The PROCESS experiment: an astrochemistry laboratory for solid and gaseous organic samples in low-earth orbit

The PROCESS (PRebiotic Organic ChEmistry on the Space Station) experiment was part of the EXPOSE-E payload outside the European Columbus module of the International Space Station from February 2008 to August 2009. During this interval, organic samples were exposed to space conditions to simulate their evolution in various astrophysical environments. The samples used represent organic species related to the evolution of organic matter on the small bodies of the Solar System (carbonaceous asteroids and comets), the photolysis of methane in the atmosphere of Titan, and the search for organic matter at the surface of Mars. This paper describes the hardware developed for this experiment as well as the results for the glycine solid-phase samples and the gas-phase samples that were used with regard to the atmosphere of Titan. Lessons learned from this experiment are also presented for future low-Earth orbit astrochemistry investigations.     

The PROCESS experiment: exposure of amino acids in the EXPOSE-E experiment on the international space station and in laboratory simulations

To understand the chemical behavior of organic molecules in the space environment, amino acids and a dipeptide in pure form and embedded in meteorite powder were exposed in the PROCESS experiment in the EXPOSE-E facility mounted on the European Technology Exposure Facility (EuTEF) platform on board the International Space Station (ISS). After exposure to space conditions for 18 months, the samples were returned to Earth and analyzed in the laboratory for reactions caused by solar UV and cosmic radiation. Chemical degradation and possible racemization and oligomerization, the main reactions caused by photochemistry in the vacuum ultraviolet domain (VUV, wavelength range 100-200?nm for photon energy from 6.2 to 12.4?eV) were examined in particular. The molecules were extracted and derivatized by silylation and analyzed by gas chromatograph coupled to a mass spectrometer (GC-MS) to quantify the rate of the degradation of the compounds. Laboratory exposure in several wavelength ranges from UV to VUV was carried out in parallel in the Cologne Deutsches Zentrum für Luft- und Raumfahrt (DLR) Center and Centre de biophysique moléculaire (CBM) laboratories. The results show that resistance to irradiation is a function of the chemical nature of the exposed molecules and the wavelengths of the UV light. The most altered compounds were the dipeptide, aspartic acid, and aminobutyric acid. The most resistant were alanine, valine, glycine, and aminoisobutyric acid. Our results also demonstrate the protective effect of meteorite powder, which reemphasizes the importance of exogenic contribution to the inventory of prebiotic organics on early Earth.     

Survival of spores of the UV-resistant Bacillus subtilis strain MW01 after exposure to low-earth orbit and simulated martian conditions: data from the space experiment ADAPT on EXPOSE-E

In the space experiment "Molecular adaptation strategies of microorganisms to different space and planetary UV climate conditions" (ADAPT), bacterial endospores of the highly UV-resistant Bacillus subtilis strain MW01 were exposed to low-Earth orbit (LEO) and simulated martian surface conditions for 559 days on board the European Space Agency's exposure facility EXPOSE-E, mounted outside the International Space Station. The survival of B. subtilis MW01 spores from both assays (LEO and simulated martian conditions) was determined by a colony-formation assay after retrieval. It was clearly shown that solar extraterrestrial UV radiation (λ≥110?nm) as well as the martian UV spectrum (λ≥200?nm) was the most deleterious factor applied; in some samples only a few spore survivors were recovered from B. subtilis MW01 spores exposed in monolayers. However, if shielded from solar irradiation, about 8% of MW01 spores survived in LEO conditions, and 100% survived in simulated martian conditions, compared to the laboratory controls. The results demonstrate the effect of shielding against the high inactivation potential of extraterrestrial solar UV radiation, which limits the chances of survival of even the highly UV-resistant strain of B. subtilis MW01 in the harsh environments of outer space and the martian surface.     

