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First Results of Mars Express—ExoMars Trace Gas Orbiter Mutual Radio Occultation
Cardesín-Moinelo, Alejandro; Wilson, Colin; Witasse, Olivier +10 more
Spacecraft-to-spacecraft radio occultations experiments are being conducted at Mars between Mars Express (MEX) and Trace Gas Orbiter (TGO), the first ever extensive inter-spacecraft occultations at a planet other than Earth. Here we present results from the first 83 such occultations, conducted between 2 Nov 2020 and 5th of July 2023. Of these, 44…
The Phase Response of a Rough Rectangular Facet for Radar Sounder Simulations of Both Coherent and Incoherent Scattering
Gerekos, C.; Haynes, M. S.; Schroeder, D. M. +1 more
With radar sounders, coherent backscattering simulations from global planetary digital elevation models (DEMs) typically display a deficit in diffuse clutter, which is mainly due to the implicit assumption that roughness at scales below the resolution of the DEM is absent. Indeed, while polynomial approximations of the phase evolution across the f…
Analysis of Two Selected Solar Events in 2011 and 2015 With Mars Express Radio Occultation Data
Witasse, Olivier; Sánchez-Cano, Beatriz; Karatekin, Ozgur +3 more
The temporal behavior of the Martian ionosphere is highly variable due to various dynamic processes including space weather events. Here, we study the effect of solar flares and coronal mass ejections (CMEs) on the Martian ionosphere for two selected solar events in 2011 and 2015, using the publicly available Mars EXpress (MEX) radio occultation (…
Martian Lander Radio Science Data Calibration for Mars Troposphere
Le Maistre, S.
The tropospheric propagation effect is one of several sources of error in radio science measurements. Systematically calibrated for the Earth troposphere disturbances, the ranging and Doppler data provided by the Martian landers have not been corrected so far for Mars troposphere effects. These effects were considered negligible because the Mars a…
CLUSIM: A Synthetic Aperture Radar Clutter Simulator for Planetary Exploration
Sánchez-Cano, B.; Witasse, O.; Orosei, R. +1 more
In this paper we present the CLUtter SIMulator (CLUSIM), a special program simulating radar side echoes from rough planetary surfaces using realistic topography data sets. A numerical model of realistic topography of the Martian surface, based on Mars Orbiter Laser Altimeter data, is developed. A specially developed computer routine for evaluation…
The processing of electron density profiles from the Mars Express MARSIS topside sounder
Gurnett, D. A.; Morgan, D. D.; Witasse, O. +3 more
here present a manual for the reduction of data from ionograms obtained from the Mars Express MARSIS Active Ionospheric Sounding topside radar sounder. Sample data are presented with the procedure for processing them explained as simply as possible. We discuss the uncertainties inherent in the measurements as well as systematic problems with the d…
Attenuation of radio signals by the ionosphere of Mars: Theoretical development and application to MARSIS observations
Withers, Paul
We investigate the ionospheric conditions required to explain Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding topside radar sounder observations of ionospheric attenuation in excess of 13 dB at 5 MHz during solar energetic particle events. We develop theoretical expressions for the attenuation caused by a layer of ionospher…
Using complex independent component analysis to extract weak returns in MARSIS radar data and their possible relation to a subsurface reflector on Mars
Nielsen, Erling; Zhang, Zhenfei
Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) radar signals returned from the surface and subsurface of the northern lowlands of Mars are mostly characterized as a prominent surface pulse followed by a tail of weak signals. We applied the method of blind source separation (BSS) using complex independent component analysis (CI…
Radar signal simulation: Surface modeling with the Facet Method
Safaeinili, A.; Kofman, W.; Herique, A. +1 more
A major finding in exploration of Mars is the indication that a large quantity of water has been present on Mars. To discover the distribution of this quantity of water, the Mars Express spacecraft is carrying a spaceborne radar sounder, called Mars Advance Radar for Subsurface and Ionospheric Sounding (MARSIS), in order to map Mars subsurface die…