Simulated Space Vacuum Research Articles

The effect of simulated space vacuum conditions on some biochemical and physiological responses of quinoa

The effect of simulated space vacuum conditions on some biochemical and physiological responses of quinoa

Strain-testing research of space solar cell array

Space solar cell array is the only power source for satellites, and the mechanical impact on solar array during its in-orbit service will directly affect the normal operation of the satellites. Therefore, it is of great significance to study the stress and strain law of space solar array. In this paper, we establish a strain-testing system for space solar array, and this system can help test the strain data of space solar array under simulated space vacuum and thermal cycling field. We find that the space solar cells suffer compression deformation at high temperature and tensile deformation at low temperature. The total maximum strain of the free cell and pasted cell under the same conditions are 1270 and 1320 με, respectively. In addition, the strain of middle area is 113% higher than that of the edge area in one space solar cell. The rupturing strain of space solar cell is 2080 με. These measured data conduce to studying the deformation characteristics of solar cells in space environment, which can help researchers get the deformation regularity of space solar cells. They also provide experimental basis for stress-relieving arrangement of space solar array. This research provides technical support for studying the deformation resistance of space solar cells.

Single-cell analysis reveals individual spore responses to simulated space vacuum

Outer space is a challenging environment for all forms of life, and dormant spores of bacteria have been frequently used to study the survival of terrestrial life in a space journey. Previous work showed that outer space vacuum alone can kill bacterial spores. However, the responses and mechanisms of resistance of individual spores to space vacuum are unclear. Here, we examined spores’ molecular changes under simulated space vacuum (~10−5 Pa) using micro-Raman spectroscopy and found that this vacuum did not cause significant denaturation of spore protein. Then, live-cell microscopy was developed to investigate the temporal events during germination, outgrowth, and growth of individual Bacillus spores. The results showed that after exposure to simulated space vacuum for 10 days, viability of spores of two Bacillus species was reduced up to 35%, but all spores retained their large Ca2+-dipicolinic acid depot. Some of the killed spores did not germinate, and the remaining germinated but did not proceed to vegetative growth. The vacuum treatment slowed spore germination, and changed average times of all major germination events. In addition, viable vacuum-treated spores exhibited much greater sensitivity than untreated spores to dry heat and hyperosmotic stress. Among spores’ resistance mechanisms to high vacuum, DNA-protective α/β−type small acid-soluble proteins, and non-homologous end joining and base excision repair of DNA played the most important roles, especially against multiple cycles of vacuum treatment. Overall, these results give new insight into individual spore’s responses to space vacuum and provide new techniques for microorganism analysis at the single-cell level.

Responses of the Black Fungus Cryomyces antarcticus to Simulated Mars and Space Conditions on Rock Analogs

The BIOMEX (BIOlogy and Mars Experiment) is part of the European Space Agency (ESA) space mission EXPOSE-R2 in Low-Earth Orbit, devoted to exposing microorganisms for 1.5 years to space and simulated Mars conditions on the International Space Station. In preparing this mission, dried colonies of the Antarctic cryptoendolithic black fungus Cryomyces antarcticus CCFEE 515, grown on martian and lunar analog regolith pellets, were subjected to several ground-based preflight tests, Experiment Verification Tests, and Science Verification Tests (SVTs) that were performed to verify (i) the resistance of our model organism to space stressors when grown on extraterrestrial rock analogs and (ii) the possibility of detecting biomolecules as potential biosignatures. Here, the results of the SVTs, the last set of experiments, which were performed in ultraviolet radiation combined with simulated space vacuum or simulated martian conditions, are reported. The results demonstrate that C. antarcticus was able to tolerate the conditions of the SVT experiment, regardless of the substratum in which it was grown. DNA maintained high integrity after treatments and was confirmed as a possible biosignature; melanin, which was chosen to be a target for biosignature detection, was unambiguously detected by Raman spectroscopy.

First results of PRECISE—Development of a MEMS-based monopropellant micro chemical propulsion system

PRECISE focuses on the research and development of a MEMS-based monopropellant micro chemical propulsion system for highly accurate attitude control of satellites. The availability of such propulsion systems forms the basis for defining new mission concepts such as formation flying and rendezvous manoeuvres. These concepts require propulsion systems for precise attitude and orbit control manoeuvrability. Application-oriented aspects are addressed by two end-users who are planning a formation flying mission for which the propulsion system is crucial. Basic research is conducted aiming at improving crucial MEMS technologies required for the propulsion system. Research and development also focuses on the efficiency and reliability of critical system components. System analysis tools are enhanced to complement the development stages. Finally, the propulsion system will be tested in a simulated space vacuum environment. These experiments will deliver data for the validation of the numerical models.

