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Geomagnetic storms are severe aspects of Space Weather. They originate due to solar transient emissions such as coronal mass ejections (CMEs), whose energetic materials propagate in the Interplanetary medium and are coupled with the magnetosphere system. CME driven Geomagnetic storms are often associated with solar radio bursts (SRBs), particularly type II and type IV bursts. In this study, we present the preliminary results of solar radio observations and their associated geomagnetic activity during solar cycle 25 (SC 25) from January 2020 to June 2023, focusing on the cycle's first four intense geomagnetic storms. The study used various radio telescopes, mainly the compound astronomical low-frequency low-cost instrument for spectroscopy and transportable observatory (CALLISTO), as well as OMNI data and the World Data Center for Geomagnetism. During the study period, it was found that 23 solar radio bursts diagnosed the geomagnetic storms with Dst < - 50 nT from 35 reported, including three severe storms of the SC 25. The time delay between the solar radio bursts and the arrival of CMEs and/or HSS near the Earth's magnetosphere is estimated with an average value of 79 h within the [48–120 h] range for 23 geomagnetic storms associated with solar radio bursts. Among 35 geomagnetic storms recorded, five are recurring geomagnetic storms associated with coronal high-speed streams (HSS), while CMEs cause the rest with average speeds of 750 km/s. The current SC 25 recognizes four major storms within the scope of the study. On 21 April 2023, a type II radio burst followed by a type IV burst diagnosed the first severe geomagnetic storm on 24 April 2023. The second severe storm was unusual and detected in the absence of the precursor as a solar radio burst. The SRBs of type II burst and type IV burst extending in IP medium on 1 November 2021 tracked the third major storm of the cycle while the group of type III radio bursts, type II and type IV bursts on 24 February 2023, predicted the major storm on 27 February 2023. These major geomagnetic storms are linked to CMEs that show expanding flux ropes, which are signatures of type II and moving type IV radio bursts identified. Furthermore, the detected SRBs and related major geomagnetic storms are proof of high solar and magnetic activity of the ascending phase of SC 25. The SC 25 has been characterized overall, and its current progress is being tracked using observations of SRBs and magnetic activity during its rising phase. [ABSTRACT FROM AUTHOR]

The University of California, San Diego (UCSD) time-dependent three-dimensional (3-D) reconstruction technique provides volumetric maps of density, velocity, and solar surface extrapolated magnetic fields by iteratively fitting our kinematic 3-D model to interplanetary scintillation (IPS) observations. While we currently use data from the Institute for Space-Earth Environmental Research (ISEE), Japan, we have also integrated this system adding data from Worldwide IPS Stations (WIPSS) network groups to increase both spatial and temporal coverage when these data are available. Some of these stations, especially the LOw Frequency ARray (LOFAR), centered in the Netherlands, currently operate in "campaign" mode only during periods of interest when the Parker Solar Probe (PSP) makes close passes to the Sun. The UCSD 3-D iterative reconstruction technique is unique in its ability to yield a low-resolution seamless extension of density and velocity parameters measured in situ, going outward into the surrounding interplanetary medium at the resolution of the volumetric data. We here present analyses using archival data sets from both ISEE, LOFAR, and BSA3 (Pushchino, Russia), mostly during PSP close passes of the Sun. These analyses provide the location of all inner planets from Mercury to Mars, and the spacecraft PSP, BepiColombo, and Solar Orbiter in the 3-D reconstructed volumes and can show the heliospheric structures that reach them as in-situ predictions of the structures present and forecasts of these parameters in near real time compared with near-Earth data sets. [ABSTRACT FROM AUTHOR]

The solar activity displays variability and periodic behaviours over a wide range of timescales, with the presence of a most prominent cycle with a mean length of 11 years. Such variability is transported within the heliosphere by solar wind, radiation and other processes, affecting the properties of the interplanetary medium. The presence of solar activity–related periodicities is well visible in different solar wind and geomagnetic indices, although their time lags with respect to the solar cycle lead to hysteresis cycles. Here, we investigate the time lag behaviour between a physical proxy of the solar activity, the Ca II K index, and two solar wind parameters (speed and dynamic pressure), studying how their pairwise relative lags vary over almost five solar cycles. We find that the lag between Ca II K index and solar wind speed is not constant over the whole time interval investigated, with values ranging from 6 years to ∼ 1 year (average 3.2 years). A similar behaviour is found also for the solar wind dynamic pressure. Then, by using a Lomb-Scargle periodogram analysis we obtain a 10.21-year mean periodicity for the speed and 10.30-year for the dynamic pressure. We speculate that the different periodicities of the solar wind parameters with respect to the solar 11-year cycle may be related to the overall observed temporal evolution of the time lags. Finally, by accounting for them, we obtain empirical relations that link the amplitude of the Ca II K index to the two solar wind parameters. [ABSTRACT FROM AUTHOR]

The Venus Express Radio Science Experiment (VeRa) was part of the scientific payload of the Venus Express (VEX) spacecraft and was targeted at the investigation of Venus' atmosphere, surface, and gravity field as well as the interplanetary medium. This paper describes the methods and the required calibrations applied to VEX-VeRa raw radio occultation data used to retrieve vertical profiles of Venus' ionosphere and neutral atmosphere. In this work we perform an independent analysis of a set of 25 VEX, single-frequency (X-band), occultations carried out in 2014, recorded in open-loop at the NASA Deep Space Network. Our temperature, pressure and electron density vertical profiles are in agreement with previous studies available in the literature. Furthermore, our analysis shows that Venus' ionosphere is more influenced by the day/night condition than the latitude variations, while the neutral atmosphere experiences the opposite. Our scientific interpretation of these results is based on two major responsible effects: Venus' high thermal inertia and the zonal winds. Their presence within Venus' neutral atmosphere determine why in these regions a latitude dependence is predominant on the day/night condition. On the contrary, at higher altitudes the two aforementioned effects are less important or null, and Venus' ionosphere shows higher electron density peaks in the probed day-time occultations, regardless of the latitude. [ABSTRACT FROM AUTHOR]

