Planetary quarantine in the solar system. Survival rates of some terrestrial organisms under simulated space conditions by proton irradiation

We have been studying the survival rates of some species of terrestrial unicellular and multicellular organism (viruses, bacteria, yeasts, fungi, algae, etc.) under simulated interstellar conditions, in connection with planetary quarantine. The interstellar environment in the solar system has been simulated by low temperature, high vacuum (77 K, 4 x 10(-8) torr), and proton irradiation from a Van de Graaff generator. After exposure to a barrage of protons corresponding to about 250 years of irradiation in solar space, tobacco mosaic virus, Bacillus subtilis spores, Staphylococcus aureus, Micrococcus flavus, Aspergillus niger spores, and Clostridium mangenoti spores showed survival rates of 82, 45, 74, 13, 28, and 25%, respectively.     

Jupiter's first 100 miles

In December, 1995, after a journey of six years, the Galileo probe plunged into Jupiter's atmosphere, becoming the first artificial object to make direct contact with an outer planet. New data supplied by the probe indicated: 1) A new radiation belt around Jupiter ten times stronger than the Van Allen belt around Earth; 2) Jupiter may be much drier than predicted. Its atmosphere contains about as much water as the Sun, but this is subject to instrument calibration uncertainties, and the location of the landing in one of the driest spots on the planet; 3) Jupiter's atmosphere appears to have about three to ten times less lightning than Earth's, while the events are about 10 times stronger, both in terms of size and amount of electrical discharge; and, 4) Jupiter's winds were stronger than expected, increasing with depth, at 330 mph.     

高空飞行相关知识：飞行的环境

中国民航《公共航空运输承运人运行合格审定规则》(121部)中第121.419条d项规定:“在7600米(25000英尺)以上高度的飞行中服务的机组成员,应当接受下列内容的教育:(1)呼吸原理;(2)生理组织缺氧;(3)高空不供氧情况下的有知觉持续时间;(4)气体膨胀; (5)气泡的形成; (6)减压的物理现象和事件。” 拥有一万小时喷气机经历、曾任奖状(Citation)飞机的教员以及飞安国际(FlightSafety International)的计划经理的Linda D. Pendleton,于1999年撰写了《飞行员应该了解的高空生理学、缺氧现象和快速释压方面的相关知识》一文,被认为是关于高空生理学和释压方面最为权威的论文。该文写于当年一架载有高尔夫球手Payne Stewart及其他五位乘客的Lear 35型飞机因不明原因的飞行员失能而失事之后,试图从高空飞行的相关因素的角度,分析可能的事故原因。供职于南航珠海有限公司飞安部的李炜晟把该文翻译成中文,本刊将陆续刊发这篇文章的内容,向读者介绍这方面的知识。     

Ground-based simulations of cosmic ray heavy ion interactions in spacecraft and planetary habitat shielding materials

This paper surveys some recent accelerator-based measurements of the nuclear fragmentation of high energy nuclei in shielding and tissue-equivalent materials. These data are needed to make accurate predictions of the radiation field produced at depth in spacecraft and planetary habitat shielding materials and in the human body by heavy charged particles in the galactic cosmic radiation. Projectile-target combinations include 1 GeV/nucleon 56Fe incident on aluminum and graphite and 600 MeV/nucleon 56Fe and 290 MeV/nucleon 12C on polyethylene. We present examples of the dependence of fragmentation on material type and thickness, of a comparison between data and a fragmentation model, and of multiple fragments produced along the beam axis.     

Analysis of the pre-flight and post-flight calibration procedures performed on the Liulin space radiation dosimeter

Liulin, a dosimetry-radiometry system, was developed to satisfy the requirements for active flux and dose rate measurements for the flight of the second Bulgarian cosmonaut in 1988. The system consists of a compact battery-operated silicon solid state detector unit and a read/write microcomputer and telemetry unit. We describe the pre-flight calibrations with charged particles, using radioactive sources and accelerated 170 MeV/nucleon proton and alpha particles at the Dubna, Russia cyclotron. We discuss comparisons with data obtained on Mir with the French-built tissue equivalent LET spectrometer NAUSICAA. Lastly, we describe post-flight calibrations performed with 1 GeV/nucleon 56Fe ions at the Brookhaven National Laboratory AGS accelerator, where the instrument was mounted in tandem with several thin position-sensitive silicon detectors behind a stopping target. The silicon detectors provided an energy spectrum for the surviving charged nuclear fragments for which the flux and absorbed dose were recorded by Liulin.     

