Volatile Evolution Research Articles

Evidence for Magnetic Reconnection as the Precursor to Discrete Aurora at Mars

AbstractDiscrete aurora at Mars are characterized as localized, short‐lasting ultraviolet emissions on the nightside. They are caused by the precipitation of accelerated electron along open magnetic field lines and their collision with the Martian atmosphere. Discrete auroral emissions detected by the Imaging Ultraviolet Spectrograph (IUVS) instrument onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft occur most frequently over the strongest crustal magnetic anomalies at Mars and under particular local time and upstream interplanetary magnetic field (IMF) conditions. These trends suggest that the onset of discrete aurora is controlled by the processes that govern the interaction between the draped IMF and the crustal magnetic anomalies. Here, we analyze MAVEN magnetometer measurements over regions of strong crustal fields during 49 discrete auroral events observed by IUVS. Our results indicate that the draped IMF orientations during each discrete auroral event show a clear tendency to be anti‐parallel to the underlying crustal anomaly magnetic fields near the location of the emission onset. This suggests that magnetic reconnection, a process that favors anti‐parallel magnetic field regimes, between the crustal fields and the draped IMF plays a role in discrete aurora formation. Of the 49 discrete auroral events analyzed, 42 (86%) occurred under draped IMF conditions that are susceptible to reconnection with the underlying crustal anomalies. This investigation produces strong evidence linking discrete aurora to magnetic reconnection at Mars and provides insights into other trends in discrete auroral activation such as local time and upstream IMF conditions.

Disentangling Photoelectrons and Penetrating Solar Wind Electrons in the Dayside Martian Upper Atmosphere

AbstractIn situ produced photoelectrons and precipitating solar wind electrons are two distinct hot electron populations in the dayside Martian upper atmosphere. While each population has been known for decades, its relative contribution to the measured hot electron flux has not been adequately characterized up to now. In this study, we implement a two‐stream kinetic model to compute the hot electron flux for a open magnetic field configuration. By comparing model results to realistic data acquired by the Mars Atmosphere and Volatile Evolution mission, we show that the electron fluxes predicted by the pure photoelectron model are enormously underestimated, especially in the direction toward Mars, but the measurements can be adequately reproduced once solar wind electron precipitation is taken into account. Such a precipitation plays a crucial role above 180 km, not only for hot electrons at all energies that move toward Mars but also for electrons above 1,000 eV that move away from Mars due to the backscattering of precipitating electrons. In contrast, the hot electron population is predicted to be mostly composed of photoelectrons below 180 km. The significance of precipitating solar wind electrons is also evaluated, revealing an appreciable impact on the structure of the dayside Martian upper atmosphere at high altitudes, where electron impact ionization is enhanced by a factor of 7 and cold electron heating enhanced by a factor of 4.

Exploring Volatility: Evolution, Advancements, Trends, and Applications

Volatility is a fundamental notion in financial markets, influencing investment decisions, risk management techniques, and market dynamics. This paper provides a thorough overview of the historical evolution and practical implications of volatility, focusing on important works and key advancements in the field. The overview begins with early conceptions of volatility and the necessity for measurement prompted by market collapses, then progresses to advanced quantitative models and computer tools. The study includes key innovations such as the Black-Scholes model, which revolutionized options pricing and pioneered the concept of implied volatility. The Autoregressive Conditional Heteroskedasticity (ARCH) and Generalized Autoregressive Conditional Heteroskedasticity (GARCH) models introduced frameworks for modeling time-varying volatility, paving the way for greater forecasting accuracy. Advancements in computing techniques have made it easier to analyze high-frequency data and estimate realized volatility, providing timely insights into market trends. The review also investigates contemporary trends, such as the use of machine learning algorithms and the issues provided by cryptocurrency marketplaces. Furthermore, the article examines the various characteristics and metrics of volatility, emphasizing its multidimensional nature and diverse uses in risk management, portfolio optimization, derivative pricing, and market analysis. Practical examples show how investors, traders, and financial professionals may use volatility to navigate complex market settings and make sound judgments. Finally, the study highlights the enduring significance of volatility in financial markets and highlights the need for continuing research and analysis to improve our understanding of market behavior. Acknowledging the complexities of volatility prepares market participants with valuable understandings to manage risks effectively and capitalize on market opportunities, thus contributing to financial stability and optimal portfolio performance.