The relationship of auroral activity indices (AE, Kp, SME) with interplanetary medium parameters during the main phase of magnetic storms is studied. For the period 1990–2020, 142 magnetic storms driven by (41) Sheath, (61) CIR, and (40) ICME events are selected. It is found that the correlation coefficient between average values of the SME index and the SW electric field for Sheath (r = 0.75) is close to correlation coefficients for CIR and ICME events. The correlation coefficient between Kp aver &Esw aver (r = 0.72) is higher than the correlation coefficient between AE aver &Esw aver (r = 0.63) at the main phase of magnetic storms induced by the Sheath events. It is shown that average values of SW dynamic pressure and IMF σB fluctuations correlate each other for all types of SW. [ABSTRACT FROM AUTHOR]

• Ionospheric disturbances over Brazilian and African due to CME, using magnetometer and VTEC. • Positive ionospheric disturbances during the geomagnetic storm main phase over Brazil and Africa. • EIA was disturbed in the American and African sectors during the main phase of the geomagnetic storm. • The EIA over the Brazilian sector was more disturbed than the African sector. Coronal mass ejection (CME) occurs when there is an abrupt release of a large amount of solar plasma, and this cloud of plasma released by the Sun has an intrinsic magnetic field. In addition, CMEs often follow solar flares (SF). The CME cloud travels outward from the Sun to the interplanetary medium and eventually hits the Earth's system. One of the most significant aspects of space weather is the ionospheric response due to SF or CME. The direction of the interplanetary magnetic field, solar wind speed, and the number of particles are relevant parameters of the CME when it hits the Earth's system. A geomagnetic storm is most geo-efficient when the plasma cloud has an interplanetary magnetic field southward and it is accompanied by an increase in the solar wind speed and particle number density. We investigated the ionospheric response (F-region) in the Brazilian and African sectors during a geomagnetic storm event on September 07–10, 2017, using magnetometer and GPS-TEC networks data. Positive ionospheric disturbances are observed in the VTEC during the disturbed period (September 07–08, 2017) over the Brazilian and African sectors. Also, two latitudinal chains of GPS-TEC stations from the equatorial region to low latitudes in the East and West Brazilian sectors and another chain in the East African sector are used to investigate the storm time behavior of the equatorial ionization anomaly (EIA). We noted that the EIA was disturbed in the American and African sectors during the main phase of the geomagnetic storm. Also, the Brazilian sector was more disturbed than the African sector. [ABSTRACT FROM AUTHOR]

Magnetic helicity, an intrinsic property of eruptive helical flux ropes (FRs) forming coronal mass ejections (CMEs), plays an important role in determining CME geoeffectiveness. In the solar atmosphere and heliosphere, helicity remains conserved in a closed volume. Considering this fact as a basis of our study, we perform a quantitative comparison between total magnetic helicity and twisted flux in interplanetary CMEs and those transported to CMEs via magnetic reconnection at low corona. At the source, twisted/poloidal flux ( ϕ pcme ) of CMEs is directly estimated from total reconnection flux, and CME helicity ( H cme ) is obtained by combining reconnection flux information with CME physical parameters. At 1 AU, the twisted/poloidal flux ( ϕ pmc ) and helicity ( H mc ) of CMEs are obtained from in situ observations. Considering uncertainties steaming from FR length, reconnection flux and CME physical parameter estimations, poloidal flux and helicity of CMEs at 1 AU are found to be highly relevant ( ϕ pmc ϕ pcme = 0.4–1.5, H mc H cme = 0.3–1) to low-corona magnetic reconnection at the wake of CMEs. This result remains unchanged despite CME association with pre-existing FRs. We show that a significant reduction in CME helicity during its heliospheric propagation may result from a high rate of FR erosion in the interplanetary medium. Our event analysis confirms that CME's intrinsic magnetic properties are transported to CME FRs during magnetic reconnection at sheared coronal arcades. A one-to-one correspondence between the chirality of 1-AU CMEs and their pre-eruptive structures complies with the fact that the sense of field line rotations in FRs may remain unchanged during coronal reconnection at the source. By connecting intrinsic magnetic properties of FRs through Sun-Earth medium, this study provides important implications for the origin of geoeffectiveness in CMEs. [ABSTRACT FROM AUTHOR]

The interplanetary magnetic field magnitude B o , proton density N p and solar wind speed V sw data from Ulysses spacecraft during its interplanetary cruise interval from Earth to Jupiter, from 18 November 1990 to 31 January 1992, are analyzed in this study. Statistical and wavelet techniques are employed to characterize some properties from the solar wind parameters near the ecliptic plane and their dependence with radial distance. The results from kurtosis analysis showed that the three solar wind parameters (B o , N p and V sw) presented a decrease of this statistical quantity with the increase of scales, indicating that these variables are intermittent in short time scales. Further, the kurtosis parameter presented an increase in all scales around 2–3 AU distance range that corresponds to a solar wind regime transition. It was noted that the interplanetary medium was dominated by solar transients (interplanetary coronal mass ejections) until the middle of 1991. Afterwards a more stable pattern of corotating interaction regions arose. Furthermore, the probability distribution functions presented a spreading shape due to the occurrence of intermittence. In order to study the temporal variability of the solar wind parameters, the wavelet approach was used. The following major periodicities were found for the three solar wind variables studied: ~13, ~26, and ~83–88 days. It was noted that the ~13 day periods presented strong spectral power in the 2 to 4 AU range, where the solar wind was dominated by ICME transients. On the other hand, the 26 day period shows higher spectral power for distances higher than 4 AU, where the interplanetary space is more dominated by CIRs. Thus, it was found in this paper a significant dependence of solar wind parameters on radial heliocentric distance which can be accounted by the dynamical evolution of solar wind structures with distance. [ABSTRACT FROM AUTHOR]

