Oral presentations and abstracts

The phenomenon, dubbed the Interplanetary Field Enhancement, occurs in the solar wind near and inside of 1 AU and is attributed to collisional dust production and subsequent solar wind pickup.  The duration and strength of these events appears to depend on the heliocentric distance of the detection, the largest event was recorded by the PVO spacecraft in orbit about Venus in 1982.  It lasted 11 hours and was over 20 million km in radial extent.  While no such large structure has been seen since by PVO or Venus Express since that time observations at 1 AU by STEREO, and the flotilla of spacecraft near the L-1 Lagrangian point have continued to see smaller events.  These are now attributed to collisions of asteroidal debris, small rocks destroying each other when they collide at a mean velocity of 20 km/s at 1 AU.  Such a speed of collision with a 1 kg rock will completely destroy a 10⁶ kg target.  Even if the number of small asteroids were constant with heliocentric distance the increased orbital speeds inside 1 AU should greatly increase the destructive power of collisions so that larger events should occur at closer distances to the Sun.  We review the statistics available from Pioneer Venus and Venus Express and compare them with 1 AU data to test this hypothesis.

How to cite: Russell, C., Lai, H., and Horbury, T.: Interplanetary Field Enhancements: An Overview, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-44, https://doi.org/10.5194/epsc2020-44, 2020.

As Mars has no intrinsic magnetic field, it is inherently strongly influenced by the solar wind. However, little is known about the scale of variability of the solar wind at this distance from the Sun. The lack of an upstream solar wind monitor at Mars sometimes necessitates assumptions about the variability of solar wind and interplanetary magnetic field (IMF) conditions at Mars, and without a clear understanding of how the solar wind varies at Mars it is difficult to know whether these assumptions are appropriate. We present a study which quantifies the variation of the IMF at Mars during periods near solar maximum and minimum, by comparing magnetometer measurements of the pristine IMF from the Mars Global Surveyor (MGS) mission (between 1997 and 1999) and the MArs Volatile EvolutioN (MAVEN) mission (between 2014 and 2016). 

This study finds the IMF to be notably steadier in field strength and cone angle direction during the MAVEN mission than the MGS mission (shown in Figures 1 and 2), with little difference in the clock angle variation between the two missions. Additionally, the variability of both the field strength and the clock angle is found to be dependant on the cone angle of the measurements, with periods of IMF oriented close to the orbital plane of Mars being considerably steadier than periods of IMF oriented approximately perpendicular to it. Results from this study suggest that the IMF at Mars is steadier at times near solar maximum than at times near solar minimum, and quantify the error in estimates of IMF parameters hours after measurement. 

However, using solar 10.7cm flux as a proxy for solar activity, we show that the time for the IMF to decorrelate does not directly depend on the solar activity. Figure 3 shows the decorrelation time and the solar activity for both the MGS and MAVEN datasets. No clear correlation is visible in the graphs, suggesting that the reason for the differences in the IMF variability between the two missions is still unclear.

How to cite: Durward, S., Wild, J., and Lillis, R.: Solar cycle changes in the interplanetary magnetic field variability at Mars, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-120, https://doi.org/10.5194/epsc2020-120, 2020.

The H2020 Europlanet-2020 programme, which ended on Aug 31^st, 2019, included an activity called PSWS (Planetary Space Weather Services), which provided 12 services distributed over four different domains (A. Prediction, B. Detection, C. Modelling, D. Alerts) and accessed through the PSWS portal (http://planetaryspaceweather-europlanet.irap.omp.eu/):

A1. 1D MHD Solar Wind Prediction Tool – HELIOPROPA,

A2. Propagation Tool,

A3. Meteor showers,

A4. Cometary tail crossings – TAILCATCHER,

B1. Lunar impacts – ALFIE,

B2. Giant planet fireballs – DeTeCt3.1,

B3. Cometary tails – WINDSOCKS,

C1. Earth, Mars, Venus, Jupiter coupling- TRANSPLANET,

C2. Mars radiation environment – RADMAREE,

C3. Giant planet magnetodiscs – MAGNETODISC,

C4. Jupiter’s thermosphere, D. Alerts.

In the framework of the starting Europlanet-2024 programme, SPIDER will extend PSWS domains (A. Prediction, C. Modelling, E. Databases) services and give the European planetary scientists, space agencies and industries access to 6 unique, publicly available and sophisticated services in order to model planetary environments and solar wind interactions through the deployment of a dedicated run on request infrastructure and associated databases.

C5. A service for runs on request of models of Jupiter’s moon exospheres as well as the exosphere of Mercury,

C6. A service to connect the open-source Spacecraft-Plasma Interaction Software (SPIS) software with models of space environments in order to compute the effect of spacecraft potential on scientific instruments onboard space missions. Pre-configured simulations will be made for Bepi-Colombo and JUICE missions,

C7. A service for runs on request of particle tracing models in planetary magnetospheres,

E1. A database of the high-energy particle flux proxy at Mars, Venus and comet 67P using background counts observed in the data obtained by the plasma instruments onboard Mars Express (operational from 2003), Venus Express (2006–2014), and Rosetta (2014–2015);

E2. A simulation database for Mercury and Jupiter’s moons magnetospheres and link them with prediction of the solar wind parameters from Europlanet-RI H2020 PSWS services.

