For nearly 40 years, Uranus and its five largest moons have been dismissed as frozen and lifeless. This view was formed by humanity’s only close encounter with the Uranian system at the edge of our cosmic neighbourhood. Data sent back by Voyager 2 in 1986 indicated that the distant ice giant was sterile and inactive. But that probe had the misfortune of flying past Uranus just when a powerful solar storm hit, creating a distorted impression of its true nature. Far from the barren worlds previously assumed, a new analysis suggests that the celestial bodies could hold hidden oceans, and perhaps even the conditions necessary to support life.
This news should put rocket boosters on the $4bn plan by Nasa, the US space agency, for a mission to return to Uranus. The clock is ticking to make it there by 2050, just in time for its planetary equinox, when sunlight floods Uranus and its moons from pole to pole. Nasa wants to launch a mission by 2032 – a timeline that allows the spacecraft to use Jupiter’s massive gravity like a slingshot and shoot a probe out to Uranus in time for its seasonal transition.
The exploration of planets in space often feels like stepping into the pages of science fiction – a genre that conjures up visions of travel to distant worlds and alien landscapes. Although this beautiful, icy-ringed world in the outer reaches of our solar system was discovered nearly two and a half centuries ago – by William Herschel, working in his garden in Bath – Uranus has comparatively rarely been featured in literature. Its freezing depths did, however, inspire Geoffrey A Landis’s 1999 short story Into the Blue Abyss.
In his tale, Landis, who also works as a Nasa scientist, explores humanity’s relentless drive to seek life in the most unexpected places, even within the deep, dark oceans of an ice giant. The story captures the tension between hope and uncertainty: the optimism of exploration against the daunting odds of finding anything alive. With the idea of a permanent human colony on Uranus as a backdrop, Landis’s narrative culminates in the discovery of a strange, simple life form in Uranus’s deep ocean. The story resonates with our real-world missions to the extent that both embody the wonder and the challenges of searching for life beyond Earth.
Reality may lack the drama of fiction, but studying Uranus and its twin, Neptune, holds immense value for understanding similar faraway worlds. In the past 30 years, more than 5,500 exoplanets – planets outside our solar system – have been discovered. Some are described as “Earth-like”, but none meet the exact conditions of a rocky planet in a star’s habitable zone, where water remains liquid instead of boiling away or freezing.
The upshot is that there might still be life out there, just not as we know it. There are uncertainties and challenges inherent in space missions. But consider the stakes: if Uranus or its moons contain hidden seas, they would join a growing list of “ocean worlds” in the solar system – places like Jupiter’s moon Europa and Saturn’s satellite Enceladus – where life could theoretically exist. Are we alone, or are the building blocks of life more common than we ever thought? Exploring the Uranian system brings humanity one step closer to answering this profound question.