Stability of amino acids and their oligomerization under high-pressure conditions: implications for prebiotic chemistry

The polymerization of amino acids leading to the formation of peptides and proteins is a significant problem for the origin of life. This problem stems from the instability of amino acids and the difficulty of their oligomerization in aqueous environments, such as seafloor hydrothermal systems. We investigated the stability of amino acids and their oligomerization reactions under high-temperature (180-400°C) and high-pressure (1.0-5.5?GPa) conditions, based on the hypothesis that the polymerization of amino acids occurred in marine sediments during diagenesis and metamorphism, at convergent margins on early Earth. Our results show that the amino acids glycine and alanine are stabilized by high pressure. Oligomers up to pentamers were formed, which has never been reported for alanine in the absence of a catalyst. The yields of peptides at a given temperature and reaction time were higher under higher-pressure conditions. Elemental, infrared, and isotopic analyses of the reaction products indicated that deamination is a key degradation process for amino acids and peptides under high-pressure conditions. A possible NH(3)-rich environment in marine sediments on early Earth may have further stabilized amino acids and peptides by inhibiting their deamination.     

Approaching Mars-like geochemical conditions in the laboratory: omission of artificial buffers and reductants in a study of biogenic methane production on a smectite clay

Methanogens have not been shown to metabolize in conditions exactly analogous to those present in Mars' subsurface. In typical studies of methanogenic metabolism, nutrient-rich buffered media and reducing agents are added to the cultures in an attempt to optimize the environment for methanogen survival and growth. To study methanogens in more Mars-relevant laboratory conditions, efforts should be made to eliminate artificial media, buffers, and reducing agents from investigations of methanogenic metabolism. After preliminary work to compare methanogen viability on montmorillonite clay and JSC Mars-1 regolith simulant, a study was conducted to determine whether biological methanogenesis could occur in non-reduced, non-buffered environments containing only H(2), CO(2), montmorillonite, and the liquid fraction extracted from a montmorillonite/deionized water suspension. Biogenic methane was observed in the microenvironments despite the omission of traditional media, buffers, and reducing agents. Mean headspace methane concentration after 96 days of observation was 10.23%?±?0.64% (% vol?±?SEM, n?=?4). However, methane production was severely decreased with respect to reduced, buffered microenvironments (Day 28: 31.98%?±?0.19%, n?=?3). Analysis of results and comparison to previous work indicate that montmorillonite clay has a strong ability to supply micronutrients necessary for methanogenic metabolism, and the liquid fraction from a montmorillonite/deionized water slurry can successfully be used as an alternative to reduced and buffered nutritive media in Mars-relevant studies of methanogenic metabolism.     

低地球轨道原子氧?太阳远紫外协合效应地面试验条件探讨

低地球轨道航天器表面聚合物材料受中性大气原子氧和太阳远紫外辐照的同时作用,表现出不同于单一因素分别作用的协合效应。文章在总结现有地面试验设备参数和不足的基础上,分析原子氧注量、远紫外曝辐照度随在轨时间变化的计算方法和输入数据特性,并以正立方体卫星为例计算得到典型轨道不同太阳活动环境下迎风面和非迎风面的原子氧注量和远紫外曝辐照度,以及远紫外曝辐照度/原子氧注量之比（注量比）随在轨时间的变化后,提出将该注量比参数作为有关地面试验条件制定的依据之一,以提高航天器外露材料原子氧?远紫外协合效应地面试验模拟的有效性。     

The Martian and extraterrestrial UV radiation environment. Part II: further considerations on materials and design criteria for artificial ecosystems.

Ultraviolet radiation is an important natural physical influence on organism function and ecosystem interactions. The UV radiation fluxes in extraterrestrial environments are substantially different from those experienced on Earth. On Mars, the moon and in Earth orbit they are more biologically detrimental than on Earth. Based on previously presented fluxes and biologically weighted irradiances, this paper considers in more detail measures to mitigate UV radiation damage and methods to modify extraterrestrial UV radiation environments in artificial ecosystems that use natural sunlight. The transmission characteristics of a Martian material that will mimic the terrestrial UV radiation environment are presented. Transmissivity characteristics of other Martian and lunar materials are described. Manufacturing processes for the production of plastics and glass on the lunar and Martian surface are presented with special emphasis on photobiological requirements. Novel UV absorbing configurations are suggested.     

