Study of martian dust aerosol with mars science laboratory rover engineering cameras.

Abstract

Planetary atmospheres other than that of Earth provide natural laboratories to test our theories and models for climate studies and can help to identify the physical processes involved in the behaviour and evolution of a planet's climate. Mars has always played a predominant role in comparative studies with Earth. Extensive efforts placed in the robotic exploration of Mars have retrieved large amount of data its atmosphere. Dust aerosol is the main driver of Mars' atmospheric variability, and the determination of the particles' properties is of high relevance for estimating its climate forcing. In particular, the angular distribution of sky brightness can be evaluated to retrieve valuable information regarding the physical properties of the aerosol particles. In this study we show that images retrieved by the Mars Science Laboratory (MSL) engineering cameras (Navcam and Hazcam) can be used to constrain the size and shape of dust aerosol particles, and to derive the column dust optical depth. A radiative transfer based iterative retrieval method was implemented in order to determine the aerosol modelling parameters that best reproduce the sky radiance as a function of the scattering angle observed by MSL engineering cameras. Results show an overall good agreement with previous studies and have contributed to extend the available data and to parameterise dust phase functions. The tools and procedures developed during this research can be implemented for the analysis of retrievals from future Mars exploration missions.