Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 – 23 September 2022
Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 September – 23 September 2022
Ionospheres of unmagnetized or weakly magnetized bodies


Ionospheres of unmagnetized or weakly magnetized bodies
Co-organized by OPS/SB
Convener: Beatriz Sanchez-Cano | Co-conveners: Christopher Fowler, Lina Hadid, Valeria Mangano, Niklas Edberg, Francisco González-Galindo
| Wed, 21 Sep, 12:00–13:30 (CEST), 15:30–18:30 (CEST)|Room Machado
| Attendance Thu, 22 Sep, 18:45–20:15 (CEST) | Display Wed, 21 Sep, 14:00–Fri, 23 Sep, 16:00|Poster area Level 1

Session assets

Discussion on Slack

Orals: Wed, 21 Sep | Room Machado

Chairperson: Beatriz Sanchez-Cano
Robin Ramstad, David Brain, James McFadden, David Mitchell, Laila Andersson, Jared Espley, Jasper Halekas, Mats Holmström, and Shannon Curry

Fundamentally, what limits the rate of atmospheric ion escape from non-magnetized planets? Previous orbit-based in situ measurements of escaping heavy ions (O+, O2+ and heavier species) at Mars have yielded conflicting estimates of the dependencies on upstream solar wind and solar extreme ultraviolet (EUV) conditions. We compile 7 years (2014-2021) of measured 0.1 eV – 30 keV ion distributions from the STATIC instrument on the MAVEN orbiter to globally map the phase-space ion flux distribution, from which we derive globally integrated outflow, inflow, and net ion fluxes. Through binning the measurements by upstream solar wind (measured simultaneously by the Mars Express orbiter) and EUV conditions, we separately quantify the O+ and O2+ escape dependencies on these external drivers. The found trends indicate that ion escape from Mars is a supply/source-limited process under low solar EUV conditions, however, the appearance and increase of gravitationally bound heavy ion return flows under moderate EUV conditions suggests that the escape process can transition to a Venus-like energy-limited state. The findings show that the state of the ion escape process does not only differ between planets, but the state and thus the drivers of ion escape can also differ under varying external conditions. We discuss the implications for ion observations at Mars during the upcoming solar activity maximum, for the evolution of the Martian atmosphere, and for our understanding of atmospheric ion escape as a general process in the solar system and beyond.

How to cite: Ramstad, R., Brain, D., McFadden, J., Mitchell, D., Andersson, L., Espley, J., Halekas, J., Holmström, M., and Curry, S.: MAVEN Observations of a State-Transition in Ion Escape from Mars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-704,, 2022.

Maria Chloi Katrougkalou, Sae Aizawa, Moa Persson, Nicolas André, and Ronan Modolo

Venus lacks an intrinsic magnetic filed, as a result, the incoming solar wind interacts directly with its atmosphere, creating an induced magnetosphere. Venus is believed to have once held a significant amount of water, which has since then disappeared from the planet as evidence by the increased, compared to Earth's, Deuterium-Hydrogen ratio measured by Pioneer Venus (Donahue et al. 1982). Its disappearance is mainly contributed to the interaction of the solar wind with the planet's induced magnetosphere. This interaction is the primary cause of atmospheric escape for elements heavier than Hydrogen, such as Oxygen (Futaana et al. 2017). Measurements from Venus Express have shown that the majority of the escape is taking place at the magnetotail, with the ration of Hydrogen to Oxygen escape being approximately equal to two during solar minimum and equal to one during solar maximum (Persson et al. 2018), indicating the escape of water from the nightside. This effect can bring rise to the question: what happens to the atmospheric loss under extreme solar wind conditions, such as under the influence of Interplanetary Coronal Mass Ejections (ICMEs)? Understanding those processes can give us valuable information on the evolution of the planet. Previous works have provided answers by investigating the impact of ICMEs on the Venusian atmospheric escape compared to nominal conditions with observations (Luhmann et al. 2007, McEnulty et al. 2010, Edberg et al. 2011, Collinson et al. 2015) and simulations (Luhmann et al. 2008, Dimmock et al. 2017) to name a few. In this study, we contribute to this subject by using observations taken from Venus Express and simulations to explore the influence of different ICME parameters on the escape.

The simulation used is a global hybrid model, called LatHyS, first developed for Mars (Modolo et al. 2017) and adapted for Venus (Aizawa et al. 2022), that has the advantage of having a self consistently calculated ionosphere. Magnetic field and particle data taken from Venus Express upstream of the bowshock are used as reference for the initial conditions of the simulations. Two ICME events are selected. The first impacted Venus on the 5th of November 2011 and created the highest observed magnetic obstacle at the planet. Upstream of the bowshock it had a temperature of 200 eV and a velocity of 900 km/s. The second event occurred on the 27th of October 2013 and had similar plasma and magnetic field parameters to the first one, but had significantly different temperature of 35 eV and velocity of 600 km/s. Idealized models of the events are simulated and compared. In order to discuss the parameter dependence, for each comparison the simulation inputs of the two events are forced to be the same, imposing either temperature or velocity to be identical, and leaving the studied variable as the only difference. We find an increase of the dayside Oxygen escape for the event with the higher velocity, but a decrease on the nightside outgoing ion flux. Since both of the selected events can be considered as fast solar wind, to better investigate the dependency of the velocity we perform an additional simulation with a much lower solar wind speed of 300 km/s. To study further the effect of the ICME parameters, in a more model driven approach, the second selected event is kept as a reference and additional simulations are performed to examine variables such as the magnetic field strength and cone angle. Finally, the results are compared with statistical data of the mean solar wind conditions on Venus and their corresponding calculated atmospheric escape.


Aizawa et al. 2022, doi:

Collinson et al. 2015, doi:

Dimmock et al. 2018, doi:

Donahue et al. 1982, doi:

Edberg et al. 2011, doi:

Futaana et al. 2017, doi:

Luhmann et al. 2007, doi:

Luhmann et al. 2008, doi:

McEnulty et al. 2010, doi:

Modolo et al. 2016, doi:

Persson et al. 2018, doi:

How to cite: Katrougkalou, M. C., Aizawa, S., Persson, M., André, N., and Modolo, R.: Investigating the impact of different Interplanetary Coronal Mass Ejection parameters on the Venusian atmospheric escape, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-469,, 2022.

Gabriella Stenberg Wieser, Mats André, Hans Nilsson, and Niklas Edberg

Venus' relatively small induced magnetosphere enables the solar wind to interact directly with the upper atmosphere (Stenberg Wieser et al., 2015), and one could guess that this would yield a larger escape rate compared to a magnetized planet. However, the escape rates reported from Earth are somewhat larger than from Venus. Singly charged oxygen dominates the ion mass outflow from Earth and the average escape rate is estimated to be a few times 1025 s-1 (André, 2015, and references therein). A strong intrinsic magnetic field creates a huge magnetosphere, which prevents direct solar wind access to the atmosphere, but the big structure instead provides a larger interaction cross section to transfer solar wind energy and momentum into the magnetosphere (e.g., Gunell et al., 2018). This can lead to a larger ion energization and atmospheric escape.

In the absence of a direct interaction between the ionosphere and the solar wind, wave-particle interaction has been identified as a major ion energization process at Earth. Several wave modes at different frequencies are able to heat ions. (André & Yau, 1997). A common type of ion heating is associated with low-frequency broadband electric wavefields (André et al., 1998). The spectral density of such broadband waves does not exhibit a peak at a certain frequency but the wave power available at the ion gyrofrequency may nevertheless efficiently energize the ions (Chang et al., 1986). At Earth this heating mechanism is definitely effective and important (André et al., 1998).

We investigate if ions originating from the Venusian ionosphere can be energized by electric wave power in a similar way as is observed at Earth.


André, M. (2015). Previously hidden low-energy ions: a better map of near-earth space and the terrestrial mass balance. Physica Scripta, 90 (12), 128005.

André, M., Norqvist, P., Andersson, L., Eliasson, L., Eriksson, A. I., Blomberg, L. Waldemark, J. (1998). Ion energization mechanisms at 1700 km in the auroral region. Journal of Geophysical Research: Space Physics, 103 (A3), 4199-4222.

André, M., & Yau, A. (1997). Theories and observations of ion energization and outflow in the high latitude magnetosphere. Space Science Reviews, 80 (1), 27-48.

Chang, T., Crew, G. B., Hershkowitz, N., Jasperse, J. R., Retterer, J. M., & Winningham, J. D. (1986). Transverse acceleration of oxygen ions by electromagnetic ion cyclotron resonance with broad band left-hand polarized waves. Geophysical Research Letters, 13 (7), 636-639

Gunell, H., Maggiolo, R., Nilsson, H., Stenberg Wieser, G., Slapak, R., Lindkvist, J., De Keyser, J. (2018). Why an intrinsic magnetic field does not protect a planet against atmospheric escape. A&A, 614.

Stenberg Wieser, G., Ashfaque, M., Nilsson, H., Futaana, Y., Barabash, S., Diéval, C., Zhang, T. L. (2015). Proton and alpha particle precipitation onto the upper atmosphere of venus. Planetary and Space Science, 113-114 , 369-377.

How to cite: Stenberg Wieser, G., André, M., Nilsson, H., and Edberg, N.: Can wave-particle interaction be important for ion heating and escape at Venus?, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-834,, 2022.

Gwen Hanley, Christopher Fowler, James McFadden, David Mitchell, and Shannon Curry

Though ion escape to space is an important mechanism for atmospheric loss on Mars, the processes that accelerate ions to escape velocity have not been identifed and quantified. The lowest altitude where suprathermal planetary ions appear is an important source region for ion escape, where electromagnetic forces and waves begin to energize ions to escape velocity. We have conducted a statistical study of O2distribution functions measured by Mars Volatile EvolutioN SupraThermal And Thermal Ion Composition (MAVEN-STATIC) in order to identify this source region for Martian ion escape. We have fit Maxwellians to each measured O2+ distribution function in order to identify distributions containing a suprathermal component. Suprathermal ions appear just above the exobase region at all solar zenith angles, but Maxwellian ion distributions persist to higher altitudes near the terminator than on the dayside or the nightside. We also investigated the effects of crustal magnetism, finding that crustal fields protect planetary plasma from energization on the dayside and enhance energization on the nightside.

