Different space weather effects in anomalies of the high and low orbital satellites

Preliminary results of the EU INTAS Project 00810, which aims to improve the methods of safeguarding satellites in the Earth’s magnetosphere from the negative effects of the space environment, are presented. Anomaly data from the “Kosmos” series satellites in the period 1971–1999 are combined in one database, together with similar information on other spacecraft. This database contains, beyond the anomaly information, various characteristics of the space weather: geomagnetic activity indices (Ap, AE and Dst), fluxes and fluences of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite anomalies was carried out for the total number of anomalies (about 6000 events), and separately for high (5000 events) and low (about 800 events) altitude orbit satellites. No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (>1500 km) and low (<1500 km) altitude orbits revealed a big difference in a behavior. Satellites were divided on several groups according to the orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found to be different for various orbits that should be taken into account under developing of the anomaly frequency models.     

Low altitude dose measurements from APEX, CRRES and DMSP

Dosimeter data taken on the APEX (1994–1996), CRRES (1990–1991) and DMSP (1984–1987) satellites have been used to study the low altitude (down to 350 km) radiation environment. Of special concern has been the inner edge of the inner radiation belt due to its steep gradient. We have constructed dose models of the inner edge of the belt from all three spacecraft and put them into a personal computer utility, called APEXRAD, that calculates dose for user-selected orbits. The variation of dose for low altitude, circular orbits is given as a function of altitude, inclination and particle type. Dose-depth curves show that shielding greater than 1/4 in Al is largely ineffectual for low altitude orbits. The contribution of outer zone electrons to low altitude dose is shown to be important only for thin shields and to have significant variation with magnetic activity and solar cycle.     

Neural network development for the forecasting of upper atmosphere parameter distributions

This paper presents a neural network modeling approach to forecast electron concentration distributions in the 150–600 km altitude range above Arecibo, Puerto Rico. The neural network was trained using incoherent scatter radar data collected at the Arecibo Observatory during the past two decades, as well as the Kp geomagnetic index provided by the National Space Science Data Center. The data set covered nearly two solar cycles, allowing the neural network to model daily, seasonal, and solar cycle variations of upper atmospheric parameter distributions. Two types of neural network architectures, feedforward and Elman recurrent, are used in this study. Topics discussed include the network design, training strategy, data analysis, as well as preliminary testing results of the networks on electron concentration distributions.     

Space radiation quality factor investigations with “NAUSICAA”-device on board the “MIR” space station

The estimation of radiation quality factor in space flights is a serious problem of space dosimetry. The solution of this problem is based on LET-spectra measurements. The “NAUSICAA”-device installed on the “MIR” station has a detector with a large geometric factor, that gives the possibility of measuring LET-spectra with sufficient statistic in relatively short time interval and hence the corresponding Q. LET-spectra are accumulated through 24 hour periods and equivalent dose (H), absorbed dose (D), quality factor and flux (F) are measured every 10 minutes. The obtained data permit the estimate of the diurnal Q and Q in South Atlantic Anomaly. These values vary in the range of 1.4 – 2.2. The analysis of these values including their comparison with the calculated results is given in this paper.     

Mini-belt as a fine spatial structure of the outer radiation belt in quiet and disturbed conditions

Electron flux data from LANL geostationary spacecrafts were statistically treated and ordered in a special magnetic coordinate system (effective L-coordinate and MLT). The data treating procedure allowed to obtain the dynamics of quasi-trapped electrons of different energies on effective L-shells ranging from 6.6 to 7.0. It was found that in quiet conditions a stable fine spatial structure of quasi-trapped electrons exists with maximum of fluxes near L = 6.78 and MLT=12. This structure may be looked at as an asymmetrical “mini-belt”. The position of the maximum depends on electron energy and changes with magnetic activity. The dynamics of this mini-belt for both quiet and disturbed periods is illustrated and discussed. During isolated magnetic storms the mini-belt maximum shifts in a regular manner outward and inward; a diffusion wave of quasi-trapped particles propagates from outside of the geostationary orbit and serves as a source of new particles for the mini-belt. The azimuthal geometry of this diffusion wave extracted from experimental data is illustrated. The possible role of the “mini-belt” is discussed in relation with well-known “anomalous” dynamics of the inner radiation belt.     

