A Nasa probe is preparing for lift-off on a mission to discover if oceans lie beneath the icy shell of Jupiter’s moon Europa that may support life.
The Europe Clipper spacecraft, which weighs 6,000kg fuelled, will embark upon a journey to explore Europa in the greatest detail, assessing its ice-covered surface and geological activity.
It was meant to take off on Thursday from Florida aboard a SpaceX Falcon Heavy carrier rocket, but unstable weather caused by Hurricane Milton has postponed the mission until the storm is over.
Nasa said it will release launch details when the storm has passed.
Nevertheless, the trip is creating great excitement among planetary scientists, among them Dr Mohamed Ramy El Maarry, associate professor of planetary science at Khalifa University in Abu Dhabi, who told The National that the probe will seek life out in the Solar System.
“Scientists believe that Europa, and potentially other ‘ocean worlds’, like Enceladus, the moon of Saturn, may be the best chance of finding life elsewhere in our Solar System, as they offer a habitat similar to Earth’s deep ocean floors, which we now know are full of life,” he said.
“Clipper is specifically well-equipped to answer that question, or at least help us address it with a future mission that can explore the ocean of Europa directly.”
What we know about Europa
The idea that Europa, Jupiter's fourth largest moon, might have an ocean beneath its icy surface was first proposed in the late 1970s, but it gained significant support during Nasa’s Galileo mission in the 1990s.
The Galileo spacecraft provided magnetic field data and evidence from surface features that suggested the presence of a salt water ocean covering the entire moon beneath the ice.
Now, scientists hope that the Clipper will offer more insights into the ocean beneath the surface and the thickness of the ice crust above it.
“Clipper will accurately measure how much the moon deforms due to tidal forces from Jupiter,” said Dr El Maarry.
“A moon that contains a global ocean – up to 100km-deep – will deform in a higher degree than a fully frozen and solid moon. So, a measurement of the tidal effects will give us important clues about the presence of the ocean and its volume.”
In addition to the tidal measurements, the spacecraft will study the reddish deposits scattered across Europa's surface, which are believed to originate from ocean water seeping through cracks in the ice.
How thick is the ice crust?
The Clipper is equipped with powerful radar to measure the thickness of Europa's icy crust and detect subsurface structures.
It also carries thermal imaging cameras and a magnetometer to measure the moon’s magnetic field, as well as spectrometers to analyse the composition of surface materials.
Dr El Maarry said that radar findings from Clipper would help in measuring the thickness of the crust.
“This is important for follow-up missions that seek to investigate the ocean of Europa ‘in situ’ [studying resources on-site, rather than bringing it back to a laboratory],” he said. “Basically, we need to understand for future missions how deep into the ice do we need to drill to reach the ocean.”
Could there be life on Europa?
While the Europa Clipper mission itself is not designed to search for life directly, its findings will pave the way for future exploration.
Dr Mark Fox-Powell, an astrobiologist whose research focuses on icy worlds, said that there is a debate over whether ocean worlds like Europa contain enough energy for life.
“I think evidence of continuing geological activity deep within Europa where the ocean meets rock would significantly advance our understanding of these icy worlds as potential habitats for life,” said Dr Fox-Powell, who is also a senior lecturer at The Open University in the UK.
“Sunlight cannot penetrate their thick ice shells, making photosynthesis impossible. But geological activity can create gradients of chemical energy within the ocean that could support biological processes.”
He said Clipper will be able to seek the signs of such chemical energy on the surface, in areas where ocean water has frozen into the ice and been exposed.
“We might even see evidence of organic chemistry, perhaps non-biological, but nevertheless the result of chemical reactions stimulated by geological activity within the ocean,” he said.
Other missions are also studying Europa, including the European Space Agency’s Jupiter Icy Moons Explorer (Juice) launched last year.
The Juice craft will also investigate Ganymede and Callisto to study their possible subsurface oceans, surface features and how they interact with Jupiter’s magnetic field, helping scientists to learn more about their potential to support life.
“So much of our understanding is built on a limited set of observations from previous missions, from which we have spent years making predictions and developing theories,” said Dr Fox-Powell. “But these new missions, flying state-of-the-art scientific instrumentation, will allow a level of detail never seen of Jupiter’s icy moons Europa and Ganymede, allowing us to test these predictions.”