Characteristic Timescales for the Dayside Martian Ionosphere: Chemistry, Diffusion, and Magnetization

Different boundaries could be defined in a planetary ionosphere where the dominant process in function switches from one to the other. Identifying these boundaries and understanding their variations are hence crucial for disentangling the complexity of the ionosphere. Focusing on Mars, we perform a data-driven analysis of various boundaries and the associated time constants based on the multi-instrument measurements made by the Mars Atmosphere and Volatile Evolution mission during six campaigns that sample broadly different internal and external conditions. The boundaries we investigate include the photochemical equilibrium (PCE) boundary, the magnetic frozen boundary, the ion collision boundary, and the ion gyration boundary. Our analysis reveals systematic solar cycle and diurnal variations in that all boundaries tend to be elevated at enhanced solar activity and on the dayside and duskside of Mars. The variations with the magnetic environment are not observed for all boundaries except for the PCE boundary that exhibits an obvious elevation in strongly magnetized regions. Finally, our analysis suggests interesting species-dependent variations of different boundaries. In particularly, the PCE boundary shows the largest variability among all, with reduced boundary locations for all terminal species (NO+, HCO+, , and H3O+) and one extra nonterminal species (CO2 +) owing to different chemical properties rendered by different ions.

Effects of the evolving early Moon and Earth magnetospheres

Recently it has been identified that our Moon had an extensive magnetosphere for several hundred million years soon after it was formed when the Moon was within 20 Earth Radii (RE) from the Earth. Some aspects of the interaction between the early Earth-Moon magnetospheres are investigated by mapping the interconnected field lines between the Earth and the Moon and investigating how the early lunar magnetosphere affects the magnetospheric dynamics within the coupled magnetospheres over time. So long as the magnetosphere of the Moon remains strong as it moves away from the Earth in the antialigned dipole configuration, the extent of the Earth’s open field lines decreases. As a result, at times it significantly changes the structure of the field-aligned current system, pushing the polar cusp significantly northward, and forcing magnetotail reconnection sites into the deeper tail region. In addition, the combined magnetospheres of the Earth and the Moon greatly extend the number of closed field lines enabling a much larger plasmasphere to exist and connecting the lunar polar cap with closed field lines to the Earth. That configuration supports the transfer of plasma between the Earth and the Moon potentially creating a time capsule of the evolution of volatiles with depth. This paper only touches on the evolution of the early Earth and Moon magnetospheres, which has been a largely neglected space physics problem and has great potential for complex follow-on studies using more advanced tools and due to the expected new lunar data coming in the next decade through the Artemis Program.

Constraining the volatile evolution of mafic melts at Mt. Somma–Vesuvius, Italy, based on the composition of reheated melt inclusions and their olivine hosts

