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Surviving in Space – Why There’s Moss on the ISS

Björn Huwe and Annelie Fiedler made the moss fit for space. Foto: Annelie Fiedler
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Björn Huwe and Annelie Fiedler made the moss fit for space. Foto: Annelie Fiedler

All the lights on campus are off. Only in Björn Huwe’s office a screen is flickering. The biologist is sitting at his desk in the institute building of the Botanical Garden, spellbound by the monitor. Over three and a half thousand kilometers away, at the Baikonur Cosmodrome, a Soyus rocket is taking off into space. Onboard is also biological cargo from Potsdam – moss and bacteria. Huwe watches it live on NASA-TV, anxious and fascinated at the same time and also a bit proud despite the uncertainty. Will it all work out? In what condition will the samples arrive at the ISS? Will it be possible to attach them to the space station’s Zvezda Module? For the young researcher it is a kind of letting go. What happens from now on is out of his control...

It is indeed an unusual story that began about five years ago. “It was at the time when increasing efforts to research extraterrestrial life were being made worldwide,” says the biology professor Jasmin Joshi, amusedly remembering some exotic suggestions like cultivating tulips on the Moon. Some projects, though, have been seriously pursued. These examine the behavior of extreme organisms under extraterrestrial conditions, among them the biological Mars experiment BIOMEX that was started in 2014. Bacteria, alga, lichens, and moss have been mounted on the exterior of ISS and are being exposed to vacuum and radiation in space. The researchers want to find out if the organisms can survive these extreme conditions and later endure transport between Earth and Mars. They are concentrating on the stability of cell structure, proteins, and DNA as well as on changes in certain pigments. If the cell components withstand space and Mars-like conditions in low earth orbit, they can be considered stabile traces of life.

BIOMEX includes 12 different packages of experiments from 25 German and international institutions. The principal investigator is the astrobiologist Jean-Pierre Paul de Vera of the DLR-Institute for Planet Research in Berlin-Adlershof. “When he asked us if we would like to contribute something, it literally seemed very far out at first,” Joshi remembers. “After looking at it more closely, we realized the potential added value for our basic research.” Moss, Joshi says, has not been exhaustively investigated yet. They do not belong to the useful plants. Research, if any, has concentrated on its secondary compounds. Geneticists have only recently discovered moss as a model plant, the biologist explains. 

Mosses are mostly haploid, i.e. they have only one set of chromosomes in contrast to higher plants. Their ability to survive long dry periods and resist the stress of large temperature fluctuations has aroused interest in the genetic properties of these evolutionarily important organisms, properties that were probably crucial in plant colonization of land about 450 million years ago.

After deciding to send moss for BIOMEX to space, the Potsdam scientists became immediately aware not just any nondescript plants from the roadside or domestic forests would do. They needed the strongest and most robust, those that have already proven on Earth that they can survive drought and heat as well as frost and extreme UV radiation. They chose moss cushions from the Swiss Alps. PhD student Huwe climbed 3000 meters up the mountains and brought down the “masters of survival” to the lab in Potsdam, where they were prepared for their space expedition. Certainly no easy task! “All samples had to look the same. We also had to exclude any interaction with other organisms,” the young biologist reports. He and the MA student Annelie Fiedler developed a special design. They painstakingly separated 50 thin stems from the moss cushions, washed them several times in double-distilled water, and reassembled them. They used original Alpine rock as soil but also Lunar and Mars-analog material from the Museum für Naturkunde Berlin and the German Aerospace Center (DLR). “Simulating space conditions as closely as possible was important,” Huwe says, explaining how they exposed the samples to different gas mixtures, UV radiation, and extreme temperatures in self-made climate chambers to find out if moss had any chance of survival, if its journey to space would be worth the effort. 

Preparing moss plants’ delicate spore capsules for space requires fine-motor skills. Fiedler found a practical solution. She designed tiny pockets of breathable, radiolucent foil, affixed them to the plants with “space glue”, and placed each capsule into bags so they would not just “fly away”.

The mosses that survived all their stress tests got their ticket to space from the European Space Agency (ESA). Only the departure date remained written in the stars. A grueling waiting period began for the researchers. As launch after launch was being postponed, the samples were drying up. Then, in early 2014, everything happened very quickly. The rocket launch was scheduled for the end of July. Fresh plants had to be fetched and prepared. “That was not easy,” Huwe remembers. “There was still snow in the mountains.” Before Easter the team of biologists worked two weeks in the lab separating, washing, reassembling, and gluing the plants onto rock pellets and then attaching Fiedler’s mini-bags. The researchers took a number of zero measurements to get reference values. Then the biological load was carefully packed, mailed to Cologne, and carried in the hand luggage of colleagues to Moscow and Baikonur.

On 23 July 2014, at 23:00 Central European Time, a space transporter took off from Baikonur for the ISS. In August the samples were attached to the exterior wall of the Zvezda Module. They remained covered at first to prevent any reaction between the residual gas in the samples and the radiation that could have impaired the glass filters. In October the astronauts removed this last protective covering during a second extra-vehicular activity. Since then the plants have been tested under extreme conditions. They have to make do without nutrients and moisture in space vacuum under Mars-like conditions for a year and a half. Joshi, however, is optimistic. She thinks that the mosses can withstand a lot. “They are most resilient under dry condition.” 

When the plants return to Earth, the researchers will examine if photosynthesis is still possible and if cell structures will have changed. Genetic damage can be diagnosed on samples of Marchantia Polymorpha, the common liverwort, which biologists from the University of Zurich added to the freight. “This species was completely sequenced before the experiment,” Joshi explains, which enables a before-after comparison. 

Dirk Wagner, Professor of Geomicrobiology and Geobiology, eagerly awaits the return of the Potsdam cargo. He contributed archaea – methanogens – to the stay in space to learn more about their survivability and detectability in Mars-analog substrate. After all, the results of the BIOMEX experiments are supposed to help in the search and identification of life on the red planet. Future Mars mission will benefit from it.

The Researchers

The biologist Prof. Jasmin Joshi studied at the University of Zurich, and completed her PhD at the University of Basel. Since 2008 she has been Professor of Biodiversity Research and Botany at the University of Potsdam. Her research interests include invasion biology and functional biodiversity research.

Contact

Universität Potsdam
Institut für Biochemie und Biologie
Maulbeerallee 1
14469 Potsdam
E-Mail: jjoshiuni-potsdamde 

Björn Huwe studied biology at the University of Potsdam and is currently a PhD student here. He is involved in the BIOMEX - Project “BIOlogy and Mars Experiment”.

Contact

E-Mail: bhuweuni-potsdamde 

The Project

The BIOMEX “BIOlogy and Mars Experiment” involves 25 institutes from around the world. It is part of ESA’s space experiment EXPOSE-R2 on the International Space Station (ISS) and is funded by the European Space Agency (ESA) and the German Aerospace Centre (DLR) 

Text: Antje Horn-Conrad, Online-Editing: Agnes Bressa, Translation: Susanne Voigt
Contact Us: onlineredaktionuni-potsdamde

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