pharmaceuticals,” they venture. “[The] product yields that can be achieved by converting carbon dioxide to a biological feedstock of carbon monoxide remain to be explored. Perhaps this exploration can be achieved with a more formal constructed model, which consists of plug-and-play modules of biological pathways and processes.”