Artificial equilibrium points for a solar balloon in the α Centauri system

This paper discusses the generation, stability, and control of artificial equilibrium points for a solar balloon spacecraft in the α Centauri A and B binary star system. The continuous propulsive acceleration provided by a solar balloon is shown to be able to modify the position of the (classical) Lagrangian equilibrium points of the three-body system on a locus whose geometrical form is known analytically. A linear stability analysis reveals that the new generated equilibrium points are usually unstable, but part of them can be stabilized with a simple feedback control logic.     

Inflatable shape changing colonies assembling versatile smart space structures

Various plants have the ability to follow the sun with their flowers or leaves during the course of a day via a mechanism known as heliotropism. This mechanism is characterised by the introduction of pressure gradients between neighbouring motor cells in the plant?s stem, enabling the stem to bend. By adapting this bio-inspired mechanism to mechanical systems, a new class of smart structures can be created. The developed overall structure is made up of a number of cellular colonies, each consisting of a central pressure source surrounded by multiple cells. After launch, the cellular arrays are deployed in space and are either preassembled or alternatively are attached together during their release or afterwards. A central pressure source is provided by a high-pressure storage unit with an integrated valve, which provides ingress gas flow to the system; the gas is then routed through the system via a sequence of valve operations and cellular actuations, allowing for any desired shape to be achieved within the constraints of the deployed array geometry. This smart structure consists of a three dimensional adaptable cellular array with fluid controlling Micro Electromechanical Systems (MEMS) components enabling the structure to change its global shape. The proposed MEMS components include microvalves, pressure sensors, mechanical interconnect structures, and electrical routing. This paper will also give an overview of the system architecture and shows the feasibility and shape changing capabilities of the proposed design with multibody dynamic simulations. Example applications of this lightweight shape changing structure include concentrators, mirrors, and communications antennas that are able to dynamically change their focal point, as well as substructures for solar sails that are capable of steering through solar winds by altering the sails? subjected area.     

On the Possibility of the Existence of Volatile Compounds in the Region of the Scott Crater on the Moon

In this paper, we analyze the illumination conditions, the thermal regime, and the possibility of deposits of volatile compounds existing in the vicinity region (NSR S5 region) near the southern pole of the Moon. It has been found that there are no permanently shadowed zones near the Scott crater and the NSR S5 region, though the temperature conditions allow the of compounds such as CH₃OH, SO₂, NH₃, CO₂, H₂S, C₂H₄, and water to remain stable relative to evaporation for a long time (≥1 Gyr). It has been also shown that compounds like CO and CH₄ cannot stably exist in these regions.     

Features of whistling electromagnetic wave propagation descending from above upon the night ionosphere

The results of numerical solution of the wave equations for the oblique incidence of whistling electromagnetic waves upon the night ionosphere from above have been obtained and analyzed. In the studied region of altitudes, within the wavelength scale, charged particle concentration varies drastically, and damping caused by collisions between the charged and neutral particles decreases considerably. Below, the sharp lower boundary of the ionosphere, the refractive index of the whistler wave approaches unity, and plasma turbulence transform into atmospheric electromagnetic waves. The dependences of the whistler reflection factor are found in terms of energy and horizontal magnetic component of the electromagnetic wave near the Earth’s surface on the frequency and the wave vector transverse component for the plain-layered medium model at two values of latitude. Strong dependences have been found on the wave angle of incidence and frequency. At rather small angles of incidence, the wave disturbances reach the Earth’s surface, and the module of reflection coefficient logarithm is in the range of 0.4–1. At large angles of incidence, the reflection coefficient module varies over a wide range depending on specific conditions. The obtained results explain the absence of oscillation modes of plasma magnetosphere maser in the night magnetosphere.     

Quasiperiodic oscillations of the sub-mHz band in near-sun plasma according to the coherent radio occultation data

In 2013 and 2015, investigations of the internal solar wind were carried out using the method of two-frequency radio sounding by signals from the Mars Express European spacecraft. The values of the S- and X-bands’ frequency and the differential frequency were registered with a sampling rate of 1s at the American and European networks of ground-based tracking stations. The spatial distribution of the frequency fluctuation’s level has been studied. It has been shown that the intensity of frequency fluctuation considerably decreases at high heliolatitudes. In some radio sounding sessions, quasiperiodic oscillations of sub-mHz band have been observed in the temporal spectra of frequency fluctuations; they are supposed to be associated with the density inhomogeneities, the sizes of which are close to the turbulence outer scale.     

Control of the Onboard Microgravity Environment and Extension of the Service Life of the Long-Term Space Station

The problem of control of the on-board microgravity environment in order to extend the service life of the long-term space station has been discussed. Software developed for the ISS and the results of identifying dynamic models and external impacts based on telemetry data have been presented. Proposals for controlling the onboard microgravity environment for future long-term space stations have been formulated.     

A Study of the Reflection of Radio Waves from the Plasma Region on the Track behind an Axisymmetric Body Moving in the Earth’s Atmosphere

The results of numerical calculation of the dependences of the electron density, the eigenfrequency and the dielectric plasma permeability on the geometric parameters and the altitude of body motion in the near and far wake behind a thin conical body with a spherical nose blunting have been presented. The electron density maximum has been shown to be located in the region of the neck of the near wake behind the body, which determines the type of this region (supercritical or subcritical). This in turn affects the propagation of radio waves through this plasma region. A comparative analysis was performed for two different bodies with the same ballistic coefficient values. No characteristic distinctions were revealed in the values of electron density or the plasma eigenfrequency in the near and far wake behind these bodies. However, it has been shown that there are differences in the values of the distance from the bottom cross section to the neck of the near wake behind these bodies.     

Detection of Molecular Scattering Field from a Polarization Analysis of the Sky Background during Transitive Twilight and Temperature Measurements near the Stratopause

The simplest version of the method of detecting the single molecular scattering field based on the polarization measurements of the twilight sky background by all-sky cameras has been considered. The method can be used during transitive twilight (with solar zenith angles of 94°–98°), when effective single scattering occurs in the upper stratosphere and lower mesosphere. The long-term measurements conducted using this method in the Moscow region and Apatity make it possible to determine the temperature of these atmospheric layers and estimate the contribution and properties of multiple scattering during the transitive twilight.     

Gravity-oriented satellite dynamics subject to gravitational and active damping torques

The dynamics of the rotational motion of a satellite moving in the central Newtonian field of force over a circular orbit under the effect of gravitational and active damping torques, which depend on the satellite angular velocity projections, has been investigated. The paper proposes a method of determining all equilibrium positions (equilibrium orientations) of a satellite in the orbital coordinate system for specified values of damping coefficients and principal central moments of inertia. The conditions of their existence have been obtained. For a zero equilibrium position where the axes of the satellite-centered coordinate system coincide with the axes of the orbital coordinate system, the necessary and sufficient conditions for asymptotic stability are obtained using the Routh–Hurwitz criterion. A detailed analysis of the regions where the conditions of the asymptotic stability of a zero equilibrium position are fulfilled have been obtained depending on three dimensionless parameters of the problem, and the numerical study of the process of attenuation of satellite’s spatial oscillations for various damping coefficients has been carried out. It has been shown that there is a wide range of damping parameters from which, by choosing the necessary values, one can provide the asymptotic stability of satellite’s zero equilibrium position in the orbital coordinate system.