Identical Mariner 6 and 7 spacecraft

Identical Mariner 6 and 7 spacecraft

Courtesy of NASA

Mariners 6 and 7 were identical spacecraft that launched one month apart, but arrived just four days apart. This was a flyby mission sent to record images of the equatorial and southern regions of Mars from about 3400 km (2100 mi) above and then collect data about the Martian surface and atmosphere. Both spacecraft missed significant geographical features that were discovered on later missions, but the data still added to what had been found by Mariner 4. Both spacecraft are now orbiting the Sun.

(Mariner 6) February 24, 1969;(Mariner 7) March 27, 1969

(Mariner 6) July 31, 1969;(Mariner 7) August 5, 1969

End of Mission
Flyby only; both Mariners 6 and 7 are now orbiting the Sun.

Transmit images and measure ultraviolet and infrared emissions from Mars.

Returned 198 images of Mars that covered 20% of the Martian surface. Images showed the surface of Mars to be very different from that of the Moon, in some contrast to the results from Mariner 4.

The spacecraft instruments measured UV and IR emissions and radio refractivity of the Martian atmosphere. Mariners 6 and 7 revealed cratered deserts, as well as depressions with no craters, huge concentrically terraced impact regions, and collapsed ridges. The south polar cap was identified as being composed predominantly of carbon dioxide. Atmospheric surface pressure was estimated at between 6 and 7 mb. Radio science refined estimates of the mass, radius and shape of Mars.