Association of CMEs with solar surface activity during the rise and maximum phases of solar cycles 23 and 24

The cyclical behaviors of sunspots,flares and coronal mass ejections(CMEs) for 54 months from 2008 November to 2013 April after the onset of Solar Cycle(SC) 24 are compared,for the first time,with those of SC 23 from 1996 November to 2001 April.The results are summarized below.(i) During the maximum phase,the number of sunspots in SC 24 is significantly smaller than that for SC 23 and the number of flares in SC 24 is comparable to that of SC 23.(ii) The number of CMEs in SC 24 is larger than that in SC 23 and the speed of CMEs in SC 24 is smaller than that of SC 23 during the maximum phase.We individually survey all the CMEs(1647 CMEs) from 2010 June to 2011 June.A total of 161 CMEs associated with solar surface activity events can be identified.About 45%of CMEs are associated with quiescent prominence eruptions,27%of CMEs only with solar flares,19%of CMEs with both active-region prominence eruptions and solar flares,and 9%of CMEs only with active-region prominence eruptions.Comparing the association of the CMEs and their source regions in SC 24 with that in SC 23,we notice that the characteristics of source regions for CMEs during SC 24 may be different from those of SC 23.     

Use of combined method for computing GEO SC corrections to minimize orbit eccentricity

The problem of transferring GEO SC to a specified standing point taking into account the SC insertion and correction error is considered. A combined method for calculating insertion corrections is suggested based on the algorithm for the optimal burn correction and numerical model for forecasting active SC COG motion, which yields a high calculation accuracy and allows one to minimize the orbit eccentricity at the end of the transferring phase. The method is software implemented and can be used to calculate transfer correction parameters during both the phase of GEO SC design and SC operation for their control.     

Shannon Entropy-Based Prediction of Solar Cycle 25

A new model is proposed to forecast the peak sunspot activity of the upcoming solar cycle (SC) using Shannon entropy estimates related to the declining phase of the preceding SC. Daily and monthly smoothed international sunspot numbers are used in the present study. The Shannon entropy is the measure of inherent randomness in the SC and is found to vary with the phase of an SC as it progresses. In this model each SC with length \(T_{\mathrm{cy}}\) is divided into five equal parts of duration \(T_{\mathrm{cy}}/5\). Each part is considered as one phase, and they are sequentially termed P1, P2, P3, P4, and P5. The Shannon entropy estimates for each of these five phases are obtained for the \(n\)th SC starting from \(n=10\,\mbox{--}\,23\). We find that the Shannon entropy during the ending phase (P5) of the \(n\)th SC can be efficiently used to predict the peak smoothed sunspot number of the \((n+1)\)th SC, i.e. \(S_{\mathrm{max}}^{n+1}\). The prediction equation derived in this study has a good correlation coefficient of 0.94. A noticeable decrease in entropy from 4.66 to 3.89 is encountered during P5 of SCs 22 to 23. The entropy value for P5 of the present SC 24 is not available as it has not yet ceased. However, if we assume that the fall in entropy continues for SC 24 at the same rate as that for SC 23, then we predict the peak smoothed sunspot number of 63±11.3 for SC 25. It is suggested that the upcoming SC 25 will be significantly weaker and comparable to the solar activity observed during the Dalton minimum in the past.     

Enhancement of on-board forecasting accuracy of GEO SC COG motion using the compensative transversal acceleration

A method is suggested for enhancing the on-board forecasting accuracy of the COG motion of a GEO SC with a long time of independent operation. The suggested method consists of introducing so-called compensative transversal acceleration (CTA), along with zonal harmonics into the right sides of the differential equations of SC motion among other disturbances due to the Earth’s gravitational field eccentricity. The CTA compensates the integral effect of the sectoral and tesseral harmonics; its value is constant for a specified point of GEO SC location (standing point) and is calculated on the Earth from numerical integration of differential equations of motion taking into account the complete set of gravitational field harmonics. The CTA value is transmitted on-board of an SC as program command data. The method is implemented in algorithms of on-board forecasting of Electro-L SC motion and can be used to enhance the on-board forecasting accuracy of the COG motion of GEO SCs with a long time of independent operation.     

Ensuring dynamic stability of the orbital structure of the Arktika-M space system

The control of the orbital structure of the satellite constellation (SC) of continuous service with spacecraft in highly elliptical orbits of the Molniya type is considered. For ensuring the SC dynamic stability, it is proposed to use passive, active, and combined approaches to the SC orbital structure control. A statement of the problem to ensur e dynamic stability is given and results of its solution for a particular variant of the orbital construction of the Arktika-M space system are presented for the passive control approach. The proposed orbital structure control is based on minimizing the evolution-induced space-time deformation of the orbital structure by means of differentiated selection of initial parameters of orbits at the stages of the SC deployment and replenishment and by means of control of the spacecraft’s ground track at the SC operation stage. Using this control method is especially important with long active life spans of spacecraft and limitations on propellant margins for orbit correction.     

