KuaFu Mission

The KuaFu mission-Space Storms, Aurora and Space Weather Explorer-is an "L1+Polar" triple satellite project composed of three spacecraft: KuaFu-A will be located at L1 and have instruments to observe solar EUV and FUV emissions, and white-light Coronal Mass Ejections (CMEs), and to measure radio waves, the local plasma and magnetic field,and high-energy particles. KuaFuB1 and KuaFu- B2 will bein polar orbits chosen to facilitate continuous 24 hours a day observation of the north polar Aurora Oval. The KuaFu mission is designed to observe the complete chain of disturbances from the solar atmosphere to geospace, including solar flares, CMEs, interplanetary clouds, shock waves, and their geo-effects, such as magnetospheric sub-storms and magnetic storms, and auroral activities. The mission may start at the next solar maximum (launch in about 2012), and with an initial mission lifetime of two to three years. KuaFu data will be used for the scientific study of space weather phenomena, and will be used for space weather monitoring and forecast purposes. The overall mission design, instrument complement, and incorporation of recent technologies will target new fundamental science, advance our understanding of the physical processes underlying space weather, and raise the standard of end-to-end monitoring of the Sun-Earth system.     

Magnetic Fields in Galaxies

Radio synchrotron emission, its polarization and its Faraday rotation are powerful tools to study the strength and structure of magnetic fields in galaxies. Unpolarized emission traces turbulent fields which are strongest in spiral arms and bars (20–30?μG) and in central starburst regions (50–100?μG). Such fields are dynamically important, e.g. they can drive gas inflows in central regions. Polarized emission traces ordered fields which can be regular or anisotropic random, generated from isotropic random fields by compression or shear. The strongest ordered fields of 10–15?μG strength are generally found in interarm regions and follow the orientation of adjacent gas spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies, and in central regions of starburst galaxies. Faraday rotation measures (RM) of the diffuse polarized radio emission from the disks of several spiral galaxies reveal large-scale patterns, which are signatures of regular fields generated by a mean-field dynamo. However, in most spiral galaxies observed so far the field structure is more complicated. Ordered fields in interacting galaxies have asymmetric distributions and are an excellent tracer of past interactions between galaxies or with the intergalactic medium. Ordered magnetic fields are also observed in radio halos around edge-on galaxies, out to large distances from the plane, with X-shaped patterns. Future observations of polarized emission at high frequencies, with the EVLA, the SKA and its precursors, will trace galactic magnetic fields in unprecedented detail. Low-frequency telescopes (e.g. LOFAR and MWA) are ideal to search for diffuse emission and small RMs from weak interstellar and intergalactic fields.     

Refinements in the data analysis of VIRTIS-M-IR Venus nightside spectra

The successful long-duration radiation measurements performed by the VIRTIS instrument aboard ESA’s Venus Express spacecraft have provided an excellent collection of atmospheric and surface data that stand out due to their high temporal and spatial coverage of the planet and due to a high diversity of measurement and environmental conditions.     

Advanced detectors and instruments for small satellites

This paper presents some approaches to the development of advanced detectors and to miniaturized instrument design which are pursued in the Institute of Space Sensor Technology of DLR (the German Aerospace Research Establishment). The instrument design approach is demonstrated for a low-weight (3 kg) dual camera system with narrow-angle in-track stereo and wide-angle multispectral features. Each camera has its own signal processor and 0,5 G Bit mass memory. The activities for advanced detector development are concentrated on two different kinds of detectors and instrumentations: infrared detector arrays and instruments at wavelengths out to about 240 μm, and superheterodyne receivers in the submillimeter and far-infrared spectral ranges.     

Cooperative research in microgravity sciences during the French manned MIR missions

During the past ten years the French laboratories working in the field of fluids and material sciences had access to regular, long-lasting manned missions onboard the Russian MIR Space Station. Beyond the French scientific program that was performed with the ALICE apparatus, a cooperative research program was developed with DLR, NASA and RSA. This cooperation was based on bartered agreements that included the joint utilization of the instruments onboard the MIR station (ALICE, TITUS furnace from DLR, vibration device from RKK Energia) and the funding of dedicated cartridges (DLR) or thermostats (DLR and NASA), as well as launch services (NASA) by the Cooperating Agencies. We present a review of this program with a particular emphasis on its scientific results and on the progress that has been achieved in science and applications. They covered a large field of condensed matter physics, from material sciences to near-critical and off-critical phase separation kinetics and near critical fluid hydrodynamics (thermoacoustic heat transport and vibrational convection). The high microgravity relevance of all these investigations naturally led to outstanding results that was published in the world's best scientific journals. The analysis of the latest experiments performed during the PEGASUS mission shows they will not be an exception to that evaluation. Off-critical phase separation with NASA, pressure-driven piston effect and equiaxed solidification with DLR, heat transport under calibrated vibrations with RKK Energia, all will be presented. The conclusion will stress the international character of this microgravity research program, the conditions of its success and what can be gained from it in the perspective of the space station utilization.     

