Mariner 4 returned the first close-up images of Mars

On July 14, 1965, NASA’s Mariner 4 swept past Mars at a range of about 6,118 miles (9,846 km), becoming the first spacecraft to photograph another planet up close. Beginning roughly 40 minutes before closest approach, its single TV camera recorded 21 complete images (plus part of a 22nd) onto a four-track tape recorder.

The data crawled home across some 134 million miles at a trickle of just 8.3 bits per second. Impatient engineers at the Jet Propulsion Laboratory hand-colored a numerical printout of the first frame with art-store pastels before the computer-processed picture was ready, creating the first image of Mars seen on television.

The grainy frames revealed a cratered, Moon-like world, not the canals and civilizations many had imagined.

The pictures showed an ancient, heavily cratered surface, quietly ending centuries of speculation about Martian life and reshaping how scientists pictured the Red Planet. Mariner 4’s success launched the modern age of Mars exploration that continues today.