Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment

At planets with induced magnetospheres, the coupling between the ionosphere, the weak draped magnetosphere, and the solar wind is very direct in comparison to Earth. The weak induced magnetosphere itself is created by the prevailing Solar wind conditions and therefore in its shape and strength dynamically depending on it. In early 2010, Mars was located behind Earth in the Solar wind; thus, we can use coordinated data from multiple near‐Earth spacecraft (Stereo, Wind) to evaluate what kind of Solar wind disturbances have passed by Earth and might consecutively hit Mars, and when. We employ plasma data from the ESA Mars‐Express mission, the ASPERA‐3 particle instrument, and the MARSIS Active Ionospheric Sounder (AIS) to investigate, for a number of isolated events in March and April 2010, how the ionosphere and the induced magnetosphere at Mars develop and decay in response to Solar wind variability in the magnetic field, density, and velocity. In a dedicated campaign mode, we use frequent long‐duration MARSIS AIS operations for several consecutive orbits, to monitor for the first time the long‐term development of the Martian plasma environment during solar wind disturbances. We find that the magnetosphere and ionosphere of Mars can become considerably compressed by solar wind dynamic pressure variations, which usually are also associated with changes in the magnetic draping of the interplanetary magnetic field around the planet. These are typically associated with corotating interaction regions and coronal mass ejections, and can last for several days. During such episodes of compression, we see signatures of increased plasma transport over the terminator and enhanced ion outflow from the upper atmosphere.

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“…[], and in two event studies for CIR‐related solar wind disturbances by Edberg et al . [] and Dubinin et al . [].…”

Section: Discussionmentioning

confidence: 99%

“…[], but it is different from the along‐terminator periapsis orbit geometry at the time of the Rosetta Mars flyby studied by Edberg et al . [].…”

Section: Campaign Overview and Instrumentationmentioning

confidence: 99%

Mars ionospheric response to solar wind variability

Opgenoorth

Andrews

Fränz³

et al. 2013

JGR Space Physics

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“…When available, studies use in situ measurements, but these can be limited in instrument (e.g., no magnetometer on Mars Express) or continuity (e.g., orbits that spend little or no time in the upstream solar wind). When direct measurements are not available, studies have utilized solar wind proxies [e.g., Crider et al ., ; Brain et al ., ], spacecraft flybys near Mars [e.g., Edberg et al ., ], and/or 1 AU in situ conditions when Earth and Mars share Parker spiral alignment [e.g., Vennerstrom et al ., ; Dubinin et al ., ; Edberg et al ., ; Opgenoorth et al ., ]. Despite the variety of techniques used to determine upstream solar wind conditions, modeling the solar wind at Mars' orbital location from initial solar conditions has only rarely been used [e.g., Jakosky et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Continuous solar wind forcing knowledge: Providing continuous conditions at Mars with the WSA‐ENLIL + Cone model

et al. 2016

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Knowledge of solar wind conditions at Mars is often necessary to study the planet's magnetospheric and ionospheric dynamics. With no continuous upstream solar wind monitor at Mars, studies have used a variety of methods to measure or predict Martian solar wind conditions. In situ measurements, when available, are preferred, but can often be limited in continuity or scope, and so studies have also utilized solar wind proxies, spacecraft flybys, and Earth‐Mars alignment to provide solar wind context. Despite the importance of solar wind knowledge and the range of methods used to provide it, the use of solar wind models remains relatively unutilized. This study uses the Wang‐Sheeley‐Arge (WSA)‐ENLIL + Cone solar wind model to calculate solar wind parameters at Mars' orbital location to provide a new approach to determining solar wind conditions at Mars. Comparisons of the model results with observations by the MAVEN spacecraft indicate that the WSA‐ENLIL + Cone model can forecast solar wind conditions at Mars as accurately as it has predicted them historically at the Earth, although at Mars the model systematically mispredicts solar wind speed and density, likely a result of magnetogram calibration. Particular focus is placed on modeling the early March 2015 interplanetary coronal mass ejections (ICMEs) that interacted with Mars. Despite the complexity of the ICMEs, the model accurately predicted the speed and arrival time of the ICME‐driven interplanetary shock, although it underpredicted other solar wind parameters. These results suggest that solar wind models can be used to provide the necessary general context of the heliospheric conditions to planetary studies.

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“…Edberg et al [] used Rosetta observations to provide the solar wind conditions in the vicinity of Mars to conclusively show that energetic (100 eV–10 keV) planetary ions were escaping in the + E SW direction. The study showed two MEX orbits with energetic planetary ions beyond the IMB, flowing away from Mars in the + E SW direction.…”

Section: Introductionmentioning

confidence: 99%

Mars Express observations of high altitude planetary ion beams and their relation to the “energetic plume” loss channel

et al. 2014

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This study presents observational evidence of high-energy (ions >2 keV) beams of planetary ions above Mars' induced magnetospheric boundary (IMB) and relates them with the energetic plume loss channel calculated from numerical models. A systematic search of the Mars Express (MEX) ion data using an orbit filtering criteria is described, using magnetometer data from Mars Global Surveyor (MGS) to determine the solar wind motional electric field (Esw) direction. Two levels of statistical survey are presented, one focused on times when the MEX orbit was directly in line with the Esw and another for all angles between the MEX location and the Esw. For the first study, within the 3 year overlap of MGS and MEX, nine brief intervals were found with clear and unambiguous high-energy O + observations consistent with the energetic plume loss channel. The second survey used a point-by-point determination of MEX relative to the E-field and contained many thousands of 192 s measurements. This study yielded only a weak indication for an Esw-aligned plume. Furthermore, the y-z components of the weighted average velocities in the bins of this y-z spatial domain survey do not systematically point in the Esw direction. The first survey implies the existence of this plume and shows that its characteristics are seemingly consistent with the expected energy and flight direction from numerical studies; the second study softens the finding and demonstrates that there are many planetary ions beyond the IMB moving in unexpected directions. Several possible explanations for this discrepancy are discussed.

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Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment

Cited by 25 publications

References 29 publications

Mars ionospheric response to solar wind variability

Mars ionospheric response to solar wind variability

Continuous solar wind forcing knowledge: Providing continuous conditions at Mars with the WSA‐ENLIL + Cone model

Mars Express observations of high altitude planetary ion beams and their relation to the “energetic plume” loss channel

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