October 7, 2010
top LRO NAC image M127247376RC processed by Rick Evans, and two smaller LRO WAC images (M117807235MC and M109554979CE) processed by Maurice Collins All images courtesy of NASA/GSFC/ASU.
There are few volcanic cones on the Moon and all are small. One of the largest is Mairan T, a steep-sided, multiply-pitted little volcano just west of the Sinus Iridum crater ejecta. WIth a low Sun (bottom left), the central depression has an odd tri-corner look. With higher illumination (bottom right), it is clear that the depression is formed of 3 or 4 overlapping pits. Higher resolution provided by the LRO Narrow Angle Camera (top) shows that the pits are highly softened by erosion and no original layering is visible in their rims. The steep conical walls suggest that Mairan T is composed of more viscous lavas than those making maria and their gentle-sided domes. Perhaps Mairan T is made of the same material as the nearby steep-sided Gruithuisen domes.
Rükl plate 3