{ "title": "HiPOD", "metadata": { "thumbnailURL": "bundle://header.jpg", "excerpt": "First imaged by one of the Viking orbiters back in the late 1970s and 1980s, our image shows frost on dunes in far greater detail." }, "version": "1.5", "identifier": "ESP_055385_1205", "language": "en", "layout": { "columns": 10, "width": 1024, "margin": 85, "gutter": 20 }, "documentStyle": { "backgroundColor": "#faf7f2" }, "components": [ { "role": "heading1", "layout": "heading1Layout", "text": "HiPOD: FRIDAY, 8 NOVEMBER 2019" }, { "role": "divider", "layout": "bigDividerLayout", "stroke": { "width": 3, "color": "#8c2028" } }, { "role": "title", "layout": "halfMarginBelowLayout", "text": "Monitoring Frost on Dunes Also Imaged by Viking" }, { "role": "photo", "layout": "fullBleedLayout", "caption": "Less than 5 km across. (NASA/JPL/University of Arizona)", "URL": "bundle://ESP_055385_1205-main.jpg" }, { "role": "body", "format": "html", "layout": "hipodMarginLayout", "text": "
Over the last 13 years, HiRISE has only imaged about 3 percent of the Martian surface. One of the reasons for this is because we often take repeat pictures in order to track changes over time.
This is one of those repeat images: looking for changes in the frost on dunes that were also imaged by the Viking Orbiters (1976-1982). The black spots are likely the result of sublimation, when a solid state transforms directly into a gaseous one. Darker subsurface material is exposed, and then is moved about by the wind.
These dunes are located within a large, unnamed crater to the southwest of the Hellas impact basin.
ID: ESP_055385_1205
date: 21 May 2018
altitude: 250 km
NASA/JPL/University of Arizona