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Microbial life that's 8 billion years old may exist on nearby exoplanets

The presence of space aliens up there in the cosmos is one of the biggest scientific fictions. But in reality, we have higher chances of finding extrasolar microbial life first than these legendary aliens. The question is, how soon?

Microbial life is closer than we think

Scientists have previously reported the existence of earth-like exoplanets around sun-like stars, and also the possible existence of life on these planets. But we may now be able to estimate how near we can find them.

According to a new research by Piero Madau, a renowned professor of astrophysics at the University of California, Santa Cruz, earthlike planets orbiting G and K spectral-type stars may serve as home to microbial life within 326 light-years of the sun.

“Within 326 light years of the Sun, there may be as many as 10,000 rocky planets in the habitable zone–the region around a star where conditions are right for liquid water on a world’s surface, also called ‘temperate terrestrial planets’ or TTPs,” Madau said.

Early star formation and microbial life

We can break the formation of TTPS in the solar vicinity into different events. The first was a burst of star formation about 10-11 billion years ago. This was followed by another event that peaked about 5 billion years ago, giving rise to the solar system. 

With three documented incidents where the Sagittarius dwarf spheroidal galaxy entered the Milky Way’s stellar disk, we can say that our own solar system was formed due to the first passing of the Sagittarius.

Madau also observed in his paper, which is appearing in The Astrophysical Journal, that although most TTPs are older than 4.5 billion years (older than the solar system), it remains unclear what part of these planets could support microbial life. 

“If microbial life did arise as soon as it did on Earth in greater than 1 percent of TTPs around K spectral type stars, then the closest ‘life-harboring Earth-like planet’ would be 65 light years away,” he added. 

Frequency of abiogenesis is crucial

We can define abiogenesis as the origin of life from non-living matter. If we assume that abiogenesis is fast and we ultimately record simple life in every existing temperate terrestrial planet, then Madau’s population study predicts that we are just 16 light years away from the closest earth-like planet where life exists.

While this is a mere prediction, the failure to discover biosignatures at this volume in the future may necessitate the reassessment of these assumptions. However, Madau suggests some “cautious optimism” in the quest to unmask habitability markers and biosignatures using next-generation technologies.

Drake’s equation and Madau’s approach 

If there is one thing the renowned Frank Drake’s 1961 equation has achieved, it is providing probabilistic parameters on the number of intelligent civilizations that might exist and relate over interstellar distances. 

But Madau believes Drake’s equation is not the full story. This is why he is proposing a mathematical model that he believes can answer questions about when the TTPs in the local neighborhood were formed, the abundance of microbial life, and whether it arrived before or after the birth of life on Earth.

If we can obtain better stats from near-term ground- and space-based telescopes, we may be closer than ever to detecting the presence of nearby extraterrestrial intelligent life.

More about temperate terrestrial planets (TTPs)

Temperate terrestrial planets, often hailed as the best candidates for finding life outside our solar system, captivate astronomers and space enthusiasts alike. As mentioned previously, these worlds are similar in size and composition to Earth. They also lie within a star’s habitable zone where conditions might just be right for liquid water — a key ingredient for life as we know it.

Location matters

The term “habitable zone” refers to the range of distances from a star where a planet’s surface can potentially maintain liquid water. Planets too close to their star boil away any surface water, while those too far freeze solid. Temperate terrestrial planets reside within this ‘Goldilocks’ zone, making them prime targets for study.

Composition and atmosphere

Like Earth, these planets primarily consist of rocky materials. They might have iron cores, silicate mantles, and a solid or liquid water surface. Their atmospheres, if present, play a crucial role in regulating their climate. While Earth’s atmosphere contains oxygen and nitrogen, temperate terrestrial planets might have different atmospheric compositions, influencing their potential to support life.

Search and discovery

Telescopes like the Kepler Space Telescope revolutionized our search for these distant worlds. By monitoring the brightness of stars, astronomers detect the minute dimming when a planet transits in front of its star. This transit method, combined with other techniques like radial velocity, has unveiled numerous temperate terrestrial planets in recent years.

Significance and future exploration

Finding these planets doesn’t only boost our hopes of discovering extraterrestrial life. They also offer insights into planetary formation, evolution, and the intricacies of planetary atmospheres and climates. As technology advances, new missions like the James Webb Space Telescope aim to further scrutinize the atmospheres of these worlds, searching for bio-signatures or other markers of habitability.

In summary, temperate terrestrial planets represent some of the most promising locales in our quest to find life beyond Earth. Every discovery brings us one step closer to answering the age-old question: Are we alone in the universe?

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