THERMAL INERTIA AT THE MSL AND INSIGHT MISSION SITES ON
MARS
D. Singh , Centre of Studies in Resources Engineering, Indian Institute of Technology Bombay, Mumbai, India
(sdeepak@umich.edu), S. Uttam, Physical Research Laboratory, Ahmedabad, India.

Abstract:
For planetary surface materials, thermal inertia is
the critical property that governs the surface’s daily
thermal response and controls the diurnal and seasonal surface temperature variations. Here we use the
ground measurements made by the MSL Curiosity
rover and the InSight lander to determine the thermal
inertia of two sites on Mars. This study compares the
variation of thermal inertia during and after the Large
Dust Storm (LDS) of Martian Year (MY) 34. We
derive a simple approximation (using energy balance), which utilizes surface albedo, surface energy
flux, and diurnal change in the surface temperature
for the surface thermal inertia determination. The
average thermal inertia in MY34 is about 39.2%,
3.7%, and 3.4% higher than MY35 average thermal
inertia for the MSL, InSight (FOV1), and InSight
(FOV2), respectively. The thermal inertia at the InSight (FOV1) is consistently lower by about 20 J m–
2 s–1/2 K–1 than the InSight (FOV2) site for all scenarios, indicating notable variation in the region’s surface composition. The best-fit surface albedo in
MY34 (determined using the KRC model) are about
0.08, 0.05, and 0.03 higher than MY35 surface albedo for the MSL, InSight (FOV1), and InSight
(FOV2), respectively. An increase in both surface
albedo and thermal inertia during the LDS indicates
that the underlying surface is both more thermally
resistant and more reflective than the overlying loose
dust.

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Figure: Estimated thermal inertia using derived formulation and observed surface temperatures. The
black dotted line indicates the boundary between
MY34 and MY35.

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