The solar wind control of the equatorial ionosphere dynamics during geomagnetic storms

The interplanetary magnetic field, geomagnetic variations, virtual ionosphere height h′F, and the critical frequency foF2 data during the geomagnetic storms are studied to demonstrate relationships between these phenomena. We study 5-min ionospheric variations using the first Western Pacific Ionosphere Campaign (1998–1999) observations, 5-min interplanetary magnetic field (IMF) and 5-min auroral electrojets data during a moderate geomagnetic storm. These data allowed us to demonstrate that the auroral and the equatorial ionospheric phenomena are developed practically simultaneously. Hourly average of the ionospheric foF2 and h′F variations at near equatorial stations during a similar storm show the same behavior. We suppose this is due to interaction between electric fields of the auroral and the equatorial ionosphere during geomagnetic storms. It is shown that the low-latitude ionosphere dynamics during these moderate storms was defined by the southward direction of the B_z-component of the interplanetary magnetic field. A southward IMF produces the Region I and Region II field-aligned currents (FAC) and polar electrojet current systems. We assume that the short-term ionospheric variations during geomagnetic storms can be explained mainly by the electric field of the FAC. The electric fields of the field-aligned currents can penetrate throughout the mid-latitude ionosphere to the equator and may serve as a coupling agent between the auroral and the equatorial ionosphere.     

A ground-based study for a shuttle BRIC experiment on gravity effects on gene expression.

A BRIC (Biological Research In a Canister) experiment to investigate the effects of reduced gravity at the molecular level using Arabidopsis has been initiated. In preparation for a space flight experiment, a series of ground-based studies were conducted. Results from these studies indicate that: 1) up to 20,000 seeds can be germinated on a 100 mm diameter Petri plate, 2) nylon membrane is the best surface for recovery of plant material after freezing, 3) depending on the age of the seedlings at the time of freezing, 20 to 40 g of tissue can be obtained from Petri plates that fit in a single canister; 4) tissue from one canister yields adequate amounts of RNA to perform differential display to isolate gravity-regulated genes. Our results indicate that the proposed BRIC experiment is feasible and can provide valuable information on the possible effects of microgravity on gene regulation.     

Small-scale deformation of the bow shock

The prediction of the bow shock location is a proof of our understanding of the processes governing the solar wind – magnetosphere interaction. However, the models describing the bow shock location as a function of upstream parameters are based on a statistical processing of bow shock crossings observed by a single spacecraft. Such crossings locate the bow shock in motion, i.e., in a non-equilibrium state and this fact can be a source of significant errors. We have carefully analyzed a long interval of simultaneous observations of the bow shock and magnetopause and another interval of bow shock observations at two well-separated points. Our results suggest that often a small-scale deformation of the bow shock front due to magnetosheath fluctuations is the most appropriate interpretation of observations. Since the low-frequency magnetosheath variations exhibit largest amplitudes, a simultaneous bow shock displacement over a distance of 10–15 R_E can be observed. We suggest that bow shock models can be probably improved if the tilt angle would be implemented as a parameter influencing the bow shock location in high latitudes.     

A new approach to solar wind monitoring

The monitoring of solar wind parameters is a key problem of the space weather program. We are presenting a new solution of plasma parameter determination suitable for small and fast solar wind monitors. The first version will be launched during the SPECTR-R project into a highly elongated orbit with apogee ∼350,000 km. The method is based on simultaneous measurements of the total ion flux and ion integral energy spectrum by six identical Faraday cups. Three of them are dedicated to determination of the ion flow direction, the other three (equipped with control grids supplied by a retarding potential) are used for determination of the density, temperature, and speed of the plasma flow. The version under development is primarily designed for the measurements in the solar wind and tail magnetosheath, thus for velocities range from 270 to 750 km/s, temperatures from 1 to 30 eV, and densities up to 200 cm⁻³. However, the instrument design can be simply modified for measurements in other regions with a substantial portion of low-energy plasma as a subsolar magnetosheath, cusp or low-latitude boundary layer. Testing of the engineering model shows that the proposed method can provide reliable plasma parameters with a high time resolution (up to 8 Hz). The paper presents not only the method and its technical realization but it documents all advantages and peculiarities of the suggested approach.     

The plasma sheet and boundary layers under northward IMF: A multi-point and multi-instrument perspective

During conditions of northward interplanetary magnetic field (IMF), the near-tail plasma sheet is known to become denser and cooler, and is described as the cold-dense plasma sheet (CDPS). While its source is likely the solar wind, the prominent penetration mechanisms are less clear. The two main candidates are solar wind direct capture via double high-latitude reconnection on the dayside and Kelvin–Helmholtz/diffusive processes at the flank magnetopause. This paper presents a case study on the formation of the CDPS utilizing a wide variety of space- and ground-based observations, but primarily from the Double Star and Polar spacecraft on December 5th, 2004. The pertinent observations can be summarized as follows: TC-1 observes quasi-periodic (∼2 min period) cold-dense boundary layer (compared to a hot-tenuous plasma sheet) signatures interspersed with magnetosheath plasma at the dusk flank magnetopause near the dawn-dusk terminator. Analysis of this region suggests the boundary to be Kelvin–Helmholtz unstable and that plasma transport is ongoing across the boundary. At the same time, IMAGE spacecraft and ground based SuperDARN measurements provide evidence of high-latitude reconnection in both hemispheres. The Polar spacecraft, located in the southern hemisphere afternoon sector, sunward of TC-1, observes a persistent boundary layer with no obvious signature of boundary waves. The plasma is of a similar appearance to that observed by TC-1 inside the boundary layer further down the dusk flank, and by TC-2 in the near-Earth magnetotail. We present comparisons of electron phase space distributions between the spacecraft. Although the dayside boundary layer at Polar is most likely formed via double high-altitude reconnection, and is somewhat comparable to the flank boundary layer at Double Star, some differences argue in favour of additional transport that augment solar wind plasma entry into the tail regions.     

Problems of improper dynamic system analysis and synthesis with regard for transfer zeroes

The notion of a transfer zero as applied to improper dynamic systems is considered. An algorithm that makes it possible to reduce the calculation of improper system zeroes to finding ordinary system zeroes is presented. A method for providing the specified position of a transfer zero set in the improper dynamic system having an equal number of inputs and outputs is proposed.     

A full color AMLCD with NVG class B compatibility

A full color active-matrix liquid crystal display (AMLCD) with night-vision-goggle (NVG) compatibility is reported. The display is a 5-in-diagonal high-resolution triad (RGB) color pixel with 80×108 color groups per inch (H/V). It has a specially designed high-brightness backlight with low profile and the above-mentioned NVG characteristics. The color coordinates of the unit are almost identical to those of the display without NVG filter, preserving the red color coordinates. This display has full avionic characteristics, such as high contrast at high ambient light and extended temperature range     

Optical interconnections for digital systems

The replacement of electrical lines and connectors by free space or guided-wave optics in high-performance digital systems is discussed. Components for such systems are considered, and prototype systems are described. Optical interconnections with only a laser, two lenses, and a detector are possible and such a free-space board-to-board interconnection has been demonstrated at 1 Gb/s with an average power dissipation of only about 40 mW