The search is on in earnest. What began as a sporadic, poorly funded (if at all), and shot-in-the-dark search for alien life by a few astronomers and scientists who in some cases kissed their grants good-bye because of their interest has now become a multibillion dollar enterprise by governments and privately sponsored groups. There was a time when a scientist did not dare say he or she was interested in finding ET for fear of ridicule by the established scientific community. The very idea was considered bizarre. The hardware and software did not exist or was extremely crude by today’s standards. Computer power was in its infancy. Technology was not advanced enough to look at but only a few stars. Budding scientists were told to stick with the tried and true and established scientific fields and save your career in the process.
But what a difference time makes. Today, nearly every planetary probe and research satellite has at least some allowance for the search for life beyond Earth. The probes in orbit around Mars and crawling around on its surface are actively searching for the signs of life if not the creatures themselves. The Kepler telescope (mission now over) and now the Tess telescope, both placed in high Earth orbit, are designed to look for planets around other stars. Scientists are particularly interested in finding planets that are in the “Goldilocks Zone” around their star. The Goldilocks Zone is an area around a star that is warm enough to support a planet with liquid water on its surface. It is not too hot, and not too cold, but just right. Of the few thousand planets so far discovered around other stars, perhaps 50 or so seem to be the right distance to have Earth-like temperatures.
It shouldn’t come as a surprise that the Earth is in the Goldilocks Zone around the sun, or we wouldn’t be here. However, both Venus, which is the next planet in, and Mars, which is the next planet out, are both just within the “zone of life.” But with temperatures on Venus hot enough to melt lead and Mars locked in planet-wide deep freeze, obviously something went wrong. So to support life, a planet has to have other characteristics other than just within the right temperature ballpark. Venus, which is about the same size as the Earth, rotates extremely slowly, taking nearly 6,000 Earth hours to make just one “day,” and it rotates backwards compared to most other planets; lots of time for the sun to heat up the sunlit side. The atmosphere is extremely dense with a high concentration of sulfuric acid. But if a Venus day was similar to an Earth day, and if Venus was smaller, it might have supported life.
Mars has the opposite problem. Though technically at the outer edge of the Goldilocks Zone and with a day length very similar to Earth’s, it is just too small to retain heat, although it was more Earth-like early in its existence. Nearly every probe to Mars is tasked in some way with looking for signs of life that might have developed there. The thin atmosphere is mostly carbon dioxide with only miniscule amounts of oxygen so not breathable. But the probes have detected occasional “spikes” or plumes of methane gas. On Earth, various life forms produce methane gas, so perhaps Mars does have some form of microbial life deep underground.
A concern with the search for life beyond Earth is that researchers are limited to only one example of what life could be: Earth life. That is a reasonable prejudice since our own example of what life could be like is all we know. But perhaps there are other forms of life that are “right before our eyes” but we do not have a frame of reference to recognize them. The search for ET now is very narrow. Perhaps we need to start looking in places that are “radical” to our point of view. Maybe liquid water is not the only medium that life constructs itself around. There may be other forms of life that we don’t even recognize as being alive. Maybe we are looking for life in all the wrong places.
Email Terry Mejdrich at firstname.lastname@example.org.