On this date in 1997, NASA's Pathfinder mission truly got underway (it arrived on July 4) as the miniature Sojourner rover drove off of its landing craft and onto the surface of Mars, becoming the first mobile vehicle to land on another planet. Being a first of its kind mission in that it was the first rover to land on another planet and the first planetary lander to use giant airbags to cushion the landing, the world was transfixed on the mission thanks to the fact that Pathfinder/Sojourner was the first great planetary surface mission in the era of mass access to cable/satellite TV and the Internet, which made it possible to watch live by previously unimaginable numbers of people.
As for the mission, the name was appropriate as it paved the way for the later, far more ambitious Twin Mars Exploration Rovers and (Spirit and Opportunity) of 2004 and the Mars Science Laboratory (Curiosity) of 2012. As for this mission itself, Pathfinder/Sojourner transmitted data for 83 days (far exceeding its 30-day design life) that included roughly 2.6 billion bits of information, including: 16,000 images, analysis for 15 rocks, and numerous weather data measurements.
Needless to say, this was the mission that truly re-ignited the interest in Mars, which had largely waned since the Vikings came up empty in their search for life in the 1970s.