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.

Astrobiological Aspects of the Mutagenesis of Cosmic Radiation on Bacterial Spores

Based on their unique resistance to various space parameters, Bacillus endospores are one of the model systems used for astrobiological studies. In this study, spores of B. subtilis were used to study the effects of galactic cosmic radiation (GCR) on spore survival and induced mutagenesis. In interplanetary space, outside Earth's protective magnetic field, spore-containing rocks would be exposed to bombardment by high-energy charged particle radiation from galactic sources and from the Sun, which consists of photons (X-rays, gamma rays), protons, electrons, and heavy, high-energy charged (HZE) particles. B. subtilis spores were irradiated with X-rays and accelerated heavy ions (helium, carbon, silicon and iron) in the linear energy transfer (LET) range of 2-200 keV/mum. Spore survival and the rate of the induced mutations to rifampicin resistance (Rif(R)) depended on the LET of the applied species of ions and radiation, whereas the exposure to high-energy charged particles, for example, iron ions, led to a low level of spore survival and increased frequency of mutation to Rif(R) compared to low-energy charged particles and X-rays. Twenty-one Rif(R) mutant spores were isolated from X-ray and heavy ion-irradiated samples. Nucleotide sequencing located the Rif(R) mutations in the rpoB gene encoding the beta-subunit of RNA polymerase. Most mutations were primarily found in Cluster I and were predicted to result in amino acid changes at residues Q469L, A478V, and H482P/Y. Four previously undescribed alleles in B. subtilis rpoB were isolated: L467P, R484P, and A488P in Cluster I and H507R in the spacer between Clusters I and II. The spectrum of Rif(R) mutations arising from spores exposed to components of GCR is distinctly different from those of spores exposed to simulated space vacuum and martian conditions.

Isolation ofrpoBMutations Causing Rifampicin Resistance inBacillus subtilisSpores Exposed to Simulated Martian Surface Conditions

ABSTRACT Bacterial spores are considered prime candidates for Earth-to-Mars transport by natural processes and human spaceflight activities. Previous studies have shown that exposure of Bacillus subtilis spores to ultrahigh vacuum (UHV) characteristic of space both increased the spontaneous mutation rate and altered the spectrum of mutation in various marker genes; but, to date, mutagenesis studies have not been performed on spores exposed to milder low pressures encountered in the martian environment. Mutations to rifampicin-resistance (Rif(R)) were isolated in B. subtilis spores exposed to simulated martian atmosphere (99.9% CO(2), 710 Pa) for 21 days in a Mars Simulation Chamber (MSC) and compared to parallel Earth controls. Exposure in the MSC reduced spore viability by approximately 67% compared to Earth controls, but this decrease was not statistically significant (P = 0.3321). The frequency of mutation to Rif(R) was also not significantly increased in the MSC compared to Earth-exposed spores (P = 0.479). Forty-two and 51 Rif(R) mutant spores were isolated from the MSC- and Earth-exposed controls, respectively. Nucleotide sequencing located the Rif(R) mutations in the rpoB gene encoding the beta subunit of RNA polymerase at residue V135F of the N-cluster and at residues Q469K/L, H482D/P/R/Y, and S487L in Cluster I. No mutations were found in rpoB Clusters II or III. Two new alleles, Q469L and H482D, previously unreported in B. subtilis rpoB, were isolated from spores exposed in the MSC; otherwise, only slight differences were observed in the spectra of spontaneous Rif(R) mutations from spores exposed to Earth vs. the MSC. However, both spectra are distinctly different from Rif(R) mutations previously reported arising from B. subtilis spores exposed to simulated space vacuum.

Response of bacteriophage T7 biological dosimeter to dehydration and extraterrestrial solar UV radiation