LARES successfully launched in orbit: Satellite and mission description

On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically ‘frame-dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei–Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation system. The data exploitation phase started immediately after the launch under a new contract between ASI and those universities. Tracking of the satellite is provided by the International Laser Ranging Service. Due to its particular design, LARES is the orbiting object with the highest known mean density in the solar system. In this paper, it is shown that this peculiarity makes it the best proof particle ever manufactured. Design aspects, mission objectives and preliminary data analysis will be also presented.     

The formation of sulfate and elemental sulfur aerosols under varying laboratory conditions: implications for early earth

The presence of sulfur mass-independent fractionation (S-MIF) in sediments more than 2.45?×?10(9) years old is thought to be evidence for an early anoxic atmosphere. Photolysis of sulfur dioxide (SO(2)) by UV light with λ?相似文献   

Mutagenesis in bacterial spores exposed to space and simulated martian conditions: data from the EXPOSE-E spaceflight experiment PROTECT

As part of the PROTECT experiment of the EXPOSE-E mission on board the International Space Station (ISS), the mutagenic efficiency of space was studied in spores of Bacillus subtilis 168. After 1.5 years' exposure to selected parameters of outer space or simulated martian conditions, the rates of induced mutations to rifampicin resistance (Rif(R)) and sporulation deficiency (Spo(-)) were quantified. In all flight samples, both mutations, Rif(R) and Spo(-), were induced and their rates increased by several orders of magnitude. Extraterrestrial solar UV radiation (>110?nm) as well as simulated martian UV radiation (>200?nm) led to the most pronounced increase (up to nearly 4 orders of magnitude); however, mutations were also induced in flight samples shielded from insolation, which were exposed to the same conditions except solar irradiation. Nucleotide sequencing located the Rif(R) mutations in the rpoB gene encoding the β-subunit of RNA polymerase. Mutations isolated from flight and parallel mission ground reference (MGR) samples were exclusively localized to Cluster I. The 21 Rif(R) mutations isolated from the flight experiment showed all a C to T transition and were all localized to one hotspot: H482Y. In mutants isolated from the MGR, the spectrum was wider with predicted amino acid changes at residues Q469K/L/R, H482D/P/R/Y, and S487L. The data show the unique mutagenic power of space and martian surface conditions as a consequence of DNA injuries induced by solar UV radiation and space vacuum or the low pressure of Mars.     

The gaussian form of the variation-of-parameter equations formulated in equinoctial elements—Applications: Airdrag and radiation pressure

In this paper the Gaussian equations are derived for the nonsingular equinoctial elements, as they are required for dissipative perturbations of a satellite orbit. As examples, airdrag and solar radiation pressure are considered and the first-order variation of the elements and time after one revolution are given explicitly.     

The BOSS and BIOMEX space experiments on the EXPOSE-R2 mission: Endurance of the desert cyanobacterium Chroococcidiopsis under simulated space vacuum,Martian atmosphere,UVC radiation and temperature extremes.

