TRKI-12遥测接收/记录机组中几个重要方面的进一步改进

本文考查了目前安装在东靶场的TRKI—12检前接收/记录机分系统中的几项主要性能,并考交了预期进一步改进的项目。介绍了两个系统的性能特点,这两个系统是由不同的厂商按同一规格分别生产的。几个需着重研究的方面是:接收部分、记录部分以及辅助测试和校准设备。 1962年,为接收/记录机分系统提出任务书的时候,就作出了这样的决定,即要求将接收机与另外一些部件分成若干组件。评述了该决定所碰到的问题及其产生的优点,但侧重于涉及即将改进的若干问题。本文最后简要列出了需进一步改进的项目。为了满足对遥测接收/记录所提的要求,这些改进是完全必要的。     

利用GPS进行精密轨道确定

全球定位系统(GPS)完全布满卫星后,将成为近地卫星的精密轨道确定(POD)强有力的工具。该系统具有连续跟踪覆盖能力,不仅可实现传统的动力学精密轨道确定方法,而且还可进行运动学轨道确定。来自至少四个GPS卫星的伪距测量值,通过载波相位测量值的平滑,可测定天线相位中心的地心位置和用户卫星的时钟修正值,因而后一技术不需要用户卫星受力的动力学模型。运动学法对测量模型的影响非常敏感,如GPS星历误差(给定的或求解的)、信号的多径、接收机噪声等等;然而,动力学方法又受参数误差和/或力模型不完善的影响。为此研究出一种利用过程噪声补偿对运动学和动力学算法进行加权的混合方案。本课题的中心点是利用仿真辅以协方差分析,研究这几种定轨方法。建立了几种动力学和测量误差模型,这些模型造成的轨道不确定性与处理实际GPS数据而估计的星历误差大致相当。协方差分析经调整能反映这些误差,能看出各种滤波技术的特性。     

RESEARCH ON NURBS SKINNING SURFACE VIA COMPLEX CURVES

ＲＥＳＥＡＲＣＨＯＮＮＵＲＢＳＳＫＩＮＮＩＮＧＳＵＲＦＡＣＥＶＩＡＣＯＭＰＬＥＸＣＵＲＶＥＳ￥ＺｈａｎｇＬｅｎｉａｎ；ＺｈｏｕＬａｉｓｕｉ；ＺｈｏｕＲｕｒｏｎｇ（ＲｅｓｅａｒｃｈｃｅｎｔｅｒｏｆＣＡＤ／ＣＡＭＥｎｇｉｎｅｅｒｉｎｇ，ＮａｎｊｉｎｇＵｎ...     

RESEARCH ON THE 3-AXES ROUGH MILLING OF MULTI-SURFACES

ＲＥＳＥＡＲＣＨＯＮＴＨＥ３┐ＡＸＥＳＲＯＵＧＨＭＩＬＬＩＮＧＯＦＭＵＬＴＩ┐ＳＵＲＦＡＣＥＳＬｉｕＺｈｕａｎｇ，ＺｈａｎｇＤｅｑｉａｎｇ，ＺｈｏｕＬａｉｓｈｕｉ，ＺｈｏｕＲｕｒｏｎｇ（ＲｅｓｅａｒｃｈＣｅｎｔｅｒｏｆＣＡＤ／ＣＡＭＥｎｇｉｎｅｅｒｉ...     

GPS用于MX导弹飞行试验的实时跟踪

霍普金斯大学应用物理实验室最近完成了一项MX导弹(和平卫士)试验飞行的实时GPS跟踪研究。因为飞向夸贾林环礁所需靶场安全提出了严格的精度要求,故分析了各种跟踪方案。本文简述了导弹跟踪的经验之后,介绍了各种系统方案。讨论了各种远站处理方案,接着专门研究了电离层误差修正方法和接收机锁相环路热噪声。最后,叙述了瞬时落点(IIP)时间协方差仿真结果。     

Titan and exobiological aspects of the Cassini-Huygens mission

Titan, the largest satellite of Saturn, has a dense N2-CH4 atmosphere rich in organic compounds, both in gas and in aerosol phases. Its surface is probably covered by oceans of liquid methane-ethane mixtures, with many dissolved organics. This quasi planet appears as a natural laboratory to study chemical evolution toward complex organic systems in a planetary environment over a long time scale. With the Cassini-Huygens mission NASA and ESA will jointly send an orbiter (Cassini) around Saturn and a probe (Huygens) in the atmosphere of Titan. This mission, currently planned to be launched in 1996-1997 for a Saturn - Titan arrival in 2004, offers a unique opportunity to study in detail extra-terrestrial organic processes. Consequently, it has important implications in the field of exobiology and the origins of life.     