How to cite: Hanley, G., Fowler, C., McFadden, J., Mitchell, D., and Curry, S.: MAVEN observations of initial ion acceleration in the Martian ionosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-277,, 2022.

Andrii Voshchepynets, Stas Barabash, Mats Holmström, Dmitri Titov, Roberto Orosei, Patrick Martin, and Beatriz Sanchez-Cano

Interaction of a spacecraft with ambient plasma results in charging of the spacecraft to a potential of the order of the electron temperature.  This is an issue for the ion measurements in the low altitude Martian ionosphere, since the potential energy of the ions in the spacecraft’s electric field is comparable to their thermal energy. However, the unique Mars Express payload makes possible the use of an innovative technique to study this low energy ionospheric population around the spacecraft. It has been discovered that operating the radar MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) onboard Mars Express results in acceleration of the local thermal ions to energies up to 800 eV. Accelerated ions are readily detected by the ion detector of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3). The analysis of these ASPERA-3 observations showed that that the voltage applied to the MARSIS antenna causes charging of the spacecraft to several hundreds of volts by the electrons of the ambient plasma. Individual observations of accelerated ions consist of almost mono-energetic ion beams that allow measuring densities of the main (O+, O2+ and CO2+) and even minor (O2++, C+, CO+) ionospheric thermal populations. This novel technique of active sounding opens new possibilities to study the Martian ionosphere.


From 2007 to 2016 2,528 Mar Express orbits were found to exhibit sounder accelerated ions (SAI). Created catalogue of the SAI events contains more than 50,000 SAI entries. This allowed to study the mechanisms that causes acceleration of thermal ions in the vicinity of an active transmitter in a plasma with no strong magnetic led. Based on it, a model was developed, that allows to estimate density of cold ionospheric ions from SAI observations.

Figure 1 shows an example of the ion density retrieved using the developed method. Top panels show the ion differential flux measured by IMA. Cold ionospheric plasma is visible as an intense signal at energy close to 10 eV. SAI are present as intense periodic disturbances within energy range between 30 and 800 eV. Bottom panels show comparison of the local electron density estimated using MARSIS ionograms and the ion density estimated from the SAI observations. As one can see, values are in a good agreement and follow similar dependence on altitude and SZA. Both methods show peak of the plasma density close to the periapsis.



Acceleration of the ionospheric plasma above thermal energy facilitates determination of the ion composition by IMA. Figure 2 shows altitude profiles for different ionospheric constituents measured using SAI by MEX. At the altitudes above 300 km main ionospheric species are O2+ and O+ . Corresponding densities decrease from 750 pp/cm3 at 300 km to 400pp/cm3 at 500 km. It is interesting to note that at the altitudes 300-350 km density of O+ is higher than the density of O2+ while on higher altitudes situation is opposite. Similar results were found by MAVEN.

Figure 2: Examples of altitude profiles of different ionospheric constituents obtained from the SAI observations.

Extensive database of the SAI covers more than one solar cycle enabling study of the variability of the Martian ionosphere. Figure 3 shows altitude profiles of the CO2+, O2+ and O+ for the periods of dierent EUV irradiance. For all of the species density increases with increase in EUV irradiance. However different species have dierent response to the increase in EUV irradiance. For the period with low EUV (left panel) density of O+ is higher than that of O2+ at the altitudes below 400 km. In the case of medium EUV flux (middle panel) the densities of these to species are almost equal. For the period of high EUV flux density of O2+ is higher.


SAI database can be used to study the impact of the Martian magnetic anomalies on the ionospheric densities. Figure 4 shows altitude density profiles for regions with closed and open magnetic field lines. Both profiles exhibit similar behavior: ion density decreases by 25% as altitude increases from 300 to 450 km. A notable difference is that the ion density above regions with open magnetic field line is much higher. This result is in agreement with the previous studies. In the open field regions, the ionosphere is more inflated than in other regions since it is easier here for plasma at lower altitudes to diffuse upward. In the regions with strong horizontal field situation is different. In these regions, horizontal drifts due to plasma pressure gradients move plasma particles toward the local magnetic equator where plasma gets trapped. The effects of this trapping on plasma density become more apparent above 170 km, where the effects of collisions between plasma and the neutral atmosphere become negligible compared with plasma transport processes. The vertical transport is inhibited by a horizontal magnetic field resulting in depletion of the ionosphere above these regions.

Figure 3: Altitude proles for O2+, O+ and CO2+ estimated from the SAI observations. Left panel: altitude profiles obtained for the period of the low EUV flux, middle panel - for the period of medium EUV flux, right panel - the period of high EUV flux.

Figure 4: Altitude profiles of the averaged ion density above the regions with strong magnetic field. Red line - modeled magnetic field angle is horizontal. Blue line - modeled magnetic field normal angle is radial.

Particle acceleration by sounders in the planetary ionospheres is a type of active experiments of great interest. These phenomena are a result of routine operation of satellite-borne sounders and do not require any additional spacecraft or mission resources, an important factor for planetary missions with scarce resources.  Sounder accelerated ions detected on Mars Express enabled development of the method that allows to retrieve ion density and composition of cold ionospheric populations. This method was used to study the variability of the Martian ionosphere composition within solar cycle. In addition it was used to study of the crustal magnetic field on the ionospheric density.

How to cite: Voshchepynets, A., Barabash, S., Holmström, M., Titov, D., Orosei, R., Martin, P., and Sanchez-Cano, B.: Sounder accelerated ions: a new technique revealing new ionospheric properties as observed by Mars Express, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-700,, 2022.

Robert Lillis, Justin Deighan, Sonal Jain, Greg Holsclaw, Matthew Fillingim, Krishnaprasad Chirakkil, Scott England, Michael Chaffin, David Brain, Hessa Al Matroushi, Fatma Lootah, Hoor Al Mazmi, Ed Thiemann, Frank Eparvier, Nick Schneider, Jasper Halekas, Suranga Ruhunusiri, Jared Espley, Jacob Gruesbeck, and Shaosui Xu

Here we report on synoptic (or “disk”) observations of Martian discrete aurora in the extreme and far ultraviolet (<200 nm), made by the Emirates Mars Ultraviolet Spectrometer (EMUS) on board the Emirates Mars Mission (EMM). EMM is well-suited to studying aurora due to its high altitude vantage point and regular observation cadence and the high sensitivity of the EMUS instrument.  The first EUV/EUV auroral spectra measured at Mars reveal O, C, and CO features from 99 to 165 nm. Auroral detection increases with solar activity and discrete aurorae display significant variability over ~20 minute timescales.  Three distinct types of discrete aurora have been identified based on these images.  The first type appears where Mars’ crustal magnetic fields are both strong and vertical and are consistent with point detections made by both Mars Express and MAVEN. The second appears in coherent patches away from crustal magnetic fields and is generally weak. The third is a new phenomenon, which we have named “sinuous discrete aurora” due to its serpentine shape, typically extending from the terminator thousands of kilometers into the nightside.  Investigation into its causes is ongoing but it likely reflects the morphology of Mars’ magnetotail current sheet.  Joint analysis of discrete aurora with EMM, MAVEN, and Mars Express promises to elucidate the processes driving the aurora on Mars.

How to cite: Lillis, R., Deighan, J., Jain, S., Holsclaw, G., Fillingim, M., Chirakkil, K., England, S., Chaffin, M., Brain, D., Al Matroushi, H., Lootah, F., Al Mazmi, H., Thiemann, E., Eparvier, F., Schneider, N., Halekas, J., Ruhunusiri, S., Espley, J., Gruesbeck, J., and Xu, S.: EMM EMUS Observations of Martian nightside discrete EUV and FUV Aurora, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-724,, 2022.

Lunch break
Chairperson: Christopher Fowler
Charles Bowers, James Slavin, Gina DiBraccio, Ben Johnston, and Nicholas Schneider

The localized crustal magnetic anomalies scattered across the surface Mars create a unique, hybrid magnetosphere. Over regions of strong crustal magnetism (100-1000 nT at the surface), the crustal anomalies protrude up to thousands of kilometers in space and a create a “mini-magnetospheric” interaction with the draped interplanetary magnetic field (IMF). One consequence of this interaction is the occurrence of discrete aurora on the nightside of Mars via electron precipitation and energy deposition into the planet’s atmosphere stimulating light emission (Bertaux et al., 2005). Discrete auroral emissions from electron impact with atmospheric CO2 in the mid ultra-violet have been observed via the Imaging Ultra-Violet Spectrograph (IUVS) instrument onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. These emissions have been preferentially observed over the region of strong crustal magnetism in the southern hemisphere (~153°-213° E longitude, 30°S-70°S latitude) and favor “open” magnetic field lines (i.e., one end connected to the IMF, the other connected to the planet) (Schneider et al., 2021). These trends suggest discrete aurora at Mars may form via magnetic reconnection between the strong crustal anomalies and the draped IMF around the planet. Magnetic reconnection is a process that can “open-up” the closed crustal magnetic fields at Mars and accelerate electrons along these magnetic field lines. However, there has yet to be a study that links these two phenomena directly, and as a result, our understanding of discrete auroral formation at Mars remains poorly understood.

In this study, we uncover the relationship between magnetic reconnection and discrete aurora at Mars by analyzing the draped magnetic field conditions during 78 discrete auroral emissions observed via nadir observations taken by the IUVS within the region of strong crustal fields. First, we simplify the crustal field region into its two primary constituents: one crustal anomaly that is positioned in the northern half of the region and closes northward, and one crustal anomaly that is positioned in the southern half of the region and closes southward (Figure 1). We note that the discrete auroral emissions tend to fall on the “footprints” of the two crustal anomalies where the dominant component of the crustal magnetic field points radially into or out of the planet. Two plasma regimes are more susceptible to reconnection when their magnetic field orientations are anti-parallel to one another. Therefore, we hypothesize that if crustal field-draped IMF magnetic reconnection plays a role in discrete auroral formation over the strong crustal anomalies at Mars, then a southward draped IMF would activate auroral emissions over the northern crustal anomaly and a northward draped IMF would activate auroral emissions over the southern crustal anomaly.