The proposed space experiments BOSS (Biofilm Organisms Surfing Space) and BIOMEX (BIOlogy and Mars experiment) will take place on the space exposure facility EXPOSE-R2 on the International Space Station (ISS), which is set to be launched in 2014. In BOSS the hypothesis to be tested is that microorganisms grown as biofilms, hence embedded in self-produced extracellular polymeric substances, are more tolerant to space and Martian conditions compared to their planktonic counterparts. Various microbial biofilms have been developed including those obtained from the cyanobacterium Chroococcidiopsis isolated from hot and cold deserts. The prime objective of BIOMEX is to evaluate to what extent biomolecules are resistant to, and can maintain their stability under, space and Mars-like conditions; therefore a variety of pigments and cell components are under investigation to establish a biosignature data base; e.g. a Raman spectral library to be used for extraterrestrial life biosignatures. The secondary objective of BIOMEX is to investigate the endurance of extremophiles, focusing on their interactions with Lunar and Martian mineral analogues. Ground-based studies are currently being carried out in the framework of EVTs (Experiment Verification Tests) by exposing selected organisms to space and Martian simulations. Results on a desert strain of Chroococcidiopsis obtained from the first set of EVT, e.g. space vacuum, Mars atmosphere, UVC radiation, temperature cycles and extremes, suggested that dried biofilms exhibited an enhanced survival compared to planktonic lifestyle. Moreover the protection provided by a Martian mineral analogue (S-MRS) to the sub-cellular integrities of Chroococcidiopsis against UVC radiation supports the endurance of this cyanobacterium under extraterrestrial conditions and its relevance in the development of life detection strategies.     

UV photochemistry of DNA in vitro and in Bacillus subtilis spores at earth-ambient and low atmospheric pressure: implications for spore survival on other planets or moons in the solar system

Two major parameters influencing the survival of Bacillus subtilis spores in space and on bodies within the Solar System are UV radiation and vacuum, both of which induce inactivating damage to DNA. To date, however, spore survival and DNA photochemistry have been explored only at the extremes of Earth-normal atmospheric pressure (101.3 kPa) and at simulated space vacuum (10(-3)-10(-6) Pa). In this study, wild-type spores, mutant spores lacking alpha/beta-type small, acid-soluble spore proteins (SASP), naked DNA, and complexes between SASP SspC and DNA were exposed simultaneously to UV (254 nm) at intermediate pressure (1-2 Pa), and the UV photoproducts cis,syn-thymine-thymine cyclobutane dimer (c,sTT), trans,syn-thymine-thymine cyclobutane dimer (t,sTT), and "spore photoproduct" (SP) were quantified. At 101.3 kPa, UV-treated wild-type spores accumulated only SP, but spores treated with UV radiation at 1-2 Pa exhibited a spectrum of DNA damage similar to that of spores treated at 10(-6) Pa, with accumulation of SP, c,sTT, and t,sTT. The presence or absence of alpha/beta-type SASP in spores was partly responsible for the shift observed between levels of SP and c,sTT, but not t,sTT. The changes observed in spore DNA photochemistry at 1-2 Pa in vivo were not reproduced by irradiation of naked DNA or SspC:DNA complexes in vitro, suggesting that factors other than SASP are involved in spore DNA photochemistry at low pressure.     

浅议行政事业单位财务管理的现状与改进

文章从行政事业单位财务管理的重要性入手,深入分析了行政事业单位在财务管理制度以及人力资源两方面的不足,从财务管理的职能和人才队伍方面提出了切实有效的改进建议.     

Using a mini-Raman spectrometer to monitor the adaptive strategies of extremophile colonizers in arid deserts: relationships between signal strength, adaptive strategies, solar radiation, and humidity

Abstract The survival strategies of one cyanobacteria colony and three terricolous lichen species from the hot subdesert of Tabernas, Spain, were studied along with topographical attributes of the area to investigate whether the protective strategies adopted by these pioneer soil colonizers are related to the environmental stressors under which they survive. A handheld Raman spectrometer was used for biomolecular characterization, while the microclimatic and topographic parameters were estimated with a Geographic Information System (GIS). We found that the survival strategies adopted by those organisms are based on different combinations of protective biomolecules, each with diverse ecophysiological functions, such as UV-radiation screening, free-energy quenching, antioxidants, and the production of different types and amounts of calcium oxalates. Our results show that the cyanobacteria community and each lichen species preferentially colonized a particular microhabitat with specific moisture and incident solar radiation levels and exhibited different adaptive mechanisms. In recent years, a number of studies have provided consistent results that suggest a link between the strategies adopted by those extremophile organisms and the microclimatic environmental parameters. To date, however, far too little attention has been paid to results from Raman analyses on dry specimens. Therefore, the results of the present study, produced with the use of our miniaturized instrument, will be of interest to future studies in astrobiology, especially due to the likely use of Raman spectroscopy at the surface of Mars. Key Words: Hot desert-Raman spectroscopy-Topography-Terricolous lichens-Cyanobacteria-Planetary exploration. Astrobiology 12, 743-753.     

