Mariner 8 was launched on May 8, 1971 and Mariner 9 was launched on May 30, 1971. It was third in the history or series of Mariner on Mars. These both were also sent by NASA as the other one in series of Mariners. Mariner 8 was failed during the launch and did not get success in staying in orbit but Mariner 9 is the first artificial satellite and it started orbiting in an orbit, where it stayed for almost a year.
Mariner 9 upon arrival faced a dust storm and it delayed the spacecraft in obtaining the data. The spacecraft waited for a long until the dust settled down and then it started working. Although it took a time to get a data but after storm the view was clearer as it was required by the spacecraft. It brought about first ever clear and closer view of Martian Moons, Deimos and Phobos. It was successful in studying the density and gravity of planet. It brought about approximately thousands of photos and was successful in launching.