Proposal for a new radiation dose control system for future manned space flights

Radiation risk on a future long-duration manned space mission appears to be one of the basic factors in planning and designing the mission. Since 1988 different active dosimetric investigations has been performed on board the MIR space station by the Bulgarian-Russian dosimeter-radiometer LIULIN and French tissue-equivalent proportional counters CIRCE and NAUSICAA. A joint French-Bulgarian-Russian dosimetry experiment and the dosimetry-radiometry system RADIUS-MD have been developed for the future MARS-96 mission. On the base of the results and experience of these investigations a conception for a new radiation dose control system for the future orbital stations, lunar bases and interplanetary space ships is proposed. The proposed system which consists of different instruments will allow personal radiation control for crew members, radiation monitoring inside and outside each habitat, analysis and forecasting of the situation and will suggest procedures to minimize the radiation risk.     

Detectability of planetary characteristics in disk-averaged spectra. I: The Earth model

Over the next 2 decades, NASA and ESA are planning a series of space-based observatories to detect and characterize extrasolar planets. This first generation of observatories will not be able to spatially resolve the terrestrial planets detected. Instead, these planets will be characterized by disk-averaged spectroscopy. To assess the detectability of planetary characteristics in disk-averaged spectra, we have developed a spatially and spectrally resolved model of the Earth. This model uses atmospheric and surface properties from existing observations and modeling studies as input, and generates spatially resolved high-resolution synthetic spectra using the Spectral Mapping Atmospheric Radiative Transfer model. Synthetic spectra were generated for a variety of conditions, including cloud coverage, illumination fraction, and viewing angle geometry, over a wavelength range extending from the ultraviolet to the farinfrared. Here we describe the model and validate it against disk-averaged visible to infrared observations of the Earth taken by the Mars Global Surveyor Thermal Emission Spectrometer, the ESA Mars Express Omega instrument, and ground-based observations of earthshine reflected from the unilluminated portion of the Moon. The comparison between the data and model indicates that several atmospheric species can be identified in disk-averaged Earth spectra, and potentially detected depending on the wavelength range and resolving power of the instrument. At visible wavelengths (0.4-0.9 microm) O3, H2O, O2, and oxygen dimer [(O2)2] are clearly apparent. In the mid-infrared (5-20 microm) CO2, O3, and H2O are present. CH4, N2O, CO2, O3, and H2O are visible in the near-infrared (1-5 microm). A comprehensive three-dimensional model of the Earth is needed to produce a good fit with the observations.     

Detectability of planetary characteristics in disk-averaged spectra II: synthetic spectra and light-curves of earth

Spatially and spectrally resolved models were used to explore the observational sensitivity to changes in atmospheric and surface properties and the detectability of surface biosignatures in the globally averaged spectra and light-curves of the Earth. Compared with previous efforts to characterize the Earth using disk-averaged models, a more comprehensive and realistic treatment of the surface and atmosphere was taken into account here. Our results are presented as a function of viewing geometry and phases at both visible/near-infrared (0.5-1.7 microm) and mid-infrared (5-25 microm) wavelength ranges, applicable to the proposed NASA-Terrestrial Planet Finder visible coronagraph and mid-infrared interferometer and to the ESADarwin mission architectures. Clouds can change the thermal emission by as much as 50% compared with the cloud-free case and increase the visible albedo by up to 500% for completely overcast cases at the dichotomy phase. Depending on the observed phase and their distribution and type, clouds can also significantly alter the spectral shape. Moreover, clouds impact the detectability of surface biosignatures in the visible wavelength range. Modeling the disk-averaged sensitivity to the "red-edge," a distinctive spectral signature of vegetation, showed that Earth's land vegetation could be seen in disk-averaged spectra, even with cloud cover, when the signal was averaged over the daily time scale. We found that vegetation is more readily discriminated from clouds at dichotomy (50% illumination) rather than at full phase. The detectability of phytoplankton was also explored, but was found to be more difficult to detect in the disk-average than land vegetation.     

