The X/X/KA-band deep space transponder for the BepiColombo mission to mercury

This paper reports the main characteristics of the deep space transponder (DST) equipment that has been designed, developed and tested by Thales Alenia Space—Italy (TAS-I) for the European Space Agency (ESA) BepiColombo mission to Mercury.     

A new universal equation for the time of transfer between two points of the central gravitational field

The paper presents the derivation of two new equations for calculating the time of transfer between two points of the central gravitational field: for hyperbolic orbits and the universal equation for elliptical and hyperbolic orbits. In the paper we have used as an independent variable, instead of the linear elements (semimajor axis, focal parameter of orbit or a chord connecting the ends of boundary radii of transfer), the angular parameter—the angle between the radius vector of an initial point of transfer and the vector of initial velocity of transfer. Paper’s material is a continuation of that presented in the “Space research“ Journal, vol. 2, March–April, 2009.     

Identification of failures in a set of sensors of a spacecraft

A method to find and identify failures in a spacecraft’s set of sensitive elements that measure vector quantities of different nature is discussed.     

On the stabilization of ribose by silicate minerals

The RNA-world theory hypothesizes that early Earth life was based on the RNA molecule. However, the notion that ribose, the sugar in RNA, is unstable still casts a serious doubt over this theory. Recently, it has been found that the silicate-mediated formose reaction facilitates the stabilization of ribose. Using accurate quantum chemical calculations, we determined the relative stability of the silicate complexes of arabinose, lyxose, ribose, and xylose with the intent to determine which would form predominantly from a formose-like reaction. Five stereoisomers were investigated for each complex. The stereoisomers of 2:1 ribose-silicate are the more stable ones, to the extent that the least stable of these is even more stable than the most stable stereoisomer of the other 2:1 sugar-silicate complexes. Thus, thermodynamically, a formose-like reaction in the presence of silicate minerals should preferentially form the silicate complex of ribose over the silicate complex of arabinose, lyxose, and xylose.     

Deducing Electron Properties from Hard X-ray Observations

X-radiation from energetic electrons is the prime diagnostic of flare-accelerated electrons. The observed X-ray flux (and polarization state) is fundamentally a convolution of the cross-section for the hard X-ray emission process(es) in question with the electron distribution function, which is in turn a function of energy, direction, spatial location and time. To address the problems of particle propagation and acceleration one needs to infer as much information as possible on this electron distribution function, through a deconvolution of this fundamental relationship. This review presents recent progress toward this goal using spectroscopic, imaging and polarization measurements, primarily from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Previous conclusions regarding the energy, angular (pitch angle) and spatial distributions of energetic electrons in solar flares are critically reviewed. We discuss the role and the observational evidence of several radiation processes: free-free electron-ion, free-free electron-electron, free-bound electron-ion, photoelectric absorption and Compton backscatter (albedo), using both spectroscopic and imaging techniques. This unprecedented quality of data allows for the first time inference of the angular distributions of the X-ray-emitting electrons and improved model-independent inference of electron energy spectra and emission measures of thermal plasma. Moreover, imaging spectroscopy has revealed hitherto unknown details of solar flare morphology and detailed spectroscopy of coronal, footpoint and extended sources in flaring regions. Additional attempts to measure hard X-ray polarization were not sufficient to put constraints on the degree of anisotropy of electrons, but point to the importance of obtaining good quality polarization data in the future.     

Global Properties of Solar Flares

This article broadly reviews our knowledge of solar flares. There is a particular focus on their global properties, as opposed to the microphysics such as that needed for magnetic reconnection or particle acceleration as such. Indeed solar flares will always remain in the domain of remote sensing, so we cannot observe the microscales directly and must understand the basic physics entirely via the global properties plus theoretical inference. The global observables include the general energetics—radiation in flares and mass loss in coronal mass ejections (CMEs)—and the formation of different kinds of ejection and global wave disturbance: the type II radio-burst exciter, the Moreton wave, the EIT “wave”, and the “sunquake” acoustic waves in the solar interior. Flare radiation and CME kinetic energy can have comparable magnitudes, of order 10³² erg each for an X-class event, with the bulk of the radiant energy in the visible-UV continuum. We argue that the impulsive phase of the flare dominates the energetics of all of these manifestations, and also point out that energy and momentum in this phase largely reside in the electromagnetic field, not in the observable plasma.     

Optimization of the centrifugal impeller flow passage in high-speed pumps

Based on the jet-vortex model for flow passage hydrodynamics in a high-speed centrifugal pump with the open-type impeller, we present the calculated relations for design and optimization of the experimentally verified pump design parameters.     

Application of the parameter-averaging method to calculations of gas ejectors with cylindrical mixing chambers

In this paper, one of the most possible methods for calculations of ejector devices equipped with the cylindrical mixing chambers is considered; the method is based on averaging the flow parameters at the chamber inlet. We present the calculation results and their comparison with the earlier published data, as well as the quantitative assessment of this method and feasibilities of its use for different technical devices embodying the concept of ejection.     

Optimization of a tool kit for machining by methods of graph theory

Some methods of optimizing a cutting tool kit by the minimum labour content criterion in milling of an article are considered. Their advantages and disadvantages are given.