High-latitude Sporadic-E and other Thin Layers – the Role of Magnetospheric Electric Fields

Observations of high-latitude sporadic-E (Es) layers and theories of their formation are reviewed. The layers are found to be composed of metallic ions, they are at times formed by tidal wind shear, and they are more common in summer than in winter. All of these properties are common to Es layers at mid-latitudes. However, the high-latitude layers are rather often formed, modified or transported by the action of magnetospheric electric fields. Taking into account the action of both tides and electric fields leads to an understanding of the daily variation of Es occurrence, the daily variation of Es heights and the occasional appearance of upward migrating Es layers. Correlations between Es and neutral metallic layers at low altitudes can be explained by neutralisation of the metallic ions in the Es layers, but joint Es and neutral layers at higher altitudes are still unexplained. The action of electric fields and the interaction with neutral layers can explain the formation of multiple Es layers and may provide an explanation for the seasonal variation of Es occurrence. Uncertainties remain as to whether the narrowness of Es layers is fully compatible with formation by electric fields, to whether neutralisation at low altitudes can provide a sufficient explanation of the seasonal variation, and to whether the quasi-periodic fine structure observed in mid-latitude Es also appears at high latitudes. The understanding of ion transport by electric fields which results from the study of Es layers leads to new insights and new questions related to other plasma layers (polar mesosphere summer echoes and winter ion layers) which appear in the high-latitude winter ionosphere.     

Rosetta Radio Science Investigations (RSI)

The Rosetta spacecraft has been successfully launched on 2nd March 2004 to its new target comet 67 P/Churyumov-Gerasimenko. The science objectives of the Rosetta Radio Science Investigations (RSI) experiment address fundamental aspects of cometary physics such as the mass and bulk density of the nucleus, its gravity field, its interplanetary orbit perturbed by nongravitational forces, its size and shape, its internal structure, the composition and roughness of the nucleus surface, the abundance of large dust grains, the plasma content in the coma and the combined dust and gas mass flux. The masses of two asteroids, Steins and Lutetia, shall be determined during flybys in 2008 and 2010, respectively. Secondary objectives are the radio sounding of the solar corona during the superior conjunctions of the spacecraft with the Sun during the cruise phase. The radio carrier links of the spacecraft Telemetry, Tracking and Command (TT&C) subsystem between the orbiter and the Earth will be used for these investigations. An Ultrastable oscillator (USO) connected to both transponders of the radio subsystem serves as a stable frequency reference source for both radio downlinks at X-band (8.4 GHz) and S-band (2.3 GHz) in the one-way mode. The simultaneous and coherent dual-frequency downlinks via the High Gain Antenna (HGA) permit separation of contributions from the classical Doppler shift and the dispersive media effects caused by the motion of the spacecraft with respect to the Earth and the propagation of the signals through the dispersive media, respectively. The investigation relies on the observation of the phase, amplitude, polarization and propagation times of radio signals transmitted from the spacecraft and received with ground station antennas on Earth. The radio signals are affected by the medium through which the signals propagate (atmospheres, ionospheres, interplanetary medium, solar corona), by the gravitational influence of the planet on the spacecraft and finally by the performance of the various systems involved both on the spacecraft and on ground.     

The Cassini Ultraviolet Imaging Spectrograph Investigation

The Cassini Ultraviolet Imaging Spectrograph (UVIS) is part of the remote sensing payload of the Cassini orbiter spacecraft. UVIS has two spectrographic channels that provide images and spectra covering the ranges from 56 to 118 nm and 110 to 190 nm. A third optical path with a solar blind CsI photocathode is used for high signal-to-noise-ratio stellar occultations by rings and atmospheres. A separate Hydrogen Deuterium Absorption Cell measures the relative abundance of deuterium and hydrogen from their Lyman-α emission. The UVIS science objectives include investigation of the chemistry, aerosols, clouds, and energy balance of the Titan and Saturn atmospheres; neutrals in the Saturn magnetosphere; the deuterium-to-hydrogen (D/H) ratio for Titan and Saturn; icy satellite surface properties; and the structure and evolution of Saturn’s rings.This revised version was published online in July 2005 with a corrected cover date.     

Space education, a tool to influence the cultural development in the society

Culture is an organized group of learned responses of a particular society, or the total round of human activities, not due to heredity, shared by members of a group. This means that culture is a dynamic process and it is in tight relationship to the civilization as a tool to master their all day's tasks. Space science is a result of the shift from the mass production civilization to the knowledge civilization. The science had opened new ways of thinking into a new environment, space. The ability to develop thinking to new living areas is already a learned response to the environment and therefore an act of culture.

The next changes in culture are a result of the different view, mankind has from earth looking back out of the spacecraft window. We see now with other eyes the small and vulnerable living area of mankind. We see no political limits partitioning the surface. We understand time zones as systems properties of the regions. This has up to now influenced big groups of the societies. As this view has to be shared by all members of the societies in the same mode, space education has to organize this effect.     

The United Nations Basic Space Science Initiative (UNBSSI)

Since 1991 the United Nations Office for Outer Space Affairs has been conducting a series of workshops on basic space science under its United Nations Programme on Space Applications. Up to 2004 the workshops focussed on capacity building efforts in basic space science, in particular for the benefit of developing countries. From 2005 onwards the workshops and their related activities contributed to the celebration of the International Heliophysical Year 2007. Together these activities and workshops constitute the United Nations Basic Space Science Initiative of the United Nations Office for Outer Space Affairs. This paper reflects on the achievements and outcomes of the Initiative and informs about considerations for its future evolution.     

Automated payload and instruments for astrobiology research developed and studied by German medium-sized space industry in cooperation with European academia

For more than a decade Kayser-Threde, a medium-sized enterprise of the German space industry, has been involved in astrobiology research in partnership with a variety of scientific institutes from all over Europe. Previous projects include exobiology research platforms in low Earth orbit on retrievable carriers and onboard the Space Station. More recently, exobiology payloads for in situ experimentation on Mars have been studied by Kayser-Threde under ESA contracts, specifically the ExoMars Pasteur Payload. These studies included work on a sample preparation and distribution systems for Martian rock/regolith samples, instrument concepts such as Raman spectroscopy and a Life Marker Chip, advanced microscope systems as well as robotic tools for astrobiology missions. The status of the funded technical studies and major results are presented. The reported industrial work was funded by ESA and the German Aerospace Center (DLR).     

A Survey of Field-Aligned Mach Number and Plasma Beta in the Solar Wind

We have surveyed solar wind plasma beta and field-aligned Alfvénic Mach number using Ulysses and Wind data. We show the characteristic timescale and occurrence frequency of ‘magnetically dominated’ solar wind, whose interaction with a planetary magnetosphere may produce a bow shock with multiple shock fronts. We discuss radial, latitudinal, and solar cycle effects. This revised version was published online in August 2006 with corrections to the Cover Date.     

机载有源相控阵（AESA）雷达系统的现状与未来趋势

AESA技术已达到了成熟的技术阶段，正被先进的雷达项目所采用。T／R模块是使之实现的关键技术，降低其成本的工作也正在进行。在未来应用方面，已经考虑了氮化镓（GaN）、微机电射频（MEMsRF）开关和瓦式T／R模块，它们将为共形和多功能AESA雷达系统铺平道路。     

Non-destructive sampling of a comet

The boundary conditions for a non-destructive sample acquisition system are outlined and the development of a new robotic sampling system suited for use on a cometary surface is briefly discussed. Additionally we present some new results on strength and deformation behaviour of synthetic cometary analogue material.