Abstract. Mount Somma–Vesuvius is a stratovolcano that represents a geological hazard to the population of the city of Naples and surrounding towns in southern Italy. Historically, volcanic eruptions at Mt. Somma–Vesuvius (SV) include high-magnitude Plinian eruptions, such as the infamous 79 CE eruption that occurred after 295 years of quiescence and killed thousands of people in Pompeii and surrounding towns and villages. The last eruption at SV was in 1944 and showed a Volcanic Explosivity Index (VEI) of 3 (0.01 km3 of volcanic material erupted). Following the 1944 eruption, SV has been dormant for the past nearly 79 years, with only minor fumarolic and seismic activity. During its long history, centuries of dormancy at SV have ended with Plinian eruptions (VEI 6) that signal the beginning of a new cycle of eruptive activity. Thus, the current dormancy stage demands a need to better understand the mechanism involved in high-magnitude eruptions in order to better predict future eruption magnitude and style. Despite centuries of research on the SV volcanic system, many questions remain, including the evolution of magmatic volatiles from deep primitive magmas to shallower more evolved magmas. Developing a better understanding of the physical and chemical processes associated with volatile evolution at SV can provide insights into magma dynamics and the mechanisms that trigger highly explosive eruptions at SV. In this study, we present new data for the pre-eruptive volatile contents of magmas associated with four Plinian and two inter-Plinian eruptions at SV based on analyses of reheated melt inclusions (MIs) hosted in olivine. We correct the volatile contents of bubble-bearing MIs by taking into account the volatile contents of bubbles in the MIs. We recognize two groups of MIs: one group hosted in high-Fo olivine (Fo85–90) and relatively rich in volatiles and the other group hosted in low-Fo olivine (Fo70–69) and relatively depleted in volatiles. The correlation between volatile contents and compositions of host olivines suggests that magma fractionation took place under volatile-saturated conditions and that more differentiated magmas reside at shallower levels relative to less evolved/quasi-primitive magmas. Using the CO2 contents of corrected MIs hosted in Fo90 olivine from SV, we estimate that 347 to 686 t d−1 of magmatic CO2 exsolved from SV magmas during the last 3 centuries (38–75 Mt in total) of volcanic activity. Although this study is limited to only few SV magmas, we suggest that further study applying similar methods could shed light on the apparent lack of correlation between the volatile contents of MIs and the style and age of eruptions. Further, such studies could provide additional constraints on the origin of CO2 and the interaction between the carbonate platform and ascending magmas below SV.

Magnetic Field Draping in Induced Magnetospheres: Evidence From the MAVEN Mission to Mars

AbstractThe Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has been orbiting Mars since 2014 and now has over 10,000 orbits which we use to characterize Mars' dynamic space environment. Through global field line tracing with MAVEN magnetic field data we find an altitude dependent draping morphology that differs from expectations of induced magnetospheres in the vertical ( Mars Sun‐state, MSO) direction. We quantify this difference from the classical picture of induced magnetospheres with a Bayesian multiple linear regression model to predict the draped field as a function of the upstream interplanetary magnetic field (IMF), remanent crustal fields, and a previously underestimated induced effect. From our model we conclude that unexpected twists in high altitude dayside draping (>800 km) are a result of the IMF component in the MSO direction. We propose that this is a natural outcome of current theories of induced magnetospheres but has been underestimated due to approximations of the IMF as solely directed. We additionally estimate that distortions in low altitude (<800 km) dayside draping along are directly related to remanent crustal fields. We show dayside draping traces down tail and previously reported inner magnetotail twists are likely caused by the crustal field of Mars, while the outer tail morphology is governed by an induced response to the IMF direction. We conclude with an updated understanding of induced magnetospheres which details dayside draping for multiple directions of the incoming IMF and discuss the repercussions of this draping for magnetotail morphology.

