landed the first landers on Mars at locations far away from the Meridiani Planum. However, both missions also included satellites (operating between 1976 and 1982) that took many images of the surface of Mars from orbit. Viking 1 and Viking 2 satellite images of what is today called the Meridiani Planum (and its adjacent regions) were studied in three works in the 1980s

and again in two 1997 papers published in the months between the launch of the Mars Global Surveyor