Microbial survival rates of Escherichia coli and Deinococcus radiodurans under low temperature, low pressure, and UV-Irradiation conditions, and their relevance to possible Martian life

Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35 degrees C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m(2)). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.     

失落了的文明

在气候炎热的危地马拉丛林中,一群人在血红色的大金字塔下站了好几个小时.他们一动不动.所有的目光都集中在塔顶的石刻上.在那儿,国王的头上佩带着翎毛,一手持一柄双首鳄节杖,正要从留有祖先信息的神堂中现身而出.这群人虽然看不到国王的动态、却懂得这种宗教仪式的奥秘:通过服用致幻药飘飘然地进入阴间.国王会使用黑曜岩刀片或鱼脊骨,刺穿他自己的阴茎.随即掏出一根绳子穿过伤口,让血液沥到几张树皮纸上.然后他拿起带血的树皮纸将它点燃,从缕缕上升的烟雾中金蛇飞舞的幻象便呈现在国王的面前.     

实时显示生成器

实时显示生成器(RTDB)是一种生成逻辑驱动显示的交互式图形工具样机。这些显示反映了当前系统状态,实时完成故障检测算法,采纳老练飞控人员的操作知识。该RTDB采用面向目标的方法,将基本操作逻辑和显示符号结合起来。要生成显示时,用户利用这种方法可规定屏幕布局和驱动逻辑。RTDB正在UNLX下用C语言开发,利用了MASSCOMP图形环境,作了适当的功能划分,以便于移植到其它图形环境。RTDB是为用户化实时数据驱动的航天飞机系统显示而开发的。使用该工具初始功能度的显示在STS—26发现者号轨道运行阶段投入了实用。目前正在NASA/JSC任务操作部开发的实时数据系统工程准备利用RTDB产生几种显示。本文介绍了这种工具的特点、目前的发展状况及其应用。     

非洲:生命源头的秘密(下)

直立人是极为成功的流动群体,事实上,他们的旅行十分顺利,人们最初发现的直立人化石距离他们原来的非洲家园有好几千公里.在19世纪90年代,尤基尼·多布尔斯,一位富于冒险精神的荷兰物理学家,他加入了荷兰军队以此为藉口到达了荷兰属的东印度群岛(即现在的印度尼西亚).多布尔斯同意查理·达尔文的理论,认为早期人类与大猿有着密切的联系.因为在东印度群岛上有猩猩存在,所以多布尔斯认为这里可能拥有“丢失链”的化石.     

Adaptational changes in the neural control of cardiorespiratory function in a confined environment: the CNEC#3 experiment

The goal of the study was to characterize the changes in neurovegetative control of the circulation, attending the presumed physiological and psychological stress originated by the isolation and confinement typical of the living condition of space stations, as simulated in a ground based unit, using time and frequency domain analysis. As a secondary goal we sought to verify the implementation of real time data acquisition, for off line spectral analisys of R-R interval, systolic arterial pressure (by Finapres) and respiration (by PVF2 piezoelectric sensors).

We addressed the cardiorespiratory and neurovegetative responses to standardized, simple Stressors (active standing, dynamic and static handgrip) on the EXEMSI 92 crew, before, during and after the isolation period.

On average the appropriate excitatory responses (to stand, dynamic and static handgrip) were elicited also in isolation and confinement.

Active standing and small masses muscular exercises are easy to be performed in a confined and isolated environment and provide a valuable tool for investigating the adaptational changes in neural control mechanisms.

The possibility there exists of using this time and frequency domain approach to monitor the level of performance and well being of the space crew in (quasi) real time.     

Psychological countermeasures for extended manned spaceflights

The authors examine psychological issues and countermeasures in extended space flight. Individual-oriented pre-flight countermeasures include basic psychological selection and training of astronaut candidates. Crew-oriented pre-flight countermeasures include crew composition based on psychological compatibility and psychological mission preparation. Psychological inflight support measures include those that address the emotional state and well-being of astronauts, performance efficiency, and prevention of task overload. Suggestions for an integrated approach to psychological countermeasures for extended flights are presented. Case reports examine psychological selection and training of German astronauts in preparation for the STS-55 mission.     

Lick Observatory Optical SETI: targeted search and new directions

Lick Observatory's Optical SETI (search for extraterrestrial intelligence) program has been in regular operation for 4.5 years. We have observed 4,605 stars of spectral types F-M within 200 light-years of Earth. Occasionally, we have appended objects of special interest, such as stars with known planetary systems. We have observed 14 candidate signals ("triple coincidences"), all but one of which are explained by transient local difficulties. Additional observations of the remaining candidate have failed to confirm arriving pulse events. We now plan to proceed in a more economical manner by operating in an unattended drift scan mode. Between operational and equipment modifications, efficiency will more than double.     

Effect on the cardiac function of repeated LBNP during a 1-month head down tilt

Cardiovascular assessment by ultrasound methods was performed during two long duration (1 month) Head Down Tilt (HDT) on 6 healthy volunteers. On a first 1 month HDT session, 3 of the 6 subjects (A, B, C) had daily several lower body negative pressure tests (LBNP), whereas the 3 subjects remaining (D, E, F) rested without LBNP. On a second 1 month HDT session subjects D, E, and F had daily LBNP tests and the A, B and C subjects did not. The cardiac function was assessed by Echocardiography, (B mode, TM mode). On all the "6 non LBNP" subjects the left ventricule diastolic volume (LVDV), the stroke volume (SV) and the cardiac output (CO) increase (+10%, -15%) after HDT then decrease and remain inferior (-5%, -5%) or equal to the basal value during the HDT. Immediately after the end of the HDT the heart rate (HR) increase (+10%, +30%) whereas the cardiac parameters decrease weakly (-5%, -10%) and normalize after 3 days of recovery. On the "6 LBNP" subjects the LVDV, SV and CO increase (+10%, 15%) after 1 h HDT as in the previous group then decrease but remain superior (+5%, +15%) or equal to the basal value. After the HDT session, the HR is markedly increased (+20%, +40%) the LVDV and SV decrease (-15%, -20%) whereas the CO increases or decreases depending on the amplitude of the HR variations. These parameters do not completely normalize after 3 day's recovery. Repeated LBNP sessions have a significant effect on the cardiovascular function as it maintains all cardiac parameters above the basal value. The LBNP manoeuvre can be considered as an efficient countermeasure to prevent cardiac disadaptation induced by HDT position and probably microgravity.     

A search for narrow band signals with SERENDIP II: a progress report

Commensal programs for the Search for Extraterrestrial Intelligence (SETI), carried out concurrently with conventional radio astronomical observing programs, can be an attractive and cost-effective means of exploring the large multidimensional search space intrinsic to this effort. Our automated commensal system, SERENDIP II, is a high resolution 131,072 channel spectrometer. It searches for 0.49 Hz signals in sequential 64,700 Hz bands of the IF signal from a radio telescope being used for an astronomical observation. Upon detection of a narrow band signal with power above a preset threshold, the frequency, power, time, and telescope direction are recorded for later study. The system has been tested at the Hat Creek Radio Astronomy Observatory 85 ft telescope and the NASA-JPL Deep Space Station (DSS 14) 64 m telescope. It is currently collecting data at the National Radio Astronomy Observatory 300 ft telescope.