Abstract In the present paper dependences of substorm activity on the solar wind velocity and southward component (Bz) of interplanetary magnetic field (IMF) during the main phase of magnetic storms, induced by the CIR and ICME events, is studied. Strong magnetic storms with close values of Dst min ≈ −100 ± 10 nT are considered. For the period of 1979–2017 there are selected 26 magnetic storms induced by the CIR and ICME (MC + Ejecta) events. It is shown that for the CIR and ICME events the average value of the AE index (AE aver) at the main phase of magnetic storm correlates with the solar wind electric field. The highest correlation coefficient (r = 0.73) is observed for the magnetic storms induced by the CIR events. It is found that the AE aver for magnetic storms induced by ICME events, unlike CIR events, increases with the growth of average value of the southward IMF Bz module. The analysis of dependence between the AE aver and average value of the solar wind velocity (Vsw aver) during the main phase of magnetic storm shows that in the CIR events, unlike ICME, the AE aver correlates on the Vsw aver. [ABSTRACT FROM AUTHOR]

Abstract This paper presents an improved understanding of the interaction of hybrid optimization method with variable low-thrust trajectory optimization requirements. To analyze fuel-optimal bang-bang control problem, a new version of homotopic algorithm, termed robust homotopic method, is investigated with the prospect of improving the efficiency and automation of the homotopic approach to achieve a high-level of robustness, and consequently enlarge its range of application. Such desired characteristics are promoted via a combination of several techniques. As an effective approach, a modified methodology of the switching detection process is presented for the bang-bang optimal-control problem. Moreover, the value of unknown costates and switching functions are mapped to new normalized intervals throughout the computational process. As a result, the optimal solution is rapidly designed to obtain the global robust-convergence to satisfy all constraints without any ambiguity. The fitting process of all iterations robustly find the unknown variables with the percent of converged solutions to maximum, and the penalty terms are quickly satisfied with predetermined high-accuracy, from the energy-optimal to the fuel-optimal solution, especially close to zero point as a critical point. Accordingly, two advanced interplanetary trajectories are optimized using two dynamic modeling approaches for the instantaneous and constant maximal thrust magnitude as a way to analyze and substantiate the robustness of the proposed algorithm. Results and performances are compared with existing solutions of the same mission problem. [ABSTRACT FROM AUTHOR]

Abstract The MASCOT lander currently flying on-board of the Japanese Hayabusa2 spacecraft, both set to explore the C-type Near-Earth Asteroid (162173) Ryugu, is not the first, but certainly one of the more complex nanolander systems having been designed for being carried along a bigger interplanetary spacecraft. Other concepts and current missions have shown the attractiveness of the class of nanosystems now increasing its application range from Earth orbiting cubesats to interplanetary scientific exploration endeavors, from orbiting to landing missions. This paper is intended to investigate nanolander options derived based on the MASCOT lander concept. For this purpose we gather interesting target bodies and analyze their respective environmental properties as well as their influence on the nanolander design, for example the landing system, the surface mobility, the power subsystem and the communication architecture. Further, an expansion of the scientific objectives of the current MASCOT lander from geological surface scout to other scientific objectives opens a range of new possibilities. For deeper analysis on this, we provide an overview over possible alternative payloads to the ones already flying on MASCOT and analyze their influence on the system design as it is. Obviously, the experience that has been gained with MASCOT provides us with a head start for future missions, if it is properly exploited. With this paper we intend to recommend MASCOT type of nanolanders for a range of possible future applications. [ABSTRACT FROM AUTHOR]

Highlights • We show the immediate fractional escape for species of mass <50 AMU at primary bodies <10,000 km in radius. • We compare escape fractions of volatiles escaping via two different sputter functions. • We present specific studies for Ceres, the Moon and Mercury. Abstract The study of exospheres can help us understand the long-term loss of volatiles from planetary bodies due to interactions of planets, satellites, and small bodies with the interplanetary medium, solar radiation, and internal forces including diffusion and outgassing. Recent evidence for water and OH on the Moon has spurred interest in processes involving chemistry and sequestration of volatile species at the poles and in voids. In recent years, NASA has sent spacecraft to asteroids including Vesta and Ceres, and ESA sent Rosetta to comet 67P/Churyumov–Gerasimenko and the asteroids Lutetia and Steins. Japan's Hayabusa spacecraft returned a sample from asteroid Itakowa, and OSIRIS-REX will return a sample from a primitive asteroid, Bennu, to Earth. In a surface-bounded exosphere, the gases are derived from the surface and thus reflect the composition of the body's regolith, although not in a one-to-one ratio. Observation of an escaping exosphere, termed a corona, is challenging. We have therefore embarked on a parametrical study of exospheres as a function of mass of the exospheric species, mass of the primary body and source velocity distribution, specifically thermal (Maxwell-Boltzmann) and sputtering. The goal is to provide a quick look to determine under what conditions and for what mass of the primary body the species of interest are expected to be bound or escaping and to quickly estimate the observability of exospheric species. This work does not provide a comprehensive model but rather serves as a starting point for further study. These parameters will be useful for mission planning as well as for students beginning a study of planetary exospheres. [ABSTRACT FROM AUTHOR]

