Numerical modeling of inhomogeneous orographic wave influence on planetary waves in the middle atmosphere

Parameterization of dynamical and thermal effects of stationary orographic gravity waves (OGWs) generated by the Earth’s surface topography is incorporated into a numerical model of general circulation of the middle and upper atmosphere. Responses of atmospheric general circulation and characteristics of planetary waves at altitudes from the troposphere up to the thermosphere to the effects of OGWs propagating from the earth surface are studied. Changes in atmospheric circulation and amplitudes of planetary waves due to variations of OGW generation and propagation in different seasons are considered. It is shown that during solstices the main OGW dynamical and heat effects occur in the middle atmosphere of winter hemispheres, where changes in planetary wave amplitudes due to OGWs may reach up to 50%. During equinoxes OGW effects are distributed more homogeneously between northern and southern hemispheres.     

Mathematical modeling of plasma drifts over equatorial low latitude regions

This paper presents a mathematical model to simulate ionospheric plasma drifts at equatorial low latitude regions by coupling of E- and F-regions. The governing non-linear differential equations (of elliptic and parabolic nature) are solved numerically through finite-difference schemes and obtained neutral winds and electric fields. The temperature and electron density profiles are generated utilizing MSIS-86 atmospheric model. The continuity equation is employed to obtain night-time E-region density profile using measured ionograms at Trivandrum (India). The computed vertical and zonal plasma drifts are comparable with measured Jacamarca plasma drifts with little variations during noon and evening times. The plasma drifts at Trivandrum (8.5° N, 76.5° E, dip 0.5° N) are compared with those of Jicamarca (12° S, 76.9° W, dip 2° N). Neutral wind simulations of present model agree well with those of horizontal wind model (HWM-93). The post-sunset enhancement and its reversal are also discussed.     

Calculation of flight vehicle main support wheel vibrations taking into account brake forces

A model of the main support of the aircraft landing gear is presented and its dynamics is studied using the equations for the distributed motion of a wheel equipped with a brake. Stability of the support wheel rolling motion is analyzed and the brake parameter values which may cause stability loss are found. The results of numerical experiments are presented.     

Sources of Interference in Spatial Long-Term Memory Retrieval

Three experiments are reported that used an interference paradigm to test the extent to which perceptual orientation to a task environment interfered with retrieval from long-term spatial memory. Visual and spatial sources of interference were tested. The findings were consistent with a spatial locus of interference and showed that orientation to the task environment disrupted the accessibility of relative direction under two retrieval conditions: when the imagined viewpoint was 180 degrees misaligned with the actual viewpoint and when the actual body location was anterior to the imagined body location. While the former finding replicates previous reports of interference in perspective-taking tasks, the latter finding is new and difficult for current models of spatial long-term memory retrieval to explain. More research is needed to articulate further the constraints that perceptual orientation to the task environment place on spatial retrieval and their implications for models of spatial memory.     

The Lunar Reconnaissance Orbiter Miniature Radio Frequency (Mini-RF) Technology Demonstration

The Miniature Radio Frequency (Mini-RF) system is manifested on the Lunar Reconnaissance Orbiter (LRO) as a technology demonstration and an extended mission science instrument. Mini-RF represents a significant step forward in spaceborne RF technology and architecture. It combines synthetic aperture radar (SAR) at two wavelengths (S-band and X-band) and two resolutions (150 m and 30 m) with interferometric and communications functionality in one lightweight (16 kg) package. Previous radar observations (Earth-based, and one bistatic data set from Clementine) of the permanently shadowed regions of the lunar poles seem to indicate areas of high circular polarization ratio (CPR) consistent with volume scattering from volatile deposits (e.g. water ice) buried at shallow (0.1–1 m) depth, but only at unfavorable viewing geometries, and with inconclusive results. The LRO Mini-RF utilizes new wideband hybrid polarization architecture to measure the Stokes parameters of the reflected signal. These data will help to differentiate “true” volumetric ice reflections from “false” returns due to angular surface regolith. Additional lunar science investigations (e.g. pyroclastic deposit characterization) will also be attempted during the LRO extended mission. LRO’s lunar operations will be contemporaneous with India’s Chandrayaan-1, which carries the Forerunner Mini-SAR (S-band wavelength and 150-m resolution), and bistatic radar (S-Band) measurements may be possible. On orbit calibration, procedures for LRO Mini-RF have been validated using Chandrayaan 1 and ground-based facilities (Arecibo and Greenbank Radio Observatories).     

