On July 20, 1976 (June 24th of the lunar calendar), Viking 1 landed on Mars and sent back photos.

July 20, 1976. A Viking spacecraft landed on Mars and sent back two extremely spectacular and clear photos showing a rocky desert area that bears astonishing similarities to Earth. The three-strut, 6-foot-tall spacecraft landed on Mars at 7:53 a.m. EDT after 11 months away from Earth. Its main mission is to analyze Martian soil for signs of water and life. Eight days later, if all goes well, a robotic arm will emerge from the Viking Mars ship and scoop up soil samples, which will be placed in three separate instruments for inspection to see if there is any sign of life. Another sister spacecraft is expected to land elsewhere on Mars in no more than three months.