Bioconversion systems for food and water on long term space missions

An imperative for prolonged Space flight missions is the conservation of resources. Extensive resupply could pose technological and logistical challenges for those responsible for the management and successful completion of the mission. Therefore, the biological waste water reclamation system (BWWR) which requires little or no expendable supplies and the waste cellulose to edible mushroom conversion system (CMCS) which is conceived as a low energy crop waste recycling system are prototype instruments which have been conceived as solutions to the mission resupply problem. Out tests, conducted with relatively crude devices based on the original concepts, indicate that further research on the basic principles underlying the systems and refinement of the engineering designs will lead to hardware with the potential to satisfy the requirement for minimal re-supply while providing recycled water and edible mushrooms.     

振荡器的计算机辅助设计与组装

本文综述了贝尔实验室在应用计算机方面的经验,包括模拟和设计、数据采集、数据分析、元件选择和其它各种各样的工作。过去,石英晶体振荡器可以很容易地应用线性电路模型来模拟。虽然存在非线性模型(例如,Spicc.Capitol等),但它们不能被用来对晶体振荡器进行闭环分析,因为其中包括有高Q参数。然而最近Waterloo大学研究的WATAND程序已变得很有效并可适用于石英晶体振荡器的闭环非线性分析。在贝尔实验室,线性和非线性两种分析程序正用于评价新设计,同时特别注意元件变化对工艺的影响。计算机完成原始数据采集任务的方法是对温度补偿晶体振荡器进行频率温度测量。附加的应用是对振荡器进行最后的室温检验,以便确定波形特征、功率损耗、电源灵敏性和频率牵引范围(对于压控晶体振荡器)。应用实时元件选择的方法有助于把电阻组合选择来与根据温度试验数据的分析所确定的数值相适应。在压控晶体振荡器和温度补偿压控晶体振荡器中,用实时元件选择的方法来调整变容二极管的工作点,使频率一电压牵引特性最佳。其他应用包括:对性能数据进行统计分析,以便于计划产量;使用模-数和数-模变换器模拟数字补偿流程图来与以微处理器为基础的计算机相对接,以及模拟双转角晶体切型的温度特性。     

静磁波振荡器的现状

当前在增加带宽和提高工作频率方面,要求不断提高现代雷达相通讯系统的性能,这就需要研究关于模拟信号处理的新技术和新工艺。实际上,用于上述目的的声表面波(SAW)器件,已经得到广泛应用,成效显著;但是对于要求中心频率高于1GHz的雷达和通讯系统,声表面波器件在制造上已经接近实际工艺的物理极限。本文介绍一种新工艺,能得到更高频率。这种工艺是以在外延铁淦氧膜(类似钇铁柘榴石[YIG])中传播的静磁波(MSW)为基础的。静磁波用于器件,使它能在0.5到30GHz微波中心频率上提供高达2.2GHz瞬时带宽。这种静磁波信号处理工艺,是在声表面波采用的横向滤波概念的基础上建立的,已经广泛研究了十年之久。本文首先研究静磁波的物理性质和极限,讨论它与声表面波的异同点。其次,讨论静磁波谐振器,并介绍静磁波振荡器的理论及现状。     

一种自动化高精度相位测量系统

一种采用了多种已有技术、具有多种特点的全自动测量系统已研制成功。这个系统为双混频时差技术的扩展而保持了它的重要特点:间歇时间为零,能进行相位差绝对测量,精度很高,能测量频率相同的振荡器并根据使用人选择的时间进行测量。对某一套设计参数来说,理论分辨度为0。2ps,测量噪声为2ps(有效值)并可在所选时间的0.1s内进行测量。由于增加了定标器以消除过去实验中发生的周期模糊(CyCle ambiguify),双混频时差技术得到了发展。在这方面,系统的功能相当于一个分频器加上钟,对设备中被测的每一个器件的恒定相位延迟进行贮存。自动化是以ANSI/IEEE—583(CAMAC)接口标准为基础的。每个测量通道包括一个混频器,过零检波器、定标器和时间间隔计数器。一个两倍宽度的标准卡马克(CAMAC)组件中安装有四个通道。这个组件安装在一个标准的CAMAC箱内,备有控制器以便与多种计算机以及与任何IEEE—488兼容的装置相对接。现有两个系统已工作数月,一个系统每天工作24小时,从NBS时标的15个钟取得数据,另一个系统在实验室的短期实验中使用。     

磁增强氢气电离器的研制

在对影响射频氢气电离器效率的工艺问题进行研究的基础上,研制了一种将直流磁场加到射频等离子体的电离器,然后测定磁场对等离子体的影响。人们发现,采用这种结构型式,电离器的功耗明显降低。利用直流磁场,还可以使效率保持在固定水平上,同时降低氢气压力。根据这些研究结果,对研制一种耗氢量低、射频功耗小的电离器进行某些探讨。