Local-area helioseismology as a diagnostic tool for solar variability

Dynamical and thermal variations of the internal structure of the Sun can affect the energy flow and result in variations in irradiance at the surface. Studying variations in the interior is crucial for understanding the mechanisms of the irradiance variations. “Global” helioseismology based on analysis of normal mode frequencies, has helped to reveal radial and latitudinal variations of the solar structure and dynamics associated with the solar cycle in the deep interior. A new technique, - “local-area” helioseismology or heliotomography, offers additional potentially important diagnostics by providing three-dimensional maps of the sound speed and flows in the upper convection zone. These diagnostics are based on inversion of travel times of acoustic waves which propagate between different points on the solar surface through the interior. The most significant variations in the thermodynamic structure found by this method are associated with sunspots and complexes of solar activity. The inversion results provide evidence for areas of higher sound speed beneath sunspot regions located at depths of 4–20 Mm, which may be due to accumulated heat or magnetic field concentrations. However, the physics of these structures is not yet understood. Heliotomography also provides information about large-scale stable longitudinal structures in the solar interior, which can be used in irradiance models. This new diagnostic tool for solar variability is currently under development. It will require both a substantial theoretical and modeling effort and high-resolution data to develop new capabilities for understanding mechanisms of solar variability.     

Experimental investigations of quasistable radiation belts formed after solar proton events in September–October 1989 and March 1991 based on measurements made by “Liulin” dosimeter-radiometer on board the “MIR” space station

Since 1988 high sensitivity dosimeter-radiometer “Liulin” has been installed on board the MIR space station. Device measured absorbed dose rate and flux of penetrating particles. Results of measurements showed that after powerful solar proton events (SPE) September–October, 1989 and March, 1991 additional quasistable radiation belts were formed in the near earth space within the interval L=1.8−3.0. These “new” belts were observed as an additional maximums in flux (and sometimes dose) channels when crossing the SAA region. “New” belts were quasi stable and existed at least several months, decaying slightly after SPE. Dose to flux ratio analysis showed that major components of these belts were energetic electrons and protons arising in connection with preceding SPEs.     

Impact of microwave discharges on the lower ionosphere and middle atmosphere

The behaviour of the lower ionosphere and middle atmosphere during microwave discharges at 30 – 60 km altitude is investigated. The developed plasmachemical model includes 166 processes for 19 minor neutral (including excited) components and for 13 charged species. The distinctive differences of this model from previous investigations are (1) the equation system is closed assuming undisturbed conditions, (2) the inclusion of additional reactions involving hydrogen components, and (3) considerable improvement of the reaction scheme for ionized components. The results are analyzed in three main aspects: the behavior of the minor neutral and excited components, variations of charged species including the electron concentration, and finally possible influence of the air heating on the plasma chemistry.     

Solar wind-driven electron radiation belt response functions at 100-min time scales

We present a simple yet numerically robust technique, using autoregressive linear filters, to remove unwanted “colored noise” from solar wind and radiation belt electron data at sub-daily resolution. The remaining signal is then studied using finite impulse response linear prediction filters to represent the driven portion of the linear dynamics that describe the coupling between solar wind speed and electron flux. Sub-daily resolution response profiles covering magnetic L-shells between 1.1 and 8.0 R_E are presented which are consistent with daily resolution response functions. Namely, while there is strong global coherence governing electron flux dynamics, there are at least two distinct responses. The first response is an immediate dropout of electrons between L = 4 and L = 7 that is at least a partly adiabatic effect associated with enhancements in the ring current. This is followed by a 1–2 day delayed enhancement across the same L-shells that is likely a result of increased radial diffusion. The second response is an immediate enhancement seen between L = 3 and L = 4 with a typical duration of less than one day. Plausible explanations for this second response are briefly discussed, but neither empirical nor theoretical evidence can establish conclusively a definite physical cause. Finally, the response profiles show significant solar cycle and seasonal dependencies, indicating that better model output might be achieved with: (1) additional simultaneous solar wind inputs; (2) more sophisticated dynamical model structures capable of incorporating non-linear feedback; and/or (3) time-adaptive linear filters that can track non-stationary dynamics in time.     

