A sunflower crater on Mars
Cool image time! The picture to the right, cropped and reduced to post here, was taken on December 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels a “pedestal crater,” a crater that, because the impact smashed the ground to make it more resistent, when the surrounding terrain eroded away it left the crater sitting high and dry.
In this case the crater is only a few feet higher than that surrounding terrain. In fact, though it looks much deeper than the crater to the northeast, both are so shallow that their depth is below the resolution of MRO’s elevation data.
Both craters however suggest the presence of a lot of near surface ice, which is confirmed by overview map above. The rectangle marks the location, inside the 2,000-mile-long northern mid-latitude strip I dub glacier country, as almost every high resolution picture suggests glacial features and near-surface ice. The crater to the northeast appears filled with glacier debris, while the sunflower-shaped apron around the pedestal crater suggests the impact hit soft ice that splashed away and then hardened.
Though this pedestal crater does not appear to sit high above the plain, the rough edges of its apron illustrate the subsequent erosion. The impact likely stripped away the dust/debris layer that protected the glacial and near-surface ice of that splash apron so that sunlight would cause it to sublimate away. Thus we have that knobby surface at the edges.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on December 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels a “pedestal crater,” a crater that, because the impact smashed the ground to make it more resistent, when the surrounding terrain eroded away it left the crater sitting high and dry.
In this case the crater is only a few feet higher than that surrounding terrain. In fact, though it looks much deeper than the crater to the northeast, both are so shallow that their depth is below the resolution of MRO’s elevation data.
Both craters however suggest the presence of a lot of near surface ice, which is confirmed by overview map above. The rectangle marks the location, inside the 2,000-mile-long northern mid-latitude strip I dub glacier country, as almost every high resolution picture suggests glacial features and near-surface ice. The crater to the northeast appears filled with glacier debris, while the sunflower-shaped apron around the pedestal crater suggests the impact hit soft ice that splashed away and then hardened.
Though this pedestal crater does not appear to sit high above the plain, the rough edges of its apron illustrate the subsequent erosion. The impact likely stripped away the dust/debris layer that protected the glacial and near-surface ice of that splash apron so that sunlight would cause it to sublimate away. Thus we have that knobby surface at the edges.