Complex organic molecules may exist in the hellish atmosphere above Venus
Scientists have long speculated about whether Venus could harbour life. Its thick, carbon dioxide atmosphere creates a powerful greenhouse effect and the surface is searingly hot (over 450°C). Indeed, the planet is often described as ‘Earth’s evil twin’. So while the surface clearly doesn’t offer any chance of liquid water or organic molecules – the fundamental prerequisites for life – the high atmosphere could offer a habitable environment. Venus is shrouded in thick cloud layers; between altitudes of 48km and 60km the atmospheric pressure and temperature are similar to those on Earth’s surface. There’s plenty of sunlight to serve as a power source for life too.
The problem, however, is that the cloud droplets are made up of concentrated sulphuric acid. This is still an exceptionally hostile environment, with virtually no available water, and is orders of magnitude more acidic than that in which extremophile organisms on Earth can survive. But could the Venusian clouds still support microorganisms using an exotic biochemistry based on organic molecules dissolved in, not liquid water, but concentrated sulphuric acid as a solvent?
The assumption has been that only simple organic chemistry – with limited functionality for supporting the complex molecules and chemical reactions of life – could be stable in concentrated sulphuric acid. But a team lead by Sara Seager at MIT has been challenging this by testing the assumption with experiments. Seager is a very active astronomer and has performed a lot of work on extrasolar planets and their atmospheres. In recent years, she has been exploring the possibility of life on Venus, including being involved in the 2020 study that made the controversial claim for the detection of phosphine gas in the Venusian cloud decks.
Last year, Seager and her colleagues showed that the building blocks of DNA and RNA, nucleic acid bases, are in fact stable for at least weeks in the concentrated sulphuric acid environment of the Venusian clouds. Now, with her own son as the first author, she has published a
