In 1974, the Mariner 10 spacecraft passed Venus and went on to Mercury. On March 29 it flew within 704 kilometers (420 miles) of Mercury and using gravity-assist techniques, returned twice during the following year. The spacecraft returned about 4,000 Mercury images, mapping 45% of the planet surface.

The images above were taken during the first encounter with Mercury. Separate photos were overlapped to create a mosaic, with a small white rectangle near the center indicating the position of the enlargement seen at right. The enlarged image shows the bright Kuiper crater on the rim of an older, larger crater. It was named in memory of Gerard P. Kuiper, a pioneer in planetary astronomy and member of the Mariner 10 TV team.