I've heard from several unsubstantiated sources that until the 1960s, it was believed that Mars harbored some form of life. Was this the actual scientific consensus? How did we know so little about the planet so late into the 20th Century?

by thestickystickman

I first heard that from this post to /r/space earlier this week, in which a world atlas from 1965 says

Its bright regions suggest the presence of vegetation which changes according to the seasons.

Then I read from the far less reliable source of the Elite Dangerous wiki that

Mars was of particular interest to Humanity for many, many years. Before the Mariner 4 probe was launched, it was thought that the planet was inhabited by intelligent life, known as Martians. After Mariner 4 made a fly-by in 1965 and the landing of the Viking landers in 1977, it was discovered that Mars was a barren, lifeless rock.

Was this actually believed by the real scientific establishment, or was it a more controversial view?

sunagainstgold

Among scientists, the crucial work to rule out life on Mars was done at the end of the 19th century and during the first quarter of the 20th. Public opinion held out longer on the strength of a nice mistranslation--canali as [constructed] "canals" instead of "channels", one astronomers' passionate writing based on that idea, and the influence of early science fiction.

This comes up at AskHistorians frequently; here's a couple of posts: