Microbes on Europa?
By Rod Myers
By Rod Myers
Even in light-polluted Rockford, you can see Jupiters four biggest moons by using only binoculars. This winter, Jupiter is easily spotted rising in the early evening in the east by northeast sky. Beyond the reaches of earth, the Hubble Space Telescope and the Galileo satellite spacecraft reveal the big, jovial moons in bigger-than-life clarity. Visual inspection of one moon, Europa, has given scientists hope of finding life on it. Its believed that Europas brownish red-tinted surface is a water ocean frozen at the top, where water meets the void of space. The temperature at this junction is -274 degrees Fahrenheit because Europa has virtually no atmosphere. One of the many indicators that water is beneath Europas ice crust is the lack of meteor impact craters. Water is filling the holes made in the ice by meteors and then refreezing.
One scientist who has examined the infrared data collected by the Hubble Space Telescope and the Galileo satellite spacecraft thinks hes solved the mystery of why Europas surface has a brownish-red tint. That scientist , astrogeophysicist Brad Dalton, says he has proof that the color is caused by frozen bacteria. Dalton took extremophile bacteria from Yellowstone National Parks geysers and froze them similar to the conditions on Europa. Then he compared the infrared signature of the frozen Earth bacteria to the infrared signature of Europas surface and found them to be extremely similar.
Extremophile bacteria on earth live in temperatures of 300 to 600 degrees Fahrenheit. Dalton believes that bacteria live in water near superheated vents at the bottom of Europas sea floor. The microbes may be circulated to the surface, where they freeze. Up to now, the standard explanation of Europas brownish-red color is the welling up of sulfate magnesium salts, but Dalton strongly disagrees. His work has shown that infrared signatures are much closer to bacteria and ice rather than sulfate magnesium sales and ice.
Scientists believe Europas core is partially molten because of the tremendous gravitational pull (squeezing from a tug of war between Jupiters pull and the tugs of the other moons). Heat from the core is what keeps the ocean from freezing, and the heat vents are probably hot enough to spawn extremophile bacteria similar to those that occur on Earth. Extremophile bacteria flourish near heat vents at the bottom of our oceans, and they may have been the first life forms on Earth some 3.8 to 4 billion years ago.
If life is eventually discovered on Europa, odds favor it being microbial. This will strongly enhance the argument that given the right conditions, life may exist anywhere in our galaxy or other galaxies. It would mean that simple matter tends to evolve into more complex matter, eventually leading, if the circumstances are right, to organic molecules and life itself.
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If life is commonplace throughout our galaxy, the vast majority of it in all probability will be microbesmicroscopic life. Now dont turn your nose up; microscopic life is the progenitor of all more complex life. Microbes were the only life forms on Earth for billions of years. The animal kingdom which we are a part of evolved from a recent branch of a very old, very large, family tree of microbes. If you think we are now apart and above microbes, think again. Our bodies are full of microscopic life, some bad, but the vast majority is good, and our bodies could not function without them.
Be it ever so humble, theres no place like our potentially microbe-filled home galaxy. For those who yearn for the more advanced forms of life, Im sure thats out there too, but in much fewer numbers.
When I look at Jupiters moons with binoculars, Im struck by how small they look. Im more amazed, though, by the possible detection of bacteria so far away. If space and distance are no barrier to microbes, then lets assume they have inherited the universe.
Rod Meyers is a local resident with an interest in nature and the environment. He is a member of the Rockford Amateur Astronomers Club, the Sinnissippi Audubon Society, Wild Ones Natural Landscapers and the Planetary Society.