Mariner was launched on Nov 5, 1964 and Mariner 4 was launched on Nov 28, 1964. Mariner were designed by NASA to examine the inner structure of solar system. Both of them Mariner 3 and 4 were same and were created to take mars flybys but the Mariner 3, the cover encasing the shuttle at the highest point of the rocket neglected to eject because it was containing heavy weight instruments with it which created problem in taking them up to Mars.
After two or three weeks gap the Mariner 4 was sent to Mars and was successful in reaching Mars. Mariner 4 is the first ever spacecraft to reach Mars and brought about hundreds of pictures from Mars. It was the first one to declare that Martian atmosphere has traces of carbon dioxide. Mariner 4 was expected by NASA scientist to be working for approximately seven to eight months but it worked for almost three years. It provided data back to earth regarding Mars till the mission was discontinued by the NASA.