An approach to the detection of microbe life in planetary environments through charge-coupled devices

The use of charge-coupled devices is suggested as a means for detecting growth of micro-organism colonies. The accuracy of the method is determined by channel width and the sensitivity by the signal/noise ratio. The method was tested on a dense nutrient medium, which is to be considered more suitable to micro-organisms of the dry Martian soil than the water solution of nutrients employed in the Viking's strategy.     

The DISC Quotient

D.I.S.C: Decipherment Impact of a Signal's Content.The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation.Building on a “position” paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an “alien” signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact.The “DISC Quotient”, which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.     

Importance of a martian hematite site for astrobiology

Defining locations where conditions may have been favorable for life is a key objective for the exploration of Mars. Of prime importance are sites where conditions may have been favorable for the preservation of evidence of prebiotic or biotic processes. Areas displaying significant concentrations of the mineral hematite (alpha-Fe2O3), recently identified by thermal emission spectrometry, may have significance in the search for evidence of extraterrestrial life. Since iron oxides can form as aqueous mineral precipitates, the potential exists to preserve microscopic evidence of life in iron oxide-depositing ecosystems. Terrestrial hematite deposits proposed as possible analogs for hematite deposits on Mars include massive (banded) iron formations, iron oxide hydrothermal deposits, iron-rich laterites and ferricrete soils, and rock varnish. We report the potential for long-term preservation of microfossils by iron oxide mineralization in specimens of the approximately 2,100-Ma banded iron deposit of the Gunflint Formation, Canada. Scanning and analytical electron microscopy reveals micrometer-scale rods, spheres, and filaments consisting predominantly of iron and oxygen with minor carbon. We interpret these objects as microbial cells permineralized by an iron oxide, presumably hematite. The confirmation of ancient martian microbial life in hematite deposits will require the return of samples to terrestrial laboratories. A hematite-rich deposit composed of aqueous iron oxide precipitates may thus prove to be a prime site for future sample return.     

组合体与飞船联合轨道维持

通过组合体与飞船联合轨道维持解决了组合体和飞船轨道多特征参数的控制问题。建立了升交点经度、轨道高度和偏心率的控制方程以及基于时间关联特性的升交点赤经和制动点高度耦合控制方程和偏心率保持的双冲量耦合控制方程。结合组合体与飞船的飞行特点,制定了组合体轨道维持实现升交点赤经和轨道偏心率以及飞船轨道维持实现制动点高度的联合控制策略。耦合控制方程使得组合体和飞船轨道维持的控制量分配合理,融合了各次控制之间存在的耦合影响,设计了联合轨道维持策略迭代计算流程。基于神舟九号交会对接飞行过程,通过多组仿真算例校验了组合体与飞船轨道多特征参数的联合优化控制,具有较好的工程应用价值。     

不同重力环境下空间机械臂神经自适应鲁棒控制

针对空间机械臂从地面装调到空间应用过程中重力项的变化问题,提出了一种神经网络自适应鲁棒补偿控制策略用于空间机械臂的末端控制,从而实现在地面重力环境下装调好的空间机械臂在空间微重力环境下实现在轨操控任务。通过神经网络在线建模来逼近系统模型中变化的重力项,逼近误差及系统的不确定性通过自适应鲁棒控制器来补偿。该控制策略不依赖于系统的模型,避免了回归矩阵的复杂计算及未知参数的估计,降低了计算量。基于李亚普诺夫理论证明了闭环系统的渐近稳定性。仿真结果表明该控制器对不同重力环境下空间机械臂的末端控制均能达到较高的控制精度,具有重要的理论研究和工程应用价值。     

空间变化场景下卫星部组件域适应识别研究

针对小样本限制下卫星部组件识别域适应困难的问题,提出一种变化场景下自适应迁移的目标识别算法.卫星部组件的识别模型框架为YOLO,迁移算法包括3个策略:基于特征关联性的样本加权策略,基于模型的参数自适应策略和最优特征变换自适应迁移策略.基于以上策略,YOLO模型建立域特征空间的相似性,选择性地迁移源域知识,同时在适应过程...     

