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- How will we ever know?
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- Several of the moons beyond Earth are thought to have liquid oceans. Mars at one time had liquid water on its surface. These certainly portray major ingredients for the presence of life.
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- Astronomy is preparing to find out with experiments here on Earth. Experiments on frozen lakes in the Arctic. Experiments in pitch dark caves in Mexico. Caves that are filled with poisonous hydrogen sulfide and carbon monoxide gases along with water laced with sulfuric acid that still contain life. These experiments are designed to prefect methods to detect this life.
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- Jupiter’s moon Europa could have similar ice-covered oceans as those found in the Arctic.
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- Mars could harbor many gas filled caves laced below its surface.
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- On Earth the studies are called “astrobiology”.
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- Much of this got started in 1961 with Drake’s Equation ( Request a separate review to learn details about this equation.). The equation tried to calculate the probability of finding life elsewhere in the Universe. It multiplied together the essential factors: How many sun-like stars are there? * how many of these have planetary systems? * how of these planets are in the habitable zone? * how many habitable zones actually support life? * how many of these life forms have intelligence? * how many have technology that we can detect or communicate with? * and, how long have the civilizations survived and overlap with our own?
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- In 1995 the first planet was detected orbiting a sun like star just 50 lightyears away (51Pegasi b).
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- By 2014 there have been over 2,000 more exoplanets discovered.
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- The factors in Drake’s Equation began to take shape beyond mere guesses. Observations brought real numbers into the factors. For example astronomers now estimate that more than 20% of sun like stars harbor habitable planets.
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- Our Sun is not an average star. It is too big to be average. More than 80% of the stars in the Milky Way Galaxy are smaller, cooler, dimmer, redder, and considered M Dwarf stars. However, to be habitable simply means the planet must orbit closer to its star.
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- Since 1971 we have known that liquid water once flowed on Mars.
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- Planets are a small number compared to moons. Moons like Europa orbiting Jupiter have a liquid water ocean beneath its icy surface. Europe being that far form the Sun we would expect to have all water be frozen solid. However, the tidal forces of Jupiter’s gravity generate enough friction to heat the interior and keep the water liquid beneath the surface.
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- Jets of water have been observed erupting from the surface of Saturn’s moon Enceladus. Saturn’s moon Titan has rivers, lakes, and rain on its surface. But, Titans liquid is not water, it is methane and ethane. Maybe a different form of life could exist in this environment.
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- The experiments done here on Earth are to learn how to detect this life using “biosignatures”. These signatures we detect would be chemical clues that suggested the presence of life, either at present or in the past.
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- The caves in Mexico contained biofilms, microbes, chemotropism, that oxidize hydrogen sulfide for their energy source. Bioverms are another life form found in these caves. Life that produces oxygen as a biosignature may be just one of many different life forms to be detected.
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- In the Arctic lakes methane is the hydrocarbon gas generated by microbes, methanogens, that are living on decayed material.
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- It may be plausible that somewhere a sulfur-cycle might have replaced the carbon-cycle the dominates our own terrestrial biology.
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- Mars is most likely our first step to find life elsewhere. It had a similar history as Earth. It was once warmer several billion years ago. It had liquid ocean at one time and a thicker atmosphere.
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- Life can be defined as a biological system that encodes information and uses that information to build complex molecules. Current technology has developed instruments that can simply detect these complex molecules. Known as “ immunoassay testing’”.
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- Earth’s organisms contain millions of different proteins, complex molecules, left-handed amino acids. Handedness is know as “chirality”. Not only is protein detection evidence for the presence of life, if chirality is detected on Mars to be right-handed that would suggest the life forms on Mars evolved independently of life-forms on Earth.
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- We know that Earth and Mars have exchanged rocks. Rocks blown into space by volcanoes, geysers, or impacts and have migrated from one gravitational capture to another . So, left-handed chirality may exist on both planets. We know the Moon was splashed into orbit due to an giant asteroid collision during Earth’s early formation. Some of that splash made it all the way to Mars.
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- If we find a life-form on Mars or on other moons we will know that just as there are billions of stars and planets and moons there are many biology’s out here.
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---------------------------- http://mars.jpl.NASA.gov
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- Stay tuned, there is much more to learn. Discoveries will bring it to us.
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RSVP, with comments, suggestions, corrections. Index of reviews available ---
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