NASA has just achieved one of the most incredible accomplishments in the history of mankind, and for an agency that has done many wonders for humanity, this is something that stands above almost all the rest. It has now been 20 years since the agency puts a rover on Mars, and two decades later, we have reaped tremendous scientific benefits from that mission.

On July 4, 1997, NASA’s Pathfinder mission first touched down on the Red Planet, delivering a small rover named Sojourner, NASA’s first wheeled Mars craft. Ever since then, eight other NASA robots have made it to Mars, and five of them are still working today.

It was an incredible mission at the time, and still is today. Pathfinder launched on Dec. 4, 1996, and spend eight months flying to Mars. When the images were released between July 4-8, 200 million people viewed them, an astonishing achievement on a still fledgling Internet.

“Pathfinder initiated two decades of continuous Mars exploration bringing us to the threshold of sample return and the possibility of humans on the first planet beyond Earth,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program at the agency’s headquarters in Washington.