The Viking 2 probe is launched toward Mars. It will gently descend on Utopia Planitia. The two Viking 1 and 2 probes took 50,000 images from Martian orbit before descending, mapping 97% of the surface. They will conduct biological experiments on the Martian surface to directly search for signs of biological life. The results are always negative, except for one experiment, where there appears to be a typical sign of metabolism. But this result will be debated for years, and further tests, deeper into the Martian atmosphere, far from the surface sterilized by solar radiation, are necessary.