Large-scale propagation properties of interplanetary disturbances revealed from IPS and spacecraft observations

Interplanetary scintillation (IPS) observations may be used to study large-scale propagation properties of transient interplanetary disturbances in a three-dimensional manner, although current IPS observations have several limitations, e.g., poor time resolution and line-of-sight integration. Comparative studies with spacecraft solar wind and white-light coronal mass ejection (CME) observations are quite helpful in interpretation of IPS observations. An interplanetary disturbance apparently in association with a disappearing solar filament, which took place near the central meridian of the Sun on late 22 April, 1979, is discussed to examine previous deductions from IPS observations. Three-station IPS observations of the flow speed and spacecraft observations suggest that a quasi-spherical interplanetary disturbance was formed around the Sun-Earth line, whereas the center of the disturbance derived from the distribution of enhanced IPS across the sky (g-maps) is located to the east of the Sun-Earth line.Permanently at Research Institute of Atmospherics, Nagoya University, Toyokawa 442, Japan.     

Acceleration Profile of the Slow Solar Wind as Inferred from Gradual Mass Ejections Observed by LASCO

The slow solar wind (< 400 km s^-1) appears to initiate from the regions in the corona where magnetic fields are closed, or from the interface between streamers and other coronal regions. The nature of the acceleration of slow solar wind is not yet well known. LASCO observations of gradually evolving mass ejections offer us a good opportunity to study the speed and acceleration profiles of the slow solar wind from a distance of 1.1 up to 30 R_⊙. We present speed and acceleration profiles of slow solar wind, derived on the basis of measurements of mass flows in several cases of gradual mass ejections and present them in perspective of earlier work. This revised version was published online in June 2006 with corrections to the Cover Date.     

Relationship of coronal transients to interplanetary shocks: 3D aspects

More than 1000 coronal mass ejections (CMEs) caused by different types of coronal transients have been analyzed up to now, based on the images from white light coronagraphs on board the OSO 7, Skylab, P78-1, and SMM spacecraft. In many cases, the CME images lead us to the impression of loop-like, more planar structures, similar to those of prominence structures often seen in H pictures. There is increasing evidence, though, for a three-dimensional bubble- or cloud-like structure of CMEs. In several cases, CMEs directed toward the earth (or away from it) were identified, as their outer fronts emerged on all sides of the coronagraph's occulting disk, thus suggesting a bubble-like appearance.There now appears to be unanimity about the crucial role that magnetic reconnection plays during the transient process. Recently, direct evidence was found for the pinch-off of CMEs, both from optical observations and from in situ measurements of isolated magnetic clouds' following transient shock waves. However, the detailed sequence of events during the generation of a CME is still unclear.Interplanetary shock waves associated with the CMEs are usually restricted in latitudinal extent to about the angular width of the optically observed CMEs. They may be somewhat less restricted in longitudinal extent. A nearly 1 1 association between CMEs and shock waves measured in situ from spacecraft (Helios 1 and 2, IMP 7 and 8, ISEE 3, Pioneer Venus) can be established, provided the CME and the spacecraft were in the same longitudinal and latitudinal range and the CME speed exceeds 400 km s^–1. Around the past solar activity minimum all CMEs observed were centered at solar latitudes of less than 60°. Around solar maximum, a significant fraction of CMEs also originated from the polar regions. Thus, there is a good chance that the Ulysses spaceprobe will encounter many shocks caused by both low- and high-latitude CMEs, when it finally starts its journey over the Sun's poles.     

Solar wind and its interaction with the magnetosphere: Measured parameters

The earth's magnetosphere absorbs only a minor fraction (≈ 10^?3) of the incident solar wind energy. Variations of the solar wind can often cause lively reactions in the earth's close environment. However, the physical mechanisms involved are not yet understood. It appears now that the combined action of the solar wind momentum flux, the direction of the interplanetary magnetic field as well as its fluctuations might play the dominant role. The behaviour of these parameters is governed in some characteristic way by the solar wind stream structure which reflects the condition of the solar corona and its magnetic field topology. Transients in the sun's atmosphere associated with solar activity cause reactions in the interplanetary medium which also show some typical, though very different, signatures. Taking into account the interdependence of the solar wind parameters in context with the underlying solar phenomena, we may be able to pinpoint the mechanism which controls the action of the solar wind on the magnetosphere.     

Thermal and Chemical Evolution of Comet Nuclei and Kuiper Belt Objects

The structure and composition of comet nuclei are mainly altered during two short phases that are separated by a very long hibernation phase. Early evolution—during and immediately after formation—is the result of heating caused by radioactive decay, the most important source being ²⁶Al. Several studies are reviewed, dealing with evolution throughout this phase, calculated by means of 1-D numerical codes that solve the heat and mass balance equations on a fixed spherically symmetric grid. It is shown that, depending on parameters, the interior may reach temperatures above the melting point of water. The models thus suggest that comets are likely to lose the ices of very volatile species during early evolution; ices of less volatile species are retained in the cold subsurface layer. As the initially amorphous ice is shown to crystallize in the interior, some objects may also lose part of the volatiles trapped in amorphous ice. Generally, the outer layers are far less affected than the inner part, resulting in a stratified composition and altered porosity distribution. The second phase of evolution occurs when comet nuclei are deflected into the inner solar system and is dominated by the effect of solar radiation. Now the outer layers are those mostly affected, undergoing crystallization, loss of volatiles, and significant structural changes. If any part of a comet nucleus should retain its pristine structure and composition, it would be well below the surface and also well above the core.