Page "Mariner 4" Paragraph 11

The electrical power for the instruments and the radio transmitter of Mariner 4 was supplied by 28, 224 solar cells contained in the four 176 x 90 cm solar panels, which could provide 310 watts at the distance of Mars.

A rechargeable 1200 W · h silver-zinc battery was also used for maneuvers and backup.

Monopropellant hydrazine was used for propulsion, via a four-jet vane vector control motor, with thrust, installed on one of the sides of the octagonal structure.

The space probe's attitude control was provided by 12 cold nitrogen gas jets mounted on the ends of the solar panels and three gyros.

Solar pressure vanes, each with an area of 0. 65 square meter ( seven ft² ), were attached to the tips of the solar panels.

Positional information was provided by four Sun sensors, and a sensor for either the Earth, Mars, or the star Canopus, depending on the time in its spaceflight.

Mariner 4 was the first space probe that needed a star for a navigational reference object, since earlier missions, which remained near either the Earth, the Moon, or the planet Venus, had sighted onto either the bright face of the home planet or the brightly lit target.

During this flight, both the Earth and Mars would be too dim to lock onto.

Another bright source at a wide angle away from the Sun was needed and Canopus filled this requirement.

Subsequently, Canopus was used as a reference point in many following missions.