Volatile loss from exoplanetary atmospheres and its possible implications for the longevity of habitable surface conditions is a topic of vigorous debate currently. The vast majority of the habitable zone terrestrial-like exoplanets known to date orbit low-mass M- and K-dwarf stars and are subject to the conditions drastically different to those of terrestrial planets in the Solar System. In particular, they orbit far closer to their host stars than similar planets around G-dwarfs similar to the Sun. Therefore they receive higher X-ray and UV fluxes, even though luminosities of M- and K-dwarfs are lower than those of heavier stars. Furthermore, due to their slower evolution, M-dwarfs retain high activity on the gigayear timescales. The combination of these two effects has led to claims that most terrestrial planets orbiting M-dwarfs may have their atmospheres stripped from the higher X-ray and UV fluxes of their host stars. Opposing this are researchers who point out that volatile inventories for terrestrial exoplanets are ill-constrained, and hence, they may be able to “weather the storm” of these higher X-ray and UV fluxes. In this article, we focus on exploring volatile loss in the upper atmospheres of terrestrial planets in our solar system and applications to those in exoplanetary systems around stars of different types.

The magnetosphere of Mercury is highly dynamic, a consequence of its small size, weak intrinsic magnetic field, and proximity to the Sun. One intriguing phenomenon is the presence of magnetic field fluctuations around 1 Hz. Here, we present a comprehensive statistical survey of these waves using the full span of the MESSENGER magnetometer measurements from 2011 to 2015. We find that ~1 Hz waves are observed during 10-20 % of the time that the spacecraft spent on closed field lines in Mercury’s magnetosphere, as determined from the KT17 magnetic field model. Wave occurrence is increased under magnetospheric conditions that favour an expanded closed field line region. We present the first global characterisation of the ~1 Hz waves at Mercury and demonstrate their dependence on both external drivers, such as upstream IMF conditions, and internal magnetospheric activity, such as the occurrence of identified dipolarization events. These results are discussed in the context of the BepiColombo mission, which will provide new opportunities to identify the nature of these waves and to assess their role in Mercury’s highly dynamic plasma environment.

The Venusian interaction with the solar wind leads to the formation of an induced magnetosphere structured by plasma boundaries. Their dynamics is complex, due to the combined influence of external (solar photons, solar wind plasma and interplanetary magnetic field (IMF)) and internal (ionized atmosphere) drivers. Studying these drivers helps understanding the transfer of energy and momentum throughout the Venusian system, and has thus implications for the erosion of the atmosphere through its coupling with the solar wind. We here analyze and rank the influence of the main drivers of the Venusian bow shock and ion composition boundary locations. We revisit the results by Signoles et al. (2023) based on Venus Express measurements by combining several methods such as the Akaike Information Criterion, Least Absolute Shrinkage Selection Operator regression, and partial correlations. These methods allow to investigate cross correlations that appear and can bias the interpretation, and allow to rank drivers with robust approaches. The bow shock appears primarily driven by the IMF intensity or Mach number, the IMF θ_bn angle separating quasi-perpendicular vs quasi-parallel shocks, and then the solar extreme ultraviolet fluxes and solar wind dynamic pressure (with little influence of the convective electric field induced asymmetries). The Ion Composition Boundary is primarily driven by extreme ultraviolet fluxes, with a more reduced influence of several solar wind parameters and IMF induced magnetic pileup asymmetries. We also compare the behaviors of both boundaries and then compare the bow shock driver rankings at Mars and Venus. Finally we propose an analysis of the drivers of the extreme bow shock and ion composition boundary excursions.

Solar Orbiter entered the topside ionosphere of Venus for the first time when performing its 4th flyby of the planet, reaching an altitude of 378 km on 18 Feb 2025. High-cadence electron density measurements showed previously unresolved fine-structuring within plasma regions and boundaries, particularly at the ionopause. During the rapid flyby, a rare snapshot of the entire induced magnetosphere was captured during calm solar wind conditions around solar maximum. A well-structured and a relatively steady plasma environment was observed. Assuming an electron temperature of 0.5 eV, pressure balance was found across the ionopause, while at the same time quasi-periodic density and magnetic field variations suggest boundary oscillations. Near closest approach, non-force free magnetic flux ropes were observed. Small-scale perturbations in both magnetic field strength and density across them indicate them being dynamically evolving, rather than in a stationary state.