Characterization of high-frequency waves in the Martian magnetosphere

Context. Various high-frequency waves in the vicinity of upper-hybrid and Langmuir frequencies are commonly observed in different space plasma environments. Such waves and fluctuations have been reported in the magnetosphere of the Earth, a planet with an intrinsic strong magnetic field. Mars has no intrinsic magnetic field and, instead, it possesses a weak induced magnetosphere, which is highly dynamic due to direct exposure to the solar wind. In the present paper, we investigate the presence of high-frequency plasma waves in the Martian plasma environment by making use of the high-resolution electric field data from the Mars Atmosphere and Volatile Evolution missioN (MAVEN) spacecraft. Aims. This study aims to provide conclusive observational evidence of the occurrence of high-frequency plasma waves around the electron plasma frequency in the Martian magnetosphere. We observe two distinct wave modes with frequency below and above the electron plasma frequency. The characteristics of these high-frequency waves are quantified and presented here. We discuss the generation of possible wave modes by taking into account the ambient plasma parameters in the region of observation. Methods. We have made use of the medium frequency (100 Hz–32 kHz) burst mode-calibrated electric field data from the Langmuir Probe and Waves instrument on board NASA’s MAVEN mission. Due to the weak magnetic field strength, the electron gyro-frequency is much lower than the electron plasma frequency, which implies that the upper-hybrid and Langmuir waves have comparable frequencies. A total of 19 wave events with wave activities around electron plasma frequency were identified by examining high-resolution spectrograms of the electric field. Results. These waves were observed around 5 LT when MAVEN crossed the magnetopause boundary and entered the magnetosheath region. These waves are either a broadband- or narrowband-type with distinguishable features in the frequency domain. The narrowband-type waves have spectral peak above the electron plasma frequency. However, in the case of broadband-type waves, the spectral peak always occurred below the electron plasma frequency. The broadband waves consistently show a periodic modulation of 8–14 ms. Conclusions. The high-frequency narrowband-type waves observed above the electron plasma frequency are believed to be associated with upper-hybrid or Langmuir waves. However, the physical mechanism responsible for the generation of broadband-type waves and the associated 8–14 ms modulation remain unexplained and further investigation is required.

Detection of magnetospheric ion drift patterns at Mars

Mars lacks a global magnetic field, and instead possesses small-scale crustal magnetic fields, making its magnetic environment fundamentally different from intrinsic magnetospheres like those of Earth or Saturn. Here we report the discovery of magnetospheric ion drift patterns, typical of intrinsic magnetospheres, at Mars using measurements from Mars Atmosphere and Volatile EvolutioN mission. Specifically, we observe wedge-like dispersion structures of hydrogen ions exhibiting butterfly-shaped distributions (pitch angle peaks at 22.5°−45° and 135°−157.5°) within the Martian crustal fields, a feature previously observed only in planetary-scale intrinsic magnetospheres. These dispersed structures are the results of drift motions that fundamentally resemble those observed in intrinsic magnetospheres. Our findings indicate that the Martian magnetosphere embodies an intermediate case where both the unmagnetized and magnetized ion behaviors could be observed because of the wide range of strengths and spatial scales of the crustal magnetic fields around Mars.

Using AI to Fine Tune the Search for Life

Using AI to Fine Tune the Search for Life

The noble gas signature of the 2021 Tajogaite eruption (La Palma, Canary Islands)

Here, we characterize the temporal evolution of volatiles during the Tajogaite eruption by analyzing the elemental (He-Ar-CO2-N2) and isotopic (He-Ar-Ne) composition of fluid inclusions (FI) in phenocrysts (olivine+pyroxene) identified in erupted lavas. Our 2021 lava samples identify substantial temporal variations in volatile composition. We show that, during the 2021 Tajogaite eruption, the He-CO2-N2 concentrations in FI increased since October 15th; this increase was accompanied by increasing 40Ar/36Ar ratios (from ∼300 to >500), and paralleled a major shift in bulk lava chemistry, with increasing Mg contents (Mg#, from 47 to 52 to 55–59), CaO/Al2O3 (from 0.65 to 0.74 to 0.75–0.90), Ni and Cr, and decreasing TiO2, P2O5 and incompatible elements. The olivine core composition also became more forsteritic (from Mg# = 80–81 to Mg# = 84–86). Mineral thermobarometry and FI barometry results indicate that the eruption was sustained by magmas previously stored in at least two magma accumulation zones, at respectively ∼6–12 km and 15–30 km, corroborating previous seismic and FI evidence. We therefore propose that the compositional changes seen throughout the eruption can be explained by an increased contribution - since early/mid-October - of more primitive, less-degassed magma from the deeper (mantle) reservoir. Conversely, Rc/Ra values (3He/4He ratios corrected for atmospheric contamination) remained constant throughout the whole eruption at MORB-like values (7.38 ± 0.22 Ra, 1σ), suggesting an isotopically homogeneous magma feeding source. The Tajogaite He isotope signature is within the range of values observed for the 1677 San Antonio lavas (7.37 ± 0.17Ra, 1σ), but is more radiogenic than the 3He/4He values (>9 Rc/Ra) observed in the Caldera de Taburiente to the north. The 3He/4He ratios (6.75 ± 0.20 Ra, 1σ) measured in mantle xenoliths from the San Antonio volcano indicate a relatively radiogenic nature of the mantle beneath the Cumbre Vieja ridge. Based on these results and mixing modeling calculations, we propose that the homogeneous He isotopic signatures observed in volatiles from the Tajogaite/San Antonio lavas reflect three component mixing between a MORB-like source, a radiogenic component and small additions (6–15%) of a high 3He/4He reservoir-derived (>9Ra) fluid components. The simultaneous occurrence of high 3He/4He (>9Ra)- and MORB-like He signatures in northern and southern La Palma is interpreted to reflect small-scale heterogeneities in the local mantle, arising from spatially variable proportions of MORB, radiogenic, and high 3He/4He components.

