Date: 5 Nov 1964
Mariner 3 was a 260 kg solar-cell and battery-powered spacecraft designed to make scientific measurements in the vicinity of Mars and to obtain photographs of the planet's surface and transmit these to Earth.
It was intended that the spacecraft would encounter Mars after a 325-million mile journey in a little less than eight months. A protective shield failed to eject after the spacecraft had passed through the atmosphere. None of the instrument sensors were uncovered, and the added weight prevented the spacecraft from attaining its prescribed Mars trajectory.