This week’s picture is a scan of an old (circa 1989) slide — it’s a picture of the engineering model of the Mariner 6 and 7 spacecraft:
In 1969, Mariner 6 and 7 completed the first dual-spacecraft reconnaissance of the planet Mars. Unfortunately, though, the technology of the time only allowed for a flyby mission — limiting the two spacecraft together to a total of 189 images of the red planet. Still, their photography covered about 20% of the planet — a substantial improvement at the time. As luck would have it, they both also flew over heavily cratered parts of the planet, so discovery of Mars’ volcanoes and water-shaped features would have to wait a few more years.