Specific features of electron distributions at altitudes of 400 km

New experimental data obtained on the orbital station ‘MIR’ in 1991 during solar maximum are discussed. Electron fluxes with E_e>75 keV were registered for three different directions as well as for electrons with E_e>300 and 600 keV. Spatial and time distributions of electron fluxes in the trapping region are presented. In the inner radiation belt an additional maximum is observed at L=1.25–1.35, and the fluxes in the 22-05^h MLT interval are 2–3 orders of magnitude smaller, than during other local times. In this region a flattening of the electron spectrum is observed. The results obtained were compared with the AE-8 model.     

Energetic neutron and gamma-ray spectra under the earth radiation belts according to “SALUTE-7”-“KOSMOS-1686” orbital complex and “CORONAS-i” satellite data

The spectra of neutrons >10 MeV and gamma-rays 1.5–100 MeV under the Earth Radiation Belts, restored from the data, obtained onboard orbital complex “SALUTE-7”-“KOSMOS-1686”, are presented. The spectra shapes are similar to those for albedo neutrons and gamma-rays, but absolute values of their fluxes (0.2 cm⁻² s⁻¹ for neutrons, 0.8 cm⁻² s⁻¹ for gamma-rays at the equator and 1.2 cm⁻² s⁻¹, 1.9 cm⁻² s⁻¹, accordingly, at L=1.9) are several times as large. It is possibly explained by the fact that most of the detected particles were produced by the cosmic ray interactions with the orbital complex matter. Neutron and gamma-ray fluxes obtained from “CORONAS-I” data are near those for albedo particles.     

Non-axisymmetrical distributions of solar magnetic activity and irradiance

Active longitudes play an important role in spatial organization of solar activity. These zones associated with complexes of solar activity may persist for 20–40 consecutive rotations, and may be caused by large-scale non-axisymmetrical components of the global magnetic field. These zones of the field concentrations are 20°–40° wide and during subsequent rotations tend to reappear at constant longitude or drift slightly eastward or westward. Since the magnetic field is the principle source of the variations of radiation on the solar surface the active longitudes affect the solar irradiance received at the Earth. In this paper I study connections between the active longitudes and irradiance variations using VIRGO/SOHO, KPO and WSO data, which covered the transition period from solar cycle 22 to cycle 23 and rising phase of cycle 23. The result of this investigation is that active longitudes are associated with increases of the total solar irradiance and are prime sources of enhanced EUV radiation and coronal heating.     

On the non-occurrence of Type I X-ray bursts from the black hole candidates

It has been justifiably questioned if the black hole candidates (BHCs) have “hard surface” why Type I X-ray bursts are not seen from them [Narayan, R., Black holes in astrophysics, New J. Phys, 7, 199–218, 2005]. It is pointed out that a “physical surface” need not always be “hard” and could be “gaseous” in case the compact object is sufficiently hot [Mitra, A., The day of the reckoning: the value of the integration constant in the vacuum Schwarzschild solution, physics/0504076, p1–p6, 2005; Mitra, A., BHs or ECOs: A review of 90 years of misconceptions, in: Focus on Black Holes Research, Nova Science Pub., NY, p1–p94, 2005]. Even if a “hard surface” would be there, presence of strong intrinsic magnetic field could inhibit Type I X-ray burst from a compact object as is the case for Her X-1. Thus, non-occurrence of Type I bursts actually rules out those alternatives of BHs which are either non-magnetized or cold and, hence, is no evidence for existence of Event Horizons (EHs). On the other hand, from the first principle, we again show that the BHCs being uncharged and having finite masses cannot be BHs, because uncharged BHs have a unique mass M = 0. Thus the previous results that the so-called BHCs are actually extremely hot, ultramagnetized, Magnetospheric Eternally Collapsing Objects (ECOs) [Robertson, S., Leiter, D., Evidence for intrinsic magnetic moment in black hole candidates, Astrophys. J., 565, 447–451, (astro-ph/0102381), 2002 ; Robertson, S., Leiter, D., MECO model of galactic black hole candidates and active galactic nuclei, in: New Developments in Black Hole Research, Nova Science Pub., NY, p1–p44, astro-ph/0602453, 2005] rather than anything else get reconfirmed by non-occurrence of Type I X-ray bursts in BHCs.     