The Earth and the near interplanetary medium are affected by the Sun in different ways. Those processes generated in the Sun that induce perturbations into the Magnetosphere-Ionosphere system are called geoeffective processes and show a wide range of temporal variations, like the 11-year solar cycle (long term variations), the variation of ∼27 days (recurrent variations), solar storms enduring for some days, particle acceleration events lasting for some hours, etc. In this article, the periodicity of ∼27 days associated with the solar synodic rotation period is investigated. The work is mainly focused on studying the resulting 27-day periodic signal in the magnetic activity, by the analysis of the horizontal component of the magnetic field registered on a set of 103 magnetic observatories distributed around the world. For this a new method to isolate the periodicity of interest has been developed consisting of two main steps: the first one consists of removing the linear trend corresponding to every calendar year from the data series, and the second one of removing from the resulting series a smoothed version of it obtained by applying a 30-day moving average. The result at the end of this process is a data series in which all the signal with periods larger than 30 days are canceled. The most important characteristics observed in the resulting signals are two main amplitude modulations: the first and most prominent related to the 11-year solar cycle and the second one with a semiannual pattern. In addition, the amplitude of the signal shows a dependence on the geomagnetic latitude of the observatory with a significant discontinuity at approx. ±60°. The processing scheme was also applied to other parameters that are widely used to characterize the energy transfer from the Sun to the Earth: F10.7 and Mg II indices and the ionospheric vertical total electron content (vTEC) were considered for radiative interactions; and the solar wind velocity for the non-radiative interactions between the solar wind and the magnetosphere. The 27-day signal obtained in the magnetic activity was compared with the signals found in the other parameters resulting in a series of cross-correlations curves with maximum correlation between 3 and 5 days of delays for the radiative and between 0 and 1 days of delay for the non-radiative parameters. This result supports the idea that the physical process responsible for the 27-day signal in the magnetic activity is related to the solar wind and not to the solar electromagnetic radiation. [ABSTRACT FROM AUTHOR]

Classification and quantification of the interplanetary structures causing intense geomagnetic storms (Dst ≤ −100 nT) that occurred during 1997–2016 are studied. The subject of this consists of solar wind parameters of seventy-three intense storms that are associated with the southward interplanetary magnetic field. About 30.14% of the storms were driven by a combination of the sheath and ejecta (S + E), magnetic clouds (MC) and sheath field (S) are 26% each, 10.96% by combined sheath and MCs (S + C), while 5.48% of the storms were driven by ejecta (E) alone. Therefore, we want to aver that for storms driven by: (1) S + E. The Bz is high (≥10 nT), high density ( ρ ) (>10 N/cm 3 ), high plasma beta (β) (>0.8), and unspecified (i.e. high or low) structure of the plasma temperature ( T ) and the flow speed (V); (2) MC. The Bz is ≥10 nT, low temperature (T ≤ 400,000 K), low ρ (≤10 N/cm 3 ), high V (≥450 km), and low β (≤0.8); (3) The structures of S + C are similar to that of MC except that the V is low ( V  ≤ 450 km); (4) S. The Bz is high, low T , high ρ , unspecified V , and low β ; and (5) E. Is when the structures are directly opposite of the one driven by MCs except for high V . Although, westward ring current indicates intense storms, but the large intensity of geomagnetic storms is determined by the intense nature of the electric field strength and the Bz. Therefore, great storms (i.e. Dst ≤ −200 nT) are manifestation of high electric field strength (≥13 mV/m). [ABSTRACT FROM AUTHOR]

The kinematics of coronal mass ejection (CME) in the interplanetary medium is very important in the concept of space-weather. Main aim of this paper is to study the propagation of four major geo-effective CMEs and their associated shocks observed in solar cycle 24. The arrival of interplanetary shocks and CMEs of these events near the Earth is seen from the ACE/wind in situ data available in OMNI data base. The CMEs considered in this study have a wide range of initial speeds 500–1900 km/s in the LASCO field of view, comprising of two slow CMEs ( V ∼ 500 km/s), one fast CME ( V ∼ 1800 km/s) and one moderate speed CME ( V ∼ 800 km/s). The observed transit time of these events are compared with transit time estimated using the empirical shock arrival model (ESA). Especially, we utilize (i) different acceleration – speed equations reported in the literature from the observations made in the last few decades and (ii) various acceleration cessation distances ( Acd ) In addition, we compared the estimated and observed transit time with that from the Drag Based Model (DBM). From the result of this analysis, we demonstrated that each CME behaves in its own way in the interplanetary medium and their propagation is governed by the CME initial speed, interplanetary acceleration and acceleration cessation distances. In the present paper, we found (i) which acceleration equation is better for the transit time calculations (ii) importance of the CME acceleration cessation distances (iii) reducing the transit time error in CME forecasting. Based on these results and on Zhao and Dryer (2014) review (that included physics-based models), the realistic statistics should be based on real-time studies, not on post-mortem case studies. [ABSTRACT FROM AUTHOR]