The plasma environment of our neighboring planets, Venus and Mars, differs significantly from Earth’s. Although neither of them possesses a dominant intrinsic dipolar magnetic field, there are still induced magnetospheres forming around the two planets, due to the interaction of the solar wind and the interplanetary magnetic field (IMF) with their conductive ionospheres, exospheres, and the localized crustal magnetic fields in the case of Mars. Induced magnetospheres, their associated plasma environments, and the physical processes within them are particularly susceptible to the changing upstream conditions. The increasing number of successful and long-lived missions during the last few decades has been key for describing the fundamental structures and processes comprising the induced magnetospheres of the two planets. Nevertheless, their induced magnetotails have been more challenging to probe, due to the restrictions of the orbital geometry of planetary missions. Here, we present the latest discoveries and a comprehensive comparison between the Venusian and Martian induced magnetotails, and we highlight the need for further exploration of these regions. Atmospheric escape and energy transfer processes and paths are inextricably linked with the climate history and the disappearance of water at Mars, though there are many unknowns still in the case of Venus. Past and current missions utilizing particle and fields instruments have explored a great part of the plasma environments of Venus and Mars. Several plasma boundaries, shaped by both internal and external factors, divide the planetary environments and magnetospheres into different plasma regimes and have been described by observations and models. Simulations and observations have also been utilized to investigate the magnetotail structure of the two planets, which appears to be governed mainly by the IMF, the solar wind dynamic pressure, and the crustal magnetic fields in the case of Mars. At Mars, the presence of the crustal magnetic fields, which are regions of crustal magnetization on the surface of the planet clustered mostly in the southern hemisphere, further complicates the interaction of the solar wind and the IMF with the planet’s plasma environment, thus justifying the term ‘hybrid’ – instead of induced – that is often used to describe the Martian magnetosphere. The existence of a magnetotail twist, as well as a first approach on mapping the structure of the current systems, has been reported at Mars, whereas different types of magnetotail current sheet flapping motion have been observed at both Mars and Venus. The magnetic topology, which describes the morphology of closed, open, and draped magnetic field lines over a planet, has also been inferred and explained for both planets. Escape processes, escape rates and their response to space weather have been reported, and we now have a better idea of the differences between the two planets. Escaping structures, contributing with a bulk removal of plasma, have also been observed in their magnetotails. Nevertheless, much still remains unknown, for example the specifics of how individual processes respond to solar drivers. Mars and Venus are not the only solar system bodies with no global intrinsic magnetic field. Induced magnetotails are formed around Saturn’s moon Titan and comets too. A comparison between those bodies and Venus and Mars will provide a broader and general picture of induced and hybrid magnetotails, which could help future investigations of the plasma environments and tails of exoplanets. Lastly, in this review paper, we also summarize the questions that remain unanswered, emphasizing the need for future missions.

Venus’s induced magnetosphere is characterized by regions with different plasma and magnetic field properties, which are separated by plasma boundaries. These boundaries’ locations and shapes vary with upstream solar wind conditions, and these variations have been characterized by several previous studies. In this study, we developed quantitative parametric models of the bow shock and ion composition boundary (ICB), which allow us to determine the location and shape of the boundaries given a set of upstream conditions. To quantitatively model these boundaries, we used a database of boundary crossings derived from plasma and magnetic field measurements by Venus Express. We modeled the bow shock as a conic section curve, which depends on the interplanetary magnetic field (IMF) magnitude and the solar wind proton flux. Furthermore, we considered the shock normal angle, the angle between the IMF and the local shock normal vector, to describe a quasi-perpendicular/quasi-parallel shock asymmetry. We modeled the dayside ICB as a half sphere that depends solely on the solar EUV flux and the solar wind proton flux. These parametric models are compared with models that average over upstream conditions; our bow shock parametric model improves the prediction accuracy by 16% and the ICB parametric model by 6%.