Glycine identification in natural jarosites using laser desorption Fourier transform mass spectrometry: implications for the search for life on Mars

The jarosite group minerals have received increasing attention since the discovery of jarosite on the martian surface by the Mars Exploration Rover Opportunity. Given that jarosite can incorporate foreign ions within its structure, we have investigated the use of jarosite as an indicator of aqueous and biological processes on Earth and Mars. The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various locations worldwide. One of the ions from the natural jarosites has been attributed to glycine because it was systematically observed in combinations of glycine with synthetic ammonium and potassium jarosites, Na(2)SO(4) and K(2)SO(4). The ability to observe these organic signatures in jarosite samples with an in situ instrumental technique, such as the one employed in this study, furthers the goals of planetary geologists to determine whether signs of life (e.g., the presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.     

Olivine-respiring bacteria isolated from the rock-ice interface in a lava-tube cave, a Mars analog environment

The boundary between ice and basalt on Earth is an analogue for some near-surface environments of Mars. We investigated neutrophilic iron-oxidizing microorganisms from the basalt-ice interface in a lava tube from the Oregon Cascades with perennial ice. One of the isolates (Pseudomonas sp. HerB) can use ferrous iron Fe(II) from the igneous mineral olivine as an electron donor and O(2) as an electron acceptor. The optimum growth temperature is ～12-14°C, but growth also occurs at 5°C. Bicarbonate is a facultative source of carbon. Growth of Pseudomonas sp. HerB as a chemolithotrophic iron oxidizer with olivine as the source of energy is favored in low O(2) conditions (e.g., 1.6% O(2)). Most likely, microbial oxidation of olivine near pH 7 requires low O(2) to offset the abiotic oxidation of iron. The metabolic capabilities of this bacterium would allow it to live in near-surface, icy, volcanic environments of Mars in the present or recent geological past and make this type of physiology a prime candidate in the search for life on Mars.     

通过超实时仿真验证轨控策略方法研究

"嫦娥一号"卫星任务中轨道复杂、轨控次数多,为保证每一次轨控的成功,需要考虑各种约束条件制定最优轨控策略,并能得以验证。本文提出通过超实时仿真验证轨控策略的方法,并以某次轨控为例,详细介绍了该方法的实施步骤。通过超实时仿真验证轨控策略可以评估轨控策略的准确性,并实现在任务执行过程中对轨控相关指令的检验。     

Ultrastructural study of iron oxide precipitates: implications for the search for biosignatures in the Meridiani hematite concretions, Mars

Two terrestrial environments that have been proposed as analogs for the iron oxide precipitation in the Meridiani Planum region of Mars include the Rio Tinto precipitates and southern Utah marble concretions. Samples of two typical Utah iron oxide concretions and iron oxide precipitates in contact with biofilms from Rio Tinto have been studied to determine whether evidence could be found for biomediation in the precipitation process and to identify likely locations for fossil microorganisms. Scanning electron microscopy, energy dispersive X-ray, and gas chromatography-mass spectrometry (GC-MS) were used to search for biosignatures in the Utah marbles. The precipitation of iron oxides resembles known biosignatures, though organic compounds could not be confirmed with GC-MS analysis. In contrast, textural variations induced by biological activity are abundant in the modern Rio Tinto samples. Although no compelling evidence of direct or indirect biomediation was found in the Utah marbles, the ultrastructure of the iron oxide cement in the concretion suggests an inward growth during concretion precipitation from an initially spherical redox front. No indication for growth from a physical nucleus was found.     

雷达导引头干扰对抗仿真技术研究

研究了复杂战场环境下,反舰导弹雷达导引头干扰对抗性能分析评估的数学仿真平台设计方法.首先介绍了仿真系统总体设计方案、模型体系结构、雷达导引头仿真建模方法,然后论述了目标起伏、闪烁、海杂波仿真建模方法,以及典型干扰原理及其仿真建模方法,最后对雷达导引头干扰对抗综合性能评估方法进行了探讨.基于该仿真系统,可以对反舰导弹在复...     

