Dust Dynamics in Gale Crater Observed Using the Line-Of-Sight Extinction Through 3,663 Sols of the Mars Science Laboratory Mission

Abstract

The Curiosity Rover has been exploring the Gale Crater using the on-board Navigation Camera to monitor the line-of-sight (LOS) dust extinction within the crater. Previous studies of the line-of-sight extinction have shown an annual trend where a minimum in extinction occurs around L_s = 100° and a maximum occurs around L_s = 300°. However, past studies have been constrained to images acquired only between 10:00 and 14:00 local time, limiting our understanding of the variation of dust extinction in Gale Crater throughout the day. Here, using a method that corrects for variable lighting geometry, we reanalyze the line-of-sight images captured throughout the mission to include images acquired in the early morning and late afternoon. Additionally, we update the line-of-sight record to include over 1,000 additional sols of the mission through sol 3,663, which updates our record of extinction in Gale to the end of Mars Year 36—a period of almost 5.5 Mars Years. Using images taken throughout the sol, we examine the diurnal trend in dust extinction, where a maximum is seen around solar noon. This diurnal trend is observed throughout the year, with a larger diurnal variation observed during the southern summer. Additionally, the geographic homogeneity in dust loading is quantified, with higher dust loading observed in the western portion of the line-of-sight images, corresponding with the north-western portion of the crater rim. These observations suggest that dust lifting from the surface and vertical mixing are factors in the diurnal, seasonal, and geographic dynamics observed in the extinctions.