The molecular dication, CO2++, was detected in the ionosphere of Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere and Volatile Evolution (MAVEN) mission [1]. This marked the first detection of a molecular dication in a planetary atmosphere. Results from photochemical models were compared with the observations with the modeled densities being significantly lower than the densities inferred from the observations. Here we show that a much better agreement between model results and observations is obtained when incorporating in the model the assumption that the ion is stable against unimolecular decay. We argue that this assumption not necessarily conflict with results from a storage ring experiment by Mathur et al. (1995) [Ref. 2]. Several modeling studies that cite [2] use a CO2++ lifetime against unimolecular decay of 4 s. This is, however, only a lower limit of the lifetime in question as the removal of the ions in the storage ring may have been strongly dominated by high energy collisions with residual gases. An experiment at a facility offering better (or variable) vacuum conditions could possible constraint the stability/longevity of CO2++.[1] Gu, H., Cui, J., Niu, D. D., et al. 2020, E&PP, 4, 396[2] Mathur, D., Andersen, L. H., Hvelplund, P., Kella, D., & Safvan, C. P. 1995, J Phys B At Mol Opt Phys, 28, 3415

On 8 January 2025, the ESA/JAXA BepiColombo mission flew by Mercury for the sixth time at an altitude of 295 km. The spacecraft took on a unique route through Mercury’s magnetic and particle environment, crossing the equator opposite the Sun on Mercury’s night side before flying over the planet’s north pole. During eclipse, in the cold shadow of the planet, as well as above the northern pole the spacecraft passed through regions where charged particles precipitate from the planet’s magnetic tail and from the solar wind towards its surface. We will detail the original electron observations obtained by the Mercury Electron Analyzer during Mercury’s sixth flyby, and compare and contrast them with electron observations obtained during previous BepiColombo flybys. All together, these new observations will provide new insights into the diversity of structures observed in these regions and the underlying mechanisms responsible for their formation and dynamics.

Although Venus appears to present a predominantly ionospheric obstacle to the solar wind, the magnetic connectivity between the solar wind and the Venus ionosphere, or magnetic topology, is important for characterizing the Venus space environment. In particular, magnetic connectivity is relevant to the magnetization state of the ionosphere, particle precipitation into the atmosphere causing ionization and auroral emissions, and planetary ion escape at Venus. The spatial distributions of different magnetic topologies were statistically analyzed, with some unexpected results. Here, we build on those results by investigating how the external factors of solar cycle phase and upstream conditions affect the occurrence rates of the three magnetic topologies and consider their implications regarding the state of Venus's induced magnetosphere. We find that both the solar cycle phase and upstream dynamic pressure variations control its expansion or contraction. Under solar minimum conditions, the interplanetary magnetic field (IMF) more deeply penetrates into the collisional atmosphere, increasing the occurrence rates of open and closed topologies at low altitudes and in Venus's wake. We also find hemispheric differences in the occurrences of dayside‐connected and nightside‐connected open fields, likely related to mass loading of the near‐Venus plasma environment by planetary pickup ions.

The ion composition of the Martian ionosphere is controlled by the ionisation of the neutral species (mainly CO2, CO and O) in the upper atmosphere and the chemical reactions that follow. The primary ions, CO2+ and O+, are reactive with O and CO2, respectively, as to produce O2+, which is the dominant ion species in the ionosphere. We apply a variety of simple chemical schemes to model the ion chemistry in the Martian dayside ionosphere using data from deep dip campaigns of the MAVEN mission. As model input we use concentrations of neutral species, as measured by the Neutral and Gas Ion Mass Spectrometer (NGIMS) onboard MAVEN, and solar EUV spectra measured by TIMED/SEE; extrapolated in distance and phase to Mars. We reach an adequate agreement between the calculated ion densities of the main ion species and those measured by NGIMS. However, the calculated ion composition does not fully match the measurements and deviations of up to a factor of 3-4 do prevail for some of the considered ion species. Several previous studies have solved similar issues by adjusting the input parameters to the calculations, such as increasing the neutral O density, reducing the neutral CO2 density or decreasing the solar irradiance. We present results from a thorough exploration of the involved parameter space and discuss possible reasons for still persisting model-observation discrepancies.

Atmospheric ion escape plays a crucial role in the evolution of planetary climate and habitability. While Mars has been the focus of extensive in-situ spacecraft observations, our understanding of ion escape at Mars has been constrained by single-point spacecraft measurements, which fail to distinguish spatial and temporal variability. Observations from NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) mission and China's Tianwen-1 mission provide complementary observations the Martian space environment and a unique opportunity to study the variability of ion escape. Here, we report that ion escape at Mars exhibits unexpected spatial-temporal variability under steady and weak external solar wind conditions. In the hemisphere where the solar wind electric field is directed toward the planet, a condition that usually hinders ion escape into space, we instead observe the transient appearance of escaping planetary ions with high energies and strong escape fluxes. This finding underscores that planetary ion escape can be unsteady and dynamic, even under stable external conditions.

