FIGURE 1. Apollo photographs of the D-shaped Ina structure.

It is 2.8 km in diameter and 60 m in depth. Main panel, the closer view from the Apollo 15 panoramic camera shows the absence of small craters on the interior of the feature and the sharp contacts between smooth mounds of low relief and brighter, hummocky floor. Stereo-photogrammetry demonstrates that the larger smooth mounds can be as high as 25 m, but there are numerous smaller relief features including scarps and floor rubble (bright areas) extending to below the available resolution (<5 m). Inset, a low-illumination view (taken with an Apollo hand-held camera) showing the depression (scale bar, 400 m).