We estimate the orientation of the draped magnetic field over this region of strong crustal magnetism using data obtained from the magnetometer instrument onboard MAVEN along the same orbit in a discrete auroral emission was detected by IUVS. We find that the estimated orientation of the draped magnetic field associated with each discrete auroral event shows a regional dependence consistent with our hypothesis: discrete auroral emissions over the footprints of the northern anomaly are associated with southward draped fields, and emissions over the footprints of the southern anomaly are associated with northward draped fields (Figure 2). We also demonstrate that these findings hold implications for other trends reported in previous studies of discrete aurora over this region of crustal fields, namely a trend in local time and upstream IMF conditions. This study is the first to more definitively link magnetic reconnection to discrete aurora formation on the nightside of Mars.

Bertaux, J., F. Leblanc, O. Witasse, E. Quemerais, J. Lilensten, S. Stern, B. Sandel, and O. Korablev (2005), Discovery of an aurora on Mars, Nature, 435(7043), 790-794.

Schneider, N., et al. (2021), Discrete Aurora on Mars: Insights Into Their Distribution and Activity From MAVEN/IUVS Observations, Journal of Geophysical Research-Space Physics, 126(10).

How to cite: Bowers, C., Slavin, J., DiBraccio, G., Johnston, B., and Schneider, N.: Magnetic Reconnection and Discrete Aurora at Mars: MAVEN Observations, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-170,, 2022.

Shaosui Xu, David Mitchell, James McFadden, Christopher Fowler, Gwen Hanley, Tristan Weber, David Brain, Gina DiBraccio, Michael Liemohn, Robert Lillis, Jasper Halekas, Suranga Ruhunusiri, Christian Mazelle, Mehdi Benna, Laila Andersson, and Shannon Curry

Discrete aurorae have been observed at Mars by multiple spacecraft, including Mars Express, Mars Atmosphere and Volatile EvolutioN (MAVEN), and most recently the United Arab Emirates’ Hope spacecraft.  Meanwhile, there have been studies on the source particle responsible for producing these detectable aurorae, that is accelerated electrons or hotter solar wind electrons (termed “auroral electrons"). By utilizing empirical criteria to select auroral electrons established by Xu et al. [2022], we conduct statistical analyses of the impact of upstream drivers on the occurrence rate and electron fluxes of auroral electrons. We find the occurrence rate is well organized and increases with upstream dynamic pressure and weakly depends on the interplanetary magnetic field strength. Meanwhile, the integrated auroral electron flux is somewhat insensitive to the upstream drivers. In the meantime, the auroral emission is not the sole effect of electrons impacting the collisional atmosphere. Auroral electrons are expected to cause significant ionization and enhance the plasma density locally. In this study, we also quantify the ionospheric impact of auroral electron precipitation, specifically the thermal ion (O+, O2+, CO2+) density enhancement, with MAVEN observations and also modeling. Our results show the ion density to increase up to 1-2 orders of magnitude at low altitudes.

How to cite: Xu, S., Mitchell, D., McFadden, J., Fowler, C., Hanley, G., Weber, T., Brain, D., DiBraccio, G., Liemohn, M., Lillis, R., Halekas, J., Ruhunusiri, S., Mazelle, C., Benna, M., Andersson, L., and Curry, S.: Auroral electrons at Mars: upstream drivers and ionospheric impact, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-302,, 2022.

High Time and Spatial Resolution Observations of the Topology of Mars' Crustal Magnetic Fields
David Mitchell, Shaosui Xu, David Brain, James McFadden, Christian Mazelle, and Jared Espley
Zachary Girazian, Jasper Halekas, Suranga Ruhunusiri, and Christopher Fowler

At Mars, the solar wind is usually decelerated and heated at the bow shock, then diverted around the planet by the induced magnetosphere. Recently, however, Crismani et. al. (2019) presented MAVEN (Mars Atmosphere and Volatile EvolutioN) observations of an interesting event, where near-pristine solar wind was observed in the collisional atmosphere below 200 km. We searched through seven years of MAVEN SWIA (Solar Wind Ion Analyzer) observations to determine how often these types of events occur. We found at least 15 orbits during which near-pristine solar wind was observed below 200 km. In this presentation, we will discuss the occurrence rate of the events and characterize the planetary and solar wind conditions under which they are observed. Finally, we will discuss the implications of solar wind having direct access to the collisional atmosphere, which may include localized (1) ionization that alters the structure of the ionosphere, (2) heating of the thermosphere, (3) energization of ions to escape speeds, and (4) patchy proton aurora.

Reference: Crismani, M. M. J., Deighan, J., Schneider, N. M., Plane, J. M. C., Withers, P., Halekas, J., et al. (2019). Localized ionization hypothesis for transient ionospheric layers. Journal of Geophysical Research: Space Physics, 124, 4870–4880. 10.1029/2018JA026251

How to cite: Girazian, Z., Halekas, J., Ruhunusiri, S., and Fowler, C.: Pristine Solar Wind Deep in the Collisional Atmosphere of Mars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-739,, 2022.

Marianna Felici and Paul Withers

At Mars, three types of aurorae have been discovered so far. The first kind of aurora is discrete aurora (Soret et al., 2021, and references therein), in which smaller patches of aurora are created mainly in the nighttime sector of the planet by particles accelerated to energies <1 keV by magnetic field reconfiguration; the altitude of emission is at about 135 km. The second kind is diffuse aurora (Schneider et al., 2018, and references therein), in which the aurora spans much of the Martian nightside and is caused by solar energetic particles accelerated to energies of about 100 keV; the peak emission altitudes are between 60 and 70 km. The third kind is proton aurora, which occurs preferentially on the Martian dayside (Hughes et al., 2019, and references therein) and is caused by penetrating protons from the solar wind; the emission enhancement appears between 110 and 150 km altitude.


We use electron density profiles collected by the MAVEN Radio Occultation Science Experiment (ROSE) (Withers et al., 2020) to understand what ionospheric structures are associated with these three different types of auroral emissions, and how the energy deposited by the precipitating particles generating these three types of aurorae affects the electron density in the ionosphere and at what altitudes. We do this by comparing ROSE data to MAVEN/IUVS detections of discrete, diffuse, and proton aurora close spatially and temporally to ROSE observations; and ROSE data to particle data displaying conditions that potentially could have triggered the aurorae.   



Soret, L., Gérard, J.-C., Schneider, N., Jain, S., Milby, Z., Ritter, B., et al. (2021). Discrete aurora on Mars: Spectral properties, vertical profiles, and electron energies. Journal of Geophysical Research: Space Physics, 126, e2021JA029495.

Schneider, N. M., Jain, S. K., Deighan, J., Nasr, C. R., Brain, D. A., Larson, D., et al. (2018). Global aurora on Mars during the September 2017 space weather event. Geophysical Research Letters, 45, 7391–7398.

Hughes, A., Chaffin, M., Mierkiewicz, E., Deighan, J., Jain, S., Schneider, N., et al. (2019). Proton aurora on Mars: A dayside phenomenon pervasive in southern summer. Journal of Geophysical Research: Space Physics, 124, 10,533–10,548.

Withers, P., Felici, M., Mendillo, M. et al. The MAVEN Radio Occultation Science Experiment (ROSE). Space Sci Rev 216, 61 (2020).



How to cite: Felici, M. and Withers, P.: Search for auroral signatures in the Martian ionosphere using MAVEN/ROSE electron density profiles, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-569,, 2022.

Oleg Shebanits, Jan-Erik Wahlund, Hunter Waite, and Michele Dougherty

Titan's ionosphere has a global presence of dusty (ion-ion) plasma a few hundreds of kilometers below the photoionization peak altitudes. Recent studies have shown that charged dust dramatically alters the electric properties of plasmas, in particular planetary ionospheres. Titan is immersed in magnetospheric plasma and magnetic field of Saturn (most of the time) and the moons ionospheric conductivities define the interaction with its environment.

We present revisited electric conductivities and the conductive dynamo region of Titan’s ionosphere using the full plasma content (electrons, ions+, and ions/dust) from 13 years of in-situ measurements by the Cassini mission. We show that the traditional approach of only using the easily detectable electron densities underestimates the Pedersen conductivities at ∼1,100–1,200 km altitude by up to 35%. The Hall conductivities are in general not affected but several cases indicate a reverse Hall effect at closest approach (∼900 km altitude) and below. We also identify a dayside-nightside asymmetry, with dayside conductivities a factor ∼7–9 larger than on the nightside (due to higher plasma densities).

Figure 1 shows the median profiles of the Pedersen, Hall and magnetic field parallel conductivities plotted in altitude and versus the neutral atmosphere, color-coded into dayside, terminator and nightside. First thing to note is that due to the extent of Titan’s atmosphere and ionosphere, plotting versus altitude results in noticeable less organized data due to atmospheric variations. These profiles scale with the plasma densities so their trends propagate – we identify solar cycle effects that match those on the heavy charge carriers.

Figure 1. Sliding median conductivity profiles: Pedersen (panels a1, b1), Hall (panels a2, b2) and Parallel (panels a3, b3). The total medians are in solid black. The colored lines are medians for the dayside (SZA<70), terminator (70≤SZA<100) and nightside (SZA≥100). Adapted from Shebanits et al. (2022).

The study is available in open access and includes the dataset: .

How to cite: Shebanits, O., Wahlund, J.-E., Waite, H., and Dougherty, M.: Electric conductivities of Titan’s dusty ionosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-799,, 2022.