The molecular dication CO _2 ^++ has, as previously reported, been detected in the Martian ionosphere by the Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution (MAVEN) mission. Photochemical models have also been developed to reproduce the CO _2 ^++ density in the Martian dayside ionosphere but underestimate significantly the observations. In this study, we examine the influence of the CO _2 ^++ natural lifetime against spontaneous dissociation on its modeled density. We show that extending the assumed CO _2 ^++ lifetime significantly reduces the discrepancy between the photochemical model predictions and MAVEN observations. Specifically, when treating CO _2 ^++ as stable against natural dissociation, instead of invoking a lifetime of 4 s as done in previous studies, the data-to-model ratio comes close to unity throughout the altitude range 160–220 km. We argue that stability of CO _2 ^++ against natural dissociation does not necessarily conflict with results from a frequently cited experimental investigation. Our study provides new insights for advancing photochemical modeling of the Martian ionosphere and underscores the need for further laboratory measurements targeting fundamental properties of doubly charged ions.

Context. The interaction of the solar wind (SW) with the coupled magnetosphere-exosphere-surface of Mercury is complex. Charged particles released by the SW can precipitate along planetary magnetic field lines on specific areas of the surface of the planet. The processes responsible for the particle precipitation strongly depend on the orientation of the interplanetary magnetic field (IMF) upstream of Mercury. Aims. During the third Mercury flyby (MFB3) by BepiColombo, the properties of the SW inferred from BepiColombo observations of a highly compressed magnetosphere corresponded to those of a very dense plasma embedded in a slow SW. The Mercury Electron Analyzer (MEA) measured continuous high-energy electron fluxes in the nightside dawn sector of the compressed magnetosphere. In order to constrain further studies related to the origin of these populations, we aim to firmly confirm the initial inferences and detail the SW properties throughout MFB3. Methods. We took advantage of a close radial alignment between Parker Solar Probe (PSP) and Mercury. We monitored the activity of the Sun using SOHO coronagraphs and we used a potential field source surface model to estimate the location of the magnetic footpoints of PSP and BepiColombo on the photosphere of the Sun. We propagated the plasma parameters and the IMF measured by PSP at BepiColombo, to check if the plasma impacted Mercury. Results. We show that during MFB3, PSP and BepiColombo connected magnetically to the same region at the solar surface. The slow SW perturbation first measured at PSP propagated to Mercury and BepiColombo, as was confirmed by similarly elevated plasma densities measured at PSP and BepiColombo. The IMF orientation stayed southward during the whole MFB3. Conclusions. Our results provide strong constraints for future studies of the magnetospheric structure and dynamics during MFB3, including tail reconnection, electron and ion energization, and subsequent plasma precipitation onto the surface of Mercury.

The Martian dayside ionosphere has been widely modeled using photochemical equilibrium calculations. These efforts have mostly focused on dominant ion species in order to make comparisons with orbital observations and on displaying non-negligible model-observation discrepancies. In this study, we investigate Ar(+)ions in the Martian dayside ionosphere, an ion species with a relatively simple chemistry, and perform both case-by-case orbital comparisons and a statistical comparison over five years of observations by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere and Volatile Evolution (MAVEN) mission. Statistically, the ratio of modeled to observed Ar(+)densities increases from similar to 1 near 130 km to similar to 4 at 220 km, with notable variations as a function of the solar zenith angle. Pressure-dependent discrepancies show a weaker correlation with the solar zenith angle. Model performance improves when incorporating (i) a higher reaction rate coefficient for the charge transfer between Ar(+)and CO2 and/or (ii) reduced solar irradiance. At altitudes above 200 km, Ar(+)loss via reactions with H-2 becomes increasingly important. However, we find that model-observation agreement varies between orbits: Some show strong consistency, particularly during Deep Dip campaigns, while others exhibit systematic deviations or significant discrepancies. We suggest that while systematic adjustments to reaction rate coefficients, ionization cross sections, solar irradiance, or background neutral densities may improve model fidelity for certain orbits, capturing the dynamic and time-varying nature of the Martian ionosphere requires further comprehensive investigations.

