Supraglacial sulfur springs and associated biological activity in the Canadian high arctic-signs of life beneath the ice

Unique springs, discharging from the surface of an arctic glacier, release H(2)S and deposit native sulfur, gypsum, and calcite. The presence of sulfur in three oxidation states indicates a complex series of redox reactions. Physical and chemical conditions of the spring water and surrounding environment, as well as mineralogical and isotopic signatures, suggest biologically mediated reactions. Cell counts and DNA analyses confirm bacteria are present in the spring system, and a limited number of sequenced isolates suggests that complex communities of bacteria live within the glacial system.     

Risks of radiation cataracts from interplanetary space missions

Recognition of the human risks from radiation exposure during manned missions in deep space has been fostered by international co-operation; interagency collaboration is facilitating their evaluation. Further co-operation can lead, perhaps by the end of this decade, to an evaluation of one of the three major risks, namely radiation cataractogenesis, sufficient for use in the planning of the manned mission to Mars.     

Stable iron isotopes and microbial mediation in red pigmentation of the Rosso Ammonitico (mid-late Jurassic, Verona area, Italy)

The iron (Fe) isotopic composition of 17 Jurassic limestones from the Rosso Ammonitico of Verona (Italy) have been analyzed by Multiple-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Such analysis allowed for the recognition of a clear iron isotopic fractionation (mean -0.8 per thousand, ranging between -1.52 to -0.06 per thousand) on a millimeter-centimeter scale between the red and grey facies of the studied formation. After gentle acid leaching, measurements of the Fe isotopic compositions gave delta(56)Fe values that were systematically lower in the red facies residues (median: -0.84 per thousand, range: -1.46 to +0.26 per thousand) compared to the grey facies residues (median: -0.08 per thousand, range: -0.34 to +0.23 per thousand). In addition, the red facies residues were characterized by a lighter delta(56)Fe signal relative to their corresponding leachates. These Fe isotopic fractionations could be a sensitive fingerprint of a biotic process; systematic isotopic differences between the red and grey facies residues, which consist of hematite and X-ray amorphous iron hydroxides, respectively, are hypothesized to have resulted from the oxidizing activity of iron bacteria and fungi in the red facies. The grey Fe isotopic data match the Fe isotopic signature of the terrestrial baseline established for igneous rocks and low-C(org) clastic sedimentary rocks. The Fe isotopic compositions of the grey laminations are consistent with the influx of detrital iron minerals and lack of microbial redox processes at the water-interface during deposition. Total Fe concentration measurements were performed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) (confirmed by concentration estimations obtained by MC-ICP-MS analyses of microdrilled samples) on five samples, and resultant values range between 0.30% (mean) in the grey facies and 1.31% (mean) in the red facies. No correlation was observed between bulk Fe content and pigmentation or between bulk Fe content and Fe isotopic compositions. The rapid transformation of the original iron oxyhydroxides to hematite could have preserved the original isotopic composition if it had occurred at about the same temperature. This paper supports the use of Fe isotopes as sensitive tracers of biological activities recorded in old sedimentary sequences that contain microfossils of iron bacteria and fungi. However, a careful interpretation of the iron isotopic fractionation in terms of biotic versus abiotic processes requires supporting data or direct observations to characterize the biological, (geo)chemical, or physical context in relation to the geologic setting. This will become even more pertinent when Fe isotopic studies are expanded to the interplanetary realm.     

NASA准备放宽中继卫星使用限制

跟踪和数据中继卫星系统以前只用于政府的航天器,但每周都有一定的空余能力。NASA目前准备向工业界想试验新技术的用户开放该通信卫星网络。NASA官员说关于如何利用该系统须由工业界决定。 中继卫星位于赤道上空35406公里的轨道上,它能将航天飞机或卫星的数据中继到新墨西哥州白沙的地面终端。     

轨道通信公司和天宝公司将合作提供数据和GPS定位信息

轨道通信公司(ORBCOMM)和天宝导航公司(Trimble)最近签订了一项将ORBCOMM的全球双向数据通信能力和天宝导航公司的全球定位及导航能力结合起来的协议。据ORBCOMM公司总裁说,实现该协议将能以很低的价格在手持通信机上进行离精度GPS信息的实时传输。     

小卫星展望——芯片卫星

航天工程师们说,随着微电子学的革命性进展和小卫星工业的进一步扩展,未来的卫星可能是一种新型的“芯片上的卫星”。这种设想基于缩小卫星元器件和设备以便能装在一块集成电路板或计算机芯片上。目前,电子设备、光学系统和机械装置的微型化进展已经为建造重量、尺寸和成本适中的高性能卫星提供了条件。     

欧空局通信卫星监视设施的现状

欧空局通信卫星监视设施(CSMF)可为参与和负责卫星研制和生产的工程师们提供跟踪卫星在轨运行情况的手段。该设施可为这些工程师们提供与制造卫星过程一样的卫星接口。这种用户接口是用“欧洲试验操作语言”(ETOL)提供的。在卫星的射前、射后操作中,这种语言允许重复使用卫星控制系统的软件。