As Nasa sends probe to Jupiter, where are the likeliest places to find life in our Solar System?
The Europa Clipper blasted off on the SpaceX Falcon Heavy rocket to investigate whether one of Jupiter's moons has the conditions to support life.
Nasa has launched a spacecraft to investigate whether Jupiter's moon Europa has conditions suitable to support life.
The Europa Clipper spacecraft blasted off from the Kennedy Space Center in Cape Canaveral on a SpaceX Falcon Heavy rocket to begin its five-and-a-half year journey to focusing on the large, subsurface ocean believed to be lurking beneath Europa's thick outer shell of ice.
But Europa is just one of multiple places in our solar system where microbial life might be found - living in oceans beneath the surfaces of planets and moons.
The icy moon Europa was picked out by NASA as one of the most likely places to support life, due to an ocean of liquid water which scientists believe might lurk beneath the surface. NASA official Gina DiBraccio described it as “one of the most promising places to look for life beyond Earth.”
The Europa Clipper mission will look for chemicals which could support life and - if those are found - another mission will try to detect life.
Europa Clipper program scientist Curt Niebur said: "It's a chance for us to explore not a world that might have been habitable billions of years ago, but a world that might be habitable today, right now."
But it’s just one of multiple places in the solar system where scientists believe microbial life could lurk.
Beneath Mars’s surface
Research based on measurements from the Mars Insight Lander in 2022 showed that there is liquid water beneath the surface of Mars.
Recent research has found organisms living deep underground on Earth - hinting that the same might be possible on Mars.
The probe found evidence of water thought to be more than seven miles beneath the surface (researchers believe Mars’s surface had lakes, rivers and oceans more than three billion years ago).
Vashan Wright of the University of California San Diego's Scripps Institution of Oceanography said in 2022: "On Earth, what we know is where it is wet enough and there are enough sources of energy, there is microbial life very deep in Earth’s subsurface.
"The ingredients for life as we know it exist in the Martian subsurface if these interpretations are correct."
Enceladus
Enceladus is the sixth largest of the 146 moon orbiting Saturn and has geysers of liquid that erupt from the surface, fed by a subsurface ocean.
The drops of liquid freeze and drift into Saturn’s E ring (a faint ring outside of the brighter main rings).
During its mission at the gas giant from 2004 to 2017, NASA’s Cassini probe flew through the plume and E ring numerous times.
Scientists found that Enceladus’ ice grains contain a rich array of minerals and organic compounds – including the ingredients for amino acids – associated with life as we know it.
Recently, scientists confirmed that phosphorus, a key element for life, is found in the icy grains.
Ganymede
Another of Jupiter’s 95 officially recognised moons, Ganymede is the largest moon in the solar system (it actually has a bigger diameter than the planet Mercury).
It’s also believed to have a gigantic underground saltwater ocean, holding more water than all of Earth’s oceans put together.
Ganymede has a thin oxygen atmosphere, and a magnetic field which helps to protect it from the Sun’s radiation (the only moon in the solar system to have one).
But while its subsurface ocean has been confirmed by Hubble observations, there has not yet been a dedicated mission to Ganymede.
The European Space Agency's JUICE (JUpiter ICy moons Explorer will orbit and scan Ganymede in 2032.
Titan
NASA says that Titan, which is Saturn's largest moon, is "one of the most Earth-like worlds we have found to date".
NASA's Dragonfly mission will send a drone to Titan's surface to study its prebiotic chemistry, launching in 2028.
Huge regions of dark dunes stretch across Titan’s landscape, mainly around the equatorial regions - but beneath the surface, there might be water.
Gravity measurements of Titan found that the moon has an underground ocean - believed to be up to 50 miles beneath the icy surface.
The seas of liquid ethane and methane on the moon's surface might also host life, NASA believes, but anything that could survive there would be very different from life on Earth.