Abstract: The Earth’s magnetosphere response to interplanetary medium conditions on January 21–22, 2005 and on December 14–15, 2006 has been studied. The analysis of solar wind parameters measured by ACE spacecraft, of geomagnetic indices variations, of geomagnetic field measured by GOES 11, 12 satellites, and of energetic particle fluxes measured by POES 15, 16, 17 satellites was performed together with magnetospheric modeling based in terms of A2000 paraboloid model. We found the similar dynamics of three particle populations (trapped, quasi-trapped, and precipitating) during storms of different intensities developed under different external conditions: the maximal values of particle fluxes and the latitudinal positions of the isotropic boundaries were approximately the same. The main sources caused RC build-up have been determined for both magnetic storms. Global magnetospheric convection controlled by IMF and substorm activity driven magnetic storm on December 14–15, 2006. Extreme solar wind pressure pulse was mainly responsible for RC particle injection and unusual January 21, 2005 magnetic storm development under northward IMF during the main phase. [Copyright &y& Elsevier]

Abstract: We have analyzed 101 Coronal Mass Ejection (CME) events and their associated interplanetary CMEs (ICMEs) and interplanetary (IP) shocks observed during the period 1997–2005 from the list given by Mujiber Rahman et al. (2012). The aim of the present work is to correlate the interplanetary parameters such as, the speeds of IP shocks and ICMEs, CME transit time and their relation with CME parameters near the Sun. Mainly, a group of 10 faster CME events (V INT >2200km/s) are compared with a list of 91 normal events of Manoharan et al. (2004). From the distribution diagrams of CME, ICME and IP shock speeds, we note that a large number of events tends to narrow towards the ambient (i.e., background) solar wind speed (∼500km/s) in agreement with the literature. Also, we found that the IP shock speed and the average ICME speed measured at 1AU are well correlated. In addition, the IP shock speed is found to be slightly higher than the ICME speed. While the normal events show CME travel time in the range of ∼40–80h with a mean value of 65h, the faster events have lower transit time with a mean value of 40h. The effect of solar wind drag is studied using the correlation of CME acceleration with interplanetary (IP) acceleration and with other parameters of ICMEs. While the mean acceleration values of normal and faster CMEs in the LASCO FOV are 1m/s2, 18m/s2, they are −1.5m/s2 and −14m/s2 in the interplanetary medium, respectively. The relation between CME speed and IP acceleration for normal and faster events are found to agree with that of Lindsay et al. (1999) and Gopalswamy et al. (2001) except slight deviations for the faster events. It is also seen that the faster events with less travel time face higher negative acceleration (>−10m/s2) in the interplanetary medium up to 1AU. [Copyright &y& Elsevier]

Abstract: In this work it is discussed the possibility of a fine-tuneable contribution to the two way Doppler acceleration either towards, either outwards a given central mass by considering a background described by an expanding locally anisotropic (ELA) metric. This metric encodes both the standard local Schwarzschild gravitational effects and the cosmological Universe expansion effects allowing simultaneously to fine-tune other gravitational effects at intermediate scales, which may be tentatively interpreted as a covariant parameterization of either cold dark matter, either gravitational interaction corrections. In particular are analysed the possible measurable effects on the outskirts of the Solar system, for heliocentric distances above , and are derived bounds for the ELA metric functional parameter by considering the bounds on the deviation from standard General Relativity on Schwarzschild backgrounds imposed by the current updated limits for the Pioneer anomaly, taking in consideration both the natural outgassing and on-board radiation pressure, resulting in an average Doppler acceleration outwards the Sun of . It is also computed the mass–energy density for the ELA metric within the bounds obtained and are discussed the respective contributions to the cosmological density parameter which, for compatibility with the model, are included in the cosmological relative density of cold dark matter (). [Copyright &y& Elsevier]

Abstract: We have analyzed 101 CMEs, and their associated ICMEs and interplanetary (IP) shocks observed during the period 1997–2005. The main aim of the present work is to study the interplanetary characteristics of metric and DH type II associated CMEs such as, shock strength, IP shock speed, ICME speed, stand off distance and transit time. Among these 101 CMEs, 38 events show both metric and DH type II bursts characteristics. There are no metric and DH type II association for 52 events. While DH type II alone is found in 7 cases, metric type II alone is found in 4 events. It is found that the mean speeds of CMEs increase progressively from CMEs without type II events to CMEs associated with metric and DH type IIs as suggested by . In addition, we found that the speeds of ICMEs and IP shocks progressively increase in the following order: events without metric and DH type IIs, events with metric alone, events with DH alone and events with both metric and DH type IIs. Similarly the Mach number is found to increase in the same order. While there is not much change in the stand-off distance among these cases, it is minimum (∼18R⊙) for CMEs with speed greater than 2200km/s. The above results confirm that more energetic CMEs can produce both metric and DH type IIs for which the interplanetary parameters such as mean values of ICME speed and IP shock speed and Mach number are found to be higher. [Copyright &y& Elsevier]

Abstract: The orbit of a solar sail can be controlled by changing the attitude of the spacecraft. In this study, we consider the spinning solar power sail IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), which is managed by Japan Aerospace Exploration Agency (JAXA). The IKAROS attitude, i.e., the direction of its spin-axis, is nominally controlled by the rhumb-line control method. By utilizing the solar radiation torque, however, we are able to change the direction of the spin-axis by only controlling its spin rate. With this spin rate control, we can also control indirectly the solar sail’s trajectory. The main objective of this study is to construct the orbit control strategy of the solar sail via the spin-rate control method. We evaluate this strategy in terms of its propellant consumption compared to the rhumb-line control method. Finally, we present the actual flight attitude data of IKAROS and the change of its trajectory. [Copyright &y& Elsevier]