Calculation of low cycle fatigue life for gas-turbine engine critical parts

The paper presents a technique of calculating the life for gas turbine engine parts in a low cycle area based on the influence coefficients taking into account analytical and operational factors. A statistical method is used to determine the influence coefficients.     

The role of space related non-governmental organizations (NGOs) in capacity building

Non-governmental organizations (NGOs) play a unique role in international affairs, providing access to resources, expertise, and assistance to supplement State resources. Sometimes the diplomatic skills and unofficial access of NGOs to policymakers through Track Two diplomacy can move a previously stalled critical issue forward and assist policymakers from different countries to find common ground outside official channels. Because they work outside of official channels, they are not bound by State policy that may inhibit negotiations between States. Some also have a convening power that sometimes makes it possible for State representatives to meet discipline experts and each other for informal discussions on issues of mutual interest. Finally, NGOs can draw attention to issues that may be overlooked or avoided by State organizations.     

Shock protection of penetrator-based instrumentation via a sublimation approach

It is often necessary for space-borne instrumentation to cope with substantial levels of shock acceleration both in the initial launch phase, as well as during entry, descent and landing in the case of planetary exploration. Current plans for a new generation of penetrator-based space missions will subject the associated on-board instrumentation to far greater levels of shock, and ways must therefore be found to either ruggedize or else protect any sensitive components during the impact phase. In this paper, we present an innovative method of shock protection that is suited for use in a number of planetary environments, based upon the temporary encapsulation of said components within a waxy solid which may then be sublimated to return the instrument back to its normal operation. We have tested this method experimentally using micromachined silicon suspensions under applied shock loads of up to 15,000g, and found that these were able to survive without incurring damage. Furthermore, quality factor measurements undertaken on these suspensions indicate that their mechanical performance remains unaffected by the encapsulation and subsequent sublimation process.     

Earth observation from space – The issue of environmental sustainability

Remote sensing scientists work under assumptions that should not be taken for granted and should, therefore, be challenged. These assumptions include the following:1. Space, especially Low Earth Orbit (LEO), will always be available to governmental and commercial space entities that launch Earth remote sensing missions.2. Space launches are benign with respect to environmental impacts.3. Minimization of Type 1 error, which provides increased confidence in the experimental outcome, is the best way to assess the significance of environmental change.4. Large-area remote sensing investigations, i.e. national, continental, global studies, are best done from space.5. National space missions should trump international, cooperative space missions to ensure national control and distribution of the data products.At best, all of these points are arguable, and in some cases, they're wrong. Development of observational space systems that are compatible with sustainability principles should be a primary concern when Earth remote sensing space systems are envisioned, designed, and launched. The discussion is based on the hypothesis that reducing the environmental impacts of the data acquisition step, which is at the very beginning of the information stream leading to decision and action, will enhance coherence in the information stream and strengthen the capacity of measurement processes to meet their stated functional goal, i.e. sustainable management of Earth resources. We suggest that unconventional points of view should be adopted and when appropriate, remedial measures considered that could help to reduce the environmental footprint of space remote sensing and of Earth observation and monitoring systems in general. This article discusses these five assumptions in the context of sustainable management of Earth's resources. Taking each assumption in turn, we find the following:(1) Space debris may limit access to Low Earth Orbit over the next decades.(2) Relatively speaking, given that they're rare event, space launches may be benign, but study is merited on upper stratospheric and exospheric layers given the chemical activity associated with rocket combustion by-products.(3) Minimization of Type II error should be considered in situations where minimization of Type I error greatly hampers or precludes our ability to correct the environmental condition being studied.(4) In certain situations, airborne collects may be less expensive and more environmentally benign, and comparative studies should be done to determine which path is wisest.(5) International cooperation and data sharing will reduce instrument and launch costs and mission redundancy. Given fiscal concerns of most of the major space agencies – e.g. NASA, ESA, CNES – it seems prudent to combine resources.