Search for conducive environment for life in space continues

The discovery of carbon dioxide (CO2) on Jupiter’s moon Europa last Thursday from research using James Webb Space Telescope (JWST) data has made scientists confident there is a huge ocean of saltwater kilometres below the ice-covered surface, making the moon a prime candidate for hosting extra-terrestrial life (such as tiny, primitive microbes), in the solar system. But determining whether this concealed ocean has the right chemical elements to support life has been difficult.
Aiming to find an answer, two US-led teams of researchers used data from JWST’s near-infrared spectrometer to map CO2 on the surface of Europa, publishing their results in separate studies in the journal Science. The most CO2 was in a 1,800km-wide area called Tara Regio, where there is a lot of “chaos terrain” with jagged ridges and cracks.
Exactly what creates chaos terrain is not well understood, but one theory is that warm water from the ocean rises up to melt the surface ice, which then re-freezes over time into new uneven crags.
The first study used the JWST data to look at whether the CO2 could have come from somewhere other than the ocean below — hitching a ride on a meteorite, for example. Samantha Trumbo, a planetary scientist at Cornell University and the study’s lead author, told AFP they concluded that the carbon was “ultimately derived from the interior, likely the internal ocean”. But the researchers could not rule out that the carbon came up from the planet’s interior as rock-like carbonate minerals, which irradiation could then have broken apart to become CO2.
In another exciting development, table salt has also been detected in Tara Regio — making the area significantly more yellow than the rest of Europa’s scarred white plains — and scientists think it may also have come up from the ocean. Looking at the same JWST data, the second study also indicated that “carbon is sourced from within Europa”. The Nasa-led researchers had also hoped to find plumes of water or volatile gases shooting out of the moon’s surface, but failed to spot any.
Meanwhile, two major space missions plan to get a closer look at Europa and its mysterious ocean. The European Space Agency’s Europa probe JUICE (JUpiter ICy moons Explorer) launched in April this year on an eight-year journey, while Nasa’s Europa Clipper mission is scheduled to blast off in October 2024, but arrive at its destination one year earlier than the former. JUICE project scientist Olivier Witasse welcomed the two new studies, saying they were “very exciting”.
JUICE will study Europa, Ganymede, and Callisto, three of the largest moons in the entire solar system. When JUICE flies past Europa twice in 2032, it will collect “a wealth of new information,” including about surface chemistry, he told AFP. Carbon has been detected in Ganymede and Callisto. The missions will get the first close-ups of Jupiter’s icy moons since Nasa’s Galileo probe visited the gas giant from 1995 and 2003.
“We learned about Europa having a subsurface ocean as a result of the Galileo mission,” says Emily Martin, a research geologist in the Center for Earth and Planetary Studies at the Smithsonian’s National Air and Space Museum. The Galileo finding ignited interest in so-called ‘ocean worlds’ that have liquid water under their thick surface ice and might be the best place to look for alien life in the solar system. Ganymede and Callisto are likely ocean worlds too.