Coffee break
Chairperson: Lina Hadid
Moa Persson and the The BepiColombo Venus flyby #2 team

As Venus lacks an intrinsic magnetic field, such as Earth’s, and crustal magnetic fields, such as Mars’, its conductive ionosphere interacts directly with the solar wind, and an induced magnetosphere is created. Therefore, the Venusian magnetosheath is one of the few examples of a gas-dynamics dominated interaction region in the solar system. Measurements of this region can help us investigate the energy transfer from the solar wind to the ionosphere of non-magnetised bodies and properties of stagnated flow near the subsolar point, without complications from magnetic fields of planetary origin.

Even though several missions have visited Venus, none of them have been able to provide high time resolution plasma particle measurements of the subsolar magnetosheath. With the 2nd Venus flyby by BepiColombo on August 10th 2021, we had the rare opportunity to make a complete tour of the Venusian magnetosheath, using measurements from several plasma instruments onboard, as the flyby passed from the nightside flank towards the stagnation region near the subsolar point and out through a quasi-perpendicular bow shock. The observations were made during the extremely rare opportunity when the Solar Orbiter spacecraft was located upstream and could provide complementary solar wind observations, which showed very stable solar wind conditions during the scenic tour. This meant that we had the chance to, for the first time, probe the full spatial structure of the Venusian magnetosheath, without large temporal variation induced by solar wind fluctuations.

Part of this work is funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No 871149.

How to cite: Persson, M. and the The BepiColombo Venus flyby #2 team: The scenic tour of the Venusian subsolar magnetosheath by BepiColombo, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-397,, 2022.

Steffy Sara Varghese and Ioannis Kourakis


Electrostatic solitary waves (ESWs), also known as “Broadband Electrostatic Noise", are associated with regions carrying field-aligned currents, i.e. electron and ion beams, and have been shown to play a particular role in particle acceleration via wave-particle interactions and magnetic reconnection [Malaspina, 2020]. In space plasmas, bipolar electric field variations of short duration travelling largely parallel to the magnetic field are treated as the signature of these solitary waves in electric field (E− field) data, in addition to monopolar pulses also (but less often) recorded in the electric field data. While the former (bipolar E-field structures) are mostly interpreted as ion/electron- acoustic solitary waves, monopolar structures are interpreted as the double layers, i.e. transitions between regions of constant (finite) potential.

ESWs have long been observed and extensively investigated in near-Earth environments. They have been detected in various regions of the magnetosphere, the magnetosheath [Pickett, 2005], magnetospheric boundary layers, and also in the magnetopause [Cattell, 2002], the polar cap boundary layer [Tsurutani, 1998], and the bow shock [Bale, 2003]. They’ve also been observed in powerful currents like those associated with the auroral acceleration area, where magnetically aligned electron and ion beams are accelerated and pierce the Earth’s upper atmosphere (the Aurora) [Temerin, 1982]. Asides in the Earth’s magnetosphere, double layers have been recorded in no other planetary magnetosphere. Electric field structures are very likely to be present in induced planetary magnetospheres and play a prominent role in the physics of magnetic field-aligned currents and plasma homogenization, but they have remained undetected due to the small number of observations capable of detecting them. Very recently, Malaspina et al., [Malaspina, 2020] reported the first-ever observation of a plasma double layer in a distant (from the Earth) space environment, in observations of electric field structures at the induced magnetosphere of Venus. Their presence is related to various plasma processes such as slowing, deflection, and the heating of solar wind particles at the induced magnetosphere of Venus. Inspired by those measurements, we have investigated the implications of electron populations in the generation of DLs in Venus’ magnetosphere and their interplay with electrostatic solitary waves.

Based on a multi-fluid plasma model, we have interpreted the significance of cooler electron concentration in the formation of electrostatic solitary wave structures in the induced magnetosphere of Venus. Our proposed theory not only explains the E-field data’s particular morphology, but it also provides a generic interpretation for observed localized structures, thus connecting the dots between the mathematical description of coherent nonlinear structures and satellite observations. Our model aims at establishing a comprehensive framework for localised pulses in E-field data recorded during satellite expeditions, which in turn will be significant in defining the microphysics of Venus’ magnetosphere and presumably other similar planetary environments. Interestingly enough, a recent study has focused for the first time on modeling ESW structures recorded by the MAVEN mission on Mars’s induced magnetosphere [Kakad et al, 2022] and those observations qualitatively resemble the recordings from Venus.


  • [1] Malaspina, D. M., Goodrich, K., Livi, R., Halekas, J., McManus, M., Curry, S., et al.,. Plasma double layers at the boundary between Venus and the solar wind. Geophysical Research Letters, 47, 2020, e2020GL090115.
  • [2]  Pickett, J. S., Chen, L. J., Kahler, S. W., Santolik, O., Goldstein, M. L., Lavraud, B., Balogh, A. On the generation of solitary waves observed by Cluster in the near- Earth magnetosheath. Nonlinear Processes in Geophysics, ,122005, (2), 181-193.

  • [3]Cattell,C.,Crumley,J.,Dombeck,J.,Wygant,J.,andMozer,F.S.,Polarobserva- tions of solitary waves at the Earth’s magnetopause, Geophys. Res. Lett., 29( 5), 2002, doi:10.1029/2001GL014046.

  • [4]Tsurutani,B.T.,J.K.Arballo,G.S.Lakhina,C.M.Ho,B.Buti,J.S.Pickett,and D. A. Gurnett , "Plasma waves in the dayside polar cap boundary layer: Bipolar and monopolar electric pulses and whistler mode waves", Geophysical Research Letters, 25, 1998, (22), pp: 4117- 4120, doi:10.1029/1998GL900114.

  • [5]  Bale, S. D., Mozer, F. S., Horbury, T. S., Density-transition scale at quasiperpen- dicular collisionless shocks. Physical Review Letters, 91, 2003, (26), 265004.

  • [6]  M. Temerin, K. Cerny, W. Lotko, and F. Z. Mozer, "Observations of double layers and solitary waves in the auroral plasma", Phys. Rev. Lett, 48, 1982, pp. 1175-1179, doi:10.1103/PhysRevLett.48.1175.

  • [7]  Bharati Kakad, Amar Kakad, H. Aravindakshan and Ioannis Kourakis, Debye- Scale Solitary Structures in the Martian Magnetosheath, submitted to Astrophys- ical Journal (under review).

How to cite: Varghese, S. S. and Kourakis, I.: Electrostatic Solitary Waves in Venus’ Magnetosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-948,, 2022.

Peter Stephenson, Marina Galand, Jan Deca, and Pierre Henri

The Rosetta spacecraft rendezvoused with comet 67P/Churyumov-Gerasimenko in August 2014 and escorted it for two years until September 2016. The plasma surrounding the comet was probed by the Rosetta Plasma Consortium (RPC), comprising five instruments. The Langmuir Probe (RPC/LAP; Engelhardt et al., 2018) and Mutual Impedance Probe (RPC/MIP; Wattieaux et al, 2020; Gilet et al., 2020) measured a cold population of electrons (< 1 eV) within the cometary environment, that was persistent throughout the mission.

Cometary electrons are typically produced at 10 eV through ionization of the neutral gas coma. This is either through photoionization, by absorption of an extreme ultraviolet (EUV) photon, or electron-impact ionization, by collisions of energetic electrons with the coma. Cold electrons are formed by cooling the warm, newly born electrons, through inelastic collisions with the cometary neutrals. Assuming they flow radially away from the nucleus, the electron cooling should only be significant for the high outgassing rates found around perihelion (Q > 3 x 1027 s-1). However, the cold population was observed at large heliocentric distances (> 3.5 au) and very weak outgassing rates (Q < 1026 s-1).

We have developed the first 3D collisional model of electrons at a comet, featuring a spherically symmetric coma of pure water.  Electric and magnetic fields are self-consistently calculated using a fully-kinetic, collisionless Particle-in-Cell simulation model (Deca et al., 2017; 2019), which are used as an input for the test particle model. Electron-neutral collisions are treated as a stochastic process. The collision processes include elastic scattering, inelastic excitations, and electron-impact ionization.

With the test particle model, we demonstrate that electrons are trapped in an ambipolar potential well around the nucleus. This greatly increases the efficiency of collisional processes compared to the case of radial outflow. A cold electron population is formed at weak outgassing rates
(Q = 1026 s-1), far below the threshold for cooling under radial outflow.

We quantify the increased efficiency of electron collisions when using the complex electric and magnetic fields, compared to radial outflow. The location of the electron cooling exobase is calculated accounting for electron trapping and compared with the cold electron measurements from Rosetta. This explains the cold electron observations at low outgassing rates.


Deca J, Divin A, Henri P, Eriksson A, Markidis S, et al. 2017. Physical Review Letters. 118(20):205101
Deca J, Henri P, Divin A, Eriksson A, Galand M, et al. 2019. Phys. Rev. Lett. 123:55101
Engelhardt IAD, Eriksson AI, Vigren E, Valières X, Rubin M, et al. 2018. 15
Gilet N, Henri P, Wattieaux G, Traoré N, Eriksson AI, et al. 2020. A&A. 640:A110–A110
Wattieaux G, Henri P, Gilet N, Vallières X, Deca J. 2020. A&A. 638:A124–A124

How to cite: Stephenson, P., Galand, M., Deca, J., and Henri, P.: Cold electrons at a weakly outgassing comet, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-972,, 2022.

Elias Odelstad, Luca Sorriso-Valvo, Anders Eriksson, and Tomas Karlsson
  • 1Swedish Institute of Space Physics, Uppsala, Sweden
  • 2KTH Royal Institute of Technology, Stockholm, Sweden

The ionospheres of comets are complex systems, where dynamic phenomena such as plasma instabilities and turbulence commonly occur as a consequence of the coupling processes between solar wind and cometary plasma. The analysis of fluctuations of plasma density, magnetic and electric fields observed by ESA’s Rosetta spacecraft during its 2-year mission to comet 67P/Churyumov-Gerasimenko suggest the existence of a turbulent state in the cometary plasma environment, which may be at the heart of important dynamical processes and have consequential impact on the cross-scale coupling.

