ESA Science & Technology - Crater Sulpicius Gallus

This mosaic of three images, taken by the advanced Moon Imaging Experiment (AMIE), shows the area around the crater Sulpicius Gallus on the Moon.
 
AMIE obtained this sequence on 18 March 2006, at a distance of about 1200 kilometres from the surface, with a ground resolution ranging from 110 to 114 metres per pixel.

The area shown in the top image is centred at a latitude of 19.7° North and longitude 12.2° East; the image in the middle is centred at a latitude of 18.2° North and longitude 12.3° East; the bottom image is centred at a latitude of 16.7° North and longitude 12.5° East. 

The prominent crater in the upper left of this mosaic is crater Sulpicius Gallus. It is a fairly fresh, bowl-shaped crater with a diameter of roughly 12 kilometres. The flat lava plains surrounding it belong to the Mare Serenitatis (Sea of Serenity) on the north-eastern quadrant of the Moon's nearside. The mountains going diagonally through the middle of the mosaic are Montes Haemus. They are denoting the edge of the huge impact crater which formed the Mare Serenitatis.

The area around crater Sulpicius Gallus is very interesting for lunar scientists - it is one of the most geologically and compositionally complex areas of the nearside of the Moon. The geologic history of this region has been shaped by impacts of different scales and at different epochs, by volcanism of variable style and composition with time, and by limited tectonics. Specific findings (Bell and Hawke, 1995) include the detection of relatively fresh highlands materials in the crater.
 
Good spectroscopic data (that is, relative to the mineralogical composition) are available both from the Clementine mission and from ground-based observations, allowing to better constrain the geological evolution of the Moon.

The area has been suggested to contain mixtures of glassy and black beads generated when large impacts melted part of the lunar surface. However, modelling the spectral properties of material similar to lunar material does not allow to unambiguously match the composition of the material to the measured data.

Colour observations of the AMIE camera will help in further clarifying these issues. So, the combination of high spatial resolution imaging and high spectral resolution spectroscopy from datasets from SMART-1, Clementine and ground based telescopes will allow to better model mineral mixtures on the Moon.

The crater Sulpicius Gallus is named after a Roman general, state man and orator. He is famous for having predicted an eclipse of the moon on the night before the battle of Pydna (168 BC). A man of great learning, in his later years he devoted himself to the study of astronomy.