Finding Life in Martian Ice

With barren ice sheets and freezing winds, Antarctica might seem an unusually sterile and harsh environment in which to look for life. But within the frozen ice caps of its lakes, many fascinating secrets are concealed.

Dr. Michael C. Storrie-Lombardi of Kinohi Institute and Dr. Birgit Sattler at the University of Innsbruck in Austria have devised an imaging technique called LIFE (laser-induced fluorescence emission) to detect bacteria in frozen Antarctic lakes. But the ultimate goal is to use the technology to identify microbial life in the extreme environments on Mars, on the icy moons of our solar system and on exoplanets.

Dr. Michael C. Storrie-Lombardi takes pictures from the surface of Lake Stancionnoye in the Schirmacher Oasis in Antarctica while using a 532-nm laser to detect biomass in the ice. Images courtesy of Birgit Sattler.

LIFE uses inexpensive commercially available cameras and lasers to elicit and record a fluorescence response from photosynthetic pigments in microbial species dwelling within Antarctic lakes. On Earth, the technology must perform both remote sensing surveys and in situ micron-scale surveys without destroying complex living systems.

In the case of exploring other planets, the task requires a simple, reliable technology that can be used either by a human explorer or by an automated robotic pattern-recognition system.

“Most orbital and in situ systems to date rely on absorption spectroscopy or imaging, including multispectral and hyperspectral imaging,” Storrie-Lombardi said. “These are highly efficient and relatively easy to implement. At the other end of the technology spectrum, Raman technology has made significant advances in robustness and sensitivity; however, collection times and target damage can still be problematic.”

Dr. Michael C. Storrie-Lombardi (in front) and Vladimir Akimov of Pushchino, Russia, set up camp at Lake Untersee in Dronning Maud Land, Antarctica.

Laser-induced fluorescence offers a midground technology that is relatively easy and inexpensive to implement and that can generate data quickly and with minimal energy input so that the risk of damage to molecular targets is minimized.

The technique, which is described in the current issue of the research journal Astrobiology, involves taking a background natural light image or spectra using a CMOS camera. Next, light from a 532-nm laser diode is used to elicit a fluorescence response, at which point another image or spectra are recorded. The laser backscatter at 532 nm is removed either by filters and/or digitally by comparing the actual response at different wavelengths in the visible and near-infrared, with the expected response in the absence of fluorescence emission.

“While similar efforts have been performed using 532-nm lasers to identify and monitor ocean phytoplankton blooms, this is the first time the technology has been applied to identify micrometer-to-millimeter accumulations of photosynthetic life living within ice itself,” Storrie-Lombardi said.

The technology is inexpensive enough that it can evolve into a small system affordable to students, researchers in multiple disciplines and even private individuals. In the meantime, Storrie-Lombardi and Sattler are applying some of the lessons learned about LIFE techniques to aid colleagues at Mullard Space Science Laboratory, part of University College London, and at Oregon State University in Corvallis.

Together, they hope to enhance current and planned missions to explore Mars’ subsurface.

Marie Freebody
mariefreebody@physics.org