BepiColombo, the joint ESA/JAXA mission to Mercury, was launched in October 2018 and is scheduled to arrive at Mercury in November 2026 after an 8-year cruise. Like other planetary missions, its scientific objectives focus mostly on the nominal, orbiting phase of the mission. However, due to the long duration of the cruise phase covering distances between 1.2 and 0.3 AU, the BepiColombo mission has been able to outstandingly contribute to characterise the solar wind and transient events encountered by the spacecraft, as well as planetary environments during the flybys of Earth, Venus, and Mercury, and contribute to the characterisation of the space radiation environment in the inner Solar System and its evolution with solar activity. In this paper, we provide an overview of the cruise observations of BepiColombo, highlighting the most relevant science cases, with the aim of demonstrating the importance of planetary missions to perform cruise observations, to contribute to a broader understanding of Space Weather in the Solar System, and in turn, increase the scientific return of the mission.

On 10 August 2021, the Mercury-bound BepiColombo spacecraft performed its second fly-by of Venus and provided a short-lived observation of its induced magnetosphere. Here we report results recorded by the Mass Spectrum Analyzer on board Mio, which reveal the presence of cold O+ and C+ with an average total flux of similar to 4 +/- 1 x 10(4) cm(-2) s(-1) at a distance of about six planetary radii in a region that has never been explored before. The ratio of escaping C+ to O+ is at most 0.31 +/- 0.2, implying that, in addition to atomic O+ ions, CO group ions or water group ions may be a source of the observed O+. Simultaneous magnetometer observations suggest that these planetary ions were in the magnetosheath flank in the vicinity of the magnetic pileup boundary downstream. These results have important implications regarding the evolution of Venus's atmosphere and, in particular, the evolution of water on the surface of the planet.

Measurements of concentrations of neutral and ion species in the upper atmosphere of Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on board the Mars Atmosphere and Volatile EvolutioN mission have served as model input and/or for comparison with model output in numerous earlier studies of the Martian dayside ionosphere. While many models reproduce the altitudinal density profiles of key ion species within a factor of a few, it has proven challenging to achieve a level of agreement within tens of percent for multiple ion species over a wide range of altitudes. We explore means to overcome this issue while keeping with a reduced chemical model and utilizing the assumptions of photochemical equilibrium and that the NGIMS data are devoid of any measurement errors. We entertain, for instance, the idea that the rate coefficient for the charge-transfer reaction between CO2+ and O may vary with altitude as a result of a pressure-controlled internal energy distribution of the CO2+ population.

The Mercury Electron Analyzer (MEA) obtained new electron observations during the first threeMercury swingbys (MSBs) by BepiColombo on 01 October 2021 (MSB1), 23 June 2022 (MSB2),and 19 June 2023 (MSB3). We identify the magnetospheric boundaries and describe the structure and dynamics of the electron populations observed in the various regions explored along the swingby trajectories. We compare and contrast our new BepiColombo electron observations with those obtained from the Mariner 10 Scanning Electron Spectrometer (SES) 50 years ago.A comparison to the averaged magnetospheric boundary crossings by MESSENGER indicatesthat the magnetosphere of Mercury was compressed during MSB1, close to its average stateduring MSB2, and highly compressed during MSB3. Our new MEA observations revealed asignificant dusk-dawn asymmetry in electron fluxes on the nightside magnetosphere, and ofstrongly fluctuating electrons with energies above 100s eV on the dawnside magnetosphere.Magnetospheric electron densities and temperatures were in the range of 10-30 cm⁻³ and above a few 100s eV in the pre-midnight-sector, and in the range of 1-100 cm ⁻³ and well below 100 eV in the post-midnight sector, respectively.MEA electron observations of different solar wind properties encountered during the first threeMSBs revealed the highly dynamic response of the solar wind-magnetosphere interactions atMercury. A good match is found between the electron plasma parameters derived by MEA in the various regions of the Hermean environment with similar ones derived for a few cases from other instruments on board BepiColombo.

