🔗 Share this article

Starting with tentative evidence of habitable planets to the surprising proposal that an visiting cosmic object may not appear what it seems, the possibility of extraterrestrial existence has consistently fascinated researchers and citizens. But specialists indicate ET is more likely to be found if we search in our immediate cosmic vicinity.

The Enceladus Discovery

The prospect was reinvigorated when researchers revealed the probability increased that Enceladus could support life after a study found it is spewing out a wider array of organic compounds than earlier understood.

"I really like Enceladus because it has all the conditions that are co-located at the same time for organisms to develop and to flourish," said Dr Caroline Freissinet.

Ideal Conditions

As well as complex organic molecules and a substantial water body of liquid water, researchers observe that the Saturn's satellite is thought to have thermal vents – supplying a form of energy – with the chemical balance of the ocean within parameters considered appropriate for biological activity.

Difficulties in Distant World Studies

While scientists should continue to seek organisms beyond the solar system, this approach brings challenges – not least that it relies on detecting molecular markers in a world's air that could be associated with life.

"It must alter the entire world so that you are able to see it on an distant planet," she said. "Essentially, isolated areas of life that do not create these planetary alterations might be overlooked."

Additionally there exists a further challenge: "Researchers cannot search for past life on an exoplanet," Freissinet said.

Detection Limitations

What's more, an exoplanet must pass in front of its star for equipment to study its air composition. And although preliminary data is found, it can be challenging to understand or verify.

"The issue with distant planets is that we have limited knowledge about the surroundings," commented a different specialist.

Advantages of Local Exploration

Conversely, local celestial objects like Saturn's sixth largest moon, which resides 1.27bn km from Earth, can be examined directly.

Space agencies are developing expeditions to Enceladus, with scientists working instruments to detect molecules on the icy satellite.

Other Candidates

But it is not the sole location beyond Earth where organisms might exist in our planetary system. Among other top contenders is Jupiter's moon, a moon of Jupiter that – like Enceladus – is thought to have an sea below its icy crust.

"In my opinion, in the our cosmic neighborhood, that's where we will find life," the researcher stated.

Complementary Research

Experts are quick to emphasize it is not simply of examining nearby worlds instead of distant planets, but rather that the two complement each other, with the solar system acting as a "natural laboratory" for collecting information.

This can be used to test theories and create simulations that can aid people's understanding of the potential habitability of the different categories of world revealed by exoplanet research.

"I think looking in our immediate vicinity is a mutually beneficial approach," commented another space scientist, noting Enceladus is a prime example of a object displaying all the indicators of potential life that scientists are also looking for in exoplanets.

Coming Consequences

"Should we find that there are indeed signs of life [on Enceladus] that enhances the pursuit beyond our planets increasingly thrilling," he said.

"If we go and find that regardless of favorable factors for habitability, we fail to detect any evidence of organisms it indicates that we may require to rethink the definition of life-supporting conditions or at least reconsider the likelihood of organisms developing on a potentially habitable world."

Broader Implications

Freissinet said examining nearby worlds could have implications for the possibility of life further afield.

"The fascinating aspect is that if we discover organisms anywhere else in the solar system ... it means that it's not accidental," she said. "It means it's widespread in the Milky Way."