Abstract: The propagation of a strong cylindrical shock wave in an ideal gas with azimuthal magnetic field, and with or without axisymmetric rotational effects, is investigated. The shock wave is driven out by a piston moving with time according to power law. The ambient medium is assumed to have radial, axial and azimuthal component of fluid velocities. The fluid velocities, the initial density and the initial magnetic field of the ambient medium are assumed to be varying and obey power laws. Solutions are obtained, when the flow between the shock and the piston is isothermal. The gas is assumed to have infinite electrical conductivity and the angular velocity of the ambient medium is assumed to be decreasing as the distance from the axis increases. It is expected that such an angular velocity may occur in the atmospheres of rotating planets and stars. The shock wave moves with variable velocity and the total energy of the wave is non-constant. The effects of variation of the initial density and the Alfven-Mach number on the flow-field are obtained. A comparison is also made between rotating and non-rotating cases. [Copyright &y& Elsevier]

Abstract: For long duration interplanetary manned missions the protection of astronauts from cosmic radiation is an unavoidable problem that has been considered by many space agencies. In Europe, during 2002–2004, the European Space Agency supported two research programs on this thematic: one was the constitution of a dedicated study group (on the thematic ‘Shielding from cosmic radiation for interplanetary missions: active and passive methods’) in the framework of the ‘life and physical sciences’ report, and the other an industrial study concerning the ‘radiation exposure and mission strategies for interplanetary manned missions to Moon and Mars’. Both programs concluded that, outside the protection of the magnetosphere and in the presence of the most intense and energetic solar events, the protection cannot rely solely on the mechanical structures of the spacecraft, but a temporary shelter must be provided. Because of the limited mass budget, the shelter should be based on the use of superconducting magnetic systems. For long duration missions the astronauts must be protected from the much more energetic galactic cosmic rays during the whole mission period. This requires the protection of a large habitat where they could live and work, and not the temporary protection of a small volume shelter. With passive absorbers unable to play any significant role, the use of active shielding is mandatory. The possibilities offered by superconducting magnets are discussed, and recommendations are made about the needed R&D. The technical developments that have occurred in the meanwhile and the evolving panorama of possible near future interplanetary missions, require revising the pioneering studies of the last decades and the adoption of a strategy that considers long lasting human permanence in ‘deep’ space, moreover not only for a relatively small number of dedicated astronauts but also for citizens conducting there ‘normal’ activities. [Copyright &y& Elsevier]

Abstract: Earth-directed interplanetary shocks associated with coronal mass ejections (CMEs) are known to have a severe impact on the magnetosphere, causing strong geomagnetic storms and substorms. Hence, early detection of such shocks is important. Here we study the feasibility of radar detection of interplanetary shocks. We consider a scattering mechanism, which is based on the induced scattering of a radar wave by anisotropic Langmuir turbulence, being generated by the shock-accelerated electrons. The problem is studied for an arbitrary angle between the electron beam and the incident radar wave, , and special emphasis is put on the study of a dependence of the scattering process on this angle. We obtain and analyze analytical expressions for the frequency shift, scattering cross-section of the turbulence, coefficient of absorption (due to scattering), and the optical depth. We show that the detection of such shocks is possible if the turbulence energy density exceeds (nT is the thermal energy density of a plasma), which is quite realistic according to our estimations. The altitudes in the solar corona where reflections may occur depend on the angle . If expressed in local plasma frequencies, , the altitudes span is for for , where is a frequency of the transmitted radar wave. Thus the scattering occurs much closer to the radar in the second case than in the first. Detection of the scattered signal, in the general case, requires a remote receiver, since the radar wave backscatters only for . [Copyright &y& Elsevier]

Abstract: In this article, we study fast shocks at CIR boundaries during an extended interval of 15 consecutive major high speed solar wind streams in 1992–1993. Ulysses was 4–5AU from the sun. The Abraham-Schrauner shock normal method and the Rankine-Hugoniot relations were used to determine fast shock directions and speeds. Out of 33 potential CIR shocks, 14 were determined to be fast forward shocks (FSs) and 14 were fast reverse shocks (RSs). Of the remaining 5 events, 2 were forward waves and 3 were reverse waves. CIR edges at latitudes below ∼30o were, for the most part, bounded by fast magnetosonic shocks. The forward shocks were generally quasi-perpendicular (average θnBo =67o). The reverse shocks were more oblique (average θnBo =52o), but they extended to all angles. Both FSs and RSs had magnetosonic Mach numbers ranging from 1 to 5 or 6. The average Mach numbers were 2.4 and 2.6 for FSs and RSs, respectively. The shock Mach numbers were noted to generally decrease with increasing latitude. The non-shock events or waves were noted to occur preferentially at high (∼−30° to −35°) heliolatitudes where stream-stream interactions were presumably weaker. These results are consistent with expectations, indicating the general accuracy of the Abraham-Schrauner technique. [Copyright &y& Elsevier]

Abstract: During the first half of November 2004, many solar flares and coronal mass ejections (CMEs) were associated with solar active region (AR) 10696. This paper attempts to identify the solar and interplanetary origins of two superstorms which occurred on 8 and 10 November with peak intensities of Dst=−373nT and −289nT, respectively. Southward interplanetary magnetic fields within a magnetic cloud (MC), and a sheath+MC were the causes of these two superstorms, respectively. Two different CME propagation models [Gopalswamy, N., Yashiro, S., Kaiser, M.L. et al. Predicting the 1-AU arrival times of coronal mass ejections. J. Geophys. Res. 106, 29207–29219, 2001; Gopalswamy, N.S., Lara, A., Manoharan, P.K. et al. An empirical model to predict the 1-AU arrival of interplanetary shocks. Adv. Space Res. 36, 2289–2294, 2005] were employed to attempt to identify the solar sources. It is found that the models identify several potential CMEs as possible sources for each of the superstorms. The two Gopalswamy et al. models give the possible sources for the first superstorm as CMEs on 2330UT 4 November 2004 or on 1454UT 5 November 2004. For the second superstorm, the possible solar source was a CME that on 0754UT 5 November 2004 or one that occurred on 1206UT 5 November 2004. We note that other propagation models sometimes agree and other times disagree with the above results. It is concluded that during high solar/interplanetary activity intervals such as this one, the exact solar source is difficult to identify. More refined propagation models are needed. [Copyright &y& Elsevier]