Atmospheric Tides at Low Latitudes in the Martian Upper Atmosphere Observed by MAVEN IUVS

AbstractThe present work studies the variation of the wave 3 structure in the Martian upper atmosphere at low latitudes. CO2 densities produced by the Imaging Ultraviolet Spectrograph (IUVS) onboard the Mars Atmosphere and Volatile EvolutioN spacecraft from October 2014 to September 2021 are utilized to study the variation of the wave 3 structure under different seasons. By normalizing the densities to a fixed Extreme Ultraviolet level and applying harmonic fitting techniques, the wave 3 structures are derived from the IUVS observations. We find that the wave 3 structure tends to propagate eastward with increasing local time and altitude at low latitudes, which is consistent with the variability of the wave 3 structure at high latitudes. The altitudinal variation of the wave 3 structure also indicates that the dissipation effects become essential in the Martian upper atmosphere. By comparing the shifting speed of the wave structure with the phase speed of prominent tides in different seasons, we find that DE2 and SE1 jointly generate the wave 3 structure at low latitudes. This is confirmed by the seasonal variations of DE2 and SE1 proposed by Mars Climate Database (MCD) latitude‐Ls predictions. Comparisons of the MCD predictions with the height‐latitude amplitude distributions of the wave 3 structure reveal the existence of both DE2 and SE1 tides. By decomposing the wave 3 structure into latitudinal symmetric and antisymmetric components and comparing it with the first few Hough modes of DE2 and SE1, we confirm that DE2 and SE1 are the possible candidates that generate the wave 3 structure.

Observations of Locally Generated Whistler-mode Waves in the Martian Magnetotail Current Sheet

The whistler-mode wave is an electromagnetic wave that commonly occurs in space plasma and has been extensively studied, especially within the Earth's magnetosphere. They have also been reported in the near-Mars space, such as Martian upstream solar wind, crustal magnetic field, ionopause, and the magnetic reconnection ion diffusion region. However, the generation of whistler-mode waves in the Martian magnetotail current sheet is still unclear. Based on observations made by Mars Atmosphere and Volatile Evolution spacecraft, we report whistler-mode waves observed within a train of proton-scale magnetic dips during a Martian magnetotail current sheet crossing. The linear growth rate analyses demonstrate that the whistler-mode waves are locally generated within the magnetic dips. Unlike in Earth's plasma environment, the train of magnetic dips in the Martian plasma sheet is attributed to electron mirror-mode instability. Our finding suggests that the mirror-mode structure in the Martian magnetotail can be an important source region for generating whistler-mode waves. This provides a new insight into how whistler-mode waves are generated in unmagnetized planets.

