Mariner 3 was designed to fly by Mars and conduct other interplanetary experiments along the way. However, soon after its launch, the shroud encasing the spacecraft atop its rocket failed to open properly and the mission was unsuccessful.

Three weeks later, the Mariner 4 spacecraft launched successfully on an eight-month journey to the Red Planet and collected the first up-close photographs of another planet.

Scientific Instruments

- Imaging system
- Magnetometer
- Plasma probe
- Cosmic ray telescope
- Trapped radiation detector
- Cosmic ray ionization
- Cosmic dust detector