Springtime in the South Polar region of Mars is a season of exciting activity. The thick coating of carbon dioxide ice that accumulated over the winter begins to sublimate (turn to vapor) as the sun rises higher in the sky and warms the ice. Sunlight penetrates through the transparent ice, and is absorbed at the base of the ice layer. The gas that forms as a result of the warming escapes through weaknesses in the ice and erupts in the form of magnificent geysers of gas and dust.

This image captures some of this activity in a region near 85 degrees south latitude that is being monitored by HiRISE. What makes this image interesting is the changing directions of the fans left behind by the geysers, indicating that the winds blew from different directions at the time that the geysers erupted. Winds from the southwest produced the dark fans at both ends of the image, whereas northwesterly winds dominated dust deposition in between. Local topography probably played a role in altering the wind direction; this shaded relief image shows that this image traverses a trough in the South Polar layered deposits, which may have funneled winds down slope along the length of the trough.



Written by: Paul Geissler   (29 October 2018)