Simulation of a Rocket Engine Nozzle Discharge Coefficient

Multiparameter studies of the discharge coefficient dependence on the nozzle geometry and the presence of a condensed phase in combustion products were performed. The simulation results obtained satisfactorily agree with the well-known generalized data. The modern computational fluid dynamics methods were shown to be able to refine the generalized empirical relations.     

Investigations of the Mars Upper Atmosphere with ExoMars Trace Gas Orbiter

Space Science Reviews - Time measured by an ideal clock crucially depends on the gravitational potential and velocity of the clock according to general relativity. Technological advances in...     

Correction to: Determining the Relative Cratering Ages of Regions of Psyche’s Surface

Space Science Reviews - Analysis of Homestake, Gallex and GNO measurements reveals evidence of variability of presumed solar-neutrino-flux measurements. Analysis of Super-Kamiokande neutrino...     

Life in space may help life on Earth

Teams of chronobiologists from the U.S., Russia, and Japan are working toward a remote computerized health care system which, once tested in space, may change how doctors diagnose and treat cardiovascular diseases, including hypertension and conditions predisposing stroke. The system is based on ongoing research indicating that swings in blood pressure charted over a span of 24 hr or longer, rather than a single systolic and diastolic reading, can reveal a new major risk factor for heart disease.     

具有无源控制空腔时正激波/湍流附面层干扰的数值模拟

采用雷诺平均N-S方程和B/L代数湍流模型计算了具有无源控制空腔时正激波/湍流附面层干扰流场。计算与实验结果的比较表明,本文方法可较准确地预测激波结构、激波与附面层干扰区流动基本特征及波后流动分离状态、激波位置、波前马赫数等参数。      

湿热对单向复合材料层合板Ⅱ型分层特性的影响

利用横向裂纹拉伸试验模型（Transverse Crack Tension-tension Test）,在3种湿热环境（室温、85℃和85℃/95%RH）条件下,对2种单向碳纤维增强树脂基复合材料（T300/QY8911和HTA/6376）层合板的Ⅱ型分层特性进行了试验研究。结果表明湿热环境导致复合材料层间断裂韧性降低,引起Ⅱ型应变能释放率门槛值显着下降,裂纹扩展速率大大提高,温度的影响较湿度更为明显。利用电镜（SEM）对试样分层表面进行了检测,湿度对断面特征无明显的影响。     

Voyager 2 Solar Wind Observations in the Outer Heliosphere

We discuss the solar wind parameters measured in the distant heliosphere from the Voyager 2 spacecraft. Periodic variations in the speed of the wind observed at roughly the solar rotation period may correspond to interaction regions between slower and faster streams of wind. Since the interplanetary magnetic field is enhanced in such regions, they are important for the study of modulation of cosmic rays. Unfortunately, direct observation of the enhanced magnetic field from Voyager 2 has been made difficult by spacecraft-associated noise since 1989.     

Composition Aspects of the Upper Solar Atmosphere Rapporteur Paper III

This rapporteur paper discusses the solar corona and the solar wind in the context of their chemical composition. The abundances of elements, both obtained by optical and by in situ observations, are used to infer the sources of the slow solar wind and of the fast streams. The first ionisation potential (FIP) fractionation effect is also discussed, in particular the agreed basics and the open questions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Solar EUV and UV Emission Line Observations Above a Polar Coronal Hole

The roll manoeuvre of SOHO on September 3, 1997 provided the opportunity to study the northern coronal hole with SUMER slits in east-west orientation, so that polar plumes and inter-plume lanes could be observed simultaneously. A preliminary analysis of the observations shows that lines emitted by ions with the lowest formation temperatures (with the exceptions of Ne⁷⁺ and Ar⁷⁺) have the largest ratios of plume to lane radiances at heights between 35 000 km and 70 000 km above the photosphere. All lines have narrower widths inside plumes than outside. Electron densities have been deduced in plumes and lanes from Si VIII and Mg VIII line radiance ratios. The Mg IX pair was used to determine the corresponding electron temperatures. Neon (with a high first-ionization potential) is found to be less abundant relative to magnesium (with low FIP) in a plume compared to an inter-plume lane, but the variation is smaller than previously determined Ne/Mg abundance ratios in a plume relative to the photosphere. This revised version was published online in June 2006 with corrections to the Cover Date.     

Galileo Probe Measurements of D/H and 3He/4He in Jupiter's Atmosphere

The Galileo Probe Mass Spectrometer measurements in the atmosphere of Jupiter give D/H = (2.6 ± 0.7) × 10-5 3He/4He = (1.66 ± 0.05) × 10-4These ratios supercede earlier results by Niemann et al. (1996) and are based on a reevaluation of the instrument response at high count rates and a more detailed study of the contributions of different species to the mass peak at 3 amu. The D/H ratio is consistent with Voyager and ground based data and recent spectroscopic and solar wind (SW) values obtained from the Infrared Spectroscopic Observatory (ISO) and Ulysses. The 3He/4He ratio is higher than that found in meteoritic gases (1.5 ± 0.3) × 10-4. The Galileo result for D/H when compared with that for hydrogen in the local interstellar medium (1.6 ± 0.12) × 10-5 implies a small decrease in D/H in this part of the universe during the past 4.55 billion years. Thus, it tends to support small values of primordial D/H - in the range of several times 10-5 rather than several times 10-4. These results are also quite consistent with no change in (D+3He)/H during the past 4.55 billion years in this part of our galaxy.