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The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA's Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.

The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA's Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS. © The Author(s) 2008.

Exactly 130 years passed between the discovery by Isaac Newton that white light was composed of colors [1] and the discovery of ultraviolet radiation by Johann Wilhelm Ritter, a German electro chemist, in 1801. We now understand that ultraviolet radiation, although representing <2% of the total number of photons that reach the surface of present-day Earth, has had an important role in the evolution of life on Earth. This is because it has a high energy, energy being proportional to the frequency of the radiation. UV radiation is damaging to a number of key macromolecules, particularly DNA. On early Earth, the lack of an ozone column probably resulted in higher biologically weighted irradiance than the surface of present-day Earth as there were no other UV absorbers in the atmosphere. This is also the case for present-day Mars and probably was for Mars in its early history.

Exactly 130 years passed between the discovery by Isaac Newton that white light was composed of colors [1] and the discovery of ultraviolet radiation by Johann Wilhelm Ritter, a German electro chemist, in 1801. We now understand that ultraviolet radiation, although representing <2% of the total number of photons that reach the surface of present-day Earth, has had an important role in the evolution of life on Earth. This is because it has a high energy, energy being proportional to the frequency of the radiation. UV radiation is damaging to a number of key macromolecules, particularly DNA. On early Earth, the lack of an ozone column probably resulted in higher biologically weighted irradiance than the surface of present-day Earth as there were no other UV absorbers in the atmosphere. This is also the case for present-day Mars and probably was for Mars in its early history.

A fraction of the number of ejecta expelled from a planet by comet or asteroid impacts end up landing on another planet. If microorganisms were living in the ground before impact, they would be transported inside ejecta to the target planet. During that p, Addresses: Mileikowsky C, KTH Royal Inst Technol, Stockholm, Sweden. KTH Royal Inst Technol, Stockholm, Sweden. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Langley Space Res Ctr, Newport News, VA USA. Observ Cote Azur, F-06003 Nice, Fra

The possibility and probability of natural transfer of viable microbes from Mars to Earth and Earth to Mars traveling in meteoroids during the first 0.5 Ga and the following 4 Ga are investigated, including: radiation protection against the galactic cosmi, Addresses: Mileikowsky C, Royal Inst Technol, Stockholm, Sweden. Royal Inst Technol, Stockholm, Sweden. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Langley Space Res Ctr, Newport News, VA USA. Observ Cote Azur, F-06003 Nice, France. DLR

For the first time, a continuous biological dosimetry for cytotoxic solar UV-radiation has been performed in Antarctica. The biological harmful UV-radiation on the ground was measured at the German Antarctic Georg von Neumayer (70°37' S, 80°22' W) from December 1990 to March 1992 using the biofilm technique. The UV-sensitive targets were dried spores of Bacillus subtilis which were immobilized on the film surface. The UV-induced inhibition of biological activity, determined photometrically from the protein synthesized after incubation and staining, was taken as measure for the absorbed UV-dose. Films were exposed in horizontal position for time invervals ranging from 4 days during summer up to 51 and 41 days before and after the polar night respectively. The use of different cut-off filters allowed the calculation of the biologically effective UVA, UVB and the complete UV-radiation (UVA+B). The data were compared with the global radiation and the ozone column thickness indicating an increase of biologically harmful UVB radiation during austral spring at reduced ozone concentrations yielding a radiation amplification factor (RAF) of 1.4, whereas for the total UV(A+B) range the RAF amounted to 0.3.

We present a model for composition of heavy ions in the solar energetic particles (SEP). The SEP composition in a typical large solar particle event reflects the composition of the Sun, with adjustments due to fractionation effects which depend on the first ionization potential (FIP) of the ion and on the ratio of ionic charge to mass (Q/M). Flare-to-flare variations in composition are represented by parameters describing these fractionation effects and the distributions of these parameters are presented.

For the first time, a continuous biological dosimetry for cytotoxic solar UV-radiation has been performed in Antarctica. The biological harmful UV-radiation on the ground was measured at the German Antarctic Georg von Neumayer (70°37' S, 80°22' W) from December 1990 to March 1992 using the biofilm technique. The UV-sensitive targets were dried spores of Bacillus subtilis which were immobilized on the film surface. The UV-induced inhibition of biological activity, determined photometrically from the protein synthesized after incubation and staining, was taken as measure for the absorbed UV-dose. Films were exposed in horizontal position for time invervals ranging from 4 days during summer up to 51 and 41 days before and after the polar night respectively. The use of different cut-off filters allowed the calculation of the biologically effective UVA, UVB and the complete UV-radiation (UVA+B). The data were compared with the global radiation and the ozone column thickness indicating an increase of biologically harmful UVB radiation during austral spring at reduced ozone concentrations yielding a radiation amplification factor (RAF) of 1.4, whereas for the total UV(A+B) range the RAF amounted to 0.3.

