18h 34min, aug 20, 1975 y - Viking 1
Successful orbiter & lander (NASA)
When Viking 1 entered orbit at Mars, it began taking pictures of the surface in search of a safe landing site for the lander. Mission planners were hoping for a July 4th landing, but the original site turned out to be too rocky. Another site was chosen and the first successful Mars landing took place on July 20, 1976, the seventh anniversary of the first Moon landing.
Added to timeline:
the videos are in the parts of Mars Exploration Rover Spirit...