Concept of wireless sensor network for future in-situ exploration of lunar ice using wireless impedance sensor

It is known that a wireless sensor network uses some sort of sensors to detect a physical quantity of interest, in general. The wireless sensor network is a potential tool for exploring the difficult-to-access area on the earth and the concept may be extended to space applications in future. Recently, lunar water has been detected by a few lunar missions using remote sensing techniques. The lunar water is expected to be in the form of ice at very low temperatures of permanently dark regions on the moon. To support the remote observations and also to find out potential ice bearing sites on the moon, in-situ measurement of the lunar ice is essential. However, a rover may not be able to reach the permanently shadowed regions due to terrain irregularity. One possibility to access such areas is to use a wireless sensor network on the lunar surface.     

VHF radio response of the near Earth space during solar activity growth in October, 2003

The analysis of observations of very high frequency radio noise intensity at the middle latitude on a frequency f = 500 MHz from 14th till 26th of October, 2003 is presented. These data are compared with the solar radio bursts in the range of frequencies 1–14 MHz registered by RAD2 receiver of the WAVES device installed on board the WIND spacecraft.     

New evidence of solar variation in temperature proxies from Northern Fennoscandia

A new summer temperature proxy was built for northern Fennoscandia in AD 1000–2004 using parameters of tree growth from a large region, extending from the Swedish Scandes to the Kola Peninsula. It was found that century-scale (55–140 year) cyclicity is present in this series during the entire time interval. This periodicity is highly significant and has a bi-modal structure, i.e. it consists of two oscillation modes, 55–100 year and 100–140 year variations. A comparison of the century-long variation in the northern Fennoscandian temperature proxy with the corresponding variations in Wolf numbers and concentration of cosmogenic ¹⁰Be in glacial ice shows that a probable cause of this periodicity is the modulation of regional climate by the secular solar cycle of Gleissberg. This is in line with the results obtained previously for a more limited part of the region (Finnish Lapland: 68–70° N, 20–30° E). Thus the reality of a link between long-term changes in solar activity and climate in Fennoscandia has been confirmed. Possible mechanisms of solar influence on the lower troposphere are discussed.     

Some issues of time-optimal control over a spacecraft programmed turn

The problem of optimal turn of a spacecraft from an arbitrary initial position to a final specified angular position in a minimum time is considered and solved. A case is investigated, when the constraint on spacecraft’s angular momentum during the turn is essential. Based on the quaternion method a solution to the posed problem has been found, and an optimal control program is constructed taking the constraints on controlling moment into account. The optimal control is found in the class of regular motions. A condition (calculation expression) is presented for determining the moment to begin braking with the use of measurements of current motion parameters, which considerably improves the accuracy of putting the spacecraft into a preset position. For a dynamically symmetrical spacecraft the solution to the problem of optimal control by the spacecraft spatial turn is presented in analytical form (expressions in elementary functions). An example of mathematical modeling of the spacecraft motion dynamics under optimal control over reorientation is given.     

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.     

Attractive manifold-based adaptive solar attitude control of satellites in elliptic orbits

The paper presents a novel noncertainty-equivalent adaptive (NCEA) control system for the pitch attitude control of satellites in elliptic orbits using solar radiation pressure (SRP). The satellite is equipped with two identical solar flaps to produce control moments. The adaptive law is based on the attractive manifold design using filtered signals for synthesis, which is a modification of the immersion and invariance (I&I) method. The control system has a modular controller–estimator structure and has separate tunable gains. A special feature of this NCEA law is that the trajectories of the satellite converge to a manifold in an extended state space, and the adaptive law recovers the performance of a deterministic controller. This recovery of performance cannot be obtained with certainty-equivalent adaptive (CEA) laws. Simulation results are presented which show that the NCEA law accomplishes precise attitude control of the satellite in an elliptic orbit, despite large parameter uncertainties.     

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.     

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.