On July 4^th 1997, Mars Pathfinder’s retro-rockets burned bright over Mars.

America’s most recent successful lander mission (we can’t forget the ongoing Mars Global Surveyor Mission, which has returned some of the most spectacular recent data) had all begun with plans for a small and lightweight rover.

The spacecraft couldn’t carry much rocket fuel. Instead, for the first time on an American mission, the plan was to use air bags, and bounce the spacecraft down on Mars.

Then, as a NASA animation showed, the spacecraft would unfold... the rover would roll down... and place its rock sniffer on the most interesting targets.

Behind the slick computer graphics the reality was years of hard work and tests, and tests, and tests of the new techniques.

The Pathfinder team did its darndest to rip the kevlar bags to pieces. They bashed them down rocky slopes to see how much they could handle.

They dropped prototype spacecraft under parachutes.

Back at JPL, the rover was put through its paces.

As a result of a student competition, it now had a name "Sojourner", after the 19th century abolitionist heroine.