Spectroscopes and Life on Mars

In 18 94, an astronomer determined that if the martian atmosphere contained any water, vapor and oxygen at all, it was too all an amount to be detected using spectroscopes. But other astronomers were showing that there was significant water vapor and oxygen in mars's atmosphere. So by 19 25, the american astronomer w s. Adams produced really good results showing that mars simply did not have the amount of water vapor or oxygen that was previously thought. That wouldn't mean that life couldn't exist, though. Even if mars was a co desert world with little or no oxygen, it could still have creatures adapted to that environment. And how did spectroscope undermine the idea of intelligent life