The main objective was to assess the influence of the seasonal stratospheric ozone depletion on the UV climate in Antarctica by using a biological test system. This method is based on the UV sensitivity of a DNA repair-deficient strain of Bacillus subtilis (TKJ 6321). In our field experiment, dried layers of B. subtilis spores on quartz discs were exposed in different seasons in an exposure box open to solar radiation at the German Antarctic Georg von Neumayer Station (70°37' S, 8°22' W). The UV-induced loss of the colony-forming ability was chosen as the biological end point and taken as a measure for the absorbed biologically harmful UV radiation. Inactivation constants were calculated from the resulting dose-response curves. The results of field experiments performed in different seasons indicate strongly season-dependent trend of the daily UV-B level. Exposures performed at extremely depleted ozone concentrations (October 1990) gave higher biologically harmful UV-B levels than expected from the calculated season-dependent trend, which was determined at normal ozone values. These values were similar to values which were measured during the Antarctic summer, indicating that the depleted ozone column thickness has an extreme influence on the biologically harmful UV climate on ground.

The main objective was to assess the influence of the seasonal stratospheric ozone depletion on the UV climate in Antarctica by using a biological test system. This method is based on the UV sensitivity of a DNA repair-deficient strain of Bacillus subtilis (TKJ 6321). In our field experiment, dried layers of B. subtilis spores on quartz discs were exposed in different seasons in an exposure box open to solar radiation at the German Antarctic Georg von Neumayer Station (70°37' S, 8°22' W). The UV-induced loss of the colony-forming ability was chosen as the biological end point and taken as a measure for the absorbed biologically harmful UV radiation. Inactivation constants were calculated from the resulting dose-response curves. The results of field experiments performed in different seasons indicate strongly season-dependent trend of the daily UV-B level. Exposures performed at extremely depleted ozone concentrations (October 1990) gave higher biologically harmful UV-B levels than expected from the calculated season-dependent trend, which was determined at normal ozone values. These values were similar to values which were measured during the Antarctic summer, indicating that the depleted ozone column thickness has an extreme influence on the biologically harmful UV climate on ground.

After Earth's origin, our host star, the Sun, was shining 20–25% less brightly than today. Without greenhouselike conditions to warm the atmosphere, our early planet would have been an ice ball, and life may never have evolved. But life did evolve, which indicates that greenhouse gases must have been present on early Earth to warm the planet. Evidence from the geological record indicates an abundance of the greenhouse gas CO2. CH4 was probably present as well; and, in this regard, methanogenic bacteria, which belong to a diverse group of anaerobic prokaryotes that ferment CO2 plus H2 to CH4, may have contributed to modification of the early atmosphere. Molecular oxygen was not present, as is indicated by the study of rocks from that era, which contain iron carbonate rather than iron oxide. Multicellular organisms originated as cells within colonies that became increasingly specialized. The development of photosynthesis allowed the Sun's energy to be harvested directly by life-forms. The resultant oxygen accumulated in the atmosphere and formed the ozone layer in the upper atmosphere. Aided by the absorption of harmful UV radiation in the ozone layer, life colonized Earth's surface. Our own planet is a very good example of how life-forms modified the atmosphere over the planets' lifetime. We show that these facts have to be taken into account when we discover and characterize atmospheres of Earth-like exoplanets. If life has originated and evolved on a planet, then it should be expected that a strong co-evolution occurred between life and the atmosphere, the result of which is the planet's climate.

The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA’s Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.

Petrographic and biological analysis of shock recovery experiments confirms the possible life transport due to an impact from Mars to Earth.

Habitats in the Antarctic provide an insight into habitats available on snowball earth. Physical UV protection on snowball earth would have been dominated by the manifestations of ice and snow in different habitats. The snowball period was a golden age of UV protection.

Extract from introduction: With regard to the impact and ejection phase we tested the case for the transfer of microorganisms from Mars to Earth. Using a high explosive set-up thin layers of bacterial endospores of Bacillus subtilis, of the lichen Xanthoria elegans and of the cyanobacterium Chroococcidiopsis sp. embedded between two plates of gabbro were subjected to 10, 20, 30, 40 and 50 GPa which is the pressure range observed in Martian meteorites [1].

Shock recovery experiments on a Martian analogue rock (gabbro) loaded with three types of microorganisms reveal that these organisms survive the impact and ejection phase on Mars at shock pressures up to about 50 GPa with exponentially decreasing survival rates.

Extract from introduction: The minerals of the Martian meteorites collected so far indicate an exposure to shock waves in the pressure range of 5 to 55 GPa [1]. As terrestrial rocks are frequently inhabited by microbial communities, rocks ejected from a planet by impact processes may carry with them endolithic microorganisms, if microbial life existed/exists on this planet.