Space weather and commercial airlines

Space weather phenomena can effect many areas of commercial airline operations including avionics, communications and GPS navigation systems. Of particular importance at present is the recently introduced EU legislation requiring the monitoring of aircrew radiation exposure, including any variations at aircraft altitudes due to solar activity. With the introduction of new ultra-long-haul “over-the-pole” routes, “more-electric” aircraft in the future, and the increasing use of satellites in the operation, the need for a better understanding of the space weather impacts on future airline operations becomes all the more compelling. This paper will present the various space weather effects, some provisional results of an ongoing 3-year study to monitor cosmic radiation in aircraft, and conclude by summarising some of the identified key operational issues, which must be addressed, with the help of the science community, if the airlines want to benefit from the availability of space weather services.     

Measurements of high-energy neutron and proton fluxes on-board “Mir-Spectr” orbital complex

The measurements of high-energy neutron (with energies 30–300 MeV) and proton (with energies 1–200 MeV) fluxes are being conducted on-board “Mir-Spectr” orbital complex. Neutrons are detected by the undirected (FOV 4π sr) scintillator spectrometer, consisting of 4 identical CsI(Tl) detector units (the effective area for neutrons 30 cm²). The gamma-quanta, which can be also detected by this instrument, are separated from neutrons by the analysis of the scintillator output pulse shape. To exclude registration of charged particles an anticoincidence plastic scintillator shield is realized in each detector unit. The proton fluxes are measured by the telescope based on 3 semiconductor detectors with small geometry factor (1 cm²×sr). As the first result of the experiment the upper limit of the integral flux of local and albedo neutrons in the equatorial region (L<1.1) was estimated. The results of this measurements can be useful for the radiation security. Also, the neutrons of solar flares can be detected in this experiment.     

Hydrogen coma of comet P/Halley

The main molecular processes to produce the hydrogen comae of comets are now well known: Water, the main constituent of cometary atmospheres, is photodissociated by the solar ultraviolet radiation to form the high (20 km s⁻¹) and low (8 km s⁻¹) velocity components of the atomic hydrogen. The hydrogen clouds of various fresh comets have been observed in 1216Å by a number of spacecrafts. Ultraviolet observations of short period comets are, however, rather rare. Consequently Comet P/Halley in this apparition is a good object to obtain new physics of the hydrogen coma. Strong breathing of the hydrogen coma of this comet found by “Suisei” provides just such an example. The rotational period of Comet Halley's nucleus, its activity in the form of outbursts alone, and the position of jet sources etc. are determined from the breathing phenomena. Atomic hydrogen from organic compounds with a velocity of 11 km s⁻¹ play an important role in that analysis. The time variations of the water production rate of Comet Halley during this apparition observed by various spacecrafts appear to be in agreement with each other and are about 1.5–2 times larger than the standard model. The difficulty of the calibration problem was emphasized.     

