Searching for Dark Extraterrestrial Life (WATCH Today’s ‘Galaxy’ Stream)




An exploration of the possibilities of low-light microbial life and how some life on earth indicates that photosynthesis at low energies is possible, and may be common in the universe. Scientists at The Australian National University (ANU) have contributed to an international study that will potentially help humans to colonise Mars and find life on other planets.

“Searching for the signature fluorescence from these pigments could help identify extra-terrestrial life,” said Jennifer Morton, a PhD scholar at the ANU Research School of Chemistry. Morton said a key discovery was identifying a significantly different mechanism of photosynthesis that enhances the understanding of photosynthesis, more broadly. “This work redefines the minimum energy needed in light to drive photosynthesis,” she said.


The study on an organism that survives in inhospitable and low-light conditions could dramatically improve our understanding of photosynthesis, the process by which plants and other organisms make and store energy from light and produce oxygen.

Cyanobacteria are one of the largest groups of bacteria on Earth, where they have existed for more than 2.5 billion years. ANU Emeritus Professor Elmars Krausz said low-light adapted cyanobacteria could be used to colonise Mars and other planets, to produce oxygen and create a biosphere.

“This might sound like science fiction, but space agencies and private companies around the world are actively trying to turn this aspiration into reality in the not-too-distant future,” said Professor Krausz, a co-author on the Science paper from the ANU Research School of Chemistry. “Photosynthesis could theoretically be harnessed with these types of organisms to create air for humans to breathe on Mars. Low-light adapted organisms, such as the cyanobacteria we’ve been studying, can grow under rocks and potentially survive the harsh conditions on the red planet.”



Certain cyanobacteria, such as the type found growing in environments including Antarctica and the Mojave Desert, have even survived on the outside of the International Space Station.

Co-author Morton said certain types of chlorophylls adapted to low-energy light were indeed vital pigments in photosynthesis both in harvesting light and driving photochemistry. “Chlorophyll adapted to absorb visible light is very important in photosynthesis for most plants, but our research identifies the so-called ‘red’ chlorophylls as critical components in photosynthesis in low-light conditions.”

Morton said studying the red chlorophylls also provided clues as to where to find life on other planets. Morton said once an organism was adapted to low light, it died immediately when exposed to sunshine. “All photosynthetic organisms, such as coral reefs, suffer severe environmental stresses from high temperatures, high light levels and ultraviolet light, so this research helps scientists to better understand these limits,” she said.

The ANU researchers used their uniquely capable optical spectrometer system to analyse the role of the red chlorophylls in photosynthesis, and they are using computer modelling to further understand their roles.

The Daily Galaxy via ANU

Image credit: An artist’s rendering of exoplanet J1407b passing in front of its parent star. (Ron Miller)


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