Problem “13” for geostationary spacecraft

We consider the problem of ensuring an energy balance of geostationary spacecraft (SCs) that will arise on October 13, 2015, during the long-duration eclipse of the solar disk visible from the SC by the Moon and the Earth. A technique for assessment of the eclipse duration, taking into account the shaded area of visible solar disk, is set forth, and results of calculating the eclipse conditions for different SC “stationary” points in the geostationary orbit are given. The data presented will allow the specialists to be prepared in advance for specific ballistic conditions of SC operation at this date and to plan operations to ensure the power balance of the SC power supply system during the prolonged shading of the Sun by the Moon and the Earth.     

Determination of spacecraft and phobos parameters of motion in the Phobos-Grunt project

For the needs of the upcoming flight to Phobos within the framework of the project Phobos-Grunt, a dynamical numerical theory of the motion of Phobos is developed on the basis of Earth-based and spacecraft (SC) optical measurements and Earth-based radio observations of the SC motion. The theory uses the most reliable astronomical constants. Within the framework of a unified dynamical model, an algorithm is proposed for the joint correction of Phobos and the spacecraft parameters of motion, among which are the secular acceleration of Phobos and its gravitational constant. The accuracy of the obtained ephemeris is estimated for the time of the SC arrival to Phobos.     

Relativistic Gravitational Experiment in the Earth Orbit: Concept,Technology, and Configuration of Satellite Constellation

An arrangement of the orbital experiment on the measurement of the light propagation delay in the gravitational field of the Earth (Shapiro effect) using laser interferometry based on a cluster of small spacecraft (SC) is proposed. SC layouts, launch technology, and high-precision measurements of their orbital parameters are considered.     

On the prevention of a possible collision of asteroid Apophis with the Earth

Currently, there is some positive probability of a collision of the asteroid Apophis with the Earth in 2036. In this study, the problem of preventing the collision by correcting the asteroid’s orbit is examined. The characteristics of the impulsive correction are investigated, as well as the ways of its implementation by kinetic and nuclear impacts. Impulsive and weak effects are compared. Weak effects leading to slow changes in the asteroid’s orbit are considered to be more usable because of the potentially higher accuracy of this correction. The characteristics of the gravitational effect of the asteroid by a special spacecraft (SC) kept by its control jet engines at a certain point near the asteroid and gravitationally perturbing the motion of Apophis are analyzed. The change in the perigee radius of the Apophis orbit in 2036 and the SC mass consumption are examined as functions of the effect duration, the SC mass, its distance to the asteroid, the start time of the correction, and the velocity of the SC engine exhaust jet.     

Extension of a polar ionospheric current to the nightside equator

A detailed analysis of rapid-run magnetograms from Guam (geomagnetic latitude = 4.2°) revealed that there are two kinds of geomagnetic sudden commencement (SC) observed in nighttime. One is the ordinary SC consisting of a main impulse only which has a smooth rise of the H-component. The other is a superposition by a small positive impulse on the very beginning part of the smooth rise of the main impulse and consequently the SC starts with a small stepwise increase of the H-component. The latter type of SC occurs between 20 and 08 h L.T. and its occurrence rate takes the maximum value of about 50% around 03 h L.T. Corresponding magnetograms from a dayside equatorial station (Huancayo, geomagnetic latitude = ?0.7°) were examined and a good correlation was found between the stepwise SC at the nightside (Guam) and SC¹ with a preliminary reverse impulse (PRI) at the dayside (Huancayo). Since PRI observed at the dayside equator may be interpreted as an extension of an ionospheric current due to an dusk-to-dawn electric field impressed on the polar ionosphere, our results show that a polar originating ionospheric current can extend to the nightside equator and produce a small but observable magnetic effect in spite of much reduced nighttime ionospheric conductivity.     