Context. The Mercury electron analyzer (MEA) obtained new electron observations during the first three Mercury flybys by BepiColombo on October 1, 2021 (MFB1), June 23 , 2022 (MFB2), and June 19, 2023 (MFB3). BepiColombo entered the dusk side magnetotail from the flank magnetosheath in the northern hemisphere, crossed the Mercury solar orbital equator around midnight in the magnetotail, traveled from midnight to dawn in the southern hemisphere near the closest approach, and exited from the post-dawn magnetosphere into the dayside magnetosheath. Aims. We aim to identify the magnetospheric boundaries and describe the structure and dynamics of the electron populations observed in the various regions explored along the flyby trajectories. Methods. We derive 4s time resolution electron densities and temperatures from MEA observations. We compare and contrast our new BepiColombo electron observations with those obtained from the Mariner 10 scanning electron spectrometer (SES) 49 yr ago. Results. A comparison to the averaged magnetospheric boundary crossings of MESSENGER indicates that the magnetosphere of Mercury was compressed during MFB1, close to its average state during MFB2, and highly compressed during MFB3. Our new MEA observations reveal the presence of a wake effect very close behind Mercury when BepiColombo entered the shadow region, a significant dusk-dawn asymmetry in electron fluxes in the nightside magnetosphere, and strongly fluctuating electrons with energies above 100s eV in the dawnside magnetosphere. Magnetospheric electron densities and temperatures are in the range of 10-30 cm(-3) and above a few 100s eV in the pre-midnight-sector, and in the range of 1-100 cm(-3) and well below 100 eV in the post-midnight sector, respectively. Conclusions. The MEA electron observations of different solar wind properties encountered during the first three Mercury flybys reveal the highly dynamic response and variability of the solar wind-magnetosphere interactions at Mercury. A good match is found between the electron plasma parameters derived by MEA in the various regions of the Hermean environment and similar ones derived in a few cases from other instruments on board BepiColombo.

IntroductionThe Venusian ionosphere interacts directly with the solar wind, and forms an induced magnetosphere. The interaction transfers energy from the solar wind to the ionospheric ions, and causes some ions to escape into the induced magnetotail (Futaana et al., 2017; Persson et al., 2020). In the magnetotail, the ions do not simply flow from Venus and outward to space. The ion flows have an additional component back towards Venus: return flows (Kollmann et al., 2016; Persson et al., 2018). These return flows was shown to decrease the total average escape rates from Venus for both H+ and O+ ions (Persson et al., 2018). In this study, we delve deeper into the structure of the ion flows in the magnetotail in order to provide further insight into these return flows.MethodTo analyse the ion flows we use the Ion Mass Analyser (IMA), a part of the ASPERA-4 instrument suite (Barabash et al., 2007b), on board Venus Express. IMA is a top-hat electrostatic analyser with an energy range of 0.01-36 keV, with ΔE/E=7%. The mass separating capabilities allows us to efficiently separate the lighter H+ from the heavier O+ ions. From the electrostatic deflector plates and the cylindrical symmetry the field-of-view has a resolution of 5.6x22.5˚ for each of the 16x16 pixels, which gives a total field-of-view of 90x360˚.We use the full dataset of IMA from 2006 to 2014 to calculate average ion velocity distributions. We combine the measurements by location in the magnetotail. As the induced magnetotail of Venus is structured by the direction of the upstream Interplanetary Magnetic Field (IMF) and the solar wind motional electric field (Jarvinen et al., 2013; McComas et al., 1986; Pérez‐de‐Tejada, 2001), we use the direction of the IMF to group the measurements together. The average ion distributions are then used to analyse the structure of flows in the magnetotail, in order to provide further insight in the return flow mechanisms.Results and discussionThe structure of the magnetotail with respect to the solar wind motional electric field implies a difference in the ion flows between the hemisphere where the electric field points away from Venus (+E) and the hemisphere where the electric field points towards Venus (-E). The magnetic field draping in the -E hemisphere provides a more narrow draping near the plasma sheet, which indicates a preference for magnetic reconnection (Zhang et al., 2010). If magnetic reconnection is the main mechanism that causes the return flows, we therefore expect a preference of return flows in the -E hemisphere. Preliminary results indicate that there is no clear dependence of the return flow with +E or -E hemisphere. In agreement with previous studies, our results show that the main anti-sunward acceleration in the magnetotail occurs in the +E hemisphere (Barabash et al., 2007a; Fedorov et al., 2011). However, the unclear relationship of the return flows with hemisphere warrants a further investigation. In this presentation, we present our results of an expanded study where we will have investigated the ion flows in the magnetotail in further detail to see if there is a preferred location or condition where the return flows are appearing.ReferencesBarabash, et al. (2007a). The loss of ions from Venus through the plasma wakes. Nature, 450(7170), 650–653. https://doi.org/10.1038/nature06434Barabash, et al. (2007b). The Analyser of Space Plasmas and Energetic Atoms (ASPERA‐4) for the Venus Express mission. Planetary and Space Science, 55(12), 1772–1792. https://doi.org/10.1016/j. pss.2007.01.014 Fedorov, et al. (2011). Measurements of the ion escape rates from Venus for solar minimum. 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