Abstract: Cometary dust trails were first observed by IRAS; they are widely known to be the origins of meteoric showers. A new window has been opened for the study of dust trails, using ground-based observations. We succeeded in obtaining direct images of the 22P/Kopff dust trail with the Kiso 1.05-m Schmidt telescope. Following this initial success, we have continued to perform a dust trail survey at Kiso. As a result of this survey, we have detected dust trails along the orbit of six periodic comets, between February 2002 and March 2004. The optical depth of these dust trails are 10−9 to 10−8, which is consistent with IRAS measurements. In this paper, we describe the observations and data reduction procedures, and report the brief result obtained between February 2002 and March 2004. [Copyright &y& Elsevier]

Abstract: The average mass of dust per volume in space equals that of the solar wind so that the interplanetary medium should provide an obvious region to study dust plasma interactions. While dust collective behavior is typically not observed in the interplanetary medium, the dust component rather consists of isolated grains screened by and interacting with the plasma. Space measurements have revealed several phenomena possibly resulting from dust plasma interactions, but most of the dust plasma interactions are at present not quantified. Examples are the production of neutrals and pick-up ions from the dust, dust impact generated field variations at spacecraft and magnetic field variations possibly caused by solar wind interacting with dust trails. Since dust particles carry a surface charge, they are exposed to the Lorentz force in the interplanetary magnetic field and for grains of sub-micrometer sizes acceleration can be substantial. [Copyright &y& Elsevier]

Abstract: Ground cosmic ray observations are used for studying several kinds of interplanetary structures. The cosmic ray data has different responses to each kind of interplanetary structure. This article has as objective to study cosmic ray muon and neutron signatures due to the passage of corotating interaction region (CIR) in the interplanetary medium, and identify the signatures in the cosmic ray data due to these events. The cosmic ray muon data used in this work are recorded by the multidirectional muon detector installed at INPE’s Observatório Espacial do Sul – OES/CRSPE/INPE-MCT, in São Martinho da Serra, RS (Brazil) and the neutron data was recorded by the neutron monitor installed in Newark (USA). The CIR events were selected in the period from 2001 to 2004. CIRs clearly affect cosmic ray density in the interplanetary medium in the Earth’s vicinity, where the magnetic field plays an important role. [Copyright &y& Elsevier]

Abstract: The STEREO mission, launched on October 25 2006, will provide the first stereoscopic view of the Sun and its magnetic environment. A suite of identical instruments on two continuously separating spacecraft will monitor the onset of solar eruptive phenomena, and track them as the shocks and ejected material propagate through the interplanetary medium (IPM). The combination of remote sensing and in situ instrumentation will provide new insights into the onset of eruptions, the extent of their effects on the global structure of the low corona, and their subsequent evolution through the IPM. These observations will provide new constraints on the processes involved and allow us to distinguish between competing models of eruptive solar phenomena. [Copyright &y& Elsevier]

Abstract: An ultraviolet–visible spectrum between 300 and 450nm of a cometary meteoroid originated from 55P/Tempel-Tuttle was investigated. The spectroscopy was carried out an intensified high definition TV camera with a slit-less reflection grating during the 2001 Leonid meteor shower over Japan. A best fit calculation mixed with atoms and molecules confirmed the first discovery of bands in the UV meteor spectrum. temperature was estimated to 10,000K with a low number density of 1.55×105 cm−3. We also discuss the possibility that enhanced emissions in a meteor and a train around 310nm are caused by the band head of OH A 2Σ+ → X 2Π. Since cometary dust may have contributed organics and water to the Earth from its early period until now, OH A–X (0,0) must be investigated. [Copyright &y& Elsevier]

Abstract: The effect of interplanetary propagation on the energy dependence of the iron mean ionic charge of solar cosmic rays is investigated. The diffusion–convection transport equation is solved numerically making use of a Monte-Carlo approach. The interplanetary propagation results in a shift of charge spectra towards lower energies due to adiabatic deceleration which becomes stronger as the particles’ scattering mean free path decreases. Taking the above effect into account, we compare predictions of our model of charge-consistent stochastic acceleration with recent ACE observations. A detailed analysis of two particle events shows that our model can give a consistent explanation of the observed iron charge and energy spectra, and allows to put constrains on the temperature, density, and the acceleration and escape time scales in the acceleration region. [Copyright &y& Elsevier]

