When the pilots let Tobias Niederwieser sit in the cockpit as the plane approached Vienna, they didn’t know that the experience would change the 8-year old’s life! Seventeen years later, Niederwieser has a private pilot certificate and is pursuing his PhD in Aerospace Engineering Sciences at the University of Colorado, Boulder! And his fascination with flying now extends far beyond the Earth’s atmosphere: “First impressed by planes, that interest moved over to human spaceflight,” he says of himself.
Although spaceflight sounds glamorous, it also involves humans consuming food, potable water, and O2, as well as producing CO2, fecal and urine waste, and water vapor. Systems currently used to support humans – onboard the International Space Station, for example – are physicochemical, with physical or chemical processes partially recovering the oxygen and water needed for life from carbon dioxide and waste water. Yet, the only technology able to sustain the “closed-loop” life support system needed for long-lasting spaceflight missions is biological – the bioregenerative process of photosynthesis. For this, algae have several advantages over higher plants: they produce biomass faster than higher plants and are also 10-50 times more efficient than crops at “fixing” CO2.
NASA has recommended that a spacecraft’s atmospheric pressure be less than the Earth’s (8.2 pounds per square inch (psi) compared to 14.7 psi measured at sea level), to prevent astronauts from getting “the bends” when they exit the craft for a spacewalk; NASA also endorses a 34% O2 concentration, rather than 21% as on Earth. Algae and humans definitely can live symbiotically, with algae using CO2, wastewater, and solid waste for nutrition, and generating cleaner water, O2, even biomass as a food source. But the big question is: Can algae thrive in the altered environment required for astronauts?
Previous studies had determined growth conditions for algal cultures in terms of temperature, pH, growth medium, and light (intensity, cycle, and spectrum); and low gravity somewhat impairs the cellular development of algae. However, the effects of altered atmospheric pressure and oxygen concentrations on algae are not yet known.
Niederwieser’s research is investigating how a spacecraft cabin’s atmosphere will affect algae cultured there. Using Chlorella vulgaris, which is very adaptable to environmental changes, he is developing a test setup capable of measuring algal metabolism as well as algal growth under differing atmospheric pressures: 8.2 psi (in spacecraft), 10.2 psi (previously used in the shuttle), 12.2 psi (in Boulder, CO, more than a mile above sea level), and 14.7 psi (at sea level). He will also study the growth and metabolism of Chlorella vulgaris at different oxygen concentrations under reduced total atmospheric pressure. Finally, Niederwieser will address the core issue: Is it feasible to use an algal photobioreactor for life support in spacecrafts?
His study is underway, with results yet to be determined. Even for Earthlings who prefer to keep their feet on terra firma, the results of his work could improve our understanding of ecosystems and help reduce the Earth’s CO2 levels. But Niederwieser is optimistic about the outcome. “Algae, or maybe even higher plants, will be used to support humans and animals in space and on foreign bodies,” he predicts. “I hope there will be hundreds of people living off the Earth supporting a spacefaring nation!”
The preceding article is part of a series featuring the scientific work of 20 young Austrian researchers, all who are active members of the OSTA's Research and Innovation Network Austria. The initial presentation of their work took place at the ASCINA poster session under the auspices of the "Austrian Research and Innovation Talk" in Toronto on October 21, 2016. Three of these scientists were subsequently awarded the ASCINA award the same evening, honoring their outstanding scientific work.