A1. An extension of the Europlanet-RI H2020 PSWS Heliopropa service in order to ingest new observations from Solar missions like the ESA Solar Orbiter or NASA Solar Parker Probe missions and use them as input parameters for solar wind prediction;

These developments will be discussed in the presentation.

The Europlanet 2020 Research Infrastructure project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654208.

The Europlanet 2024 Research Infrastructure project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 871149.

How to cite: André, N., Génot, V., Opitz, A., Cecconi, B., Achilleos, N., Guio, P., Milillo, A., Mura, A., Futaana, Y., and Hess, S.: Sun Planet Interactions Digital Environment on Request (SPIDER) for Europlanet RI H2024, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-256, https://doi.org/10.5194/epsc2020-256, 2020.

How to cite: Aizawa, S., Griton, L., Fatemi, S., Exner, W., Deca, J., Pantellini, F., Yagi, M., Heyner, D., Génot, V., André, N., Amaya, J., Murakami, G., and Usui, H.: Cross-comparison of global simulation models applied to Mercury's dayside magnetosphere, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-261, https://doi.org/10.5194/epsc2020-261, 2020.

In April 2001 Mars Odyssey spacecraft with High Energy Neutron Detector (HEND) onboard was launched to Mars. HEND/Odyssey was switched on measurement mode most of transit to Mars to monitor variations of spacecraft background and solar activity. Although HEND/Odyssey was originally designed to measure martian neutron albedo and to search for martian subsurface water/water ice, its measurements during cruise phase to Mars are applicable to evaluate spacecraft ambient radiation background. The biological impact of neutron component of this radiation background should be understood to take it into account in planning future manned missions to Mars.  We modeled spacecraft neutron spectral density and compare it with HEND measurements to estimate equivalent neutron dose rates during Odyssey cruise phase, which corresponds to the solar maxim period (23^th solar cycle). It was found that Odyssey ambient neutron environment during May – September 2001 produces 6.3±1.0 mSv per day in energy range 0-15 MeV or about 23 mSv per day if extrapolated to 0-1000 MeV energy range for sun quiet intervals without Solar Particle Events (SPEs). The occurrence of SPEs may additionally increase the total neutron radiation dose accumulated for 6 months of Odyssey cruise phase up to 10%. We have also extrapolated HEND/Odyssey measurements to the different periods of solar cycle and found that during solar minimum (maximum of GCR flux) neutron equivalent rate during cruise to Mars could be as high as 40 mSv per day.  These values are in good agreement with results reported for a similar measurement made with an instrument aboard the Mars Science Laboratory during its cruise to Mars in 2011-2012.

How to cite: Litvak, M., Mitrofanov, I., Sanin, A., Bakhtin, B., and Zeitlin, C.: Observations of neutron radiation environment during Odyssey cruise to Mars, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-972, https://doi.org/10.5194/epsc2020-972, 2020.

The Mio spacecraft for the BepiColombo mission was successfully launched on 20 October 2018. BepiColombo will arrive at Mercury in the end of 2025, and it has 7-years cruise with the heliocentric distance range of 0.3-1.2 AU. The long cruise phase also includes 9 planetary flybys: once at the Earth, twice at Venus, and 6 times at Mercury. The Mio spacecraft has a complete package of plasma instruments, a spectral imager for the exosphere, and a dust monitor. Even though the Mio spacecraft is surrounded by the Mio’s sunshield and observation capabilities of some instruments are constrained during the cruise phase, it still includes many important opportunities to investigate the inner heliosphere and planetary environments by Mio. Here we present the initial results of the first Earth flyby and cruise observations, and updated operations plans during the cruise phase.

How to cite: Murakami, G. and Benkhoff, J.: Exploring planetary space weather and inner heliosphere by BepiColombo/Mio: updates of cruise science, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-1059, https://doi.org/10.5194/epsc2020-1059, 2020.

Auroral Kilometric Radiation (AKR) is radio emission that originates in particle acceleration regions along magnetic field lines that coincide with discrete auroral arcs. Radio astronomy instruments aboard various spacecraft have been used to derive the flux density, source direction and other parameters of emissions of various origin. The Wind spacecraft has been in operation for 25 years and the WAVES radio instrument has previously been considered for a technique to also derive the Stokes parameters of a partially polarised radio source. While previous applications of the technique have seen it modified to study solar radio emissions, further examination is needed for its application to AKR. After correcting appropriately for the characteristics of the AKR emissions, this technique can be used to produce a utile dataset of AKR observations. Statistical properties of AKR can be examined, with the extent of local time sampling of Wind bolstering previous studies. The previously observed correlation between morphological changes in the source region and magnetospheric substorm onset can be studied further, and lists of substorm phase timings can be used to examine the general variability during these events.

How to cite: Waters, J., Jackman, C., Whiter, D., Lamy, L., Bonnin, X., Cecconi, B., and Issautier, K.: Towards a Multi-Decadal Dataset of Auroral Kilometric Radiation (AKR) Source Parameters with Wind/WAVES, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-1087, https://doi.org/10.5194/epsc2020-1087, 2020.