Carbonaceous matter in the Sariçiçek meteorite

As of today, the Sariçiçek (SC) meteorite is the newest howardite and the only confirmed fall among the 17 known howardites. In this study, we present isotopic, infrared, and Raman data on three distinct pieces of the SC meteorite. Our oxygen isotopic measurements show that Δ¹⁷O values of the pieces are close to each other, and are in good agreement with other howardites, eucrites, and diogenites. The carbon isotopic measurements, which were conducted by combusting terrestrial contamination selectively at temperatures lower than 500–600 °C, show the presence of indigenous carbon in the SC specimens. The matrix of these specimens, investigated via infrared microspectroscopy, appears to be dominated by clinopyroxene/orthopyroxene, forsterite, and fayalite, with minor contributions from ilmenite, plagioclase, and enstatite. Carbon‐rich regions were mapped and studied via Raman imaging microspectroscopy, which reveals that both amorphous and graphitic carbon exist in these samples. Synchrotron‐based infrared microspectroscopy data show the presence of very little aliphatic and aromatic hydrocarbons. The SC meteorite is suggested to be originating from the Antonia impact crater in the Rheasilvia impact basin on 4 Vesta (Unsalan et al. 2019). If this is in fact the case, then the carbon phases present in the SC samples might provide clues regarding the impactor material (e.g., carbonaceous chondrites).     

Geomagnetic effects of interplanetary sector structure

In this paper the geomagnetic effects of the interplanetary magnetic sector structure are studied on the basis of some new criteria and working hypotheses.Thus, we assume that the recurrence of geomagnetic disturbances should be understood in a dynamical sense, in connection with the evolution of the full sector structure, and not necessarily as a 27-day recurrence. Accordingly, on the representation of the sector structure during 1968, as deduced by Wilcox and Colburn, we have defined four ‘main recurring lines’, which link the sector boundaries recurrent in successive solar rotations. The term ‘group of SC and SI events’, abbreviated as gr(SC + SI), introduced by us in previous works to designate the morphological grouping of the individual SC and SI events in collective events, is also used.It should be pointed out that the bulk of gr(SC + SI) events are either associated with sector boundaries, or recurrent in successive solar rotations. Part of these events reveal the existence of some ‘secondary recurring lines’, within the magnetic sectors.The above working hypotheses and observations have been checked by the superposed epoch analysis, performed for each main recurring line in part and for all the main recurring lines combined.The following parameters are analysed: the number of SC events, the number of collective events gr(SC + SI), the total number of SC and SI events and the geomagnetic activity index Kp.The main result of the superposed epoch analysis consists in the appearance of a sharp maximum for all the parameters considered on the day of sector boundary. This fact proves that the effects of the sector boundaries are important and general, in regard to all aspects of geomagnetic activity. Essentially these effects consist of the occurrence of gr(SC + SI) events and of a specific increase in the Kp index, when the sector boundaries pass by the magnetosphere. This suggests that the sector boundaries are accompanied by corotating shocks and magnetohydrodynamical turbulence.The high frequency in the occurrence of the SC events on the days of sector boundaries is also noticeable.Each main recurring line presents a certain ‘individuality’, expressed particularly by secondary specific maxima in all the parameters, corresponding to the ‘secondary recurring lines’. One suggests that these secondary recurring lines might be due to some corotating distortions within the magnetic sectors and might be related to the ‘subsector’ or ‘filaments’.The distribution of the geomagnetic disturbances near the sector boundaries depends on the direction of the field polarity change.All these results lead to the conclusion that most of the geomagnetic disturbances can be accounted for by the interaction between corotating distortions in the solar wind connected with the sector structure and the magnetosphere, the flare-induced disturbances representing statistically the secondary mechanism.     

The Projects for Onboard Autonomy (PROBA2) Science Centre: Sun Watcher Using APS Detectors and Image Processing (SWAP) and Large-Yield Radiometer (LYRA) Science Operations and Data Products

The PROBA2 Science Centre (P2SC) is a small-scale science operations centre supporting the Sun observation instruments onboard PROBA2: the EUV imager Sun Watcher using APS detectors and image Processing (SWAP) and Large-Yield Radiometer (LYRA). PROBA2 is one of ESA’s small, low-cost Projects for Onboard Autonomy (PROBA) and part of ESA’s In-Orbit Technology Demonstration Programme. The P2SC is hosted at the Royal Observatory of Belgium, co-located with both Principal Investigator teams. The P2SC tasks cover science planning, instrument commanding, instrument monitoring, data processing, support of outreach activities, and distribution of science data products. PROBA missions aim for a high degree of autonomy at mission and system level, including the science operations centre. The autonomy and flexibility of the P2SC is reached by a set of web-based interfaces allowing the operators as well as the instrument teams to monitor quasi-continuously the status of the operations, allowing a quick reaction to solar events. In addition, several new concepts are implemented at instrument, spacecraft, and ground-segment levels allowing a high degree of flexibility in the operations of the instruments. This article explains the key concepts of the P2SC, emphasising the automation and the flexibility achieved in the commanding as well as the data-processing chain.     

