用于稳定光电瞄准线的动调陀螺

商业市场中的动调陀螺（DTG）主要是作为一种低成本、小体积的双轴速率敏感器用在战术导弹上，且在这一领域被广泛应用。动调陀螺也适用于稳定光电瞄准线，尽管有关该领域的文献很少，初看起来，该陀螺似乎采用的是普遍应用于单轴积分陀螺中的相同的锁定回路技术，但不管怎样，它们还是存在很微妙但却很重要的差别，不注意这些差别可能会导致陀螺性能降低或失效，有关这些内容及DTG在瞄准稳定系统中应用的其它问题将被讨论，讨论内容也将包含工作原理，接口电路，锁定回路设计及光电系统中典型误差源分析。     

相位比较器的取样对频率合成器性能的影响

简单的锁相环频率合成器可以看做一对锁相振荡器。锁相环相位比较仪的取样在理论上和实践上对频率合成器的转换速度都有限制作用。取样还限制了用锁相技术所能达到的输出频谱的改善。文中给出了若干结果。并将这些结果与分析频率合成器系统一模型的连续数据和取样数据进行了比较。     

阿里安运载火箭推进系统的下一步改进

一、引论阿里安运载火箭下一步改进的目标是:——对于进入转移轨道的双星发射,有效载荷能力约增加20%(2×900公斤);——对于进入低轨道的重型卫星,可将有效载荷提高约50～100%(7～10吨);——降低每公斤有效载荷入轨的发射费用;——进一步发展可用于未来空间计划的技术。     

MX导弹测试系统多路复用器组合

MX导弹测试系统多路复用器组合用于采集导弹飞行试验的测量数据。多路复用器组合包括一个多路复用器编程控制单元(MU)、2至32个远置多路复用单元(RU)以及若干个电源检查单元(PSV)。 MU的主要用途是作为可编程序的系统控制器,接收本地输入数据并将这些数据与来自RU的数据一道编成PCM的格式输出。RU通过指令和应答数据总线与MU相接口,进行远距离数据采集。PSV为模拟信号源提供精确的激励电压并控制模拟信号的偏移以进行校验检查。 32个RU中有31个通过飞行器上的两对数据总线与MU相接,余下的1个RU经脐带或数据总线接到飞行器。这个留在地面上的RU与飞行器上的相同,但对其功能要求却完全不同。它主要用来装入并校验MU程序。飞行器上的每条数据总线最长可达130英尺,脐带总线最长为250英尺。MX导弹无法使用理想的终端负载总线,因为导弹分离时总线的配置要改变。级间分离时电缆将发生开路或短路。为保证总线上剩余的RU正常工作,接口隔离变压器绕有电流和电压绕组以提供最大的次级信号电平而反射失真最小。数据总线使用Manchester Ⅱ型码,工作频率为3.2MHz。 MU可对160个本地差分模拟信道进行采样,增益与偏移可编程,最大采样率为170,665次/秒。由96个离散通道中可以编程的灵活组合方式取出8路离散输入,采样率可达每秒51,200次。MU还可以接受4路串行数据通道的数据并提供向8条命令通道的输出。命令可在飞行前从地面发出,发射后这些命令按时间事件驱动的方式编程,同时也按在两种工作之间来回重复的格式编程。PCM码速率为1.6Mbps。MU在16位4096字的CMOS RAM存贮器中存贮5种格式供飞行中选用。每个RU可访问28条模拟通道和8条数字通道,并可控制2条命令通道和6条检验通道。PSV不同数据总线相连,对它的控制通过MU或RU命令通道执行。系统可由外部同步或按内部时钟工作,传送方式经过仔细考虑,从而减少数据丢失。系统主要特点是体积小、重量轻、功耗低和可靠性高。弹内装载的监测器和计算机控制的全自动测试设备提供了快速和可观的参数检测手段,从而在很大程度上减少了故障。     

轻便型氢脉泽研制计划的试验结果

在美国空军支持下西格玛-托标准公司承担的定名为“轻便型氢脉泽的研究和发展计划”已经完成。从小型腔脉泽的新概念开始,通过对试验电路板脉泽的测试,该项工作已经从试验性泡和腔的最佳选择进展到对称之为“小型氢脉泽”第一台工作样机的设计、制造和测试。为了达到计划的目的,在过去的实践基础上提出一些新的试制和改进的要求。这些要求是:改进氢源,改善射束光学设备,新的选态器、新的腔频控制技术和Q的提高以及更小型的高效电子系统。本文介绍“小型氢脉泽”最近的试验结果,同时也将讨论氢脉泽进一步小型化和在改善大泡氢脉泽方面改进加工工艺的意义。     

Artificial gravity: a possible countermeasure for post-flight orthostatic intolerance

Four payload crewmembers were exposed to sustained linear acceleration in a centrifuge during the Neurolab (STS-90) flight. In contrast to previous studies, otolith–ocular reflexes were preserved during and after flight. This raised the possibility that artificial gravity may have acted as a countermeasure to the deconditioning of otolith–ocular reflexes. None of the astronauts who were centrifuged had orthostatic intolerance when tested with head-up passive tilt after flight. Thus, centrifugation may also have helped maintain post-flight hemodynamic responses to orthostasis by preserving the gain of the otolith–sympathetic reflex. A comparison with two fellow Neurolab orbiter crewmembers not exposed to artificial gravity provided some support for this hypothesis. One of the two had hemodynamic changes in response to post-flight tilt similar to orthostatically intolerant subjects from previous missions. More data is necessary to evaluate this hypothesis, but if it were proven correct, in-flight short-radius centrifugation may help counteract orthostatic intolerance after space flight.     

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.     

COSAC onboard Rosetta: a bioastronomy experiment for the short-period comet 67P/Churyumov-Gerasimenko

The COSAC (Cometary Sampling and Composition Experiment) onboard the Rosetta mission is a combined gas chromatograph (GC)-mass spectrometer (MS). It is situated on Philae, the lander of the mission, which is intended to land on the nucleus of comet 67P/Churyumov- Gerasimenko. The purpose of the experiment is to analyze the volatile fraction of soil samples retrieved by a drill. For investigation, the samples will be pyrolysed, and the emanating gases fed into a GC, into an MS, or the combination of both. In the first part of this paper, the bioastronomical relevance of such measurements is outlined. In the second part the details of the hardware and its performance are described.