The Mariner 6 mission, launched on February 1969, was designed with the use of design plans of earlier flyby probes of the Mariner series. This model of the Mariner probe carried a rocket engine for telemetry corrections, and had continuous telemetry transmission. For fuel economy this probe was solar powered except for the rocket used in telemetry corrections. Like the previous Mariner probes, Mariner 6 had no way of attaining a Martian orbit.
Mariner 6 was an important step in the exploration of Mars, because of the technological innovations involved in its design and in the results of the mission. The technological novelties included in this vehicle were a rocket for trajectory corrections and a new arrangement of equipment. Besides the standard photography equipment, this version of the Mariner series included instruments for planetary experiments housed in seven distinct electronic compartments.
Besides the increased instrumentation and the increased capability for planetary data collection, this new probe had one more innovation with respect to its predecessors. The fully automated on-board computer could be reprogrammed from mission control after the launch. This meant that the mission was more reliable, because modifications could be carried out if necessary. This program feature was not part of the on board computer of previous Mariner missions to Mars.
The mission was designed to place the probe in a trajectory to fly over the equator and the southern hemisphere of the Red planet. Transmission of images to Earth began only when the probe reached these points, no images were taken before or after the flyby of Mars. The low gain antenna of the probe transmitted the images of both the Martian equator and the Martian southern hemisphere back to Earth. This antenna also helped to provide mission control with constant telemetry of Mariner 6.
The images and technical innovations of Mariner 6, obtained during the flyby of July 1969, laid the ground work for the Viking Project. Aspects of Mariner 6 such as a reprogramable computer and continuous telemetry were included in the design of the Viking lander and orbiter package. The images obtained by the cameras of this probe were used to select landing sites for the Viking spacecraft.