Exposed on the Space Station

A test of how microbes survive in space

Cosmonauts installed ESA’s Expose-R2 facility on the outside of the space station in 2014.

A kind of closing ceremony is being held this week in Berlin, with scientists presenting the most intriguing results from the European Space Agency’s BIOMEX mission on the International Space Station.

BIOMEX, which stands for Biology and Mars Experiment, is led by Jean-Pierre de Vera from the German AeroSpace Center. Its purpose is to investigate the limits of life, while creating a database of which biological markers are retained when microorganisms are exposed to harsh environmental stresses—especially ultraviolet irradiation, desiccation, and low temperature. Bacteria, lichen, algae, fungi and other microorganisms were mixed with minerals and then exposed to space on the Expose-R2 facility located outside the Russian Zvezda module on the space station. Results from the mission are also detailed in a recent special issue of the journal Astrobiology.

In general, it was found that the tested microorganisms survived space and Mars-like conditions remarkably well. Most of the damage was caused by hard ultraviolet (UVC) irradiation. Daniela Billi from the University of Rome, for example, exposed dried cyanobacteria to UV radiation for 469 days and to a Mars-like atmosphere for 722 days, then examined the resulting damage to photosynthetic pigments and DNA.

Another intriguing study was presented by Natalia Kozyrovska from the Institute of Molecular Biology and Genetics in Kiev, Ukraine. Her group tested a terrestrial micro-ecosystem in space—a biofilm form of a natural assemblage of probiotic bacteria and yeasts, called Kombucha Multimicrobial Community. The test showed that even though biofilms incur damages in space, they also provide significant protection. And yes, the microorganisms are extracted from the beverage of the same name.

Although this meeting officially ends the BIOMEX project, research will continue, and more exciting insights may come in the future, for example from single-cell sequencing analyses of microbes exposed to space and simulated Mars conditions. That work is currently done in Marina Walther-Antonio’s lab at the Mayo Clinic, with the goal of revealing what genetic changes are caused by space conditions.

So what’s next? A follow-on mission called BIOSIGN (Biosignatures and habitable niches) might be in space as soon as 2022. Its main objective is to analyze the extent to which selected organisms and fossils can survive space exposure and conditions on other planets. BIOSIGN will test various deep-sea microbes under simulated conditions similar to what might exist on the icy moons Enceladus and Europa. It also will expand the set of bio-molecules whose products and mechanisms of degradation will be studied.

The BIOMEX project is a great example of insightful science that’s possible to conduct in Earth orbit at relatively low cost, without having to send a spacecraft into deep space. It might even shed some light on the topic of panspermia—the possibility that microorganisms can survive the journey from one planetary body to another.

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