All stages of liftoff were successful, and some ten minutes after countdown Mariner 6 was under way.
Shortly after launch, Mariner 6's radio tried to lock on itself instead of on the ground signal transmitted to it. The spacecraft would then not have been able to communicate with Earth for navigational purposes. The problem was not solved; rather, it solved itself: a few weeks later the radio turned out not to be locked on itself anymore.
Afterwards, when the scientific platform was released from its protective restraints, particles were released. Shining in the uninterrupted sunlight of
interplanetary space, they looked brighter than Canopus, so the star-tracking sensors on Mariner 6 locked on them instead. This problem was solved by using the gyroscopes for orientation instead of the star-tracking system for a while.
Canopus is not exactly 90 degrees from the Sun, so, as Mariner 6 moved around the Sun, Canopus appeared to change position, moving in a circle. This means that the spacecraft's tracker must move constantly to keep locked on the star. On 20 april, the Canopus sensor moved in the wrong direction, losing the star completely. Ground control was able to move the sensor back in the right direction, but only the same distance it had moved originally. The ground team tried to use the
Large Magellanic Cloud instead, but the sensor would lock off periodically, since it is not a bright enough source. After a while, the sensor finally responded to the initial ground commands and moved another step in the right direction, locking onto Canopus. Weeks later there was a similar problem, but this time the sensor responded immediately to the commands sent from Earth.
The rest of the cruise phase went with no other threats to the mission.
Every instrument, with the exception of one of the two detectors of the infrared spectrometer, functioned as planned. Their data was collected and transmitted to Earth for analysis.
Pictures of MarsOn 28 july, Mariner 6 was some 1,255,000 kilometers from Mars. It was then that its scientific instruments were turned on and it began to gather data. It also took 33 pictures at 37-minute intervals. A second series of 17 pictures was begun as soon as the first series had been downloaded to Earth and the craft's memory had been erased. It was as these 17 pictures were taken that the craft reached its final approach to Mars and the climax of its mission. It then took a final set of twenty-odd close-up pictures.
The craft crossed and imaged the planet's equatorial regions primarily. Combined, the images taken by Mariners 6 and 7 cover about 20% of the planet's surface.
The closest approach to the planet was 3,431 kilometers from the surface.
Although they did show the
craters which were expected, Mariner 6's pictures of Mars showed that the planet was not as similar to
the Moon as had been thought when Mariner 4 sent its own pictures. Rather, the red planet had its own personality and characteristics. It was shown to be a vast, cold, dry desert with several different
terrain types and a thin
carbon dioxide atmosphere with
clouds and frost.
The photographs also showed what is now known as
chaos: chaotic terrain scarred by a labyrinth of small ridges and featuring no craters at all. It is believed that these regions formed when underground ice or water escaped from below, although the exact reason for their existence is still unknown.
Far-encounter pictures taken by Mariner 6
Near-encounter pictures taken by Mariner 6
Mosaics created with the pictures taken by Mariner 6
Click on images to enlarge them.
Posted Image Mosaic created from pictures 1-8
Posted Image Mosaic created from pictures 9-25
Mariner 6's trajectory
The martian atmosphereReadings of Mars's atmosphere at the tropics returned warmer temperatures than predicted by theory. In other places, however, the temperature readings were consistent with theory. Data indicated that carbon dioxide clouds could form at any altitude near the
north pole. Atmospherical composition turned out to be dominated by carbon dioxide (CO
2) and its chemical derivatives, especially
carbon monoxide (CO). It was surprising at the time that no nitrogen or
ozone was detected.
Clouds on Mars are formed by CO
2 ice, water ice and dust particles. Although it was determined to be impossible for rain to fall on Mars, frost was detected and snow was predicted (the snow was confirmed almost four decades later by
Phoenix).
Temperature readings indicated highs of about 16°C near the equator during summer and lows of about -151°C near the south pole.