Prebiotic synthesis of nucleotides at the Earth orbit in presence of Lunar soil.

Modern studies now favor the fact that extraterrestrial organic molecules served as an important source of biological important substances on the primitive Earth. It is presumed that these space-made organic molecules could be transported safely to the Earth surface being associated with mineral grains. It is important to test whether nucleotides synthesized in Earth orbit could be protected by lunar surface regolite. The phosphorylation of adenosine, uridine and thymidine has been studied with respect of their further transformations and degradation in presence of mineral bed. After retrieval, HPLC analysis is used to identify all the mononucleotides of certain nucleosides. It has been shown, that exposure of the investigated nucleosides as dry films in space conditions in the presence of Lunar soil increases the yield of synthesized nucleotides in 1.1-3.0 times as compared with the exposure of the same samples in absence of Lunar soil. To identify and evaluate the principal source of energy in open space responsible for nucleotide synthesis reaction laboratory experiments were performed. It has been shown, that vacuum ultra violet (VUV 145 nm) radiation promotes nucleotide synthesis more effectively than ultra violet (UV 254 nm) while the presence of Lunar soil increases reaction yield in 1.5-2.0 times. Formation of 5'-mononucleotides seemed to be the most effective reaction both in flight and in laboratory experiments. Protective action of lunar soil on synthesized nucleotides against UV radiation has been shown in open Space conditions.     

Thymine photoproduct formation and inactivation of intact spores of Bacillus subtilis irradiated with short wavelength UV (200-300nm) at atmospheric pressure and in vacuo.

Vacuum exposure renders the survival of spores of Bacillus subtilis approximately five times more sensitive to ultraviolet light irradiation than exposure under atmospheric conditions. The photoproduct formation in spores irradiated under ultrahigh vacuum (UHV) conditions is compared to the photoproduct formation in spores irradiated at atmospheric pressure. Compared to irradiation at atmospheric pressure, where only the "spore photoproduct" 5-thyminyl-5,6-dihydrothymine (TDHT) can be detected, two additional photoproducts, known as the c,s and t,s isomers of thymine dimer (T<>T) are produced in vacuo. The spectral efficiencies for photoproduct formation in spores under atmospheric and vacuum conditions are compared. Since there is no increased formation of TDHT after irradiation in vacuum, TDHT cannot be made responsible for the observed vacuum effect. "Vacuum specific" photoproducts may cause a synergistic response of spores to the simultaneous action of ultraviolet light (UV) and UHV. Three different mechanisms are discussed for the enhanced sensitivity of B. subtilis spores to UV radiation in vacuum. The experiments described contribute valuable research information on the chance for survival of microorganisms in outer space.     

Infrared spectrometer PFS for the Mars 94 orbiter

Thin films containing a mixture of aliphatic (glycine) and aromatic (tryptophan or tyrosine) amino acids were exposed to a vacuum ultraviolet radiation (VUV) with wavelenghts 100–200 nm. Dipeptides (glycyl-tryptophan and glycyl-tyrosine) were synthesized in these conditions. We compared the actions of VUV and γ-radiation. Polymerization is an essential step in prebiological evolution and we have shown that this stage probably occured over an early Solar system history.     

The effects of vacuum-UV radiation (50-190nm) on microorganisms and DNA.

Early difficulties with the light source in the study of vacuum-UV effects on biological materials were overcome largely by the introduction of the synchrotron radiation source in 1977. Highly monochromatic vacuum-UV radiation has been used to obtain action spectra of various biological targets in the range 50-190 nm. Bacillus subtilis spores were particularly suitable because of their inherent tolerance to vacuum, and action spectra for inactivation were measured down to 50 nm. Action spectra for DNA strand breaks were also measured in the same range with isolated plasmid DNA. Studies are in progress of vacuum-UV induced molecular changes in nucleic acids and their model compounds, especially of chain scission and base modification.     