Place learning in humans: The role of distance and direction information

Although the process of establishing a memoryof a location is necessary for navigation,relatively little is known about theinformation that humans use when forming placememories. We examined the relative importanceof distance and angular information aboutlandmarks in place learning. Participantsrepeatedly learned a target location inrelation to three distinct landmarks in animmersive computer-generated (virtual)environment. Later, during testing, theyattempted to return to that location. Theconfigurations of landmarks used during testingwere altered from those participants learned inorder to separate the effects of metricdistance information and information aboutinter-landmark angles. In general,participants showed greater reliance ondistance information than angular information. This reliance was affected by nonmetricrelationships present during learning, as wellas by the degree to which the learnedenvironment contained right or straightangles.     

The role of HZE particles in space flight: results from spaceflight and ground-based experiments.

Selected results from experiments investigating the potentially specific radiobiological importance of the cosmic HZE (= high Z, energetic) particles are discussed. Results from the Biostack space flight experiments, which were designed to meet the experimental requirements imposed by the microdosimetric nature of this radiation field, clearly indicate the existence of radiation mechanisms which become effective only at higher values of LET (linear energy transfer). Accelerator irradiation studies are reviewed which conform with this conjecture. The recently discovered production of "micro-lesions" in mammalian tissues by single HZE particles is possibly the most direct evidence. Open questions concerning the establishment of radiation standards for manned spaceflight, such as late effects, interaction with flight dynamic parameters, and weightlessness, are indicated.     

The extravehicular mobility unit: A review of environment, requirements, and design changes in the US spacesuit

Requirements are rarely static, and are ever more likely to evolve as the development time of a system stretches out and its service life increases. In this paper, we discuss the evolution of requirements for the US spacesuit, the extravehicular mobility unit (EMU), as a case study to highlight the need for flexibility in system design. We explore one fundamental environmental change, using the Space Shuttle EMU aboard the International Space Station, and the resulting EMU requirement and design changes. The EMU, like other complex systems, faces considerable uncertainty during its service life. Changes in the technical, political, or economic environment cause changes in requirements, which in turn necessitate design modifications or upgrades. We make the case that flexibility is a key attribute that needs to be embedded in the design of long-lived, complex systems to enable them to efficiently meet the inevitability of changing requirements after they have been fielded.     

Pulsating aurora and quasiperiodic VLF hiss in the auroral zone morning sector: The event of December 30, 2011

The spatial–temporal variations in aurora and VLF emissions during an weak intensification in the auroral zone morning sector on December 30, 2011, have been analyzed. The event was accompanied by a negative bay (~70 nT) in the X component of the magnetic field at ground stations in northern Scandinavia. At the recovery phase of this bay, the precipitation zone moved and VLF emission frequency simultaneously increased over ten minutes, which may indicate that waves and precipitating electrons had a common source. VLF noise bursts in the 600–1000 Hz band with a characteristic modulation scale of ~10 s and the corresponding aurora intensifications localized in the ~100 km region were observed during the following ten minutes, which also confirms that recorded waves are related to electron precipitation. This correspondence of the pulsating aurora periods and VLF noise modulation has been revealed for the first time. The role of VLF wave generation processes during the cyclotron interaction with electrons in the magnetosphere and the propagation of these waves from the magnetosphere to the observation point are discussed.