Plasma clouds and snowplows: Bulk plasma escape from Mars observed by MAVEN

Halekas, J. S.; Brain, David; Ruhunusiri, S.; McFadden, J. P.; Mitchell, David; Mazelle, C.; Connerney, J. E. P.; Harada, Yuki; Hara, Takuya; Espley, J. R.; DiBraccio, G. A.; Jakosky, B. M.

doi:10.1002/2016gl067752

Cited by 41 publications

(50 citation statements)

References 35 publications

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“…Therefore, magnetic fields penetrating into the Martian magnetosphere can drag the bulk ionospheric ions with E × B drift motion. On the other hand, Halekas et al () observed the plasma clouds caused by “snowplow” effect which is also effective in the −E hemisphere. In this case, ions appear to be unmagnetized and they are accelerated by the polarization electric fields, leading to the same energy acceleration.…”

Section: Discussionmentioning

confidence: 99%

Statistical Study of Heavy Ion Outflows From Mars Observed in the Martian‐Induced Magnetotail by MAVEN

et al. 2019

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It is important to include the effects of cold ions when we consider heavy ion outflows from Mars. We here report on statistical properties of heavy ion outflows (including cold ion outflows) observed by Mars Atmosphere and Volatile EvolutioN in the optical wake region. Using data from July 2015 to December 2017, we statistically investigate the effects of solar wind convection electric fields and crustal magnetic fields on the heavy ion outflows. Results show that the average density ratio of O+:O2+:CO2+ is ~29:68:04. In the southern hemisphere where the strong crustal magnetic fields are located, the heavy ion outflow flux becomes smaller and the relative contribution of molecular ions to heavy ion outflows is larger than the northern hemisphere. The solar wind convection electric field strongly affects the heavy ion outflows. Heavy ion density is larger in the −E (electric field) hemisphere than in the +E hemisphere, while the dependence of velocity is opposite. Acceleration by the solar wind convection electric field in the +E hemisphere is expected to cause these dependencies. The heavy ion flux is larger in the −E (total O: 8.6 × 106 cm–2/s) than in the +E hemisphere (2.9 × 106 cm–2/s) due to the large density in the −E hemisphere. Velocity ratios of O+ to O2+ suggest that heavy ion outflows with large velocities tend to have the same energy to each other, while the O+ to O2+ ions are more likely to have the same velocity in outflows with small velocities.

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Section: Discussionmentioning

confidence: 99%

Statistical Study of Heavy Ion Outflows From Mars Observed in the Martian‐Induced Magnetotail by MAVEN

et al. 2019

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“…Instead, the interspersed populations with solar wind and magnetospheric origins must indicate either complex spatial structure or large amplitude fluctuations in the position of the boundary. These could represent shear‐driven instabilities such as Kelvin‐Helmholtz [ Penz et al ., ] and/or bulk loss of clouds of magnetosphere plasma [ Halekas et al ., ]. Inside the magnetosphere, energy‐time dispersed ions [ Halekas et al ., ] appear throughout the magnetosphere, suggesting acceleration by significant electric fields, possibly associated with the upstream and/or sheath dynamics.…”

Section: Maven Solar Wind Ion Analyzer (Swia) Measurements and In‐flimentioning

confidence: 99%

Structure, dynamics, and seasonal variability of the Mars‐solar wind interaction: MAVEN Solar Wind Ion Analyzer in‐flight performance and science results

et al. 2017

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We report on the in‐flight performance of the Solar Wind Ion Analyzer (SWIA) and observations of the Mars‐solar wind interaction made during the Mars Atmosphere and Volatile EvolutioN (MAVEN) prime mission and a portion of its extended mission, covering 0.85 Martian years. We describe the data products returned by SWIA and discuss the proper handling of measurements made with different mechanical attenuator states and telemetry modes, and the effects of penetrating and scattered backgrounds, limited phase space coverage, and multi‐ion populations on SWIA observations. SWIA directly measures solar wind protons and alpha particles upstream from Mars. SWIA also provides proxy measurements of solar wind and neutral densities based on products of charge exchange between the solar wind and the hydrogen corona. Together, upstream and proxy observations provide a complete record of the solar wind experienced by Mars, enabling organization of the structure, dynamics, and ion escape from the magnetosphere. We observe an interaction that varies with season and solar wind conditions. Solar wind dynamic pressure, Mach number, and extreme ultraviolet flux all affect the bow shock location. We confirm the occurrence of order‐of‐magnitude seasonal variations of the hydrogen corona. We find that solar wind Alfvén waves, which provide an additional energy input to Mars, vary over the mission. At most times, only weak mass loading occurs upstream from the bow shock. However, during periods with near‐radial interplanetary magnetic fields, structures consistent with Short Large Amplitude Magnetic Structures and their wakes form upstream, dramatically reconfiguring the Martian bow shock and magnetosphere.

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“…At Mars, observations of magnetic reconnection (Dubinin et al, 2008;Eastwood et al, 2008;Harada et al, 2015aHarada et al, , 2017, flux rope formation (DiBraccio et al, 2015;Eastwood et al, 2012;Hara et al, 2017), current sheet flapping , Marsward and tailward ion flows (Harada et al, 2015b), magnetic lobe dependence on IMF orientation Romanelli et al, 2015) and ionosphere magnetization , and bulk plasma escape (e.g., Brain et al, 2010;Halekas et al, 2016) have been reported in the magnetotail. At Mars, observations of magnetic reconnection (Dubinin et al, 2008;Eastwood et al, 2008;Harada et al, 2015aHarada et al, , 2017, flux rope formation (DiBraccio et al, 2015;Eastwood et al, 2012;Hara et al, 2017), current sheet flapping , Marsward and tailward ion flows (Harada et al, 2015b), magnetic lobe dependence on IMF orientation Romanelli et al, 2015) and ionosphere magnetization , and bulk plasma escape (e.g., Brain et al, 2010;Halekas et al, 2016) have been reported in the magnetotail.…”

Section: 1029/2018gl077251mentioning

confidence: 99%

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

DiBraccio

Luhmann

Curry

et al. 2018

Geophysical Research Letters

110

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Measurements provided by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft are analyzed to investigate the Martian magnetotail configuration as a function of interplanetary magnetic field (IMF) BY. We find that the magnetotail lobes exhibit a ~45° twist, either clockwise or counterclockwise from the ecliptic plane, up to a few Mars radii downstream. Moreover, the associated cross‐tail current sheet is rotated away from the expected location for a Venus‐like induced magnetotail based on nominal IMF draping. Data‐model comparisons using magnetohydrodynamic simulations are in good agreement with the observed tail twist. Model field line tracings indicate that a majority of the twisted tail lobes are composed of open field lines, surrounded by draped IMF. We infer that dayside magnetic reconnection between the crustal fields and draped IMF creates these open fields and may be responsible for the twisted tail configuration, similar to what is observed at Earth.

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Plasma clouds and snowplows: Bulk plasma escape from Mars observed by MAVEN

Cited by 41 publications

References 35 publications

Statistical Study of Heavy Ion Outflows From Mars Observed in the Martian‐Induced Magnetotail by MAVEN

Statistical Study of Heavy Ion Outflows From Mars Observed in the Martian‐Induced Magnetotail by MAVEN

Structure, dynamics, and seasonal variability of the Mars‐solar wind interaction: MAVEN Solar Wind Ion Analyzer in‐flight performance and science results

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

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