Progress on Space Solar Telescope in 2002-2004

The progress on Chinese Space Solar Telescope (SST) in 2002-2004 is introduced. The documentations on plans and outlines based on the standards of Chinese aerospace industry for SST mission has been fulfilled. The key technical problems of SST satellite platform and payloads are tackled during pre-study stage of the mission. The laboratory assembly and calibration of the main optical telescope of 1.2 m spherical mirror and 1 m plain mirror have been carried out with the accuracy of λ/40 and λ/30, respectively. The prototype at 17.1 nm for extreme ultraviolet telescope is under development and manufacture with a diameter of 13 cm. Its primary and secondary mirrors have a manufacturing error of 5nm with a roughness degree of less than 0.5 nm and a multiplayer reflection factor of better than 20%. The on-board scientific data processing unit has been developed. Prototypes for other payloads such as H and white light telescope, wide band spectroscopy in high energy and solar and interplanetary radio spectrometer have been developed accordingly.     

Progress on Solar Physics Research in China

The progress on Chinese Space Solar Telescope (SST) in 2002-2004 is introduced. The documentations on plans and outlines based on the standards of Chinese aerospace industry for SST mission has been fulfilled. The key technical problems of SST satellite platform and payloads are tackled during pre-study stage of the mission. The laboratory assembly and calibration of the main optical telescope of 1.2 m spherical mirror and 1 m plain mirror have been carried out with the accuracy of λ/40 and λ/30, respectively. The prototype at 17.1 nm for extreme ultraviolet telescope is under development and manufacture with a diameter of 13 cm. Its primary and secondary mirrors have a manufacturing error of 5 nm with a roughness degree of less than 0.5 nm and a multiplayer reflection factor of better than 20%. The on-board scientific data processing unit has been developed. Prototypes for other payloads such as H. and white light telescope, wide band spectroscopy in high energy and solar and interplanetary radio spectrometer have been developed accordingly.     

Study of the peptide prebiotic synthesis in context of exobiological investigations on earth orbit.

Dry films of amino acids mixtures glycine+ tryptophan and tryptophan were exposed on the surface of "Mir" station. Similar films were irradiated by vacuum ultra violet (145 nm) and ultra violet (254 nm) in the laboratory experiments. Gly-Gly, Trp-Gly, Gly-Trp, Tpr-Trp and Trp-Trp-Trp were the main reaction products for the experimental mixture glycine + tryptophan and Tpr-Trp and Trp-Trp-Trp for tryptophan. The presence of Lunar soil both in flight and in laboratory experiments increases the reaction yield by 1.5-2.0 times. Therefore, the hypothesis concerning the possibility of safe delivery of peptides and amino acids required for the emergence of life and associated with mineral have got yet another approval.     

A material experiment for small satellites to characterise the behaviour of carbon nanotubes in space – development and ground validation

Over the last years, Carbon Nanotubes (CNT) drew interdisciplinary attention. Regarding space technologies a variety of potential applications were proposed and investigated. However, no complex data on the behaviour and degradation process of carbon nanotubes under space environment exist. Therefore, it is necessary to investigate the performance of these new materials in space environment and to revaluate the application potential of CNTs in space technologies.Hence, CiREX (Carbon Nanotubes – Resistance Experiment) was developed as a part of a student project. It is a small and compact experiment, which is designed for CubeSat class space satellites. These are a class of nanosatellites with a standardized size and shape. The CiREX design, electrical measurements and the satellites interfaces will be discussed in detail. CiREX is the first in-situ space material experiment for CNTs.To evaluate the data obtained from CiREX, ground validation tests are mandatory. As part of an extensive test series the behaviour of CNTs under solar ultra violet light (UV) and vacuum ultraviolet light (VUV) was examined. Single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and MWNT/resin composite (ME) were exposed to different light sources. After the exposure, the defect density was investigated with Raman spectroscopy. There is a clear indication that UV and VUV light can increase the defect density of untreated CNTs and influence the electrical behaviour.     

Ultraviolet images of galaxies from the Optical Monitor on XMM-Newton

A large number of galaxies, both normal and active, have been observed in ultraviolet light by the Optical Monitor on XMM-Newton. These are some of the deepest wide-field ultraviolet images of these galaxies yet obtained, and in many cases the first collected in this waveband. We present images of five active galaxies, and discuss the potential uses of the ultraviolet surface brightness distribution and morphology, in association with X-ray data, for Active Galactic Nuclei, star formation and galaxy evolution studies.     

Radiation and thermal stabilities of adenine nucleotides.

