by Edna DeVore - Deputy CEO
Does life exist beyond our small planet, Earth? This fundamental question drives scientists to search near and far. Using astronomical tools, SETI (search for extraterrestrial intelligence) researchers seek the telltale sign of distant technological civilizations by listening for faint signals emitted by alien transmitters in planetary systems orbiting distant suns.These SETI scientists employ the largest ears on Earth giant radio telescopes to seek faint signals amidst the general noise of the universe. So far, a signal from ET has not been detected and the search continues. Stay tuned!Closer by, we search other planets and moons in our own solar system for signs of life. We have detailed photographs of the surfaces of all but Pluto and parts of Mercury hostile places to live. No cities, vast roadway systems or great walls to keep out enemies have been found.Landers have settled on the surface of Mars, sniffed the thin air, tasted the soil, sampled the rocks and photographed the terrain. One tiny robot geologist, Sojourner, wandered about, sampling and testing a variety of rocks and thrilling us Earthlings. Alas, no Martian family photographs have been returned from the Red Planet. But the question persists: are there Martians? Most planetary scientists believe we have just begun to search for life on Mars. Weve landed successfully in three places and have only sampled the surface.Recent photographic evidence for layered formations indicates the need for robotic paleontologists on Mars. We need to look for fossils in regions that show sedimentary layers. These are like the sedimentary layers visible in desert regions of the southwestern United States and elsewhere on Earth. Here, these sediments hold the fossil record of life and likewise, Martian sediments could be embedded with ancient, extinct Martians. Scientists are working now to determine where to land robots and how to look for Martian fossils.But what if we wanted to look for living Martians? How could we find them? So far, our landers and rovers havent found large creatures wandering about the harsh surface of the planet. So, many scientists expect that we need to look for small, microscopic life forms. On Earth, microbes are by far the most common living species. They are found everywhere on and in the planet, living in a variety of extreme conditions from the permanent ice-covered sub-Antarctic lakes to high in the atmosphere. They are found at the bottom of oceans, embedded in rocks like the Columbia River Basin basalts and inside of us. How do we distinguish microbes from dust, living from non-living matter? One way is to test for the byproducts of microbe metabolism. This is just what the two Viking landers did when they landed on Mars in the mid 1970s.Did Viking find life? The greatly disappointed scientific community said no. The Viking experiments scooped up Martian soil, added water to one sample and "chicken soup" (nutrients) to another. At first, the samples seemed to behave as though there were microbes present: gases were generated in a way that could have been interpreted as being a byproduct of metabolism. Later analysis showed that they were actually the byproduct of a chemical reaction between water and the unusual soils of Mars. Future missions to Mars will seek life and will return samples for analysis in Earth-based laboratories. Will we find that we have cousins on Mars? Exploration and experimentation can help us answer this question.