The Aouda.X space suit simulator and its applications to astrobiology

We have developed the space suit simulator Aouda.X, which is capable of reproducing the physical and sensory limitations a flight-worthy suit would have on Mars. Based upon a Hard-Upper-Torso design, it has an advanced human-machine interface and a sensory network connected to an On-Board Data Handling system to increase the situational awareness in the field. Although the suit simulator is not pressurized, the physical forces that lead to a reduced working envelope and physical performance are reproduced with a calibrated exoskeleton. This allows us to simulate various pressure regimes from 0.3-1 bar. Aouda.X has been tested in several laboratory and field settings, including sterile sampling at 2800 m altitude inside a glacial ice cave and a cryochamber at -110°C, and subsurface tests in connection with geophysical instrumentation relevant to astrobiology, including ground-penetrating radar, geoacoustics, and drilling. The communication subsystem allows for a direct interaction with remote science teams via telemetry from a mission control center. Aouda.X as such is a versatile experimental platform for studying Mars exploration activities in a high-fidelity Mars analog environment with a focus on astrobiology and operations research that has been optimized to reduce the amount of biological cross contamination. We report on the performance envelope of the Aouda.X system and its operational limitations.     

EXPOSE-E: an ESA astrobiology mission 1.5 years in space

The multi-user facility EXPOSE-E was designed by the European Space Agency to enable astrobiology research in space (low-Earth orbit). On 7 February 2008, EXPOSE-E was carried to the International Space Station (ISS) on the European Technology Exposure Facility (EuTEF) platform in the cargo bay of Space Shuttle STS-122 Atlantis. The facility was installed at the starboard cone of the Columbus module by extravehicular activity, where it remained in space for 1.5 years. EXPOSE-E was returned to Earth with STS-128 Discovery on 12 September 2009 for subsequent sample analysis. EXPOSE-E provided accommodation in three exposure trays for a variety of astrobiological test samples that were exposed to selected space conditions: either to space vacuum, solar electromagnetic radiation at >110?nm and cosmic radiation (trays 1 and 3) or to simulated martian surface conditions (tray 2). Data on UV radiation, cosmic radiation, and temperature were measured every 10?s and downlinked by telemetry. A parallel mission ground reference (MGR) experiment was performed on ground with a parallel set of hardware and samples under simulated space conditions. EXPOSE-E performed a successful 1.5-year mission in space.     

Survival of spores of the UV-resistant Bacillus subtilis strain MW01 after exposure to low-earth orbit and simulated martian conditions: data from the space experiment ADAPT on EXPOSE-E

In the space experiment "Molecular adaptation strategies of microorganisms to different space and planetary UV climate conditions" (ADAPT), bacterial endospores of the highly UV-resistant Bacillus subtilis strain MW01 were exposed to low-Earth orbit (LEO) and simulated martian surface conditions for 559 days on board the European Space Agency's exposure facility EXPOSE-E, mounted outside the International Space Station. The survival of B. subtilis MW01 spores from both assays (LEO and simulated martian conditions) was determined by a colony-formation assay after retrieval. It was clearly shown that solar extraterrestrial UV radiation (λ≥110?nm) as well as the martian UV spectrum (λ≥200?nm) was the most deleterious factor applied; in some samples only a few spore survivors were recovered from B. subtilis MW01 spores exposed in monolayers. However, if shielded from solar irradiation, about 8% of MW01 spores survived in LEO conditions, and 100% survived in simulated martian conditions, compared to the laboratory controls. The results demonstrate the effect of shielding against the high inactivation potential of extraterrestrial solar UV radiation, which limits the chances of survival of even the highly UV-resistant strain of B. subtilis MW01 in the harsh environments of outer space and the martian surface.     

Thyroid cell growth: sphingomyelin metabolism as non-invasive marker for cell damage acquired during spaceflight

Prolonged spaceflights are known to elicit changes in human cardiovascular, musculoskeletal, and nervous systems, whose functions are regulated by the thyroid gland. It is known that sphingomyelin metabolism is involved in apoptosis (programmed cell death) of thyroid cells induced by UVC radiation, but at present no data exists with regard to this phenomenon, which occurs during space missions. The aim of this study was to analyze, for the first time, the effect of spaceflight on the enzymes of sphingomyelin metabolism, sphingomyelinase, and sphingomyelin synthase, and to determine whether the ratio between the two enzymes might be used as a possible marker for thyroid activity during space missions. Both quiescent thyroid cells and thyroid cells stimulated to proliferate with thyrotropin (TSH) were cultured during the Eneide and Esperia missions on the International Space Station. The results show that during space missions the cells treated with TSH grew only 1.5?±?0.65-fold and, thus, behave similarly to quiescent cells, while on the ground the same cells, maintained in experimental conditions that reproduced those of the flight, grew 7.71?±?0.67-fold. Comparison of the sphingomyelinase/sphingomyelin-synthase ratio and the levels of Bax, STAT3, and RNA polymerase II in proliferating, quiescent, pro-apoptotic, or apoptotic cells demonstrated that thyroid cells during space missions were induced into a pro-apoptotic state. Given its specificity and the small amount of cells needed for analysis, we propose the use of the sphingomyelinase/sphingomyelin-synthase ratio as a marker of functional status of thyroid cells during space missions. Further studies could lead to its use in real time during prolonged spaceflights.