Jet Propulsion Laboratory (U.S.). Mariner Mars'69 Project.

When launched February 24,1969 and March 27, 1969 abroad Atlas/Centaur launch vehicles, the JPL flight project Mariner Mars '69 became respectively Mariner 6 and 7. The Atlas/Centaur launch vehicle system was used for the first time in a planetary mission. It presented a number of new features to the Mariner program including increased payload capability and better injection accuracy. It had single-burn and double-burn capability and was able to perform a yaw maneuver during the ascent.

Mariner 6 and 7 comprised a dual-spacecraft mission to Mars, the fourth mission in the Mariner series of spacecraft used for planetary exploration in the flyby mode. The primary objectives of this mission were to study the surface and atmosphere of Mars during close flybys. Also, to establish the basis for future investigations, particularly those relevant to the search for extraterrestrial life; and to demonstrate and develop technologies required for future Mars missions and other long-duration missions far from the Sun. Mariner 6 also had the objective of providing experience and data, which would be useful in programming the Mariner 7 encounter 5 days later. Each spacecraft carried a wide-and narrow-angle television camera, an infrared spectroscope, an infrared radiometer, and an ultraviolet spectroscope. The spacecraft were oriented entirely to planetary data acquisition, and no data were obtained during the trip to Mars or beyond Mars.

Two launches, two flights and two Mars encounters were planned for Mariner Mars '69. The hardware elements were identical for the two, but the conditions were different. The launches were scheduled relatively far apart during the launch opportunity; and the encounter conditions were established, according to the desires of the experimenters, to maximize the return from either one or two successful flyby passes.

The characteristics of the Mariner spacecraft, based principally on 1964-65 flight experience, included relatively long operating life. Three-axis attitude stabilization through celestial and inertial references and cold-gas thrusters, in-flight course corrections through a small onboard fixed and programmable computer, sequenced scientific instrument pointing control (relative to spacecraft attitude), and onboard science data storage all contributed to the mission technically. The programmable spacecraft computer was a new feature; in addition, a multi-channel telemetry system with engineering data rates of 8 and 33 bits/s, science rates of 66 and 270 bits/s, and an experimental high-rate channel with 16.2 kbits/s was introduced.