{ "title": "Bright and Dark Dunes", "authors": "HiRISE", "metadata": { "thumbnailURL": "https://static.uahirise.org/anews/2021-02-15/ESP_067775_1120.jpg", "excerpt": "Martian dunes near the poles often have bright patches in the spring, when seasonal frost is lingering." }, "version": "1.5", "identifier": "ESP_067775_1120", "language": "en", "layout": { "columns": 10, "width": 1024, "margin": 85, "gutter": 20 }, "documentStyle": { "backgroundColor": "#faf7f2" }, "components": [ { "role": "heading1", "layout": "heading1Layout", "text": "HiPOD: 15 February 2021" }, { "role": "divider", "layout": "bigDividerLayout", "stroke": { "width": 3, "color": "#8c2028" } }, { "role": "title", "layout": "halfMarginBelowLayout", "text": "Bright and Dark Dunes" }, { "role": "photo", "layout": "fullBleedLayout", "caption": "A cutout using the red-green-blue center swath. Less than 1 km across. (NASA/JPL/UArizona)", "URL": "https://static.uahirise.org/anews/2021-02-15/ESP_067775_1120.jpg" }, { "role": "body", "format": "html", "layout": "hipodMarginLayout", "text": "


This image shows a large sand dune with bright patches. Martian dunes near the poles often have bright patches in the spring, when seasonal frost is lingering. However, this image is from late summer, when frost is long gone. What is going on here?

A close-up look with HiRISE provides some clues. The bright patches are made up of large ridges that look like wind-blown bedforms. Additionally, the bright patches are yellowish in the infrared-red-blue image. In enhanced color, most sand on Mars is blue but dust is yellow. This suggests that the bright bedforms are either built from, or covered by, dust or material with a different composition.

" }, { "role": "photo", "layout": "fullBleedLayout", "caption": "The bright patches are yellowish in the infrared-red-blue cutout. Less than 1 km across. (NASA/JPL/UArizona)", "URL": "https://static.uahirise.org/anews/2021-02-15/ESP_067775_1120-2.jpg" }, { "role": "body", "format": "html", "layout": "hipodMarginLayout", "text": "

ID: ESP_067775_1120
date: 10 January 2021
altitude: 247 km (154 mi)

NASA/JPL/UArizona

" }, { "role": "caption", "format": "html", "layout": "halfMarginBothLayout", "text": "Enhanced color image is less than 1 km across; black and white is less than 5 km. For full images with scalebars, see the above ID link to our website.

" } ], "textStyles": {}, "componentLayouts": { "noMarginLayout": { "columnStart": 0, "columnSpan": 7 }, "niceMarginLayout": { "columnStart": 0, "columnSpan": 10 }, "hipodMarginLayout": { "columnStart": 0, "columnSpan": 9 }, "heading1Layout": { "columnStart": 0, "columnSpan": 7, "margin": { "top": 24, "bottom": 3 } }, "halfMarginBelowLayout": { "columnStart": 0, "columnSpan": 10, "margin": { "bottom": 12 } }, "fullMarginBelowLayout": { "columnStart": 0, "columnSpan": 7, "margin": { "bottom": 24 } }, "fullMarginAboveHalfBelowLayout": { "columnStart": 0, "columnSpan": 7, "margin": { "top": 24, "bottom": 12 } }, "bigDividerLayout": { "ignoreDocumentMargin": "right", "columnStart": 0, "columnSpan": 10, "margin": { "top": 6, "bottom": 6 } }, "fullBleedLayout": { "ignoreDocumentMargin": true }, "halfMarginBothLayout": { "columnStart": 0, "columnSpan": 8, "margin": { "top": 12, "bottom": 12 } }, "fullMarginAboveLayout": { "columnStart": 0, "columnSpan": 7, "margin": { "top": 24 } }, "halfMarginAboveQuarterBelowLayout": { "columnStart": 0, "columnSpan": 7, "margin": { "top": 12, "bottom": 6 } } }, "componentStyles": {}, "componentTextStyles": { "default": { "fontName": "DINAlternate-Bold", "textColor": "#222222", "fontSize": 16, "lineHeight": 22, "linkStyle": { "textColor": "#D5B327" } }, "default-body": { "fontName": "MiloSerifOT-Text", "fontSize": 20, "lineHeight": 30, "paragraphSpacingBefore": 12, "paragraphSpacingAfter": 12, "linkStyle": { "textColor": "#378DBD" } }, "default-title": { "fontName": "MiloSerifOT-Text", "fontSize": 44, "tracking": 0, "lineHeight": 48, "textColor": "#2e5284" }, "default-intro": { "fontName": "DINAlternate-Bold", "fontSize": 18, "lineHeight": 22, "textColor": "#A6AAA9" }, "default-byline": { "fontName": "DINAlternate-Bold", "fontSize": 15, "lineHeight": 18, "textColor": "#53585F" }, "default-heading2": { "fontName": "DINAlternate-Bold", "tracking": 0.05, "textColor": "#53585F" }, "default-heading1": { "fontName": "MiloOT-Light", "tracking": 0.12, "textColor": "#53585F" }, "bodyFirstDropCap": { "dropCapStyle": { "fontName": "DINAlternate-Bold", "textColor": "#A6AAA9", "numberOfLines": 2 } }, "default-heading2": { "fontName": "IowanOldStyle-Roman", "fontSize": 48, "lineHeight": 44, "textColor": "#53585F" }, "default-caption": { "fontName": "MiloSerifOT-Text", "fontSize": 14, "lineHeight": 18, "paragraphSpacingBefore": 12, "paragraphSpacingAfter": 12, "textColor": "#53585F" }, "default-pullquote": { "fontName": "DINAlternate-Bold", "fontSize": 30, "lineHeight": 36, "textColor": "#A6AAA9", "hangingPunctuation": true }, "attribution": { "fontName": "DINAlternate-Bold", "fontSize": 12, "lineHeight": 16, "tracking": 0.12, "textColor": "#53585F", "textAlignment": "right" } } }