Crater Hopmann by SMART-1

Article written: 6 May , 2006
Updated: 29 Mar , 2013

ESA’s SMART-1 spacecraft captured this photograph of Crater Hopmann, located on the Moon. Only a quarter of the full crater is visible in this photograph, and it contains several other smaller craters inside of it. The small crater chains are created when secondary debris is blasted off the surface of the Moon, and then falls back in an arc of molten droplets. This area isn’t visible from the Earth because it’s on the far side of the Moon – only spacecraft have ever seen it.

This image, taken by the advanced Moon Imaging Experiment (AMIE) on board ESA’s SMART-1 spacecraft, shows one quarter of crater Hopmann – an impact structure about 88 kilometres in diameter.

AMIE obtained this image on 25 January 2006 from a distance of about 840 kilometres from the surface, with a ground resolution of 76 metres per pixel.

The imaged area, not visible from Earth because it is located on the far side of the Moon, is positioned at latitude of 51.7 degrees South and longitude 159.2 degrees East. It covers a square of about 39 kilometres per side.

The crater (centred at 50.8 degrees South, 160.3 degrees East) is situated on the edge of the giant South Pole-Aitken basin SPA, the largest impact crater in the solar system with a diameter of 2500 kilometres and a depth of 13 kilometres. The SPA basin shows distinctive chemical composition with unusual mineralogy types, and possible exposure of rocks from the lower crust or the upper mantle.

The hills on the lower left side are the crater wall of Hopmann. This crater is very old – many small craters can be seen on its flat floor, the largest one showing an interesting double-ringed structure. The outer rim has been also eroded by later impacts.

The small crater chains to the left of Hopmann can be interpreted as series of so-called ‘secondary craters’, created by the impact of the material ejected from a nearby large impact. This ejected material flies away in molten state, and fall in large ‘droplets’. When these impact on the surface, they form typical crater chains as those visible in this image.

The crater is named after Josef Hopmann (1890-1975), an astronomer that worked in Bonn, Leipzig and as Director of the Vienna Observatory.

Original Source: ESA Portal

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