COMRING：一个适用于地球观测任务和空间站的小卫星数据中继系统

ＣＯＭＲＩＮＧ（通信环）是一种适用于低轨卫星的数据中继系统新设想，该系统可在低轨迹这航天器与地面间连续传递数据（典型的可传便时间为８０～１００％）该系统可提供连续的全球覆盖而无需大规模的地面站网和不可靠的星上数据记录仪，ＣＯＭＲＩＮＧ采用７～９颗小卫星（每颗重１６０ｋｇ）以等间隔配置在用户星同一轨道上，数据的中继经由星际链路完成，用户星可以是一颗遥感卫星或一颗军用侦察卫星，用于空间站的ＣＯＭＲＩＮ     

美国通信卫星平台

美国从本世纪6O年代初期就开始发展通信卫星事业了，那时“电星”（Telstar）、“辛康”（Syncom）和“晨鸟”（zanyBird）等卫星处于技术世界领先水平。一些参与了早期通信及其他卫星领域开发的公司在其后3O年中积累了丰富的经验，现在卫星已经是他们成熟的产品之一。但是卫星从来没有，将来也不可能会像汽车或波音747飞机那样造得那么多。卫星的数量相对太少了，每一颗卫星都是为了覆盖某一特定地区服务而专门制作的。也许情况会因引入低轨道卫星星座有所改变，但就目前为止，这类卫星并没有统一的标准，目前制造商们正致力于使其产品建…     

用于同步轨道确定的地面站天线指向性能

本文给出了雷杜站跟踪欧空局ECS-1和OTS-2通信卫星所得近一年的角跟踪数据进行精度鉴定的结果。可从另一个地面站得到另外的测距数据的时间内,可以以较高的精度直接测出这些误差。测得的角误差代入相应的解析式中,就可以预测用类似跟踪系统对于其他同步轨道任务的定轨精度。     

可延伸喷管出口锥的缩比级间分离加载试验

级间分离试验的目的是改善关于在收叠位置的可延伸喷管出口锥(以下简称“ENEC”)在级分离期间的受载情况予测。缩比的固体火箭试验发动机系统带有收叠的 ENEC 和模拟级间分离的试验设备。海平面实验数据由发动机的短时间静态点火中获得。试验测到的点火瞬变状态和初始条件被输入到计算机编码,以模拟级间分离影响,用于与试验数据进行比较。结果表明,级间段平均压力、发动机推力,以及两级的相对轴向位移相当接近。测量的级间压力峰值高于计算值10%,作用在 ENEC 内外表面上的最大平均压力差是5磅/英寸~2。在缩比的级间分离环境中,通过 ENEC 载荷和级间压力的明显波动,指出了与气体流动现象有关 ENCE重要的动态加载条件。     

Increased urinary excretion rates of serotonin and metabolites during bedrest

Astronauts are often on a voluntarily reduced energy intake during space missions, possibly caused by a metabolic or emotional stress response with involvement of the central serotonergic system (SES). We investigated 24 h urinary excretion (24 h-E) of serotonin (5-HT) and 5-hydroxyindol acidic acid as indicators of the SES in healthy males under two different normocaloric conditions: normal physical activity (NPA) and -6 degree head-down-tilt (HDT). HDT or NPA were randomly arranged with a recovery period of 6 months in between. 24 h-E of hormones varied widely among individuals. Values were higher in HDT compared to NPA. Assuming that the 24 h-E values are, beside being indicators for alterations in the number and metabolism of platelets. Also indicators of central SES, HDT condition seems to activate central SES in a higher degree compared to NPA. Therefore, changes in central SES might be involved in the mechanisms associated with space flight or microgravity, including possible maladaptations such as voluntary undernutrition.     

Vanguard--a European robotic astrobiology-focussed Mars sub-surface mission proposal

We present a new European Mars mission proposal to build on the UK-led Beagle2 Mars mission and continue its astrobiology-focussed investigation of Mars. The small surface element to be delivered to the Martian surface--Vanguard--is designed to be carried by a Mars Express-type spacecraft bus to Mars and adopts a similar entry, descent and landing system as Beagle2. The surface element comprises a triad of robotic devices--a lander, a micro-rover of the Sojourner class for surface mobility, and three ground-penetrating moles mounted onto the rover for sub-surface penetration to 5 m depth. The major onboard instruments on the rover include a Raman spectrometer/imager, a laser plasma spectrometer, an infrared spectrometer--these laser instruments provide the basis for in situ "remote" sensing of the sub-surface Martian environment within a powerful scientific package. The moles carry the instruments' sensor head array to the sub-surface. The moles are thus required to undergo a one-way trip down the boreholes without the need for recovery of moles or samples, eliminating much of the robotic complexity invoked by such operations.     

Immobilization induces a very rapid increase in osteoclast activity

We studied in a randomized, strictly controlled cross-over design, the effects of 6 days 6 degrees head-down tilt bed rest (HDT) in eight male healthy subjects in our metabolic ward. The study consisted of two periods (phases) of 11 days each in order to allow for the test subjects being their own controls. Both study phases were identical with respect to environmental conditions, study protocol and diet. Two days before arriving in the metabolic ward the subjects started with a diet. The diet was continued in the metabolic ward. The metabolic ward period (1l days) was divided into three parts: 4 ambulatory days, 6 days either HDT or control and 1 recovery day. Continuous urine collection started on the first day in the metabolic ward to analyze calcium excretion and bone resorption markers. On the 2nd ambulatory day in the metabolic ward and on the 5th day in HDT or control blood was drawn to analyze serum calcium, parathyroid hormone, and bone formation markers. Urinary calcium excretion was, as early as the first day in immobilization, increased (p<0.01). CTX- and NTX-excretion stayed unchanged in the first 24 h in HDT compared to the control. But already on the 2nd day of immobilization, both bone resorption markers significantly increased. We conclude from these results--pronounced rise of bone resorption markers--that already 24 h of immobilization induce a significant rise in osteoclast activity in healthy subjects. Thus, it appears possible to use short-term bed rest studies as a first step for the development of countermeasures to immobilization.     

Research on Biolab, a multi-user facility for APM

A study carried out by a team of seven scientists appointed by ESA resulted in the design of a biological laboratory "Biolab" for Columbus APM. The basis for the study were four pre-Phase A studies performed by industry on the assumption that 15 racks would be available to biology and biotechnology in the APM. Due to the constraints newly imposed by the Columbus project, only five racks are now allocated. The tasks of the Biolab scientific team were: (i) to define the scientific objectives of biological research in Columbus; (ii) to review the requirements of the industrial studies; and (iii) to design a multi-purpose facility compatible with the present constraints and satisfying the requirements of the biological investigations considered in the four studies. The Biolab team was able to define a facility capable of accommodating in five racks the following biological objects: small plants (up to 40 cm), insects like drosophila, frog eggs, single cells from animals, bacteria, slime molds and protozoa, as well as human physiology, but restricted to general diagnostic needs. The Biolab facility includes instruments and devices providing the capacity of holding and/or growing the organisms as well as to perform basic experimentation and a minimum essential diagnostic inflight. Within the growth unit the growth chambers/incubators are exchangeable, permitting the use of growth chambers of different sizes. The temperature will be adjustable to the requirements of the objects under investigation, i.e. either 20 or 37 degrees C. Thus a considerable level of flexibility will permit to investigate a broad spectrum of living systems.