Suisei Planitia is a large basin on Mercury. Ghost craters are unusual forms that occur in the Suisei Planitia. They are buried and rounded in profile, with only their rim crests rising above the surrounding smooth plains. It has been suggested that the smooth plains that Suisei Planitia is part of (Caloris Planitia) might be ejecta from Caloris that were melted by the impact. The name for this Planitia was approved in 1976.  The MESSENGER Mercury orbiter crashed into the plain in April 30, 2015, near the crater Janáček.