UNKNOWN -- The United States Air Force launched a giant balloon, 962 feet tall, to support the National Aeronautics and Space Agency's ’s Viking Project designed for landing an unmanned spacecraft on Mars in 1976.
The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2.spacecraft were composed of two main parts: an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface. The orbiters also served as communication relays for the landers once they touched down.
The Viking program grew from earlier, even more ambitious, Voyager Mars programs, which were not related to the successful Voyager deep space probes of the late 1970s. Viking 1 was launched on August 20, 1975, and the second craft, Viking 2, was launched on September 9, 1975, both riding atop Titan IIIE rockets with Centaur upper stages. Viking 1 entered Mars orbit on June 19, 1976, with Viking 2 following suit on August 7, 1976..
After orbiting Mars for more than a month and returning images used for landing site selection, the orbiters and landers detached; the landers then entered the Martian atmosphere and soft-landed at the sites that had been chosen. The Viking 1 lander touched down on the surface of Mars on July 20, 1976, and was joined by the Viking 2 lander on September 3, 1976.. The orbiters continued imaging and performing other scientific operations from orbit while the landers deployed instruments on the surface.
The project cost roughly 1 billion in 1970's dollars, equivalent to about 5 billion today.. The mission was considered successful and is credited with helping to form most of the body of knowledge about Mars through the late 1990's and early 2000's.