The face inversion effect in microgravity: is gravity used as a spatial reference for complex object recognition?

Complex objects are better recognized under a specific orientation. When presented upside down, a face, even very familiar, is recognized with greater difficulty than when presented upright ("Inversion effect"). Up to now it was not possible to decide whether the direction provided by gravity or the one provided by the retina and the body constitutes the spatial reference involved in this "Inversion effect". Three cosmonautes learned photographed faces on the ground and had to recognize them both on ground and on flight. Other photographed faces were learned in flight and where presented for recognition on flight. Results show that the Inversion effect is still present on flight for faces that have been learned on ground as well as for those learned on flight. Persistence of the inversion effect in 0-G shows that gravity is not involved as a spatial reference in recognition of faces. Learning and recognition performances of faces learned in flight were significantly lower than performances for faces learned on ground. A possible role of gravity in configural processing, but not in the Inversion effect, is suggested.     

Effects of repeated long duration +2Gz load on man's cardiovascular function

Usefulness of a short-arm human centrifuge is expected when it is used in space as a countermeasure against cardiovascular deconditioning, problem of bone-calcium metabolism, etc. However, nothing is solidly established regarding the most desirable program for artificial G application. Accordingly, this study was designed to analytically evaluate the effects of repeated long duration +Gz load on human cardiovascular function. Recently heart rate spectral analysis has been recognized as a powerful tool for quantitatively evaluating parasympathetic and sympathetic activity separately in human. It is reported that power of the high frequency component (HF-p) is mediated selectively by parasympathetic activity and the power ratio of low to high frequency components(LF/HF) is indicative of cardiac sympathetic activity or cardiac sympathovagal balance. Sequence method is developed to examine spontaneous baroreceptor reflex sensitivity (BRS). We studied cardiovascular control function by using these methods in 9 healthy men before and after 7 days of daily repeated 1hour +2Gz load. When compared with the data of pre-G load period, post-G load period, decrease of HR, increases of HF-p and BRS were statistically significant. SBP, DBP and LF/HF tended to decrease, however, these changes were not statistically significant. This results indicate that repeated +2Gz load increases parasympathetic activity and arterial baroreceptor-cardiac reflex sensitivity. In recent years, many investigators suggest that space flight and head-down bedrest leads to impaired baroreceptor-cardiac reflex responses and decrease of parasympathetic activity, which may contribute to orthostatic intolerance. So our results suggest that daily repeated 1hour +2Gz load would be useful in preventing post-flight orthostatic intolerance.     

美国TDRSS的发展及其新应用

本文将以1996年第二届TDRSS专题研讨会的内容为主,介绍美国TDRSS的现状,新研制星TDRS—H,I,J的主要技术指标改进,高精度定轨技术,TDRSS工作频段向Ka波段的过渡,几代用户转发器的发展情况,并较全面地介绍近几年来试验成功的若干TDRSS新应用,例如用于极区数据采集站高速数据中继,长期气球、无人飞行器和海上浮标的数据采集,运载火箭全程遥测数据的转发,遥感飞机高速图象数据和前向信息的传递以及正在研究的利用TDRSS对运载火箭发送靶场安全指令,为小卫星服务的按需接址业务等。     

NASA深空网（DSN）的现状及发展趋势

详细介绍了美国深空网的发展过程、目前的状况以及未来的主要发展计划。     

欧洲空间操作中心的精密轨道确定

目前,欧洲空间操作中心正在进行着一项需4年时间的开发计划,以支持未来的需要高精度轨道确定的ESA近地飞行任务。该工作是围绕着欧洲空间操作中心已开发的供轨道确定和误差分析用的一个软件系统进行的,该软件含有适合于各种轨道摄动和测量类型的先进模型。除了卫星轨道参数外,它还能对地球物理参数和测地参数进行估计和误差分析。     

哥达德航天中心天基、地基测控网的Ka频段过渡计划

1　工作于Ka频段的驱动因素NASA天基测控网 (SN)目前通过TDRSS卫星和白沙设施 (WSC)的地面设备以S和Ku频段为各种近地轨道科学卫星提供通信服务。同样 ,NASA地基测控网 (GN)利用分布于全球的地面站通过直接对地的S和X频段为科学卫星提供通信服务。按NASA预测许多科学卫星提出的测控需求 ,需要 1Gbit/s或更高的数传速率 ,这些快速上升的数据吞吐速率不可能以现用的Ku和X频段来满足。此外 ,NASA分配给TDRSSKu频段前、返向链路频率在国际电信联盟 (ITU)只是二级用户 ,固定卫星业务 (主用户 )地球站地球 -空间方向的发射会给…     

用于NASA局TDRSS第二地面终端站的综合接收机的设计与性能

Interstate电子公司正在开发一种综合接收机,准备用于TDRSS第二地面终端站(STGT,NASA天基测控网的一个重要组成部分)的S波段多址、S波段单址、K波段单址、S波段航天飞机返向链路(SSHR)和K波段航天飞机返向链路(KSHR)。广泛采用甚大规模集成/专用集成电路(VLSI/VSIC)设计方案,该综合接收机(IR)将解调器、符号同步器、伪码跟踪、载波恢复和数据提取功能结合到一个集成单元内。本文介绍该接收机的总体设计及研制,突出了解调和跟踪环的功能。给出了实验室测量结果,证明了良好的误码率特性。     

广角目视模拟技术的新评价

前言1970年召开了两次飞行模拟技术会议(AIAA 于三月在佛里罗达州卡纳维拉尔角召开,RAES 于十月在英国伦敦召开),但对广角目视模拟技术没有作出客观的评价。在1967年第二届海军训练装置中心和工业会议、1968年3月于洛杉矶召开的 AIAA 会议上,威廉、埃贝林提供了对窄视场目视系统的简要评述。     

Pre-adaptation to shiftwork in space

Astronauts are often required to work in shift schedules. To test pre-mission adaptation strategies and effects on the circadian system, a study was performed using microgravity simulation by head-down bedrest. Eight male subjects were studied over 4 control days, and 7 days each for pre-mission adaptation, bedrest, and readjustment. The circadian system was assessed by monitoring ECG and temperature, and by collecting urine for determination of hormones and electrolytes. Rhythms did not achieve complete adjustment within the adaptation period when the sleep-wake cycle was shortened by 1 h/day, but resynchronization continued during bedrest. After the bedrest period when the time shift was reversed by a 7-h delay within 2 days, resynchronization was achieved satisfactorily only within 7 days. From the results it is concluded that a sleep-wake cycle advance as used in this study is insufficient to keep the circadian system in pace. Under operational conditions the circadian system of astronauts may become longer and more destabilized than under controlled laboratory conditions.