Only 10 years before the Viking mission launched, Mars was still just a mottled orange ball when viewed through even the best Earthbound telescopes, with few discernable features.  Three NASA missions flew past in the 1960s, snagging grainy snapshots of a sliver of Mars as they hurtled by. In 1971, the Mariner 9 spacecraft arrived, […] The post Viking: 50 Years on Mars appeared first on NASA Science .