The experiment “Phage and uracil response” (PUR) will be accommodated in the EXPOSE facility of the ISS. Bacteriophage T7/isolated T7 DNA will be exposed to different subsets of extreme environmental parameters in space, in order to study the Responses of Organisms to the Space Environment (ROSE). Launch into orbit is preceded by EXPOSE Experiment Verification Tests (EVT) to optimize the methods and the evaluation. Bacteriophage T7/isolated T7 DNA thin layers were exposed to vacuum ( 10 - 6 Pa ), to monochromatic (254 nm) and polychromatic (200–400 nm) UV radiation in air as well as in simulated space vacuum. Using neutral density (ND) filters dose-effect curves were performed in order to define the maximum doses tolerated. The effect of temperature fluctuation in vacuum was also studied. The structural/chemical effects on bacteriophage T7/isolated T7 DNA were analyzed by spectroscopic and microscopical methods. Characteristic changes in the absorption spectrum and in the electrophoretic pattern of phage/DNA have been detected indicating the damage of isolated and intraphage DNA. DNA damage was also determined by quantitative PCR (QPCR) using 555 and 3826 bp fragments of T7 DNA. We obtained substantial evidence that DNA lesions (e.g. strand breaks, DNA-protein cross-links, cyclobutane pirimidine dimers (CPDs) etc.) accumulate throughout exposure. Preliminary results suggest a synergistic action of space vacuum and UV radiation with DNA being the critical target.

DNA damage under simulated extraterrestrial conditions in bacteriophage T7

Abstract The experiment “Phage and Uracil response” will be accommodated in the EXPOSE facility of the International Space Station. Its objective is to examine and quantify the effect of specific space conditions on nucleic acid models, especially on bacteriophage T7 and isolated T7 DNA thin films. In order to define the environmental and technical requirements of the EXPOSE, the samples were subjected to the experiment verification test (EVT). During EVT, the samples were exposed to vacuum (10 −4 –10 −6 Pa) and polychromatic UV-radiation (200–400 nm) in air, in inert atmosphere, as well as in simulated space vacuum. The effect of extreme temperature in vacuum and the influence of temperature fluctuations around 0 °C were also studied. The total intraphage/isolated DNA damage was determined by quantitative PCR using 555 and 3826 bp fragments of T7 DNA. The type of the damage was resolved using a combination of enzymatic probes and neutral and alkaline agarose gel electrophoresis; the structural/chemical effects were analyzed by spectroscopic and microscopical methods. We obtained substantial evidence that DNA lesions accumulate throughout exposure, but the amount of damage depends on the thickness of the layers. According to our preliminary results, the damages by exposure to conditions of dehydration and UV-irradiation are larger than the sum of vacuum alone, or radiation alone case, suggesting a synergistic action of space vacuum and UV radiation with DNA being the critical target.

UV Photochemistry of DNAIn Vitroand inBacillus subtilisSpores 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.

Response of Bacillus subtilis spores to dehydration and UV irradiation at extremely low temperatures.

Spores of Bacillus subtilis have been exposed to the conditions of extreme dehydration (argon/silica gel; simulated space vacuum) for up to 12 weeks at 298 K and 80 K in the dark. The inactivation has been correlated with the production of DNA-double strand-breaks. The temperature-dependence of the rate constants for inactivation or production of DNA-double strand-breaks is surprisingly low. Controls kept in the frozen state at 250 K for the same period of time showed no sign of deterioration. In another series of experiments the spores have been UV irradiated (253.7 nm) at 298 K, 200 K and 80 K after exposure to dehydrating conditions for 3 days. Fluence-effect relationships for inactivation, production of DNA-double strand-breaks and DNA-protein cross-links are presented. The corresponding F37-values for inactivation and production of DNA lesions are significantly increased only at 80 K (factor of 4 to 5). The data indicate that the low temperatures that prevail in the outer parts of the Solar System or at the nightside of Mars or the Moon are not sufficiently low to crucially inhibit inactivation by dehydration. Our data place further constraints on the panspermia hypothesis.

Operating gears in a simulated space vacuum. The vacuum facility and several techniques : M. F. Federline and C. E. Vest, Lubrication Eng., 23 (4) (1967) 134–144; 12 figs., 4 tables, 8 refs.

Operating gears in a simulated space vacuum. The vacuum facility and several techniques : M. F. Federline and C. E. Vest, Lubrication Eng., 23 (4) (1967) 134–144; 12 figs., 4 tables, 8 refs.

Operating gears in a simulated space vacuum: M F Federline and C E Vest,Lubrication Eng, 23,April 1967, 134–144.

Operating gears in a simulated space vacuum: M F Federline and C E Vest,Lubrication Eng, 23,April 1967, 134–144.

Operating gears in a simulated space vacuum—the vacuum facility and several techniques: M F Federline and C E Vest, Amer Soc Lubricating Engs, May 1966, Paper 66Am7A4

Operating gears in a simulated space vacuum—the vacuum facility and several techniques: M F Federline and C E Vest, Amer Soc Lubricating Engs, May 1966, Paper 66Am7A4