Effects of ion composition on escape and morphology on Mars

Abstract. We refine a recently presented method to estimate ion escape from non-magnetized planets and apply it to Mars. The method combines in situ observations and a hybrid plasma model (ions as particles, electrons as a fluid). We use measurements from the Mars Atmosphere and Volatile Evolution (MAVEN) mission and Mars Express (MEX) for one orbit on 1 March 2015. Observed upstream solar-wind conditions are used as input to the model. We then vary the total ionospheric ion upflux until the solution fits the observed bow shock location. This solution is a self-consistent approximation of the global Mars–solar-wind interaction at the time of the bow shock crossing for the given upstream conditions. We can then study global properties, such as the heavy-ion escape rate. Here, we investigate in a case study the effects on escape estimates of assumed ionospheric ion composition, solar-wind alpha-particle concentration and temperature, solar-wind velocity aberration, and solar-wind electron temperature. We also study the amount of escape in the ion plume and in the tail of the planet. Here, we find that estimates of total heavy-ion escape are not very sensitive to the composition of the heavy ions or to the number and temperature of the solar-wind alpha particles. We also find that velocity aberration has a minor influence on escape but that it is sensitive to the solar-wind electron temperature. The plume escape is found to contribute 29 % of the total heavy-ion escape, in agreement with observations. Heavier ions have a larger fraction of escape in the plume compared to the tail. We also find that the escape estimates scale inversely with the square root of the atomic mass of the escaping ion species.

Modelling of large biomass and coal particle based on a novel C-DAEM: A numerical study on heat transfer and pyrolysis behavior

Using two kinds of large-size fuel particles with thermal resistance, i.e., lignocellulosic biomass (Beech, BH) and Shenmu bituminous coal (SMBC), a comprehensive and systematic study on volatile evolution and temperature distribution history inside the particle was conducted in this work. The pyrolysis behaviors of BH and SMBC were characterized through a novel C-DAEM and traditional DAEM. Pyrolysis experiments of large biomass and coal particles were conducted in three different particle size ranges of two different heating temperatures. Results showed that C-DAEM was better than DAEM. Moreover, both particle size and heating temperature have an influence on overall temperature but through different ways. Thermal disturbance peak (TDP) existed in TDSC curves, while pyrolysis reaction peak (PRP) existed only in 773 K of BH. Particle size affected the overall temperature mainly by changing the thermal disturbance transfer time, e.g., TDP of BH-L1 happened in 27.3s, TDP of BH-L2 happened in 56.2s, and TDP of BH-L3 happened in 94.4s. Heating temperature affected the overall temperature mainly by directly changing the heat flux, e.g., time of TDP in BH-L3 and BH–H3 was nearly the same, while the corresponding peak value was consistent with the increase in heating temperature.

Magnetic Reconnection in the Martian Magnetotail: Occurrence Rate and Impact on Ion Loss

AbstractThe current sheet is crucial in releasing magnetic free energy in cosmic plasmas via fast magnetic reconnection or wave excitation. This research investigates the characteristics of the Martian tail current sheet by analyzing data acquired from the Mars Atmosphere and Volatile EvolutioN spacecraft over 7 years. For the first time, we find that approximately 15% of the current sheet events display reconnection signatures, including Hall magnetic fields and fast proton flows. These reconnecting current sheets are detected more frequently on Mars than on Earth. The Martian tail current sheet is first demonstrated to be on the proton scale, which can explain the high reconnection occurrence rate. The research also reveals that the current sheets are thinner in regions closer to Mars and in the –E hemisphere. On average, reconnecting current sheets carry high fluxes of protons rather than oxygen ions.

Plasma-catalytic pyrolysis of polypropylene for hydrogen and carbon nanotubes: Understanding the influence of plasma on volatiles

Plasma-catalytic pyrolysis was developed for upgrading polypropylene (PP) pyrolysis volatiles to co-produce carbon nanotubes (CNTs) and hydrogen. To uncover the role of plasma on the plastic catalytic pyrolysis process, the pyrolysis of polypropylene (PP) over Fe/γ-Al2O3 was carried out in a two-stage pyrolysis system with a coaxial dielectric barrier discharge (DBD) plasma reactor. The results showed that the plastic pyrolysis volatiles were further cleaved and activated with plasma, resulting in more active carbon species for the growth of CNTs. Compared to conventional catalytic pyrolysis, plasma addition shifted the initial formation temperature of CNTs to a lower ambient temperature by ∼100 °C, and significantly promoted the conversion of liquid and gaseous products to CNTs and hydrogen, with higher carbon and hydrogen yields of ∼322 mg/gplastic and 30 mmol/gplastic, respectively. In addition, the degree of graphitization of the CNTs in the presence of the plasma was significantly enhanced with less defectivity. The influence of catalytic temperature variation caused by plasma on CNTs growth was also discussed from the perspective of volatile evolution. This work highlights the potential of plasma-catalytic pyrolysis for the production of hydrogen and high-value carbon materials from plastic waste.