Rosetta’s prolonged stay in the inner plasma environment of 67P provided the instruments of the Rosetta Plasma Consortium (RPC) with an unprecedented long-term view of the inner coma and plasma environment of an intermediately active comet. We use data from the Langmuir probe (RPC-LAP), magnetometer (RPC-MAG) and mutual impedance probe (RPC-MIP) to investigate the fluctuations and dynamics of plasma density, magnetic and electric fields across time-scales from ~10-1-103 s. Recurring density enhancements of several hundred percent occur on typical time scales of a few minutes, c.f. Figure 1a. Similar enhancements are also seen in the magnetic field magnitude, though not quite as large (δB/B~1), c.f. Figure 1b. Time-averaged wavelet spectra of both density and magnetic field from a 4-hour interval (including the example time series in Figure 1), c.f. Figure 2, exhibit clear maxima at a period of about 3 minutes, quantifying and confirming the importance of this characteristic time scale in the cometary plasma environement, at least for this time period.

The observed 3-min structures represent a source of energy, corresponding to a peak in the power spectral density and to the saturation scale of the second order structure function of the field fluctuations, c.f. Figures 3a and 4a. At shorter time scales, spectra show power law scaling with exponents close to 5/3, typical of Kolmogorov turbulence. A power-law scaling range is also observed between 3 min and ~1 s for the normalized fourth-order moment of the scale-dependent fluctuations, the "flatness", a standard indicator of intermittency in turbulence, shown in Figures 3b and 4b. The scaling exponent of the flatness is comparable with typical observations in the turbulent solar wind. Kolmogorov spectra and strong intermittency are a robust indication that the dynamics is dominated by nonlinear interactions, which induce a cross-scale transfer of energy, the so-called turbulent cascade, over a broad range of smaller scales. This turbulent cascade can heavily influence particle heating and acceleration at the comet, as well as the structure and dynamics of the plasma in the inner coma, and thus play an important role for shaping the cometary plasma environment.

How to cite: Odelstad, E., Sorriso-Valvo, L., Eriksson, A., and Karlsson, T.: Plasma turbulence at comet 67P, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1140,, 2022.

Display time: Wed, 21 Sep 14:00–Fri, 23 Sep 16:00

Posters: Thu, 22 Sep, 18:45–20:15 | Poster area Level 1

Chairperson: Beatriz Sanchez-Cano
Hector Pérez-de-Tejada and Rickard Lundin

A suitable view of the distribution of the velocity vectors of the H+ solar wind ions measured with the VEX spacecraft projected on a plane transverse to the wake direction is reproduced in Figure 1 to describe a vortex shape configuration. The velocity distribution is oriented in a geometry different from what would be produced by magnetic tension forces along the field lines from the Venus polar regions. Instead, flow motion is dominant to produce the vortex shape in the particle displacement.

Figure 1. Velocity vectors of the H+ ions projected on the YZ-plane compiled from the VEX measurements (From Lundin et al., GRL, 40(7), 273,  2013).


By collecting data from VEX orbits obtained when the spacecraft entered and exited a vortex structure between 2006 and 2013 those crossings are indicated with the segments placed in Figure 2. As a whole there is a general difference between segments located within two circles that are traced with a preference to occur farther away from Venus (located at the left side) in the 2006-2009 orbits (left circle) with respect to those in the 2010-2013 orbits (right circle). At the same time, there is a corresponding difference in the width of the segments with larger values (higher values in the vertical coordinate) for those placed in the right circle. In particular, since minimum solar cycle conditions were present during the 2009-2013 orbits there is an indication that under such conditions the position of the vortex structures occurred closer to Venus along the wake and at the same time their width becomes larger.

Figure 2. Width of vortex structures in 20 VEX orbits measured downstream from Venus. The numbers at the side of each segment represent the two last digits of the year between 2006 and 2009 prior to a solar cycle minimum (left circle) and between 2009 and 2013 during that time period (right circle) (Pérez-de-Tejada and Lundin. IntechOpen, ISBN-978-1-83969-313-7), 2021.

 Such properties are compatible with the shape of a corkscrew flow in fluid dynamics depicted in Figure 3 in which its thickness decreases with distance downstream from an object immersed in a flow.

The decrease of the overall size of vortices with distance along the Venus wake as noted in Figure 2 has important implications regarding its effects on the motion of the planetary ions that stream in the wake. Most notable is that their kinetic energy around those features depends on the scale size of vortices and if the latter become smaller with the downstream distance as produced by the expansion of the solar wind into the wake the energy released should be assimilated by particles that remain moving in the smaller size vortices. In addition, such particles have directed motion along the wake and as a result, some of that energy may contribute to enhance their speed in that direction. It is thus possible that a fraction of planetary O+ ions dragged along by the solar wind may be gradually accelerated along the Venus wake. 

The acceleration of those particles can be estimated in terms of the change that the cross section of the vortex structures experience along the wake and that as shown in Figure 4 produces an increase in their speed in both panels from ~10 km/s by ~5 103 km altitude to ~40 km/s by ~104 km.  Following the shape of a vortex structure downstream from Venus similar to that indicated in the equivalent form past an object in Figure 3 we can suggest a shape that by two planetary radii downstream from Venus the thickness of the vortex should have decreased. The outcome of that geometry is that when the thickness of the corkscrew flow decreases along the wake the speed of the particles has to be larger so that their kinetic energy density integrated over the area of the cross section is preserved.


Figure 3. View of a corkscrew vortex flow in fluid dynamics. Its geometry is equivalent to that expected for a vortex flow in the Venus wake. The vortex flow becomes thinner when it is detected further downstream from Venus as suggested from the data in Figure 2 (from Pérez de Tejada and, Lundin, Intech Open (ISBN-978-1-83969 -313-7), 2021


Figure 4. Speed profiles of the solar wind and ionospheric ions as a function of altitude measured in the dawn-dusk (left) and in the noon-midnight meridian (right) (from Lundin et al., ICARUS, 215, 751, 2011).

 Variations in the speed profiles with altitude measured in the dawn-dusk and in the dawn-dusk meridians across the Venus wake are compatible with those expected from the shape of the corkscrew flow in Figure 3 where larger speed values should be encountered where the cross section of the vortex structure is smaller. Thus, the data points in Figure 4 at low altitudes refer to the motion of the spacecraft through a wide vortex in a region close to Venus and at higher altitudes apply where the cross section of the vortex is smaller and hence the flow speeds are larger as it is the case by ~104 km altitude.

An implication also consistent with the shape of a corkscrew flow shape in Figure 3 is the abrupt ending of the speed profile by ~ 1.5 104 km altitude in both panels of Figure 4 and that is not related to any drastic change in the density profile since comparable density values were measured above and below that altitude. Instead, the abrupt ending of the speed profile at that altitude may imply the exit of the spacecraft from the corkscrew flow region along its trajectory. Measurement of planetary ion flows in the Venus near wake also suggest that they proceed under superalfvenic conditions and thus are unrelated to magnetic field effects (Pérez-de-Tejada et al., JGR, 118, doi: 10.1002/2013JA019029, 2013). At the same time the flow direction appears to be independent of the magnetic field orientation (Lundin, personal communication).                                                                   

How to cite: Pérez-de-Tejada, H. and Lundin, R.: Particle acceleration in the Venus plasma wake, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-64,, 2022.

Anna Turner, Christopher Fowler, and Laila Andersson

The thermal electron temperature, Te, is an important quantity in planetary ionospheres because many photochemical reaction rates depend on it. Te thus plays a role in driving ion composition, structure and dynamics. In addition, enhancements in Te with altitude have been shown to drive ambi-polar electric fields that can energize cold planetary ions and lead to ion escape to space.


The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission acquires Te profiles on each orbit and as a result, a comprehensive data set exists that spans the full range of Mars local times, latitudes and solar zenith angles. We will determine which physical processes control the Te profile shapes and temperature values. In particular, we will focus on the “transition region” where Te values can rapidly increase from small values (<500 K) at lower altitudes, to larger values (>1000 K), over a relatively narrow altitude range. The suite of plasma instruments carried by MAVEN allows us to investigate the role of, for example, electron-neutral collisions, ion temperature, wave heating, etc. Understanding the physical processes that control the form of Te profiles will inform us of the mechanisms key to structuring the current day Mars ionosphere. Such understanding will also provide key insight needed for studies of ionospheric escape to space and long term evolution of the Mars atmosphere.

How to cite: Turner, A., Fowler, C., and Andersson, L.: Determining the physical processes that control thermal electron temperature profiles in the Mars ionosphere., Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-146,, 2022.

Christopher Fowler, Gwen Hanley, James McFadden, Jasper Halekas, Steven Schwartz, Christian Mazelle, Michael Chaffin, David Mitchell, Laila Andersson, Jared Espley, Robin Ramstad, Yaxue Dong, and Shannon Curry

Mars is an unmagnetized planet meaning that it has no internally generated global dipole magnetic field; the solar wind interaction with Mars is thus highly dependent on upstream conditions that include the orientation of the Interplanetary Magnetic Field (IMF). This interaction controls the transfer of energy and momentum from the solar wind into the magnetosphere, ionosphere and atmosphere, driving structure and dynamics within each. The Mars-solar wind interaction has been studied in detail for “nominal” Parker Spiral IMF conditions, but few studies exist that investigate the interaction under less typical “radial IMF” conditions. We utilize in-situ measurements made by NASAs Mars Atmosphere and Volatile EvolutioN (MAVEN) mission during radial IMF conditions at Mars to identify several prominent features that arise during this interaction:

  • Highly disturbed magnetic and plasma conditions exist over the nose of the planet, which are reminiscent of foreshock like conditions and indicative of radial IMF.
  • Solar wind protons and alphas are observed to penetrate directly into the dayside ionosphere down to MAVEN periapsis altitudes (~230 km).
  • The magnetic pileup region (or magnetic barrier) forms deep within the dayside ionosphere, directly exposing significant heavy planetary ion densities above to the solar wind flow.
  • Planetary ions above the magnetic barrier are mass loaded by the solar wind flow, characterized by signatures consistent with VxB acceleration under near radial IMF conditions.
  • Thermal ion distributions in the ionosphere are observed to possess significant suprathermal energetic tails, suggesting that additional energization mechanisms are present that heat the cold ion core. Electron and ion temperatures are 2-10 times higher than average values that occur under more typical IMF conditions.
  • Significant erosion of the dayside upper ionosphere occurs and appears to drive substantial ion escape to space.