We have investigated in detail radiation and thermal stabilities and transformations of adenosine mono- and triphosphates in liquid and frozen solid aqueous solutions within a wide range of absorbed radiation dose (up to 75 kGy) and temperature (up to 160 degrees C). Dephosphorylation is the main pathway of high temperature hydrolysis of adenine nucleotides. Basic thermodynamic and kinetic parameters of this process have been determined. Radiolysis of investigated compounds at room temperature results in scission of N-glycosidic bond with a radiation yield about of 1 mol/100 eV. Solution freezing significantly enhances radiation stability of nucleotides as well as other biomolecules. This circumstance is essential in the discussion of panspermia concepts.     

Biological responses to space: results of the experiment "Exobiological Unit" of ERA on EURECA I.

Spores of different strains of Bacillus subtilis and the Escherichia coli plasmid pUC19 were exposed to selected conditions of space (space vacuum and/or defined wavebands and intensities of solar ultraviolet radiation) in the experiment ER 161 "Exobiological Unit" of the Exobiology Radiation Assembly (ERA) on board of the European Retrievable Carrier (EURECA). After the approximately 11 months lasting mission, their responses were studied in terms of survival, mutagenesis in the his (B. subtilis) or lac locus (pUC19), induction of DNA strand breaks, efficiency of DNA repair systems, and the role of external protective agents. The data were compared with those of a simultaneously running ground control experiment. The survival of spores treated with the vacuum of space, however shielded against solar radiation, is substantially increased, if they are exposed in multilayers and/or in the presence of glucose as protective, whereas all spores in "artificial meteorites", i.e. embedded in clays or simulated Martian soil, are killed. Vacuum treatment leads to an increase of mutation frequency in spores, but not in plasmid DNA. Extraterrestrial solar ultraviolet radiation is mutagenic, induces strand breaks in the DNA and reduces survival substantially; however, even at the highest fluences, i.e. 3 x 10(8) J m-2, a small but significant fraction of spores survives the insolation. Action spectroscopy confirms results of previous space experiments of a synergistic action of space vacuum and solar UV radiation with DNA being the critical target.     

Results from the Far Ultraviolet Space Telescope (FAUST)

We present early results from the Far Ultraviolet Space Telescope (FAUST), which flew in March 1992 with the ATLAS space shuttle mission. The telescope provides wide-field images in the far ultraviolet (1400–1800 Å). Studies underway using the data obtained on this mission include establishing the brightness and distribution of far ultraviolet stars in the halo of our Galaxy, establishing the far ultraviolet properties of nearby galaxies and nearby clusters of galaxies, analyzing the diffuse galactic light, and searching for the origin of the extragalactic ultraviolet light. We discuss the instrument performance, and early results from these observations.     

Processing of amorphous carbon grains produced in hydrogen-rich atmosphere.

Recent laboratory experiments, compared with observations, have strongly suggested that the amount of hydrogen, present in the grain formation regions, around C-rich stars, can play a major role in the definition of the spectral characteristics of the freshly formed carbon dust particles. Such spectral characteristics could also be modified, during the thermal processing, due to the shock waves and/or the strong radiation field, that the grains undergo after their formation. In this work we report about a series of laboratory tests, during which submicronic dust particles of amorphous carbon, condensed in an hydrogen-rich atmosphere, have been processed, by means of two different methods. Some samples have been annealed into an oven at different temperatures, while others have been exposed to strong ultraviolet radiation. Their spectra have been obtained before and after the processing in the full range from ultraviolet (200 nm) to far infrared (0.1 mm). The results of the experiment are presented and discussed, together with their astrophysical implications.     

Variation of the full Sun hydrogen Lyman profiles through solar cycle 23

The hydrogen Lyman (Lyα, 121.267 nm and Lyβ, 102.572 nm) lines are important contributors to the solar extreme ultra violet (EUV) flux which illuminates the upper Earth’s atmosphere. From high resolution spectral observations performed with the solar ultraviolet measurement of emitted radiations (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO), the detailed profiles of these two lines have been obtained. Some insights into the variation of the shape of the profiles, sampled throughout the present solar cycle 23, are given and discussed.     

