www.elsevier.com/locate/planspasci Imaging the surface ofMercury using ground-based telescopes

We describe and compare two methods of short-exposure, high-de4nition ground-based imaging of the planet Mercury. Two teams have recorded images of Mercury on di+erent dates, from di+erent locations, and with di+erent observational and data reduction techniques. Both groups have achieved spatial resolutions of ¡ 250 km, and the same albedo features and contrast levels appear where the two datasets overlap (longitudes 270–360). Dark albedo regions appear as mare and correlate well with smooth terrain radar signatures. Bright albedo features agree optically, but less well with radar data. Such con4rmations of state-of-the-art optical techniques introduce a new era of ground-based exploration of Mercury’s surface and its atmosphere. They o+er opportunities for synergistic, cooperative observation