涡轮级轮缘封严内非定常流场的准三维LDV测量

研究涡轮级封严内流动和主流的相互作用、相互影响,进一步认识盘腔内燃气入侵等非定常现象,急需流场实验数据验证。针对轮缘封严内空间狭窄、光路安排困难等问题,本文发展了一种用于测量涡轮级轮缘封严内非定常流场的准三维LDV技术,即测量分两步,首先在机匣上安置二维测速系统用符合方式测出径向、切向速度及湍流度,再在轮毂内安置一维探头重复测量,从两次测量数据中计算出轴向速度;该技术借助锁相采样等技术能测出不同动静叶相对位置情况下封严及盘腔内的周期性非定常流场细节,本文给出了部分典型的动态流场测量结果。      

涡轮叶栅前缘上游端壁气膜冷却的传热实验研究

对前缘上游有单排和双排孔冷却的涡轮导向叶栅端壁进行了详细的传热实验,在吹风比1,2,3下获得了当地气膜冷却效率和换热系数,结合流场测量结果分析了端壁冷却和换热规律。结果表明端壁气膜冷却在很大程度上受二次流的影响,冷却效果主要由吹风比决定,低吹风比喷射时,压力面附近的一个三角形区域没有冷气的覆盖,中、高吹风比喷射可以大幅度提高平均冷却效率并使冷气很均匀的覆盖在端壁上,双排孔喷射比单排孔喷射平均效率提高1倍左右。结果还表明尽管冷气喷射使端壁换热系数随吹风比的增大而显著增大,气膜冷却还是能有效的降低端壁的热负荷,其中以中吹风比双排孔喷射的效果最为显著。      

DARA就小卫星利用商业卫星通信系统传递数据的概念性研究结果

国家对航天计划的预算要求航天工程低成本和高效费比。德国航天局（ＤＡＲＡ）规定了一项指标，通过综合利用新概念来减少小卫星的开发和操作费用。ＤＡＲＡ提出一项研究课题，研究利用现有或即将建成的商业卫星通信系统来减少小卫星操作费用的替力，本文就介绍该项研究的成果。设想了多种数据传输方案，分析了低轨小卫星（科学）和下列通信卫星星座之间的几种方案：ａ）低轨通信卫星，即铱和全球星系统；ｂ）中轨卫星，即ＩＣＯ系统     

低截获概率雷达的特征和机载系统

1 低截获概率雷达的特征 许多组合特性有助于防止低截获概率（LPI）雷达被现代截获接收机探测到。这些特性集中在天线（天线方向图和扫描图形）和发射机（辐射波形）中。     

史密森天文物理观测台研制的冷氢激射器及有关装置

低温冷却激射器为测量频率偏移和存储壁涂敷材料的弛豫特性创造了有利条件。这种涂敷材料是从常态变为气态物质而被冻结在存储壁上的。我们对FEP—120聚四氟乙烯在77K至48K之间的原始测试结果作了报道,并把这些测量结果和法国de Saintfuscien在372K至77K之间的测试数据进行了比较。对激射器的某些设计性能作了说明。低溫激射器的氢分离器,完全密封在真空环境中,其温度77k。本文还介绍了在真空中工作的分离器和其它一些装置。这些装置已在常温激射器中被采用并进行了测试。它们既适合于太空环境又适合于在地面使用。     

Input Parameters for Models of Energetic Electrons Fluxes at the Geostationary Orbit

The results of cross-correlation analysis between electrons fluxes (with energies of > 0.6MeV, > 2.0 MeV and > 4.0MeV), geomagnetic indices and solar wind parameters are shown in the paper. It is determined that the electron fluxes are controlled not only by the geomagnetic indices, but also by the solar wind parameters, and the solar wind velocity demonstrates the best relation with the electron fluxes. Numerical value of the relation efficiency of external parameters with the highly energetic electrons fluxes shows a periodicity. It is presented here the preliminary results of daily averaged electrons fluxes forecast for a day ahead on the basis of the model of neuron networks.