How to cite: Fowler, C., Hanley, G., McFadden, J., Halekas, J., Schwartz, S., Mazelle, C., Chaffin, M., Mitchell, D., Andersson, L., Espley, J., Ramstad, R., Dong, Y., and Curry, S.: A MAVEN case study of radial IMF at Mars: impacts on the dayside ionosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-233,, 2022.

Erwan Jariel, Sae Aizawa, Ronan Modolo, Ludivine Leclercq, Claire Baskevitch, Nicolas Andre, and Moa Persson

Unlike Earth, Venus doesn’t have an intrinsic magnetic field shielding it from the solar wind. However, an induced
magnetic field is generated from the interaction of solar wind and the dense atmosphere of the planet. Recent
Venus flybys by the BepiColombo mission in October 2020 and August 2021, and by Parker Solar Probe and Solar
Orbiter, are unique opportunities to further study the interaction between Venus and the Sun.

Observational data are essential in the study of this interaction but they are limited by the mission’s trajectory,
offering a constrained view of the processes that take place. On the other hand, simulations offer a global view
of the interactions, allowing us to get results with physical significance that would not have been possible from
observational data only. LatHyS is a three-dimensional parallel multi-species model using the hybrid formalism,
that represents the electrons as a massless fluid conserving the neutrality of the plasma, and the ions by numerical
macroparticles with variable weights. Ions and electrons are coupled together using the Maxwell equations, and the
macroscopic plasma parameters determine the evolution of the magnetic field (Ledvina et al. 2008). It was initially
developed at LATMOS, Paris, France, for Mars (Modolo et al. 2005) and later parallelized (Modolo et al. 2016) for
performance and optimization purposes. It has the advantage of having a self consistently calculated ionosphere.
LatHyS was recently adapted to the simulations of the interaction between the solar wind and Venus at IRAP,
Toulouse, France (Aizawa et al. 2022).

The work conducted aims at adapting a multi-grid method, initially adapted to LatHyS by Leclercq et al. 2016
for the study of Mars and Ganymede, to the case of Venus. The multi-grid refinement allows a more efficient use
of computing resources and an improved accuracy of the simulation thanks to a spatial resolution equivalent to or
lower than the ionospheric plasma scale height.

First, the multi-grid method is presented. Then, simulations using the multi-grid method on the solar wind’s
interaction with Venus are conducted, and their results are compared to simulations made using LatHyS with a
single homogeneous grid.
Finally the outputs of the numerical simulations are compared to data on the magnetic field and charged particles
from recent flybys and from the Venus Express mission, that orbited the planet from 2006 to 2014.



Aizawa et al. 2022.

Leclercq et al. 2016.

Ledvina et al. 2008.

Modolo et al. 2005.

Modolo et al. 2016.

How to cite: Jariel, E., Aizawa, S., Modolo, R., Leclercq, L., Baskevitch, C., Andre, N., and Persson, M.: Adapting a multi-grid method to a numerical simulation model of the interaction between Venus and the solar wind, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-417,, 2022.

Comparison Between Ionospheric and Surface Level Magnetic Fields at Mars
Matthew Fillingim, Catherine Johnson, Anna Mittelholz, Benoit Langlais, Steve Joy, Peter Chi, Heidi Haviland, Robert Lillis, Jared Espley, Jasper Halekas, Sue Smrekar, and Bruce Banerdt
Kerstin Peter, Martin Pätzold, Feng Chu, Robin Ramstad, Ed Thiemann, Markus Fränz, Zachary Girazian, Andy Kopf, Silvia Tellmann, Bernd Häusler, Yoshifumi Futaana, and Mats Holmström

While the orbital and environmental parameters (e.g. orbit-Sun-distance, planetary mass/diameter, rotation rate, surface pressure) of Venus and Mars are very different, their planetary ionospheres show many similarities. The photochemically dominated regions of the undisturbed dayside ionospheres of Venus (Figure 1) and Mars (Figure 2) contain two major features: The ionospheric main peak (V2 at Venus and M2 at Mars) both originate from photoionization by solar EUV radiation, while the weaker secondary V1/M1 region is based on the primary and secondary ionization by solar X-ray radiation [1]. The upper region of the Venus and Mars dayside ionospheres is dominated by transport processes. The extent and shape of these regions in Venus Express Radio Science (VEX-VeRa) and Mars Express Radio Science (MEX-MaRS) observations is highly variable on temporal scales and ranges from an undisturbed exponential decay (Figure 1a and 2a) to strongly compressed shapes (Figure 1b and 2b). 

In this work, 9 years of VEX-VeRa (2006-2014) and 18 years of MEX-MaRS (2004-ongoing) radio science observations are used to study the behavior of the upper ionospheric region of Venus and Mars. The identified parameters will be compared to other characteristics of the solar wind interaction region of both planets identified by Venus Express [2], Mars Express [3] and MAVEN [4] to improve our understanding of the solar wind interaction of planets without a global magnetic field. The effect of potential drivers on the temporal variability of the upper ionosphere are investigated for Venus and Mars by comparison with pristine solar wind parameters (e.g. VEX-ASPERA4 [5], MEX-ASPERA3 [6]) and solar radiation fluxes (FISM-V2 model [7], MAVEN EUV monitor [8]).





  [1] Fox et al. (1996)  Adv. Space Res., 17 (11).

  [2] Titov et al. (2006)  Cosmic Research 44 (4).

  [3] Fletcher (2004)  Mars Express. The scientific payload. ESA.

  [4] Jakosky B. M. et al. (2015)  SSR, 195, 3-48.

  [5] Barabash et al. (2007)  PSS, 55 (12).

  [6] Barabash et al. (2006)  SSR, 126, 113-164.

  [7] Chamberlin et al. (2020) Space Weather, 18 (12).

  [8] Thiemann et al. (2017)  JGR Space Phys., 122 (3).

How to cite: Peter, K., Pätzold, M., Chu, F., Ramstad, R., Thiemann, E., Fränz, M., Girazian, Z., Kopf, A., Tellmann, S., Häusler, B., Futaana, Y., and Holmström, M.: The variability of the topside ionospheres of Venus and Mars in light of radio science observations, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-857,, 2022.

Zoe Lewis, Arnaud Beth, Kathrin Altwegg, Anders Eriksson, Marina Galand, Charlotte Götz, Pierre Henri, Kevin Héritier, Laurence O'Rourke, Ingo Richter, Martin Rubin, Peter Stephenson, and Xavier Vallieres

The European Space Agency Rosetta mission escorted comet 67P/Churyumov-Gerasimenko for two years, during which it acquired an extensive dataset, revealing unprecedented detail about the neutral and plasma environment of the coma. The measurements were made over a large range of heliocentric distances, and therefore of outgassing activities, as Rosetta witnessed 67P evolve from a low-activity icy body at 3.8 AU to a dynamic object with large-scale plasma structures and rich ion and neutral chemistry near perihelion at 1.2 AU. One such plasma structure is the diamagnetic cavity, a region of negligible magnetic field surrounding the comet nucleus. It is formed through the interaction of the unmagnetized outwardly expanding cometary plasma with the incoming solar wind. This region was encountered many times by Rosetta between April 2015 and February 2016, as the comet moved towards and away from perihelion.

In this study, we focus on the changing role of chemistry during the escort phase, particularly on trends in the detection of high proton affinity species near perihelion and within the diamagnetic cavity. NH4+ is produced through the protonation of NH3 which has the highest proton affinity of the neutral species and is therefore the terminal ion. The ratio of this species to the major ion species H3O+ can then be an indicator of the importance of ion-neutral chemistry as an ion loss process compared to transport. We use data from the high resolution mode of the ROSINA (Rosetta Orbital Spectrometer for Ion-Neutral Analysis)/DFMS (Double Focussing Mass Spectrometer) instrument, which allows certain ions of the same integer mass per charge ratio to be separated from one another, most importantly H2O+ and NH4+. This data is then analysed alongside a range of plasma properties from the RPC (Rosetta Plasma Consortium) suite of instruments, to determine features of the plasma within and outside of the diamagnetic cavity that may systematically impact the ion species detected in the mass spectrometer, for example through the spacecraft potential.

For the same period, ion ROSINA/DFMS ion data are analysed together with simultaneous observations of the cometary plasma properties by RPC instruments, in order to identify systematic plasma features or biases which may impact the ion composition detected by ROSINA. In addition, the ion composition measurements are compared to ionospheric simulations. We evaluate the relative significance of ion-neutral chemistry and transport such that their impacts on the ion composition in different interaction regions are identified.

How to cite: Lewis, Z., Beth, A., Altwegg, K., Eriksson, A., Galand, M., Götz, C., Henri, P., Héritier, K., O'Rourke, L., Richter, I., Rubin, M., Stephenson, P., and Vallieres, X.: Ionospheric composition of comet 67P near perihelion with multi-instrument Rosetta datasets, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-960,, 2022.

