Atmospheric Imaging Results from the Mars Exploration Rovers: Spirit and Opportunity

Abstract

A visible atmospheric optical depth of 0.9 was measured by the Spirit rover at Gusev crater and by the Opportunity rover at Meridiani Planum. Optical depth decreased by about 0.6 to 0.7% per sol through both 90-sol primary missions. The vertical distribution of atmospheric dust at Gusev crater was consistent with uniform mixing, with a measured scale height of 11.56 +/- 0.62 kilometers. The dust's cross section weighted mean radius was 1.47 +/- 0.21 micrometers (mm) at Gusev and 1.52 +/- 0.18 mm at Meridiani. Comparison of visible optical depths with 9-mm optical depths shows a visible-to-infrared optical depth ratio of 2.0 +/- 0.2 for comparison with previous monitoring of infrared optical depths.

Quantitative compositional analysis of martian mafic regions using the MEx/OMEGA reflectance data 1. Methodology, uncertainties and examples of application

“…and with olivine at 5% (blue). (Lemmon et al, 2004;. The surface spectra retrieved from these observations (dashed lines) are similar, which further validates our approach.…”

“…This model is based on a Monte-Carlo radiative transfer code that includes multiple scattering, coupled with optical properties of aerosols constrained from previous studies (Ockert-Bell et al, 1997;Tomasko et al, 1999) and specific Emission Phase Function (EPF) OMEGA observations (Vincendon et al, 2007b). A validity test of the aerosol removal method was performed in January 2006 thanks to an EPF observation of Terra Meridiani by OMEGA, while Panoramic Camera (Pancam) aboard Opportunity was measuring the aerosol optical depth from the ground (Lemmon et al, 2004;Vincendon et al, 2007b). Briefly stated, the model depends on two parameters: the wavelength dependent albedo of the surface and the optical depth of aerosols at one wavelength.…”

Mechanisms of the diurnal cycle in the atmospheric boundary layer of Mars

“…The ratio τ IR /τ vis can be estimated from Table IV and Figure 1 as C abs (9.1 µm)/C ext (0.6 µm). This ratio appears to be about 0.5 for all three size distributions from the present Mie calculations, a value recommended by Forget (1998) and Lemmon et al (2004), but it is smaller and temperature-dependent if IR broadband values are considered instead of 9.1 µm.…”

Experimental and theoretical simulation of sublimating dusty water ice with implications for D/H ratios of water ice on Comets and Mars

“…This dust is most likely similar in character to the atmospheric particles which cover the planet. These particles average 1.6 microns in radius as determined from the Imager for Mars Pathfinder [32] and Mars Exploration Rover missions [31] and are similar in spectra and composition to JSC Mars-1 analog, the dust simulant used in our experiments.…”

“…However, in order to obtain dust (e), a grain size representative of martian airfall dust, it was first necessary to process the sieved JSC Mars-1. The grain size of martian airfall dust comes from the 1.6 μm radius particle peak of the distribution of dust observed in the martian atmosphere from landed spacecraft, as determined by studies of the martian atmosphere [31][32][33]. This material was produced by taking raw JSC Mars-1 and crushing it using a mortar and pestle before pouring the resulting detritus into a 10 cm deep water settling tank for 30 minutes.…”