Goals: Mars Pathfinder was designed primarily to demonstrate a low-cost way of delivering a set of science instruments and a free-ranging rover to the surface of the Red Planet. The unique airbag system cushioned the lander in a cocoon after a parachute and rocket descent through the thin Martian atmosphere. Its rover, about the size of a microwave oven, was solar powered, but its mission was enabled by the use of radioisotope heater units.
Accomplishments: The Sojourner rover was the forerunner of the more advanced Spirit, Opportunity and Curiosity rovers. This first rover demonstrated key technologies and built technical competencies needed for designing and operating the later generations of wheeled Martian explorers. The rover outlived its designed lifespan by 12 times and returned more than 550 images, plus multiple chemical analyses of rocks at the landing site.