Where exactly is Mariner 4 today

Mariner 4: 50 years ago today: The first photo of another planet

Fifty years ago today, on July 15, 1965, mankind for the first time reached a photograph that was taken from near another planet: NASA's Mariner 4 probe flew past Mars, taking a total of 22 images of its surface.

The Mariner mission dates back to a time when space travel and planetary research were still in the experimental stage and represents a technical masterpiece - even if the difference to the brilliant, razor-sharp image of Pluto that was published yesterday could hardly be greater. The Mariner photos are not only black and white, but also quite low resolution, only 16 pictures were usable.

In addition, they showed a section of the Martian surface that was rather untypical from a geological point of view. Most of the images are from the southern highlands, which show significantly more craters than the rest of the planet. The scientists initially got the erroneous impression that the surface structure of the red planet was very similar to the earth's moon. The camera was able to resolve terrain details with a diameter of about three kilometers in a strip about 250 kilometers wide.

The German Aerospace Center describes how the photos, which were stored on an internal magnetic tape 100 meters long, came to earth: The data transmission rate was only 8.33 bits per second, so that each of the 200 by 200 pixels was sent Pictures took eight and a half hours. "The process of how these first images of Mars reached the scientists' tables also seems a bit archaic - namely, not on a monitor, but photographed from a cathode tube in the Jet Propulsion Laboratory in Pasadena (California) and then printed on paper using a wet chemical process," he wrote DLR. Number-coded printouts were also generated, which impatient scientists then colored in with crayons to get a first impression of the surface.

Mariner 4 also determined some physical data about Mars, such as the extremely low density of its atmosphere. The measuring devices on board the probe also recorded that Mars, unlike Earth, has no magnetic field. After this flyby, it took another eleven years until the Viking 1 probe landed safely on the Red Planet for the first time.