Beatriz Sanchez-Cano, Mark Lester, Simon Joyce, Olivier Witasse, Johannes Benkhoff, Daniel Heyner, Marco Pinto, Richard Moissl, and Rami Vainio

BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. It was launched in October 2018 and it is due to arrive at Mercury in late 2025. It consists of two spacecraft, the Mercury Planetary Orbiter (MPO) built by ESA, and the Mercury Magnetospheric Orbiter (MMO) built by JAXA, as well as a Mercury Transfer Module (MTM) for propulsion built by ESA. The cruise phase to Mercury will last ~7 years and constitutes an exceptional opportunity for studying the evolution of the solar wind, solar transients, as well as for planetary science and planetary space weather. On this last topic, BepiColombo is proving to be an important upstream solar wind monitor for the terrestrial planets. This is especially important for case of Mars where we currently do not have many observations of the upstream interplanetary magnetic field or solar wind. As consequence, the analysis and interpretation of ionospheric observations is challenging, especially when coronal mass ejections and solar energetic particles hit Mars and we do not have Earth plasma observatories in good alignment with Mars to provide the space weather context. While Mars missions such as Mars Express or MAVEN are able to investigate the impact of the solar wind on the ionosphere, BepiColombo can be the solar wind sentinel for Mars, so we can see the cause and effect. Therefore, this work focuses on the response of the Martian ionosphere to solar transient events which have been previously detected by BepiColombo, and for which we can provide the right upstream solar wind context, such as during the last months of 2021. The objective is to evaluate the response of the Martian ionosphere and its dynamics with more accuracy knowing the exact energy inputs from the solar wind as detected in-situ in the solar wind by BepiColombo.

How to cite: Sanchez-Cano, B., Lester, M., Joyce, S., Witasse, O., Benkhoff, J., Heyner, D., Pinto, M., Moissl, R., and Vainio, R.: BepiColombo as upstream solar wind monitor for Mars’ ionosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-994,, 2022.

Niklas J. T. Edberg, Fredrik Leffe Johansson, Anders I. Eriksson, Erik Vigren, Pierre Henri, and Johan De Keyser

The Rosetta spacecraft followed comet 67P/Churyumov-Gerasimenko (67P) for more than two years, at slow walking pace (about 1 m/s) within 1500 km from the nucleus. During one of the radial movements of the S/C in the early phase of the mission the radial distribution of the plasma density could be estimated, and the ionospheric density was found to be inversely proportional to the cometocentric distance r from the nucleus (a 1/r-distribution). In this study we characterise the radial distribution of plasma around 67P throughout the mission further, and expanding on the initial results. We also investigate how a 1/r-distribution can be perceived during a flyby with a fast (10's km/s) spacecraft, such as the upcoming Comet Interceptor mission, when there is also an asymmetry introduced to the outgassing over the comet surface. We use data from the Rosetta Plasma Consortium (RPC) Langmuir probe (LAP) and Mutual Impedance (MIP) instruments during six  intervals throughout the mission, when Rosetta moved radially with respect to the comet, to determine the radial distribution of the plasma. We then simulate what radial distribution a fast flyby mission would actually observe during its passage through a coma when there is a 1/r plasma density distribution but also an asymmetric outgassing introduced. The plasma density around comet 67P is found to roughly follow a 1/r dependence, although significant deviations occur in some intervals. If normalizing all data to a common outgassing rate (or heliocentric distance) and combining the intervals to cover a the full radial range of 10-1500 km, a 1/r^1.19 average distribution is found. The simulated observed density from a fast S/C flying through a coma with a 1/r-distribution but with an asymmetric outgassing can in fact appear as both a 1/r-distribution, a 1/r^2-distribution, or an even steeper distribution, due to the combined effect of the radial variation in plasma with the variation in density arising from the spacecraft moving over an asymmetrically outgassing body.


How to cite: Edberg, N. J. T., Johansson, F. L., Eriksson, A. I., Vigren, E., Henri, P., and De Keyser, J.: Radial distribution of plasma at comet 67P and implications for cometary flyby missions, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-631,, 2022.

Özgür Karatekin, Ananya Krishnan, Sebastien Verkercke, Gregoire Henry, Beatriz Sánchez-Cano, and Olivier Witasse

Electron density structure and its temporal/spatial variations is one of the critical quantities in understanding an upper atmosphere. Mars has currently several orbiters studying its upper atmosphere and in particular electron density profiles.  The Mars Express (MEX), in the orbit since 2003 has been measuring Mars upper atmosphere through remote measurements by the MARSIS (Sub-Surface Sounding Radar Altimeter) sounder and radio occultations by MaRS (Radio Science Experiment - sounding of the internal structure, atmosphere and environment). The Mars Atmosphere and Volatile EvolutioN,  MAVEN mission  whose science objectives include exploration of the interactions of the Sun and the solar wind with the Mars magnetosphere and upper atmosphere has  complete plasma package. Maven has been performing in-situ composition measurements since November 2014, in particular, the Langmuir Probe and Waves  (LPW) instrument onboard MAVEN provide electron density using current-voltage sweeps.

Here we  present the comparison of multi-instrument spacecraft measurements of Mars upper atmosphere for selected dates, using remote sensing (MEX) and in-situ measurements (MAVEN).  The mutual observations are selected from publicly available data on ESA Planetary Science Archive as well as MAVEN Science Data Center. The L2 level Radio Occultation data are analyzed to obtain the Mars upper Atmosphere Electron density profiles. The MARSIS and LPW provide top side electron profiles whereas Radio occultations provide the full electron density profile. We focuse on the photochemical equilibrium region of the Martian ionosphere–thermosphere  below 200 km. The analysis  also includesz the  Deep Dip  campaigns of MAVEN making in-situ measurements of the region near the ionospheric peak.

The comparison of independent measurements using different techniques will be presented and the differences and similarities between the observations will be discussed to help to validate our understanding of the physical and chemical processes occurring in the atmosphere.

Figure 1: Comparison of MEX Radio Occultations (RO) with the MAVEN Langmuir Probe and Waves (LPW) for 3 selected mutual observation in March 2015

How to cite: Karatekin, Ö., Krishnan, A., Verkercke, S., Henry, G., Sánchez-Cano, B., and Witasse, O.: Multi-instrument/Spacecraft observations of Mars upper Atmosphere Electron density, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-688,, 2022.

Features and Trends Identified in Observations at Mars and Comets
Laila Andersson, Hadi Madanian, Steven Schwartz, and David Andrews
Mark Lester, Beatriz Sanchez-Cano, Simon Joyce, Dikshita Meggi, Hermann Opgenoorth, Robert Lillis, Olivier Witasse, Roberto Orosei, and Marco Cartacci

Radars in orbit around Mars such as MARSIS on Mars Express and SHARAD on Mars Reconnaissance Orbiter provide evidence for the nature of the surface and some sub-surface layers.  We have now extended our earlier work, which has indicated solar energetic particles are responsible for the attenuation of the reflected MARSIS and SHARAD radar signals from the surface of Mars, often resulting in radar blackouts. The MARSIS instrument also operates in a topside sounding mode, the Advanced Ionospheric Sounder AIS mode), which also receives surface reflections and we now investigate the impact of the solar energetic particles on the surface reflection during ionospheric sounding observations made by MARSIS. We present observations during two intervals in December 2014 and in September 2017. MARSIS AIS was making observations on the nightside as Mars Express moved towards periapsis and then towards the dayside. The nightside AIS observations clearly demonstrate a similar loss of the surface signal to that seen in the MARSIS sub-surface mode. In addition there is evidence of a reflection from the enhanced layer created by the electrons which is responsible for the attenuation in the signal. The critical frequency is of order 1 MHz, which is equivalent to a peak electron density of order 1010 m-3, at an altitude of about 100 km. These characteristics are similar to our previous modelling work of the impact of the solar energetic electrons.


How to cite: Lester, M., Sanchez-Cano, B., Joyce, S., Meggi, D., Opgenoorth, H., Lillis, R., Witasse, O., Orosei, R., and Cartacci, M.: Radar Blackouts at Mars: Evidence for a low altitude ionisation layer, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1040,, 2022.

Catherine Regan, Andrew Coates, Anne Wellbrock, Richard Haythornthwaite, Geraint Jones, Beatriz Sánchez-Cano, Mats Holmström, Rudy Frahm, and Philippe Garnier

Global dust storms at Mars engulf the entire planet in a dusty haze, causing increases in temperature and ion escape as dust is lifted up to 80 km in altitude. The two most recent storms occurred in 2007 (Mars Year (MY) 28) and 2018 (MY34), and have been observed by spacecrafts such as Mars Express (MEx). MEx has been operating at Mars since 2004, and has produced a long time-base of plasma measurements from as low as 250 km. Using MEx, we investigate whether the 2007 dust storm has influenced the magnetosphere of Mars by looking at the position of the bow shock and induced magnetospheric boundary, compared to the expected position provided by 3D magnetohydrodynamical models. To identify boundary positions, we use data from the ASPERA-3 instrument (Analyser of Space Plasma and EneRgetic Atoms) onboard MEx, which contains an electron spectrometer (ELS), ion mass analyser (IMA), neutral particle imager (NPI) and neutral particle detector (NPD). For this study, we use data from ELS and IMA. We consider a number of influences on the boundary position, including the solar wind conditions and the crustal fields. Our study period includes time before, during, and after the MY28 global storm, and we expected the bow shock and induced magnetospheric boundary to increase in altitude due to the storm. Out results show that the system is more complex, and multiple influences need to be distinguished to leave any change due to the dust storm itself.

How to cite: Regan, C., Coates, A., Wellbrock, A., Haythornthwaite, R., Jones, G., Sánchez-Cano, B., Holmström, M., Frahm, R., and Garnier, P.: Investigating the Global Dust Storm in Mars Year 28 with Mars Express, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-527,, 2022.

Ananya Krishnan, Özgür Karatekin, Sebastien Verkercke, Gregoire Henry, and Olivier Witasse

Space weather events are one of the many major factors affecting the escape and evolution of Martian atmosphere. The Sun-planet interaction is affected by several factors such as the heliocentric distance, chemical composition of the atmosphere, solar illumination and its intrinsic magnetic field. Mars has a varied environment of magnetic field. It has little or no intrinsic magnetic field, but there exist some strong, crustal magnetic field patches. Thus, it becomes one of the solar system's best models for understanding the interaction of weakly ionized plasma with a highly irregular magnetic field.

