Does Phobos reflect solar wind protons? Mars Express special flyby operations with and without the presence of Phobos

Abstract. We report on new simultaneous in-situ observations at Mars from Rosetta and Mars Express (MEX) on how the Martian plasma environment is affected by high pressure solar wind. A significant sharp increase in solar wind density, magnetic field strength and turbulence followed by a gradual increase in solar wind velocity is observed during ~24 h in the combined data set from both spacecraft after Rosetta's closest approach to Mars on 25 February 2007. The bow shock and magnetic pileup boundary are coincidently observed by MEX to become asymmetric in their shapes. The fortunate orbit of MEX at this time allows a study of the inbound boundary crossings on one side of the planet and the outbound crossings on almost the opposite side, both very close to the terminator plane. The solar wind and interplanetary magnetic field (IMF) downstream of Mars are monitored through simultaneous measurements provided by Rosetta. Possible explanations for the asymmetries are discussed, such as crustal magnetic fields and IMF direction. In the same interval, during the high solar wind pressure pulse, MEX observations show an increased amount of escaping planetary ions from the polar region of Mars. We link the high pressure solar wind with the observed simultaneous ion outflow and discuss how the pressure pulse could also be associated with the observed boundary shape asymmetry.

Download Full-text

Solar Wind induced waves in the skies of Mars: Ionospheric compression, energization, and escape resulting from the impact of ultra-low frequency magnetosonic waves generated upstream of the Martian bow shock

10.5194/egusphere-egu2020-1966 ◽

2020 ◽

Author(s):

Glyn Collinson ◽

Lynn Wilson III ◽

Nick Omidi ◽

David Sibeck ◽

Jared Espley ◽

...

Keyword(s):

Solar Wind ◽

Low Frequency ◽

Ulf Waves ◽

Mars Atmosphere ◽

Transient Phenomena ◽

Mars Express ◽

Linearly Polarized ◽

Using Data ◽

Atmospheric Loss ◽

The Impact

<p>Using data from the NASA Mars Atmosphere and Voltatile EvolutioN (MAVEN) and ESA Mars Express spacecraft, we show that transient phenomena in the foreshock and solar wind can directly inject energy into the ionosphere of Mars. We demonstrate that the impact of compressive Ultra-Low Frequency (ULF) waves in the solar wind on the induced magnetospheres drive compressional, linearly polarized, magnetosonic ULF waves in the ionosphere, and a localized electromagnetic "ringing" at the local proton gyrofrequency. The pulsations heat and energize ionospheric plasmas. A preliminary survey of events shows that no special upstream conditions are required in the interplanetary magnetic field or solar wind. Elevated ion densities and temperatures in the solar wind near to Mars are consistent with the presence of an additional population of Martian ions, leading to ion-ion instablities, associated wave-particle interactions, and heating of the solar wind. The phenomenon was found to be seasonal, occurring when Mars is near perihelion. Finally, we present simultaneous multipoint observations of the phenomenon, with the Mars Express observing the waves upstream, and MAVEN observing the response in the ionosphere. When these new observations are combined with decades of previous studies, they collectively provide strong evidence for a previously undemonstrated atmospheric loss process at unmagnetized planets: ionospheric escape driven by the direct impact of transient phenomena from the foreshock and solar wind.</p>

Download Full-text

(Non)-radial propagation of the solar wind flow

10.5194/egusphere-egu2020-2736 ◽

2020 ◽

Author(s):

Zdeněk Němeček ◽

Tereza Ďurovcová ◽

Jana Šafránková ◽

Jiří Šimůnek ◽

John D. Richardson ◽

...

Keyword(s):

Solar Wind ◽

Radial Velocity ◽

Orbital Motion ◽

Wind Flow ◽

The Sun ◽

Mars Express ◽

The Earth ◽

Solar Wind Flow ◽

Magnetospheric Tail ◽

Radial Propagation

<p>The solar wind aberration due to non-radial velocity components and the Earth orbital motion is important for the overall magnetosphere geometry because the magnetospheric tail is aligned with the solar wind flow. This paper investigates an evolution of non-radial components of the solar wind flow along the path from the Sun to 6 AU. A comparison of observations at 1 AU and closer to or further from the Sun based on measurements of many spacecraft at different locations in the heliosphere (Wind, ACE, Spektr-R, THEMIS B and C, Helios 1 and 2, Mars-Express, Voyager 1 and 2) shows that (i) the average values of non-radial components vary with the distance from the Sun and (ii) they differ according to solar wind streams.</p>

Download Full-text

Solar Wind-Induced Atmospheric Erosion at Mars: First Results from ASPERA-3 on Mars Express

Science ◽

10.1126/science.1101860 ◽

2004 ◽

Vol 305 (5692) ◽

pp. 1933-1936 ◽

Cited By ~ 160

Author(s):

R. Lundin

Keyword(s):

Solar Wind ◽

Mars Express ◽

First Results

Download Full-text

Comparison of plasma data from ASPERA-3/Mars-Express with a 3-D hybrid simulation

Annales Geophysicae ◽

10.5194/angeo-25-1851-2007 ◽

2007 ◽

Vol 25 (8) ◽

pp. 1851-1864 ◽

Cited By ~ 23

Author(s):

A. Bößwetter ◽

S. Simon ◽

T. Bagdonat ◽

U. Motschmann ◽

M. Fränz ◽

...

Keyword(s):

Solar Wind ◽

Hybrid Simulation ◽

Bow Shock ◽

Proton Density ◽

Model Calculations ◽

Mars Express ◽

Characteristic Features ◽

Hybrid Approximation ◽

Individual Particles ◽

Characteristic Scales

Abstract. The ELS and IMA sensors of the ASPERA-3 experiment onboard of Mars-Express (MEX) can measure electron as well as ion moments. We compare these measurements for a specific orbit with the simulation results from a 3-D hybrid model. In the hybrid approximation the electrons are modeled as a massless charge-neutralizing fluid, whereas the ions are treated as individual particles. This approach allows gyroradius effects to be included in our model calculations of the Martian plasma environment because the gyroradii of the solar wind protons are in the range of several hundred kilometers and therefore comparable with the characteristic scales of the subsolar ionospheric interaction region. The position of both the bow shock and the Ion Composition Boundary (ICB) manifest in the MEX data as well as in the results from the hybrid simulation nearly at the same location. The characteristic features of these boundaries, i.e. an increase of proton density and temperature at the Bow Shock and a transition from solar wind to ionospheric particles at the ICB, are clearly identifiable in the data.

Download Full-text