In the context of Lithopanspermia investigations have been performed to investigate the ability of different organisms to resist scenarios of the natural interplanetary transfer of life from a donor planet (host planet) to an acceptor planet. Whereas the main focus of previous studies was on the resistance of bacteria and their colony forming capacity after space exposure, only a few experiments on eukaryotic microorganisms and especially on symbiotic organization forms such as lichens, have been performed in space (de la Torre et. al. 2007, Sancho et al. 2007). These experiments have concentrated on photosynthesis analysis as a first step to understand the maintenance of physiologic activity of eukaryotic organisms after exposure to space conditions. As a next step, physiologic activity, reproduction capacity and “healthy” cell structures as essential parts of vitality check were analyzed after the last ESA experiment on BIOPAN-6 on Foton M3. Besides the examination of photosynthetic activity determination by use of chlorophyll a-fluorescence, CLSM analysis by the use of LIVE/DEAD staining dyes and culture experiments for verification of germination and growth capacity of both of the lichen symbionts (alga and fungi), were performed. In this case, new results are now clearly emphasizing quantitatively the high survival capacity and maintenance of germination and growth capacity of both of the investigated symbionts which form the epilithic lichen species of Rhizocarpon geographicum and Xanthoria elegans, although they were exposed to harsh space conditions with an exposure time of 10 days. About 80% to 90% of ascospores of both of the analyzed lichens were able to germinate and to grow into well-developed mycelia. In detail: results of germination and growth capacity analysis of ascospores of the lichen X. elegans have shown no damage on growth behavior, if compared to the control analysis, differing only in the starting point of germination, w

In the context of Lithopanspermia investigations have been performed to investigate the ability of different organisms to resist scenarios of the natural interplanetary transfer of life from a donor planet (host planet) to an acceptor planet. Whereas the main focus of previous studies was on the resistance of bacteria and their colony forming capacity after space exposure, only a few experiments on eukaryotic microorganisms and especially on symbiotic organization forms such as lichens, have been performed in space (de la Torre et. al. 2007, Sancho et al. 2007). These experiments have concentrated on photosynthesis analysis as a first step to understand the maintenance of physiologic activity of eukaryotic organisms after exposure to space conditions. As a next step, physiologic activity, reproduction capacity and “healthy” cell structures as essential parts of vitality check were analyzed after the last ESA experiment on BIOPAN-6 on Foton M3. Besides the examination of photosynthetic activity determination by use of chlorophyll a-fluorescence, CLSM analysis by the use of LIVE/DEAD staining dyes and culture experiments for verification of germination and growth capacity of both of the lichen symbionts (alga and fungi), were performed. In this case, new results are now clearly emphasizing quantitatively the high survival capacity and maintenance of germination and growth capacity of both of the investigated symbionts which form the epilithic lichen species of Rhizocarpon geographicum and Xanthoria elegans, although they were exposed to harsh space conditions with an exposure time of 10 days. About 80% to 90% of ascospores of both of the analyzed lichens were able to germinate and to grow into well-developed mycelia. In detail: results of germination and growth capacity analysis of ascospores of the lichen X. elegans have shown no damage on growth behavior, if compared to the control analysis, differing only in the starting point of germination, w

After Earth's origin, our host star, the Sun, was shining 20–25% less brightly than today. Without greenhouselike conditions to warm the atmosphere, our early planet would have been an ice ball, and life may never have evolved. But life did evolve, which indicates that greenhouse gases must have been present on early Earth to warm the planet. Evidence from the geological record indicates an abundance of the greenhouse gas CO2. CH4 was probably present as well; and, in this regard, methanogenic bacteria, which belong to a diverse group of anaerobic prokaryotes that ferment CO2 plus H2 to CH4, may have contributed to modification of the early atmosphere. Molecular oxygen was not present, as is indicated by the study of rocks from that era, which contain iron carbonate rather than iron oxide. Multicellular organisms originated as cells within colonies that became increasingly specialized. The development of photosynthesis allowed the Sun's energy to be harvested directly by life-forms. The resultant oxygen accumulated in the atmosphere and formed the ozone layer in the upper atmosphere. Aided by the absorption of harmful UV radiation in the ozone layer, life colonized Earth's surface. Our own planet is a very good example of how life-forms modified the atmosphere over the planets' lifetime. We show that these facts have to be taken into account when we discover and characterize atmospheres of Earth-like exoplanets. If life has originated and evolved on a planet, then it should be expected that a strong co-evolution occurred between life and the atmosphere, the result of which is the planet's climate.

The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA’s Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.

Shock recovery experiments on a Martian analogue rock (gabbro) loaded with three types of microorganisms reveal that these organisms survive the impact and ejection phase on Mars at shock pressures up to about 50 GPa with exponentially decreasing survival rates.

Extract from introduction: With regard to the impact and ejection phase we tested the case for the transfer of microorganisms from Mars to Earth. Using a high explosive set-up thin layers of bacterial endospores of Bacillus subtilis, of the lichen Xanthoria elegans and of the cyanobacterium Chroococcidiopsis sp. embedded between two plates of gabbro were subjected to 10, 20, 30, 40 and 50 GPa which is the pressure range observed in Martian meteorites [1].

Habitats in the Antarctic provide an insight into habitats available on snowball earth. Physical UV protection on snowball earth would have been dominated by the manifestations of ice and snow in different habitats. The snowball period was a golden age of UV protection.

Extract from introduction: The minerals of the Martian meteorites collected so far indicate an exposure to shock waves in the pressure range of 5 to 55 GPa [1]. As terrestrial rocks are frequently inhabited by microbial communities, rocks ejected from a planet by impact processes may carry with them endolithic microorganisms, if microbial life existed/exists on this planet.

Petrographic and biological analysis of shock recovery experiments confirms the possible life transport due to an impact from Mars to Earth.