Mariner 4 - Results

Results

The total data returned by the mission was 5.2 million bits (about 634 kB). All instruments operated successfully with the exception of a part of the ionization chamber, namely the Geiger-Müller tube, which failed in February 1965. Also, the plasma probe had its performance degraded by a resistor failure on December 8, 1964, but by taking this failure into account, experimenters were able to recalibrate the instrument and still interpret the data. The images returned showed a Moon-like cratered terrain, which later missions showed was not typical for Mars, but only for the more ancient region imaged by Mariner 4. A surface atmospheric pressure of 4.1 to 7.0 millibars (410 to 700 pascals) and daytime temperatures of −100 degrees Celsius were estimated. No magnetic field or Martian radiation belts were detected.

Images of craters and measurements of a thin atmosphere, indicating a relatively inactive planet exposed to the harshness of space, generally dissipated hopes of finding intelligent life on Mars. Life on Mars had been the subject of speculation and science fiction for centuries. If there was life on Mars, after Mariner 4 most concluded it would probably be smaller, simpler forms. Others concluded that a search for life on Earth at kilometer resolution, using several thousand photographs, did not reveal a sign of life on the vast majority of these photographs; thus, based on the 22 photographs taken by Mariner 4, one could not conclude there was no intelligent life on Mars.

Mariner 4 may have concluded the gradual change, in science fiction, from describing intelligent aliens as dwellers on other planets in our Solar System, to describing them as living on planets circling distant stars.

The total cost of the Mariner 4 mission is estimated at $83.2 million. Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.