Damage escape and repair in dried Chroococcidiopsis spp. from hot and cold deserts exposed to simulated space and martian conditions

The cyanobacterium Chroococcidiopsis, overlain by 3?mm of Antarctic sandstone, was exposed as dried multilayers to simulated space and martian conditions. Ground-based experiments were conducted in the context of Lichens and Fungi Experiments (EXPOSE-E mission, European Space Agency), which were performed to evaluate, after 1.5 years on the International Space Station, the survival of cyanobacteria (Chroococcidiopsis), lichens, and fungi colonized on Antarctic rock. The survival potential and the role played by protection and repair mechanisms in the response of dried Chroococcidiopsis cells to ground-based experiments were both investigated. Different methods were employed, including evaluation of the colony-forming ability, single-cell analysis of subcellular integrities based on membrane integrity molecular and redox probes, evaluation of the photosynthetic pigment autofluorescence, and assessment of the genomic DNA integrity with a PCR-based assay. Desiccation survivors of strain CCMEE 123 (coastal desert, Chile) were better suited than CCMEE 134 (Beacon Valley, Antarctica) to withstand cellular damage imposed by simulated space and martian conditions. Exposed dried cells of strain CCMEE 123 formed colonies, maintained subcellular integrities, and, depending on the exposure conditions, also escaped DNA damage or repaired the induced damage upon rewetting.     

Meteors do not break exogenous organic molecules into high yields of diatomics

Meteoroids that dominate the Earth's extraterrestrial mass influx (50-300 microm size range) may have contributed a unique blend of exogenous organic molecules at the time of the origin of life. Such meteoroids are so large that most of their mass is ablated in the Earth's atmosphere. In the process, organic molecules are decomposed and chemically altered to molecules differently from those delivered to the Earth's surface by smaller (<50 microm) micrometeorites and larger (>10 cm) meteorites. The question addressed here is whether the organic matter in these meteoroids is fully decomposed into atoms or diatomic compounds during ablation. If not, then the ablation products made available for prebiotic organic chemistry, and perhaps early biology, might have retained some memory of their astrophysical nature. To test this hypothesis we searched for CN emission in meteor spectra in an airborne experiment during the 2001 Leonid meteor storm. We found that the meteor's light-emitting air plasma, which included products of meteor ablation, contained less than 1 CN molecule for every 30 meteoric iron atoms. This contrasts sharply with the nitrogen/iron ratio of 1:1.2 in the solid matter of comet 1P/Halley. Unless the nitrogen content or the abundance of complex organic matter in the Leonid parent body, comet 55P/Tempel-Tuttle, differs from that in comet 1P/Halley, it appears that very little of that organic nitrogen decomposes into CN molecules during meteor ablation in the rarefied flow conditions that characterize the atmospheric entry of meteoroids approximately 50 microm-10 cm in size. We propose that the organics of such meteoroids survive instead as larger compounds.     

大型复杂航天器结构有限元模型的验证策略研究

大型复杂航天器结构有限元模型的合理性和准确性在航天器研制过程中具有重要意义, 它是开展星箭耦合分析以及力学环境条件设计等工作的基础。首先综合有限元建模、模 态试验、相关分析和模型修正等技术构造了一套系统的航天器结构有限元模型试验验证策略 ;然后,针对我国新一代大型卫星平台——东方红四号卫星开展了整星有限元模型的试验 验证研究,其中整星模态试验以及模型修正等研究工作属首次在东方红四号卫星平台上成功 实施。修正后有限元模型对整星主模态频率预测误差小于5％,模态置信准则大于0.6,预 示精度达到工程要求。
     