Variability of Draped Interplanetary Magnetic Field in the Subsolar Martian Ionosphere

In the absence of an intrinsic magnetic field, the solar wind interacts directly with the Martian atmosphere, and the interplanetary magnetic field (IMF) drapes around the ionosphere. With the aid of multi-instrument measurements from Mars Atmosphere and Volatile Evolution (MAVEN), we investigate the altitudinal profiles of the draped magnetic field in the subsolar Martian ionosphere. Our analysis of 141 profiles found that they have a median profile with a nearly constant field strength of about 30 nT above 160 km. However, these profiles also show large variability, for example, with a standard deviation of 16 nT at 250 km. Timescale analysis found that magnetic field transport with downward ion plasma motion dominates the draping of IMF at high altitudes. At low altitudes, magnetic diffusion takes over due to increasing collisions. At even lower altitudes, approaching the ionospheric peak, the draped field is quickly damped owing to high conductivity. We used a 1D model simulation to confirm the above processes involved and further indicate that undulating magnetic fields with oscillation periods longer than tens of minutes can penetrate deeply into the ionosphere. This causes the large variability of draped field observed down to below 200 km. The diverse profiles of draped field observed by MAVEN are thus likely due to varying IMF conditions.

Effects of stealth CME to ion energisation at ionospheric altitudes of Mars

The declining phase of Solar cycle 24 produced a slow coronal mass ejection (CME), which was categorized as stealth CME based on the absence of associated low coronal signatures. This CME impacted Mars and caused a major space weather event during 27–28 August 2018 (max vsw = 580 km s−1 near 1.5 AU). The impact of the stealth CME on the topside of the Martian ionosphere is investigated using the data from Solar Wind Ion Analyzer (SWIA), Solar Energetic Particle (SEP) and Suprathermal and Thermal Ion Composition (STATIC) instruments onboard Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. The variations of ion and electron fluxes within the plasma boundaries during the passage of ICME event were observed using Electron Spectrometer (ELS) and the Ion Mass Analyzer (IMA) sensors onboard Mars Express (MEX) mission. The plasma boundaries of the induced magnetosphere of Mars showed considerable enhancement in the observed fluxes during the event. SWIA observations during the interaction of the CME with Martian plasma environment showed enhancement in the ion flux. STATIC observations showed energisation of planetary heavy ions like O+ and O2+ to energies between 10 eV up to hundreds of eV at altitudes below 300 km. SEP measurements of energetic O+ pick-up ions at energies below 50 keV further support the claim on planetary ion energisation.

Ion Loss within a Reconnection Exhaust near Mars: MAVEN Observations

We present observations from Mars Atmosphere and Volatile EvolutioN of a reconnection exhaust, which was probably not ongoing, in the Martian magnetosheath. The reconnection jet with abundant heavy ions is directed outward to space. The magnetic field lines within the exhaust are found to be draped, suggesting that the reconnection exhaust was detached from the ionosphere and the heavy ions within it escaped from Mars. The dimensionless reconnection rate estimated from proton measurements is about 5.56%. The total oxygen loss rate via the reconnection exhaust is calculated to be 1.3 × 1021 s−1. This much lower ion loss rate than that estimated in active magnetic reconnection at the ionopause suggests that the reconnection associated with the reconnection exhaust is not ongoing, so most of the heavy ions have already escaped. Our results demonstrate that magnetic reconnection can directly contribute to the ion loss of Mars. Due to the participation of multiple heavy ions, the characteristics of magnetic reconnection could be very different.