Mariner-H, also commonly known as Mariner 8, was part of the Mariner Mars '71 project. It was intended to go into Mars orbit and return images and data, but a launch vehicle failure prevented Mariner 8 from achieving Earth orbit and the spacecraft reentered into the Atlantic Ocean shortly after launch.
The Mariner 9 spacecraft, identical to Mariner 8
Launch of Mariner 8
Mariner 8 during solar arrays installation
Mariner 8 diagram
Mariner 9 was a robotic spacecraft that contributed greatly to the exploration of Mars and was part of the NASA Mariner program. Mariner 9 was launched toward Mars on May 30, 1971, from LC-36B at Cape Canaveral Air Force Station, Florida, and reached the planet on November 14 of the same year, becoming the first spacecraft to orbit another planet – only narrowly beating the Soviet probes Mars 2 and Mars 3, which both arrived at Mars only weeks later.
The Mariner 9 spacecraft
Mariner 9 launch
A schematic of Mariner 8/9, showing the major components and features