In a new study published on Tuesday, scientists said the ridges that criss-cross the icy surface of Jupiter's moon Europa indicate there are shallow pockets of water beneath, much close to the surface. This new revelation could boost hopes in the search for extraterrestrial life in the solar system.
Europa has been a long-standing candidate for finding life in our solar system due to its vast ocean, which is widely thought to contain liquid water – a key ingredient and marker for life. However, the ocean is predicted to be buried 25-30 kilometers (15-17 miles) beneath the moon's icy shell.
But water could be closer – buried 5 kilometers beneath the moon's ice shell – to the surface than previously thought, according to new research published in the journal Nature Communications earlier this week.
The finding came partly by sheer happenstnce, when geophysicists studying an ice sheet in Greenland watched a presentation about Europa and spotted a feature they recognised, an AFP report explains.
“We were working on something totally different related to climate change and its impact on the surface of Greenland when we saw these tiny double ridges,” the study's senior author Dustin Schroeder, a geophysics professor at Stanford University, says in the AFP report.
The scientists realised that the M-shaped icy crests on Greenland looked like smaller versions of double ridges on Europa, which are the most common feature on the moon. These double ridges were first photographed by US space agency Nasa's Galileo spacecraft in the 1990s, but little was known about how they were formed.
Scientists used ice-penetrating radar to observe that Greenland's ridges were formed when water pockets around 30 metres (100 feet) below the ice sheet's surface refroze and fractured. "This is particularly exciting, because scientists have been studying double ridges on Europa for more than 20 years and have not yet come to a definitive answer for how double ridges form," the study’s lead author Riley Culberg, an electrical engineering PhD student at Stanford, told AFP. "This was the first time that we were able to watch something similar happen on Earth and actually observe the subsurface processes that led to the formation of the ridges," Culberg adds. “If Europa's double ridges also form in this way, it suggests that shallow water pockets must have been (or maybe still are) extremely common.”
The search for life on Europa – which scientists often describe as an “ocean world” – is picking up pace. In 2024, US space agency Nasa’s Europa Clipper will be launched to conduct a detailed reconnaissance of Europa and investigate whether the icy moon could harbor conditions suitable for life. While Jupiter has many known natural satellites, the moons discovered by Galileo—Io, Europa, Ganymede, and Callisto—are among the largest in the Solar System.
The mission – which will travel for five and half years and is expected to arrive at Jupiter in April 2030 – will place a spacecraft in orbit around Jupiter in order to perform a detailed investigation of Europa. The mission will send a highly capable, radiation-tolerant spacecraft into a long, looping orbit around Jupiter to perform repeated close flybys of the icy moon.
With its massive solar arrays and radar antennas, Europa Clipper will be the largest spacecraft Nasa has ever developed for a planetary mission. The spacecraft will make nearly 50 flybys of Europa at closest-approach altitudes as low as 16 miles (25 kilometers) above the surface, soaring over a different location during each flyby to scan nearly the entire moon, the mission website explains.
Also read: Exoplanets: Why Earth remains unique