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The cryosphere harbours diverse microbial communities which are contributing to the global carbon budget. Various ice ecosystems like ice covers of freshwater lakes, sea ice and supraglacial areas are highly sensitive to temperate rise due to resulting enhanced availability of liquid water which is the prerequisite for life. To assess the overall importance of these communities we require a non-invasive tool which provides high resolution measurements of photosynthetic pigments such as phycoerythrin. Here we present the preliminary calibration processes for L.I.F.E. (laser induced fluorescence emission).

Once thought to be a barren desert devoid of life, it now appears that Earth's cryosphere is an ice ecosystem harbouring a rich community of metabolically active microorganisms inhabiting ice, snow, water, and lithic environments. The ability to rapidly survey this ecosystem during in situ and orbital missions is of considerable interest for monitoring Earth's carbon budget and for efficiently searching for life on Mars or any exoplanet with an analogous cryosphere. Laser induced fluorescence emission (L.I.F.E.) imaging and spectroscopy using excitation in ultraviolet (UV) wavelengths have been proposed as non-destructive astrobiological survey tools to search for amino acids, nucleic acids, microbial life, and polycyclic aromatic hydrocarbons (PAHs) deep in the Mars regolith. However, the technique is easily adapted to search for larger, more complex biomolecular targets using longer wavelength sources. Of particular interest is the ability for excitation at blue, green, and red wavelengths to produce visible and near infrared fluorescence of photosynthetic pigments in cyanobacteria-dominated microbial communities populating the ice of alpine, Arctic, and Antarctic lakes, glaciers, ice sheets, and even the supercooled water-ice droplets of clouds. During the Tawani 2008 International Antarctic Expedition we tested the in situ use of the technique as part of a field campaign in the Dry Valleys of Schirmacher Oasis and Lake Untersee, Queen Maud Land, Antarctica. In the spring of 2009, we performed airborne remote sensing tests of the technology in Alaska. In this paper we review our in situ laser detection experiments and present for the first time preliminary results on our efforts to detect cryosphere L.I.F.E. from an airborne platform.

In January 2002 the Planetary Studies Foundation returned to Antarctica to conduct a systematic search for meteorites on the blue ice fields near the Pecora Escarpment. The Pecora Escarpment area was previously searched by two National Science Foundation (NSF) teams that collectively recovered 526 meteorites. The two primary goals of the PSF Antarctica 2002 expedition were to determine if a significant number of meteorites could be found in a previously searched area, and to collect ice core samples to determine the presence or absence of microbial life. Several days' fieldwork resulted in the recovery of 33 meteorites, which included one stony-iron, two achondrites, an enstatite chondrite, and the collection of numerous ice samples. One particularly intriguing question that needed to be answered concerned the possibility that microbial life present in the ice may contaminate the meteorites. Antarctica was once considered to be a pristine environment with little or no biological contamination. This concept was particularly significant to the study of carbonaceous chondrites in order to insure that the organic compounds present in the meteorite were truly extraterrestrial in origin and not a product of terrestrial contamination. The preliminary results of this study indicated that microbial life was present in every ice sample.

A permanent ice covered water body, called Lake Paula, was detected in Patriot Hills in the West Antarctic and sampled for the first time ever for microbial life. The ice sheet measured approximately 2,5m thickness and the water body has a depth of about 10m. The lake is situated near a moraine which partly ablates from snow and provides meltwater from the slopes to the lake during austral summer. These running waters which are kept liquid by the heating up of the dark soil are penetrating the lower ice cover and thus softening up the lakeside part if the ice core. It is inoculated by nutrients, active microbes and diatoms of terrestrial origin. A distinct gradient concerning bacterial numbers, biomass and production which is 10 fold at the ice-water interface compared to the exposed part is observable. Temperature sensitivity of the embedded microbes reflect the gradient as well: Bacteria isolated from the upper part showed growth optima at 10°C, the lower part at 25°C, phylogenetic properties done by 16s rDNA reveal distinct communities depending on their vertical position, some clones are similar to those retrieved in Lake Vostok ice cores. These results offer the conclusion that even in this harsh environment like the Antarctic continent a dynamic system like microbial ice aggregates can be sustained as long as the supply of liquid water which is essential for an active bacterial metabolism is provided at least for a small time frame.

Transformation of organic and inorganic material in the atmosphere has been presumed to be caused by physical and chemical processes in the gas phase and in aerosol particles. Here we show that bacterial metabolism can play a measurable role in the production and transformation of organic carbon in cloud droplets collected at high altitudes, even at temperatures at or well below 0 degree(s)C. Although bacterial abundance and biomass in cloud water is low, compared to other oligotrophic aquatic environments, growth and carbon production rates per cell are approximately as high as in aquatic ecosystems. We hypothesize that microorganisms could play a crucial role in the transformation of airborne organic matter and the chemical composition of snow and rain. It has been recognized, the microbes can act as cloud condensation nuclei but we consider the impact on the global climate as low. With an increasing trend in cloudiness cloud systems can be seen as an ecosystem for active microbes with a seeding effort both for aquatic and terrestrial realms. Furthermore, air currents can distribute microbes over long distances to remote areas e.g. like ice caps and snow fields.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.