The Planets: Mars Before Viking

Observing the planets in our solar system from Earth provided limited scope for astronomers wishing to explore them in more detail. To get a better understanding of planets such as Mars, astronomers needed to get a closer look through the use of unmanned space probes which could beam data back remotely. In this Lecture, Carl Sagan explores the surprising discoveries made by Mariner 9, the first unmanned space probe to orbit another planet. This mission went on to provide scientists with a glimpse at Mars that was wildly different from their expectations. Sagan explores the features of Mars as uncovered by Mariner 9, including the formation of craters, presence of volcanoes, polar regions and the significance of its winding sinuous valleys and tributaries. These findings point towards a planet that has undergone considerable climate change, with early evidence that it might once have been conducive to terrestrial life.