On the classification of comet plasma tails

The investigation of plasma tails of comets is an important part of comet research. Different classifications of plasma tails of comets are proposed. Plasma acceleration in the tails is investigated in sufficient detail. Several cometary forms are explained. Plasma tails of Mars and Venus were observed during the first studies of these planets. They are associated with the capture of ionized atoms and exosphere molecules by the solar wind magnetized plasma flow. Distinct plasma tails of Mars and Venus are caused by the mass loading of the solar wind with heavy ions. It was shown that the transverse dimension of the tails of Mars, Venus, and comets can be quite accurately determined by production rate of the obstacle to the solar wind flow. While plasma tails of Mars and Venus are investigated by in situ measurements from spacecraft, observations of comet tails from the Earth make it possible to see the entire object under study and to monitor changes in its structure. A certain similarity of cometary and planetary tails can be explained by the nonmagnetic nature of both types of bodies. Thus, it is reasonable to suppose that investigations of plasma tails of comets can supplement the information obtained by in situ methods of the study of the planets. In this paper, plasma tails of comets, presumably analogous to the plasma tails of Mars and Venus, have been identified on modern photographs of comets (more than 1500 photographs viewed). Only quasi-steady laminar tails are considered. They are divided into two types: double structures and outflows. The paper attempts to define the 3D structure of double structures and to determine certain characteristics of outflows.     

On the history of the solar wind discovery

The discovery of the solar wind has been an outstanding achievement in heliophysics and space physics. The solar wind plays a crucial role in the processes taking place in the Solar System. In recent decades, it has been recognized as the main factor that controls the terrestrial effects of space weather. The solar wind is an unusual plasma laboratory of giant scale with a fantastic diversity of parameters and operating modes, and devoid of influence from the walls of laboratory plasma systems. It is also the only kind of stellar wind accessible for direct study. The history of this discovery is quite dramatic. Like many remarkable discoveries, it had several predecessors. However, the honor of a discovery usually belongs to a scientist who was able to more fully explain the phenomenon. Such a man is deservedly considered the US theorist Eugene Parker, who discovered the solar wind, as we know it today, almost “with the point of his pen”. In 2017, we will celebrate the 90^th anniversary birthday of Eugene Parker.     

Initial analysis of ion fluxes in the magnetotail of Mars based on simultaneous measurements on Mars Express and Maven

Simultaneous operation of two Mars satellites, equipped with instruments for the study of the plasma environment close to Mars, the European satellite Mars Express and American satellite MAVEN, allows one to investigate the influence of the interplanetary environment on the Martian magnetosphere and atmospheric losses, induced by the solar wind, for the first time, with a sufficient degree of confidence. In this paper, the data from measurements on the Mars Express satellite (MEX) of heavy ion losses are analyzed in comparison with the solar wind and magnetic field measurements on the MAVEN satellite. The main issue is the spatial structure of the escaping ion flux and the influence of the nonstationarity of the solar wind flux on the escape rate.     

DI-aries panoramic energy-mass spectrometer of ions for the Phobos-Grunt project

One of the main goals of the Phobos-Grunt project is to analyze the surface composition of Phobos. Plasma methods of the studies make it possible to complete direct surface studies with measurements of the minor components of the solar wind, which are produced when a material sputtered from the surface of Phobos is ionized. The surface of Phobos is sputtered under the action of solar wind protons, energetic ions, hard solar radiation, and meteorites. In addition to the studies of Phobos, the experiment also includes the study of the interaction between the solar wind and Mars. An energy-mass spectrometer, which makes it possible to measure instantaneously complete unobscured distribution of the flux of different ions in the hemisphere, has been designed based on the new CAMERA analyzer of charged particles proposed previously (Vaisberg et al., 2001, 2005; Vaisberg, 2003). The instrument’s electro-optics model and the results of the numerical and laboratory tests are described in this paper. Such an instrument can be used in magnetospheric studies and to study different objects of the Solar System.     

Questions in photoelectric photometry

The paper reviews generally well-known, though still frequently overlooked, procedural points in photoelectric photometry. Some examples, which point up the value of high photometric precision, are included.     

Ion distribution dynamics near the Earth’s bow shock: first measurements with the 2D ion energy spectrometer CORALL on the INTERBALL/Tail-probe satellite

The dynamics of the ion distribution function near the Earths bow shock is studied on the basis of quasi-3D measurements of ion energy spectra in the range of 30–24200 eV/q with the Russian-Cuban CORALL instrument on the INTERBALL/Tail-probe satellite. The instrument was designed for observations of magnetospheric plasma and measures ions, in an angular range of 36°-144° from the Earth-Sun direction. Ion populations generated by the Earth bow shock are often observed upstream from the bow shock. In the solarwind stream compressed and heated by the passing of very dense magnetic cloud (CME), two types of these ion populations were measured upstream and before the bow shock crossing on 25 August 1995 at 07:37 UT. Both populations were observed in the energy range above 2 keV. At 06:20 UT, when the angle between the direction of the interplanetary magnetic field and normal to the bow shock _Bn was w 43° the instrument observed a narrow, fast (800 km/s) field-aligned beam moving from the Earth. At 07:30, when _Bn 28°, the wide ion pitch-angle distribution was observed. A similar suprathermal ion population is observed in the magnetosheath simultaneously with the solar-wind ion population being heated and deflected from the Sun-Earth direction. The similarity of observations during the mentioned time-interval and under usual solar-wind conditions allows us to conclude that types of suprathermal ion populations upstream and downstream from the bow shock do not depend on the solar-wind disturbance generated by magnetic cloud.