Nasa's Mariner 4 completed the first successful flyby of Mars in the summer of 1965. The spacecraft had a camera onboard to capture Martian vistas, but transmitting all the data to Earth was slow, taking 19 days. So while waiting for Earth-bound electronics to convert the data into fully processed images, Richard Grumm of the nasa Jet Propulsion Laboratory decided to take matters into his own hands. He stapled strips of paper with incoming pixel brightness values onto a wall and then hand-colored the numbers with corresponding pastels. When Grumm was finished, the lighter zone filling most of the frame (above) showed the bottom edge of Mars fading into the darkness of space. The paint-by-numbers panel became the first image of Mars based on data collected by an interplanetary probe, as well as the first close-up image of the planet broadcast on television. In total, the mission delivered 21 complete images of the planet. This month marks the 50th anniversary of the launch of the Mariner 4 spacecraft, which took place on November 28, 1964.
This article was originally published with the title "What is it?"