  Airborne dust plays an active role in determining the thermal structure and
chemical composition of the present-day atmosphere of Mars and possibly the
planet's climate evolution over time through radiative--convective and cloud
microphysics processes. Thus, accurate measurements of the distribution and
variability of dust are required. Observations from the Mars Global
Surveyor/Thermal Emission Spectrometer Mars Mars Reconnaissance Orbiter/Mars
Climate Sounder and Mars Express/Fourier Transform Spectrometer and the
Curiosity Rover have limited capability to measure dust. We show that
spacecraft occultation of the Martian atmosphere at far-infrared frequencies
between 1 and 10 THz can provide the needed global and temporal data on
atmospheric dust by providing co-located measurements of temperature and dust
opacity from the top of the atmosphere all the way down to the surface. In
addition, spacecraft occultation by a small-satellite constellation could
provide global measurements of the development of dust storms.
