Tansen crate. View of the Tansen crater on the surface of the planet Mercury. Tansen is among Mercury's smaller named craters at just 27 kilometres in diameter. The ejecta rays formed by the impact appear prominent in this colour mosaic, as does the small, fresh crater ejecta deposit at the very top of the image. Imaged by the Wide Angle Camera (WAC) on NASA's MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft on 9th September 2013.