Here on Earth, all life is based on carbon and requires water, so this means two of the essential ingredients for life may exist on this distant moon.
Scientists have been intrigued by Europa since it was first seen close up by the Voyager spacecraft in 1979. The entire surface is covered in ice, but it has been cracked and shifted in some areas similar to the way the surface of a frozen lake changes during spring breakup.
This suggests activity of liquid water from the saltwater ocean many kilometres beneath the solid ice on the surface possibly contains more water than all the oceans on Earth.
Researchers believe the carbon spotted on the surface of Europa is in the form of carbon dioxide that emerged through cracks in the ice from that ocean below. The Webb telescope used its Near-Infrared Spectrograph, which can identify the light emitted by particular molecules, to identify carbon dioxide the researchers think must be continually released from the ice.
While the presence of carbon does not prove there is life in Europa’s ocean, it is a good starting point in the search for it.
To help explore beneath the ice and answer this question, two spacecraft and a prototype ice-penetrating submarine experiment on Earth are underway to probe the mystery hiding under Europa’s ice.
The European Space Agency launched the Jupiter Icy moons Explorer, or Juice, mission in April on an eight-year journey that will send it into orbit around Jupiter to examine not only Europa, but two of its other icy moons: Ganymede and Callisto.
Next year, NASA will launch its Europa Clipper mission which will study Europa with a suite of instruments, including radar, to determine how thick the ice cover is and characterize the subsurface ocean.
Both Juice and the Europa Clipper will take observations from Jupiter’s orbit, and will not include landers. But in preparation for a future mission to explore that ocean directly, a group in Germany will be using the thick ice of Antarctica to test a robot that can penetrate the ice and reach a sub-glacial lake, similar to the way a future lander on Europa might burrow through its ice to the ocean below.
The program, called TRIPLE (Technologies for Rapid Ice Penetration and subglacial Lake Exploration) will use heat to melt through the glacial ice, then release miniature autonomous submarines that will autonomously explore the water below.
Performing the same task in the cold reaches of deep space, where the ice of Europa could be much thicker than Antarctica, will be even more difficult — but the rewards would be tremendous.
If the small submarines are swallowed by alien fish, that would be very interesting. But the more likely scenario is that any life in Europa’s ocean would be microscopic. Of course, it could be something truly surprising.
Our centuries-long quest to answer the question of whether we are alone in the universe may be closer to being answered. Rovers Curiosity and Perseverance are examining rocks on Mars for signs of past life, while telescopes continue to search for Earth-like planets orbiting distant stars.
Any form of life found on another world, whether it be an icy moon, Mars or a distant exoplanet, will raise the next big question: how similar is that life to us? Is it based on the same carbon chemistry and DNA as we are, or something entirely different?
But first we have to find that alien life — and Europa may be the best place to look.