Numerical simulations of the radiance from the comet 46P/Wirtanen in the various configurations of the measurements during “Rosetta” mission

The work we present deals with the spectrometric measurements of VIRTIS instrument of the Comet P/Wirtanen planned for the Rosetta mission. This spectrometer can monitor (VIRTIS M channel: 0.250μm – 0.980μm; Δκ=20cm⁻¹; 0.980 – 5.0 μm; Δκ = 5cm⁻¹; VIRTIS H channel: 2.0 μm – 5.0 μm; Δκ=2cm⁻¹) the nucleus and the coma in order to provide a general picture of coma's composition, the production of gas and dust, the relationship of coma production to surface composition and the structure and variation of mineralogy of the nucleus surface. During the mission the observation conditions of the spectroscopic investigation change due to different relative positions spacecraft/comet, and to the different illumination conditions of the surface at various distances of the comet to the Sun. The nucleus surface is continuously modified by the ice sublimation accompanied by gas and dust emission. Consequently the surface also its spectrophotometric properties changes and their monitoring can give a new insight. The important role of simulations is to predict the results of measurements in various experimental condition what, in the future, can help in interpretation of the measured data.

In this paper the first results of our simulation the radiance from the comet in the 0.25–5.0μm spectral range at two distances from the Sun (1AU and 3AU) are shown. The distance between the Rosetta orbiter and the nucleus surface as well as the sun zenith angles are taken into account according to the Rosetta mission phases. In fact the surface and coma properties vary along the comet orbit, and should be taken into account in our calculations. The optical parameters of the dust on the surface (e.g. reflectance) and in the coma (e.g. Q_ext) were calculated from optical constants of possible comet analogues. The thermodynamic parameters of the comet are taken from the models of comet evolution. Through this kind of modelling it is possible to identify the surface characteristics in spectra of the radiation from the surface of nucleus transmitted through the coma loaded with dust and gases.

Even if the “Rosetta mission” is postponed, with the consequence of a target change, we think that our idea and the method used for the simulations can be useful also for the new Rosetta target - the comet 67P/Churyumov Gerasimenko.     

星载半导体电子探测器关于辐射带电子探测的一些结果

本文给出了我国卫星上半导体电子探测器的一些探测结果。通过对数据的分析,得到了内辐射带中心区电子通量的典型值,大于0.5MeV和1.0MeV两个能档的全向通量分别为1.9×108和6.7×107ele./s·cm2.同时也给出了在典型轨道上电子通量随时间的变化剖面。此外,还得到了同步高度上述两个能档电子的全向通量分别为20.43×106和4.25×105ele./s·cm2.同时也给出了观测到的同步高度外辐射带电子的日变化。结果与国外观测资料基本相符。      

Energetic particle fluxes data base of “CORONAS-I” satellite observations

The data base DB SCR uses data obtained by the SCR instrument package on the CORONAS-I satellite. DB SCR contains information about fluxes of relativistic electrons (0.5–124 MeV), protons (1–300 MeV), nuclei (1–19 MeV/nucl) and γ-radiation (0.1–7 MeV) in the low altitude region (500 km). The time resolution of the data is 2.5 s. Magnetic field parameters (B, magnetic latitude and longitude), L-shell and local times (LT and MLT) are included in DB SCR. Since all parameters are equivalents it is possible to perform the multidimensional analysis for any set of DB SCR parameters. The additional DB SCR software packages may be used to develop different semi-empirical models.     

Variation of ionospheric electron and ion temperatures during periods of minimum to maximum solar activity by the SROSS-C2 satellite over Indian low and equatorial latitudes

To study the variation of ionospheric electron and ion temperatures with solar activity the data of electron and ion temperatures were recorded with the help of Retarding Potential Analyzer payload aboard Indian SROSS-C2 satellite at an average altitude of ∼500 km. The main focuses of the paper is to see the diurnal, seasonal and latitudinal variations of electron and ion temperatures during periods of minimum to maximum solar activity. The ionospheric temperatures in the topside show strong variations with altitude, latitude, season and solar activity. In present study, the temperature variations with latitude, season and solar activity have been studied at an average altitude ∼500 km. The peak at sunrise has been observed during all seasons, in both electron and ion temperatures. Further, the ionospheric temperatures vary with latitude in day time. The latitudinal variation is more pronounced for low solar activity than for high solar activity.