Martian ionosphere owes its existence to the photoionization of neutral species by solar extreme ultraviolet (EUV) and X-ray photons. Martian ionosphere has a stratified structure with two main layers in its electron density profile (Ne). The primary layer (M2 layer) is formed by solar EUV radiation (~20-90 nm) and has a peak electron density at around 120-140 km altitude with a peak density of ~1011 m-3. The second layer (M1 layer) occurs at lower altitude with a peak electron density of ~109 m-3 and is formed by solar soft X-ray and electron impact ionization. The electron densities and the altitudes at which these peaks are very variable.

Radio Occultation (RO) experiments are the first and major explorer of the Martian ionosphere and electron density profiles. RO experiments precisely measure the Doppler shift observed on the link between a planetary spacecraft and Earth, as the spacecraft passes into occultation behind the planet. The RO data can be processed to extract the vertical electron density profiles of the ionosphere. Apart from vertical electron density profiles, RO can also provide density, temperature and pressure profiles of the neutral atmosphere. Thus, it is also a powerful tool to understand the both the neutral atmosphere and ionosphere.

Here we study the effect of solar flares and coronal mass ejections on the whole Martian atmosphere using the publicly available Mars Express radio occultation data from ESA Planetary Science Archive (PSA). For this, we selected two major solar disturbed periods occurred during 6th to 13th of June 2011 and 16th February to 31st March 2015. Using the Level 2 data we calculated the Ne profiles in the ionosphere as well as the temperature profiles of lower atmosphere. We also compare our results with numerical models and available measurements like MARSIS and Langmuir probe on NASA's MAVEN in the selected period.

Figure 1: a. Electron density profiles observed by MEX on 2011 following a solar event on the 8th of June 2011.

How to cite: Krishnan, A., Karatekin, Ö., Verkercke, S., Henry, G., and Witasse, O.: Effect of Solar Event on Mars Atmosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-673,, 2022.

Eduard Dubinin, Markus Fraenz, and Martin Paetzold

The Martian magnetosphere contains elements of induced and intrinsic origin.  We will focus on three questions concerning its structure. Reconnection of the draping IMF with crustal field leads to a twisting of classical induced configuration. Why this twist is so stable and well arranged despite of a very complex topology of the crustal magnetic field.  Another interesting question is a significant asymmetry of the Martian magnetosphere. The observations show that additionally to the main draping of the interplanetary magnetic field lines in the antisunward direction a draping in the opposite direction to the motional electric field arises. What origin is of such asymmetry? The third question is related to the fact that Mars occurs not only in the flow of solar wind but also in the flow of ‘oxygen wind’ originating from the extended hot oxygen corona. What effects arise during such type of the interaction? We will discuss possible answers on these questions.

How to cite: Dubinin, E., Fraenz, M., and Paetzold, M.: Do we understand well how the Martian magnetosphere is organized?, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-71,, 2022.

Mats Holmstrom, Qi Zhang, Xiao-Dong Wang, and Shahab Fatemi

We estimate ion escape from Mars by combining observations and models. Assuming that upstream solar wind conditions are known, a computer model of the interaction between the solar wind and the planet is executed for different ionospheric ion production rates. This results in different amounts of mass loading of the solar wind. Then we obtain the ion escape rate from the model run that best fit observations of the bow shock location. This method enables studies of how escape depend on different parameters, and also escape rates during extreme solar wind conditions, applicable to studies of escape in the early solar system, and at exoplanets. This approach also allows us to use data sets traditionally not used for ion escape estimates, such as magnetic field and electron observations. We can also estimate the escape rate from a very small set of observations, during every orbit of a spacecraft around a planet or during one flyby of a planet.

How to cite: Holmstrom, M., Zhang, Q., Wang, X.-D., and Fatemi, S.: Estimations of Ion Escape from Mars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-239,, 2022.

Peter Stephenson, Kathrin Altwegg, Arnaud Beth, Jim Burch, Christopher Carr, Jan Deca, Anders Eriksson, Marina Galand, Karl-Heinz Glassmeier, Charlotte Goetz, Pierre Henri, Kevin Heritier, Fredrik Johansson, Zoe Lewis, Hans Nilsson, and Martin Rubin

The Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko for two years along its orbit, from Aug 2014 to Sep 2016, observing the evolution of the comet from a close perspective. The Rosetta Plasma Consortium (RPC) monitored the plasma environment at the spacecraft throughout the escort phase.

Cometary electrons are produced by ionization of the neutral gas coma. This occurs through photoionization by extreme ultraviolet photons, and through electron-impact ionization (EII) by collisions of energetic electrons with the coma. Far from perihelion, EII is, at times, more prevalent than photoionization (Galand et al., 2016; Heritier et al., 2018), but the EII frequency has not been assessed across the whole mission. The source of the cometary electrons, and the origin of the ionizing electrons is still unclear.

We have calculated the electron impact ionization (EII) frequency throughout the Rosetta mission and at its location from measurements of RPC’s Ion and Electron Sensor (RPC/IES). EII ionization is confirmed as the dominant source of cometary electrons and ions when far from perihelion but is much more variable than photoionization. We compare the EII frequency with properties of the neutral coma and cometary plasma to identify key drivers of the energetic electron population. The EII frequency is structured by outgassing rate and magnetic field strength.

The first 3D collision model of electrons at a comet (Stephenson et al. 2022) is also utilised to assess the origin of electrons within the coma. The model uses self-consistently calculated electric and magnetic fields from a fully-kinetic and collisionless Particle-in-Cell model (Deca et al. 2017, 2019)as an input. The modelling approach confirms cometary electrons are produced by impacts of energetic electrons at low outgassing. The ionizing electrons are identified as solar wind electrons that have undergone acceleration in an ambipolar potential well, confirming the results of the data analysis.

Deca J, Divin A, Henri P, Eriksson A, Markidis S, et al. 2017. Physical Review Letters. 118(20):205101
Deca J, Henri P, Divin A, Eriksson A, Galand M, et al. 2019. Physical Review Letters. 123:55101
Galand M, Héritier K L., Odelstad E, Henri P, Broiles TW., et al. 2016. Monthly Notices of the Royal Astronomical Society. 462:S331–51
Heritier KL, Galand M, Henri P, Johansson FL, Beth A, et al. 2018. A&A, p. 618:A77–A77
Stephenson P, Galand M, Deca J, Henri P, Carnielli G. 2022. Monthly Notices of the Royal Astronomical Society. 511(3):4090–4108

How to cite: Stephenson, P., Altwegg, K., Beth, A., Burch, J., Carr, C., Deca, J., Eriksson, A., Galand, M., Glassmeier, K.-H., Goetz, C., Henri, P., Heritier, K., Johansson, F., Lewis, Z., Nilsson, H., and Rubin, M.: The source of electrons at a weakly outgassing comet, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1047,, 2022.

Daniel Marsh, Wuhu Feng, John Plane, Juan Diego Carrillo-Sánchez, Diego Janches, Matteo Crismani, Jean-Yves Chaufray, François Forget, Francisco González-Galindo, and Nicholas Schneider

The Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has been used to observe the Mg+ in the upper atmosphere of Mars since 2015. These observations reveal significant diurnal, seasonal and latitudinal variations. For example, a factor of two change in Mg+ occurs during the day at the equator and Mg+ above 100 km decreases across the globe during the Southern Hemisphere summertime.  Possible causes include the influence of photo-chemistry, atmospheric dynamics and the injection rate of meteoric material. To delineate these sources of variability, a 3-dimensional model of the Martian Mg has been developed. The model is based on the Laboratoire de Météorologie Dynamique (LMD) Mars global circulation model (GCM), which is capable of simulating the seasonal cycles in the Martian atmosphere arising from changes in heating rates from orbital geometry and the distribution of dust in the lower atmosphere. The model solves for the dynamics and primary constituents of the atmosphere from the surface to the thermosphere. For this study, the chemistry has been augmented with neutral and ion chemistry for meteoric metals within a CO2 atmosphere, incorporating 7 neutral and 8 ionized Mg-containing species and an additional 42 neutral and ion-molecule reactions. The atmospheric input of meteoric material is specified from seasonal and latitudinal fits to new estimates of the deposition of the ablated metals in the atmosphere. Here we present the first detailed intercomparison of the MAVEN IUV Mg+ observations with simulated Mg+ from the LMD Mars GCM. Model variability is consistent with observations and indicates tropical variability is caused by a combination of photochemistry and vertical transport by atmospheric tides. Comparisons of simulations performed with variable and fixed meteoric input show that the high latitude variations are caused by both seasonal variation in ablation rates and the residual circulation. Finally, we show how Mg+ varies in relation to neutral Mg and the remaining Mg-containing species to determine how Mg+ may be used as a proxy for total Mg variability.

How to cite: Marsh, D., Feng, W., Plane, J., Carrillo-Sánchez, J. D., Janches, D., Crismani, M., Chaufray, J.-Y., Forget, F., González-Galindo, F., and Schneider, N.: Martian Meteoric Mg+: an intercomparison of MAVEN/IUVS observations with simulations using the LMD Mars GCM, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-644,, 2022.

Skylar Shaver, Laila Andersson, and Scott Thaller


An investigation of the locations where the bulk thermal pressure is balanced by magnetic pressure in the Martian ionosphere is reported on. We present a statistical study in which we characterize the location where the plasma and magnetic pressures are equal to one another. The data, recorded by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, have been analyzed from the transition altitude in which the ionospheric ions become magnetized, up to an altitude of ~800km. The electron temperature and density measurements for the plasma thermal pressure were made by the Langmuir Probe and Waves (LPW) instrument, and the magnetic field strength for determining the magnetic pressure was measured by the Magnetometer (MAG) instrument. The three major trends in this pressure balance are: (a) the magnetic pressure is always larger, (b) a clear transition at low altitudes from thermal pressure to magnetic pressure is observed, and (c) the dominant pressure is changing back and forth between the two over a range of altitudes. The findings are studied in congruence with orbital parameters of the MAVEN satellite (including solar local time, latitude, location with respect to crustal fields) to divulge possible explanations of the transition between pressures.

How to cite: Shaver, S., Andersson, L., and Thaller, S.: Locations where the cold thermal pressure balances the magnetic pressure in the Martian ionosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-552,, 2022.