时间代价启发式多月基装备协同任务规划方法

针对月球科研站构建中优化整体任务用时的需求,提出时间代价启发式多月基装备协同任务规划方法。面向月球科研站构建过程中的原位和路径任务,构建双类型任务关系图,并提出多位置转移时间代价启发式策略引导此图的搜索方向,使规划器沿局部最短耗时任务路径逐个处理任务,降低装备路径转移的时间代价;提出时间代价启发式装备选择策略,从而均衡月基装备任务负载,缩短装备工作时长。最后,以包含资源开采、物料运输、设施建设等任务的月球科研站构建场景为例,对规划算法进行仿真验证。结果表明,此算法能够生成满足复杂约束的多装备协同规划序列。与传统规划方法相比,本文方法得到的月基装备任务序列冗余路径少、任务用时短,可实现多装备在多任务中的高效分时复用。     

Evaluation of theories of complex movement planning in different levels of gravity

Due to high redundancy of degrees of freedom in the human body, we can perform any movement, from the simplest to the most complex, in many different ways. Several studies are still trying to identify the motor strategies that master this redundancy and generate the movements whose characteristics are highly stereotyped. The aim of this work is to build a simulator that is able to evaluate different motor planning hypotheses. The most interesting applications of this tool occur in studies of the motor strategy in microgravity conditions. The comparison between simulated movements and kinematics data recorded both on Earth, and during a 5-month mission on board the Mir station shows that for a complex whole-body movement (such as trunk bending) a single planning criterion cannot explain all movement aspects. However, the simulator allows an understanding of the motor planning adaptation of astronauts. In space, the lack of equilibrium constraint (which on Earth brings about the center of mass control) leads to a new motor strategy that minimizes dynamic interactions with the floor.     

The importance of exploring the asteroid belt

Following life's innate tendency to expand into every available space, technological civilizations will inevitably colonize the entire galaxy establishing space habitats around all its well-behaved stars. The most reasonable place in our solar system to test this possibility is the asteroid belt, which is an ideal source of raw materials for space colonies.     

变锥角SGCMG系统的奇异躲避路径规划策略

将锥体上五个单框架控制力矩陀螺（SGCMG）框架轴与底面的锥角视为姿态机动任务前的调整变量,建立了锥角可调的五棱锥构型SGCMG模型。通过锥角可调SGCMG系统的复杂奇异性分析,推导了陀螺奇异测度对时间的导数与陀螺框架角速度的关系,进而提出考虑奇异躲避的路径规划策略。基于Gauss伪谱法的路径规划结果表明：锥角可调的五棱锥构型SGCMG系统可有效提高特定机动方向的控制能力,显著减少空间站姿态机动所需时间;所提出的考虑奇异躲避的路径规划策略可有效避免陀螺奇异。     

Development and imperialism in space

This article analyses established models of imperialism and seeks to apply them to possible space development scenarios. Inherent in such an analysis is a critique of the predominant rationales for advanced Solar System development (permanent planetary bases, settlements and colonies). The argument that emerges suggests that no single rationale is sufficiently strong to propel humans towards Solar System expansion as yet. However, in the instance that an extraterrestrial material becomes economically valuable, Solar System development will probably proceed. Under this scenario the present politico-legal regimes which govern prospective space development (and, moreover, the philosophical inclinations of many of those involved in formulating such regimes) dictate that Solar System development will be of an imperialistic nature.     

ESA strategic planning for space exploration

The European Space Agency (ESA) is pursuing an independent strategic planning process for consolidating a destination driven (LEO, Moon, Mars) space exploration strategy. ESA's space exploration strategy is driven by the goals to maximise knowledge gain and to contribute to economic growth. International cooperation is a key pillar of ESA's strategy as it is considered both, an enabler for achieving common goals and a benefit, opening new perspective for addressing future challenges. The achievement of ESA's space exploration strategy is enabled through international partnerships. The interagency coordination process conducted within the framework of the International Space Exploration Coordination Group (ISECG) plays an important role in laying the foundations for future partnerships. It has achieved so far the development of a common vision for space exploration, a common plan for implementing the vision in the form of the Global Exploration Roadmap, as well as a common approach for articulating the value of global space exploration. ESA has been a strong promoter and supporter of the interagency coordination process conducted within ISECG and thanks to its unique expertise in international cooperation the Agency has contributed to its success.