Raman spectroscopic analysis of a desert cyanobacterium Nostoc sp. in response to UVB radiation

Cyanobacteria are capable of tolerating environmental extremes. To survive in extreme environments, cyanobacteria have developed the capability to adapt to a variety of stresses. For example, cyanobacteria have adopted a number of strategies with which to survive UV stress, including expression of UV-screening pigments and antioxidant systems. We have previously shown that several antioxidants are significantly expressed in Nostoc sp. by UVB irradiation. We report here that the content of UV-responsive biomarkers such as β-carotene and scytonemin can be easily detected by Fourier transform Raman spectroscopy with use of a small sample size and that the content of β-carotene is dependant on the UVB intensity and exposure time. Our results indicate that Raman spectroscopy may be a helpful tool to analyze UV-protective molecules of cyanobacterium in astrobiological studies without access to large sample sizes and complicated extractions, which are needed by other analytical techniques such as high-performance liquid chromatography and mass spectrometry.     

处理太空垃圾刻不容缓

居住在美国北卡罗来纳州阿什维尔市的NASA退休科学家唐纳德·克斯勒尔经常在自己住宅的后院平台上架起塞莱斯特望远镜观测太空。虽然这台望远镜算不上是最先进的,但却是克斯勒尔最珍爱的物品。1978年,克斯勒尔发表的一篇论文《人造卫星频繁碰撞：碎片带的产生》,使他在航天界名声鹊起。     

The PROCESS experiment: amino and carboxylic acids under Mars-like surface UV radiation conditions in low-earth orbit

The search for organic molecules at the surface of Mars is a top priority of the next Mars exploration space missions: Mars Science Laboratory (NASA) and ExoMars (ESA). The detection of organic matter could provide information about the presence of a prebiotic chemistry or even biological activity on this planet. Therefore, a key step in interpretation of future data collected by these missions is to understand the preservation of organic matter in the martian environment. Several laboratory experiments have been devoted to quantifying and qualifying the evolution of organic molecules under simulated environmental conditions of Mars. However, these laboratory simulations are limited, and one major constraint is the reproduction of the UV spectrum that reaches the surface of Mars. As part of the PROCESS experiment of the European EXPOSE-E mission on board the International Space Station, a study was performed on the photodegradation of organics under filtered extraterrestrial solar electromagnetic radiation that mimics Mars-like surface UV radiation conditions. Glycine, serine, phthalic acid, phthalic acid in the presence of a mineral phase, and mellitic acid were exposed to these conditions for 1.5 years, and their evolution was determined by Fourier transform infrared spectroscopy after their retrieval. The results were compared with data from laboratory experiments. A 1.5-year exposure to Mars-like surface UV radiation conditions in space resulted in complete degradation of the organic compounds. Half-lives between 50 and 150?h for martian surface conditions were calculated from both laboratory and low-Earth orbit experiments. The results highlight that none of those organics are stable under low-Earth orbit solar UV radiation conditions.     

星载铷原子钟用兰宝石灯的研制

由于具有现代技术水平的全玻璃铷光谱灯中 GPS 星载原子钟真空环境条件下使用时明显失效,提出了研制一种寿命比玻璃灯大一个数量级的新型灯的计划。采用兰宝石和类兰宝石材料的实际经验证明,用这些材料制成的灯将满足这种要求。因此,已经研制出几个这种类型的灯。初步结果表明,它们的工作特性几乎在各个方面都很类似于玻璃灯,但有两个例外:首先,点火特性稍有不同。其次,由于臭氧的产生而伴随有明显的紫外线输出。这个问题已经通过将一层薄的吸收紫外线的涂层粘到灯的外边而被排除了。最后结论是,目前已经有可供利用的对这些灯进行一年加速寿命测试所必需的工艺技术。     

Near Earth Vortices Driving of Field Aligned Currents Based on Magnetosphere Multiscale and Swarm Observations

A long-standing mystery in the study of Field-Aligned Currents (FACs) has been that:how the currents are generated and why they appear to be much stronger at high altitudes than in the ionosphere.Here we present two events of magnetotail FACs observed by the Magnetospheric Multiscale Spacecraft (MMS) on 1st July and 14th July 2016,to show how the Substorm Current Wedges (SCW) were formed.The results show that particles were transferred heading towards the Earth during the expansion phase of substorms. The azimuthal flow formed clockwise (counter-clockwise) vortex-like motion,and then generated downward (upward) FACs on the tailward/poleward side of the distorted field with opposite vorticity on their Earthward/equatorward side.We also analyzed the Region 1 FACs observed by the Earth Explorer Swarm spacecraft on 1st July 2016 and found that they were associated with FACs observed by MMS,although differing by a factor of 10.This difference suggests that either there was the closure of the currents at altitudes above 500 km or the currents were not strictly parallel to B and closed at longitudes away from where they were generated.      

高级靶场测量飞机

本文描述了高级靶场测量飞机(ARIA)及其目前和未来在全球范围内保障试验和鉴定活动的计划。     

ZETA网罟星事件(五)

利用皇家天文观察站的星位目录中的15个恒星的资料,斯蒂格特认为,由于星位数据不同,星位模型也就不同,(GLIESE59号恒星的星位误差比较大.GLIESE系列恒星统计目录总汇建立时,使用了光测计、角测仪和天文望远镜视角差的测量方法,经过对各个星位数据的不同的数学评价之后得出了结论:“星位数据表列中的数据误差能够修正过来,”斯蒂格特说:“这是研究这张星图的下一步计划.”杰弗里·L·克雷特持有同样的观点,他是研究生,在埃文斯顿西北大学的J·艾伦·海尼克     

中央情报局与UFO（下）

科学家小组比“天外来客”小组迟到现场一会儿,于是,专家们对坠毁的飞碟开始调查.据施德曼讲述:调查人员通过打碎的舷窗一个接一个地进入飞碟.飞碟上的舷窗很难同飞碟外壳区分开来,看上去酷似金属,可是后来才搞清楚,原来,这些舷窗都是透明的.调查人员在飞碟舱室内发现两个类人生物,他们的身高为1.2米.由于飞碟坠毁时的强大惯力,两个乘员被重重地摔到仪器盘上,他们的尸体被烧成深褐色.其余的12具外星人尸体都两臂张开地躺在舱室的地上.实际上,飞碟上总共有14具尸体,而不是斯卡利所说的16具.     

在飞碟上的十五分钟

1989年9月中旬,我在雅布鲁诺夫卡村附近采蘑菇.忽然,面前掠过一个椭圆形的“云彩”,我抬头一看,发现大约距离100米的地方有一个降落伞正在盘旋降落,在距地面70米时便开始垂直下降.我虽然是怀疑论和现实主义者,但我一开始就把飞碟当成宇宙飞船.特别是当我看到掀起机舱的门帘,从里面走出穿密封飞行服的“宇宙航行员”的时候,     

跟踪和数据中继卫星系统在欧洲的应用可能性

美国航空航天局(NASA)打算在1981年左右用两颗中继卫星组成的跟踪和数据中继卫星系统(TDRSS),取代美国用于跟踪低轨卫星并进行数据和指令传输的现有地面站网。除本国用户使用外,NASA还可将该系统提供给其它国家的用户使用。本文就美国采取了该措施后对欧洲产生何种影响进行了分析。根据欧洲在八十年代到九十年代间需要执行的任务,这里提出了两种可供选择的方案。在相同工作能力下,从费用以及其它方面,将欧洲中继卫星的两种方案与租用TDRS系统进行了比较。通过比较可看出,采用本文提出的欧洲中继卫星系统方案更有利一些。