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HiPOD: Translucent Ice on Dunes

Coordinating with the CaSSIS instrument on the ExoMars Trace Gas Orbiter, we acquired an image at this site for seasonal monitoring. At the time of year we took the image, the whole scene was probably covered in carbon dioxide ice. Some of this ice is translucent, so you can see the dark dunes through it.

ID: ESP_076844_2550 date: 18 December 2022 altitude: 316 km

HiPOD: A Curious Case of Positive-Relief

This observation captures a curious, fractured feature on the South Polar layered deposits: is this an active feature? We saw this in a much earlier image, but it was very hard to find changes with such an extreme difference in lighting direction. This will be part of a series to reproduce the lighting and compare any changes.

ID: ESP_076876_0920 date: 20 December 2022 altitude: 246 km

The Shifting Winds of Hellas Plantia

Sand dunes on Mars are subject to variety of wind regimes and impacting conditions that have produced a diverse catalog of dune shapes and sizes. Simple wind regimes, where atmospheric flow is directed in one direction, typically lead to the formation of crescentic dunes called barchans. These simple dunes are common in craters across the Southern Highlands. For example, see this observation where a fleet of barchans are migrating to the left (west).

This region also hosts remarkably complex dunes like this field in the Hellespontus Montes mountain range. Dunes here migrate both east and west, coalescing and eventually converging at a central area where star dunes are found. Diurnal and seasonal shifting winds are responsible for the dune’s formation and activity.

Ultimately, it is the outsized influence of the giant Hellas Planitia basin, which is directly to the east, that controls most of the regional atmospheric flow. (See also: Multidirectional Dune Dynamics Under Seasonal Winds on Mars).

ID: ESP_016339_1380 date: 20 January 2010 altitude: 255 km