Search Publications
Annual variations in the Martian bow shock location as observed by the Mars Express mission
Holmström, M.; Fränz, M.; Lester, M. +12 more
The Martian bow shock distance has previously been shown to be anticorrelated with solar wind dynamic pressure but correlated with solar extreme ultraviolet (EUV) irradiance. Since both of these solar parameters reduce with the square of the distance from the Sun, and Mars' orbit about the Sun increases by ∼0.3 AU from perihelion to aphelion, it i…
Solar cycle variations in the ionosphere of Mars as seen by multiple Mars Express data sets
Pätzold, M.; Lester, M.; Milan, S. E. +11 more
The response of the Martian ionosphere to solar activity is analyzed by taking into account variations in a range of parameters during four phases of the solar cycle throughout 2005-2012. Multiple Mars Express data sets have been used (such as Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) in Active Ionospheric Sounding, MARS…
Empirical model of the Martian dayside ionosphere: Effects of crustal magnetic fields and solar ionizing flux at higher altitudes
Gurnett, D. A.; Němec, F.; Morgan, D. D. +1 more
We use electron density profiles measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument on board the Mars Express spacecraft to investigate the effects of possible controlling parameters unconsidered in the empirical model of Němec et al. (2011, hereafter N11). Specifically, we focus on the effects of crustal magneti…
Ionospheric loss from Mars as predicted by hybrid particle simulations
Brecht, Stephen H.; Ledvina, Stephen A.; Bougher, Stephen W.
This paper reports the results of hybrid simulations of the Mars-solar wind interaction. The focus is on the loss rates of O+ and O2+ from the Martian ionosphere while examining the importance of including 3-D dimensional neutral atmospheres with their associated neutral winds. The simulation loss rates are found t…
A survey of superthermal electron flux depressions, or "electron holes," within the illuminated Martian induced magnetosphere
Fränz, M.; Lester, M.; Andrews, D. J. +4 more
Since Mars lacks a global intrinsic magnetic field, the solar wind interacts directly with the Martian upper atmosphere and ionosphere. The presence of localized intense remnant crustal magnetic fields adds to this interaction, making the Martian plasma system a unique environment within the solar system. Rapid reductions in the electron flux, ref…
Plasma observations during the Mars atmospheric "plume" event of March-April 2012
Gurnett, D. A.; Barabash, S.; Holmström, M. +10 more
We present initial analyses and conclusions from plasma observations made during the reported "Mars plume event" of March-April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude "plume" over the Martian dawn terminator, the cause of which remains to be explained. The estimated brightness of the pl…
Comparative aeronomy: Molecular ionospheres at Earth and Mars
Withers, Paul; Moore, Luke; Vogt, Marissa F. +6 more
The ionospheres in our solar system vary not only in their electron densities but also in the dominance of atomic versus molecular ions at their altitudes of peak plasma density. With the exception of Earth's F layer composed of atomic oxygen ions and electrons, all other planets have their peak ionospheric layers composed of molecular ions and el…
Emission of hydrogen energetic neutral atoms from the Martian subsolar magnetosheath
Kallio, E.; Barabash, S.; Futaana, Y. +3 more
We have simulated the hydrogen energetic neutral atom (ENA) emissions from the subsolar magnetosheath of Mars using a hybrid model of the proton plasma charge exchanging with the Martian exosphere to study statistical features revealed from the observations of the Neutral Particle Detectors on Mars Express. The simulations reproduce well the obser…
On improving the accuracy of electron density profiles obtained at high altitudes by the ionospheric sounder on the Mars Express spacecraft
Gurnett, D. A.; Němec, F.; Morgan, D. D.
We attempt to improve the standard inversion routine used to obtain electron density profiles from the data measured by the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) topside radar sounder on board the Mars Express spacecraft. Artificial ionospheric traces corresponding to how the MARSIS instrument would see model electro…
Some new aspects of the transient ionization layer of comet Siding Spring origin in the Martian upper atmosphere
Venkateswara Rao, N.; Rao, S. V. B.; ManasaMohana, P. +1 more
The close encounter of comet Siding Spring with Mars resulted in the formation of a dense transient ionization layer in the Martian upper atmosphere at altitudes between 80 and 120 km. Instruments on three spacecraft orbiting Mars detected the presence of this layer, as reported in previous publications. In this study, we reanalyzed the ionograms …