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  Night Sky

Enjoy the starry night skies
Be a considerate neighbor. Reduce nighttime glare.
Shield your outside lights downward.
Let the stars light up the night.

January 2015 night sky

—Charlie Christmann

New year, new discoveries

Ask a biologist, an astronomer, and a geologist to define “life,” and you might get more than three answers. A strict definition is difficult to write down, but most agree on this: life consumes resources, procreates, and excretes waste. While many agree that liquid water is a necessary ingredient for life to form, a few think other elements would work as well.

Saturn’s moon Titian is another possible place science is beginning to think may have created life. In its cold oceans of liquid natural gas, it might be possible for large single-celled creatures to form. At surface temperatures averaging around three hundred degrees below zero, water ice serves the same function as rock here on Earth, methane and ethane take the place of water, raining from the orange clouds and collecting into rivers, lakes and oceans. Any life there would be moving at a very slow pace. Another place scientists are looking is Jupiter’s moon Europa, with is larger watery ocean under its icy surface. Its possible thermal vents, like in Earth’s oceans, could support life.

The one example we have of how life operates is here on Earth, so scientists look to planets similar to Earth, both in our solar system and around other stars, as the best hope for finding life elsewhere. Oxygen in the atmosphere is hard to create without some form of respiration to crack carbon dioxide into carbon and oxygen. Another possible signature would be methane in the atmosphere; not like Europa’s massive quantities, but at least detectable amounts. Methane in the habitable zone of a star is quickly degraded by ultraviolet light. Something must continuously create methane if it is being found in the                 atmosphere.

To search for life outside our home world, there are three planets in our solar system inside the habitable zone: Venus has a runaway greenhouse atmosphere hot enough to melt lead and destroy organic material as we know it; Earth obviously has life; and Mars is a bit colder and dryer than Earth, but discoveries have widened the habitats where earthly creatures can survive.

So, Mars is the best, and relatively nearby, place to look. Two Viking landers arrived on the surface in 1976. They scooped up a sample of soil, mixed it with some organic foodstuff, containing radioactive carbon. Surprisingly, detectors on the landers found large quantities of gas coming from the soil sample with the radioactive carbon. Could life be converting the nutrients into radioactive carbon gas? After several more experiments, most NASA scientists conclude that the carbon containing gas was a product of some unexpected chemistry, not life. Yet, we have not given up the search for water and life on the Red Planet.

Today, we are sure Mars once had oceans, lakes, and rivers of liquid water. The last question is, did that water allow life to form, and is some of it still there?

In December of 2014, NASA announced the Curiosity rover had detected several spikes in the amount of methane in the Martian atmosphere. Evidently there was a seasonal source creating that methane. Then, they announce the discovery, also by Curiosity, of organic materials in the soil. The next question is how did that organic material get to Mars? We know that meteorites contain organic material. That could be the source.

Another possibility is now being discussed: the organic material could be from Earth! NASA has found that Moraxella bacteria survives in hydrogen peroxide (disinfectant), Streptomyces lives in sodium hydroxide (drain cleaner), and Gracilibacillus thrives eating perchlorates (a rocket fuel ingredient), which just happens to be abundant in Martian dirt. We also know that many strains of common bacteria can survive months exposed to the deadly environment of space—the International Space Station has found bacteria on its outside hull.

It would be interesting to think that we might discover, instead of alien life, our own germs that survived their long ride on our space probes now making a new home for themselves on those distant worlds.

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