Evaluating the robustness of the enantioselective stationary phases on the Rosetta mission against space vacuum vaporization

The European Space Agency’s Rosetta mission was launched in March 2004 in order to reach comet 67P/Churyumov–Gerasimenko by August 2014. The Cometary Sampling and Composition experiment (COSAC) onboard the Rosetta mission’s lander “Philae” has been designed for the cometary in situ detection and quantification of organic molecules using gas chromatography coupled to mass spectrometry (GC–MS). The GC unit of COSAC is equipped with eight capillary columns that will each provide a specific stationary phase for molecular separation. Three of these stationary phases will be used to chromatographically resolve enantiomers, as they are composed of liquid polymers of polydimethylsiloxane (PDMS) to which chiral valine or cyclodextrin units are attached. Throughout the ten years of Rosetta’s journey through space to reach comet 67P, these liquid stationary phases have been exposed to space vacuum, as the capillary columns within the COSAC unit were not sealed or filled with carrier gas. Long term exposures to space vacuum can cause damage to such liquid stationary phases as key monomers, volatiles, and chiral selectors can be vaporized and lost in transit. We have therefore exposed identical spare units of COSAC’s chiral stationary phases over eight years to vacuum conditions mimicking those experienced in space and we have now investigated their resolution capabilities towards different enantiomers both before and after exposure to space vacuum environments. We have observed that enantiomeric resolution capabilities of these chiral liquid enantioselective stationary phases has not been affected by exposure to space vacuum conditions. Thus we conclude that the three chiral stationary phases of the COSAC experiment onboard the Rosetta mission lander “Philae” can be considered to have maintained their resolution capacities throughout their journey prior to cometary landing in November 2014.     

热控涂层紫外辐照试验方法的研究

几种有机热控涂层在真空下进行模拟太阳紫外辐照的试验。在真空条件和大气条件下测试涂层性能的变化,以比较热控涂层在进行紫外辐照时,原位测试和非原位测试的差异。     

The SOHO CELIAS/SEM EUV database from SC23 minimum to the present

The SOHO Solar EUV Monitor has been in operation since December 1995 onboard the SOHO spacecraft. This instrument is a highly stable transmission grating solar extreme ultraviolet spectrometer. It has made nearly continuous full disk solar irradiance measurements both within an 8 nm bandpass centered at 30.4 nm and throughout the 0.1 to 50 nm solar flux region since launch. The 30.4 nm flux, the 0.1 to 50 nm flux and the extracted soft X-ray (0.1 to 5 nm) flux are presented and compared with the behavior of solar proxies.     

Recent developments in ultraviolet filters and coatings

A number of new high efficiency optical coatings have recently been developed at wavelengths in the ultraviolet and vacuum ultraviolet for use in space science experiments. The development of these coatings has resulted in the design and manufacture of wavelength selective filters used in reflectance at near normal incidence that have high VUV reflectance with little near-UV and visible reflectance. Very narrow band transmission filters are now available at wavelengths as short as 1500Å with bandwidths as narrow as 35–40Å. In addition, high efficiency anti-reflection coatings as well as neutral density filters are now available at many wavelengths in this region.Material limitations, more severe than those in the visible, place certain restrictions on the size, wavelength, and degree of selectivity that is achievable with present technology. A summary of the current commercial technology along with the material limitations is presented.     

新一代星敏感器遮光罩—— 碳纳米管遮光罩技术研究

针对目前星敏感器遮光罩普遍存在的尺寸和质量较大、杂光消除能力受限等问题,从提高吸光涂层吸光率入手,提出碳纳米管遮光罩新概念,研制一套钛合金基底生长碳纳米管涂层的新技术,使得涂层吸光率达到99%以上,并成功制作出可等效替代现有飞行产品遮光罩的碳纳米管遮光罩.通过真空原子氧、紫外辐照、高能粒子辐照、热真空、力学环境等各项空间环境实验,证明其空间环境适用性.与现有星敏感器遮光罩产品的杂光比对试验结果表明,使用碳纳米管遮光罩的星敏感器杂光灰度降低了56%,显示出杂光消除性能的优势.本文创新成果突破了碳纳米管技术在杂光消除领域实际应用的瓶颈技术,对促进星敏感器技术的提高具有重要的工程价值.