Abstract: A Magnetosheath – interplanetary medium (MIPM) reference frame is introduced to study various dynamical processes in the region between the planetary bow shock and the magnetosphere. The MIPM reference frame uses recently developed analytical models to determine the bounding magnetopause and bow shock surfaces, and a fractional distance across the magnetosheath. The inputs of the model are the magnetic field and solar wind plasma parameters measured in the interplanetary medium. Angular coordinates of the MIPM reference frame (zenith and clock angles) correspond to those used in the geocentric interplanetary medium (GIPM) frame. The MIPM reference frame is applied then for a statistical study of the frequency of mirror type magnetic field depressions (linearly polarized, relatively large amplitude and symmetric shape) in the terrestrial magnetosheath based on the 10 years long 4s resolution ISEE-1 magnetic field observations. It was found that these events most frequently occurred in the inner regions of the magnetosheath: close to the magnetopause at larger zenith angles and closer to the middle of the sheath in the subsolar region. Mirror type depressions were least frequently observed in the ‘dawn’ magnetosheath of the MIPM reference frame (downstream of the quasiparallel part of the bow shock), but their relative intensity was the largest in this region. The relative intensity of mirror type depressions was smaller in magnetosheath regions located closer to the bow shock and farther away from the subsolar point. These results suggest that pressure anisotropy raising downstream of quasiperpendicular bow shocks is favorable for the generation of mirror mode waves in addition to magnetic field draping at the magnetopause. [Copyright &y& Elsevier]

Abstract: The L5 point is a promising location for forecasting co-rotating high-speed streams in the solar wind arriving at the Earth. We correlated the solar wind data obtained by the Nozomi spacecraft in interplanetary space and by the Advanced Composition Explorer (ACE) at the L1 point, and found that the correlation is significantly improved from that of the 27-day recurrence of ACE data. Based on the correlation between the two spacecraft observations, we estimated the correlation of the solar wind velocity between the L5 point and at the Earth, and found that the correlation coefficient was about 0.78 in late 1999, while that of the 27-day recurrence was 0.51. Eighty-eight percent of the velocity difference falls within 100km/s between the L5 point and the Earth. This demonstrates the potential capability of solar wind monitoring at the L5 point to forecast the geomagnetic disturbances 4.5 days in advance. [Copyright &y& Elsevier]

Abstract: We consider the scientific aims and features of the Radio Plasma Waves (RPW) Analyzer on board the future mission Solar Orbiter. We emphasise on the solar radio observations in particular at hectometric, decametric and metric wavelengths. Two main parts are reviewed and re-examined: the classic observed spectral features and the main constraints due to the observational conditions on the ground and in space. We show that the RPW experiment is an excellent challenge and a good opportunity towards a better comprehension of the solar corona physics. Three main aspects are discussed: the micro-scale phenomenon, the propagation modes of the radio waves, and the localization of the radiation source regions. [Copyright &y& Elsevier]

Abstract: Magnetic clouds are the interplanetary manifestation of coronal mass ejections, which are transient expulsions of major quantities of magnetized plasma, from the Sun toward the heliosphere. The magnetic flux and helicity are two key physical magnitudes to track solar structures from the photosphere-corona to the interplanetary medium. To determine the content of flux and helicity in magnetic clouds, we have to know their 3D structure. However, since spacecrafts register data along a unique direction, several aspects of their global configuration cannot be observed. We present a method to estimate the magnetic flux and the magnetic helicity per unit length in magnetic clouds, directly from in situ magnetic observations, assuming only a cylindrical symmetry for the magnetic field configuration in the observed cross-section of the cloud. We select a set of 20 magnetic clouds observed by the spacecraft Wind and estimate their magnetic flux and their helicity per unit length. We compare the results obtained from our direct method with those obtained under the assumption of a helical linear force-free field. This direct method improves previous estimations of helicity in clouds. [Copyright &y& Elsevier]

WIND solar wind data and POLAR UV imaging data are used to study magnetospheric responses to interplanetary shocks. It is found that the solar wind preconditions determine the different auroral responses. A ∼ 1.5 hr “precondition” (upstream of the interplanetary shocks) gives good empirical results. If the upstream IMF Bz is strongly southward preceding interplanetary shocks, a substorm expansion phase results (44% of all events). If the IMF Bz is ∼ 0, pseudobreakups occur. If Bz is northward, there is no obvious resultant nightside geomagnetic activity. [Copyright &y& Elsevier]

Major disturbances of the interplanetary medium have a significant impact on cosmic ray flux and anisotropy, affecting the first harmonic as well as higher-order terms. Cosmic ray phenomena are observed not only during solar wind disturbances, but also prior to their arrival at Earth, and are thus of major importance to forecasting space weather. Using the worldwide network of neutron monitors, we have studied the cosmic ray anisotropy associated with major magnetic storms, mostly between 1978 and 1982. In this paper we discuss and illustrate their common features. [Copyright &y& Elsevier]

The nature and location of energetic particle acceleration (excluding planetary magnetospheres) in the inner heliosphere (< 6 A.U.) is controversial. A likely reason for this controversy is that some acceleration occurs in the interplanetary medium, some occurs at the site of solar flares and some occurs in the solar corona. Relativistic electrons are certainly accelerated at the Sun and they manifest themselves readily through the microwave and non-thermal X-ray emissions they produce. Electron acceleration also occurs in the corona near the Sun, and when this happens it is sometimes in association with fast coronal mass ejections. The role of strong shocks accompanying very fast (> 1000 km/sec) coronal mass ejections is examined, but we find that they are not normally associated with relativistic energetic particle acceleration, although they may enhance the energy of particles already present in the vicinity of the shock. There is no evidence that relativistic electron acceleration occurs in the interplanetary medium, except possibly for a very few isolated cases. A similar situation exists for the relativistic ions, although in this case the only electromagnetic signature they produce is gamma ray emission through nuclear interactions, which is not measured currently with high sensitivity. The extent of particle acceleration in the interplanetary medium in corotating interaction regions is only to sub-relativistic energies. Evidence to support these claims is reviewed. [Copyright &y& Elsevier]