The curious temporal behavior of the frequency of different class flares

We investigate the frequency of all (X-ray flare events higher than class B1.0), B, C, M and X-class flares, respectively, derived from the National Geophysical Data Center (NGDC) list of solar flares between May 1983 and September 2014, which corresponds to the two complete solar cycles (SCs) 22 and 23 as well as the rise and maximum phases of SC 24. Analysis shows that the temporal behavior for these various class flares is quite different. The main findings of this study, confirmed by using the Hinode flare catalog where possible, are as follows. (1) The B-class flares are in complete antiphase with all, C, M and X-class flares. (2) While, there is a small decreasing trend in the peak values of the smoothed monthly C-class flare numbers from SC 22 to 24, the occurrence rate of M and X-class flares dropped by almost half and two-thirds, respectively, during SC 23 and remained almost the same during SC 24. This class-dependent temporal behavior provides support for dynamo models that involve the coexistence of a deep global and a superficial local dynamo.     

Primeval substance delivery from Phobos to the Earth—the Phobos-Soil project: Ballistics,navigation, and flight control

This paper is concerned with the problems of ballistics, navigation, and flight control of the space craft (SC) in the Phobos-Grunt mission. We consider an insertion into the Earth-Mars transfer trajectory, the Earth-Mars transfer, the strategy of corrections, and the accuracy of the insertion of the SC into Martian orbit. During the orbital maneuvering stage in the sphere of influence of Mars, we set up a scheme that allows for the insertion of the SC, with the prescribed accuracy, into a point 80-km above the Phobos surface over the theoretical landing area. We specify the sequence for a controlled landing and provide methods for solving the problems of navigation and control during a self-c ontained landing. We also consider the liftoff from Phobos, insertion into the parking orbit, and the Mars-Earth transfer.     

Interferometric observations for oxygen-containing organic molecules toward Orion-KL

High spatial resolution observations (approximately 5") were made for the 3 mm transitions of methanol (CH3OH), methyl formate (HCOOCH3), and dimethyl ether [(CH3)2O] toward Orion-KL using the Nobeyama Millimeter Array. The 15(3)-14(4) A- CH3OH emission appears to be elongated along the line connecting IRc2 and "the southern condensation (SC)", which may suggest a relation between methanol and the outflow from IRc2. The HCOOCH3 (7(1,6)-6(1,5)) and (CH3)2O (15(2,13)-15(1,14)) emissions appear to be well concentrated toward SC with an angular size of approximately 6".5 (at the 2 sigma level). There also exists another oxygen-rich condensation to the west of IRc2 (angular size approximately 4".5) having column densities of HCOOCH3 and (CH3)2O comparable to those of SC. We derive the total column densities 6.8 x 10(16) cm-2, 1.4 x 10(16) cm-2 and 2.7 x 10(16) cm-2 for CH3OH, HCOOCH3, and (CH3)2O, respectively, at the core of SC.     

Dynamics and control of a solar collector system for near Earth object deflection

A solar collector system is a possible method using solar energy to deflect Earth-threatening near-Earth objects.We investigate the dynamics and control of a solar collector system including a main collector (MC) and secondary collector (SC).The MC is used to collect the sunlight to its focal point,where the SC is placed and directs the collected light to an asteroid.Both the relative position and attitude of the two collectors should be accurately controlled to achieve the desired optical path.First,the dy...     

A search for H i in some peculiar faint dwarf galaxies

We present a deep Giant Metrewave Radio Telescope (GMRT) search for H  i 21-cm emission from three dwarf galaxies, viz. POX 186, SC 24 and KKR 25. Based, in part, on previous single-dish H  i observations, these galaxies have been classified as a blue compact dwarf (BCD), a dwarf irregular and a transition galaxy, respectively. However, in conflict with previous single-dish detections, we do not detect H  i in SC 24 or KKR 25. We suggest that the previous single-dish measurements were probably confused with the local Galactic emission. In the case of POX 186, we confirm the previous non-detection of H  i but with substantially improved limits on its H  i mass. Our derived upper limits on the H  i mass of SC 24 and KKR 25 are similar to the typical H  i mass limit for dwarf spheroidal (dSph) galaxies, whereas in the case of POX 186, we find that its gas content is somewhat smaller than is typical of BCD galaxies.     

Solar flare alpha to proton ratio changes following interplanetary disturbances

A discussion is presented on the half hour averaged low energy solar alpha to solar proton flux ratios observed following the three large solar flares of May 23, 1967. One of the large changes observed in the particle ratios (following a sudden commencement (SC) storm observed on the earth) is interpreted as due to a source effect. The second large change, again observed following an SC, is observed in the equal velocity and equal rigidity ratios and not in the equal energy/charge ratios. This observation suggests that electric fields in an interplanetary disturbance may be the cause of the modulations.