Summary: Is there life out there? Researchers are pursuing three paths to find out.
Original author and publication date: Robert Naeye – September 17, 2020
Futurizonte Editor’s Note: We know now that there are exoplanets able to have life. How soon will find intelligent alien life?
From the article:
Many of science’s greatest mysteries surround questions of how much life is in the universe and what forms it might take. And, given the popularity of sci-fi movies depicting alien creatures, interest is clearly not limited to researchers alone.
For millennia, great minds have contemplated the origin, nature, and prevalence of extraterrestrial life. But despite the impressive brainpower brought to bear, the frustrating reality is that we really don’t know who or what is out there. Scientists have good reason to think billions of inhabited worlds are sprinkled throughout our galaxy in a universe teeming with life — perhaps even technologically advanced life. But maybe the genesis and long-term survival of life on Earth has been a once-in-a-galaxy fluke. Maybe we’re living on one of the precious few miracle worlds where life evolved to staggering levels of diversity and complexity.
Scientists can debate these questions until they’re blue in the face. And they have. But the only way to find out the definitive answer is to observe and explore. And here’s the good news: Never before have scientists had so many tools at their disposal. Excitement is palpable that in 10 to 20 years, astrobiology could make the critical leap from theory to direct observation, no longer suffering the ignominy of being a science whose subject matter is not proven to exist.
Although there’s no official competition or roadmap, scientists across multiple disciplines are pursuing three general pathways for detecting extraterrestrial life. First, they’re hunting for life in the solar system using robotic or sample return missions. Second, they’re searching for compelling evidence of life-bearing worlds by probing exoplanet atmospheres. Third, they’re chasing the ultimate jackpot: evidence of intelligent life through purposefully seeking out alien signals or receiving them by serendipity.
Life on Mars
A major challenge in any search for life is defining exactly what we’re looking for. Terrestrial life assumes such a dizzying variety of forms — from acid-loving bacteria to kangaroos — that attempts to define it inevitably leave out entire classes of critters. Plus, what’s out there in the greater universe might be even more extreme than anything we can imagine from our limited geocentric perspective.
In their recent book, Imagined Life, planetary scientist Michael Summers and physicist James Trefil identify three kinds of life: life like us, life not like us, and life really not like us. The first centers around all terrestrial biota: life based on organic (carbon-based) chemistry using liquid water as a solvent. The second involves chemistry based on elements other than carbon, such as silicon. The third is the wild card: life-forms so far outside our conceptual horizon that we might not even recognize them as being alive.
Scientists are familiar with the first type of life, so they have some idea of what they’re looking for. Better yet, solar system exploration over the past five decades has greatly increased the inventory of relatively nearby candidate worlds that might harbor some form of familiar biology.
Mars remains the most compelling target due to its proximity and overwhelming evidence that liquid water once covered much of its surface. Claims of martian life date back more than a century, to Percival Lowell’s popularization of its fabled canals. In 1976, the Viking Labeled Release experiments returned positive test results for metabolizing microbes, a result that most (but not all) scientists attribute to active soil chemistry. Two decades later, a NASA and Stanford University team led by David McKay reported evidence for ancient microorganisms in Mars meteorite ALH 84001, a claim that remains in dispute.