SETI Reset—Part 1

I have been taking an online course on astrobiology from the University of Arizona—where robust astronomical research has been the norm. I have taken a couple of previous courses from the university's astronomy team and appreciate their teaching abilities. This course blends their preeminence in astronomy with some of the latest discoveries of thousands of Earth-like planets around other stars and the potential for these planets to harbor life in some form; maybe similar to Earth.

Here is a question that has repeatedly arisen in the human mind: Is planet Earth alone in the universe at harboring life, or might there be other life-sustaining worlds? Is life common, rare, or nonexistent elsewhere in this cosmos? Does intelligent life exist out there—say, critters as smart as we think we are?

We are getting closer and closer to finding answers to these questions. As I have posted here several times, our search is being aided and abetted by the recent discovery of thousands of planets circling local stars. Without planets, you can't have life elsewhere.

A consistent search process for extraterrestrial life was begun a few decades ago—dubbed SETI—the Search for Extraterrestrial Intelligence. Its premise is that intelligent civilizations “out there” would have reached a technological capability at some point—as we have—and would have transmitted electromagnetic signals (EM) into space; signals that could eventually arrive at Earth. If so, might we receive them and verify that we're not alone? After all, we've been inadvertently transmitting EM signals from our planet for decades. Old TV episodes of “I Love Lucy” are currently flying through interstellar space, just waiting to be captured by some alien technology; maybe to the amusement of otherworldly beings.

So SETI was established decades ago—having been designed to receive some of those alien civilizations' equivalent TV programs, or, hopefully (and more likely) signals consciously sent out to inform beings like us that we're not alone. Yet my online course professor made the point that, although we're searching for outer space life, SETI is not really designed to locate outer-space intelligent life, but to discover extraterrestrial technology that is similar to ours.

We haven’t yet detected a signal, let alone determined the presence of either intelligence or the existence of life elsewhere. At best we currently can register the presence of EM signals that would indicate some sort of advanced technological civilization. One issue in our search for ET that possibly is being dealt with inappropriately is, Would intelligence “out there” display itself anything like what on Earth has evolved?

Furthermore, there is another key question that was posed many decades ago, by a prominent physicist/astronomer: If there are other advanced civilizations in outer space, where are they? Why haven't we already heard from them? This is a troubling question for many cosmologists. Again, we're not yet able to determine if there is or is not intelligence out there—we're asking if they have evolved technologies like ours, and, if so, where are the signals?

I can imagine several reasons why we've yet to capture a signal that we can confidently say came from outer space (and maybe never will): (1) The distances are simply too vast; signals from even the closest stars take many years to reach us; so, were we to detect a more distant signal, it may have been transmitted thousands of years ago. Any signal we might receive could be from a distant past, from a civilization that is no longer even existing. Where might our technology be, in another thousand years? Would our current primitive way of interstellar communication even be useful then? 

Other possibilities next time…

Unlikely Alone—Part 2

If life is discovered on other worlds, it will have a profound impact on our psyches. Some of us will have the foundations of our beliefs dramatically shifted and will have to rethink our basic convictions. Earth and humans will no longer occupy the pinnacle; this precious little planet will no longer be the only vital place in the universe. Others will rejoice that the cosmos is as rich as we could ever have imagined. 

The discovery of extraterrestrial life—if it comes—will not come any time soon, however. Moreover, the forms of life we discover will quite probably be of a type that we as yet can't begin to guess. Our current expectations of what we might find are probably too restrictive. The various scenarios that TV and movies have portrayed (aliens who usually look and talk like us—especially using modern English) are far too limiting.

Scientists have frequently speculated on what kinds of life we might find out there—describing the conditions under which “life as we know it” may exist. We’re coming to see that that view is too narrow, as we've been taken aback by the new types of life we've found right here on Earth—the so-called “extremophiles” that I mentioned earlier. Clearly our understanding of types of beings that we can't currently conceive of will soon be expanded even more, as we continue to explore our planet. 

I also wonder if we could even recognize some other strange form of life elsewhere in the universe, were we to encounter it tomorrow. It took us a long time to “discover” some of those extremophiles right here on Earth. 

To date, we have only one example of life and only one vital planet that we know about. With just a single sample, there's no saying that life has evolved “out there” as it has here. Even if we could rewind history and replay evolution on Earth, there's no telling what creatures would roam our planet today—but it certainly would be dramatically different. So many random events occurred along the way that would never be repeated—events that changed the course of evolution and altered life. (Think of the improbable asteroid that blew away the dominant dinosaurs, 65 million years ago, removing them and opening up so many niches for mammals.)   

Furthermore, it's taken something on the order of 3-4 billion years for life on Earth to evolve from some unknown ancient seed to the complexity we see today—that’s several billion years for a technologically proficient form of life to evolve on our friendly little planet. The chances of our finding life on some distant planet that is anywhere near as advanced (or immature) as humans are has got to be incredibly remote—given that they may have begun billions of years before us or are just getting started. We might find ourselves unable to communicate with beings who are either primitive or much further advanced than we. 

And the distances involved! The universe may be teeming with life, but those beings could be so unimaginably far away that we may remain ignorant of them forever.

So, where are we, in being able to answer the question, Are we alone? We've no more a definitive answer than 100 years ago. It's still an unknown, even though the likelihood seems to be much greater than even a year ago. Expect to live with the mystery for a good while yet. Don't hold your breath—just open your mind a little more to the possibility.

Unlikely Alone—Part 1

Ever since we humans came to understand that those points of light in the night sky are stars like our sun, many of us have wondered if some of those stars host planets that may contain some form of life. Are we alone in this grand universe? Is it possible that life may be thriving on other worlds out there, just as it does on our precious little planet?

These questions have lingered in people’s minds for millennia, but the means to answer them have eluded us until recently. The pursuit of this inquiry has not been encouraged by our religious institutions—particularly those that teach that human beings are special creatures molded by God, and thus at the center of the universe. This perspective remains convinced that Earth is unique and at the center of the universe. Despite that dogmatic view, many people have wondered if we may not be alone and maybe not that exceptional.

The issue has received increasing scientific attention in the last few decades. A number of projects are actively exploring the matter and are gradually leading us toward an answer. The possibility of life existing elsewhere has recently been given a major boost by two different areas of scientific research: (1) in astronomy, by the discovery of numerous planets around nearby stars by NASA and (2) in biology, by the discovery of several bizarre life-forms right here on our planet.

NASA's Kepler mission has now identified hundreds of planets around close-by stars—evidence we didn't have just a few years ago. Astronomers have for some time expected planets to be common, but until their existence could be demonstrated, we didn't really know. Now we do. The result: it is highly likely that there are billions of planets out there; just in our galaxy alone! So the likelihood of extraterrestrial life is definitely boosted—given that the more planets there are, the more chance that life could have formed on some of them.

The second recent finding—the discovery of Earthly forms of life we once did not think possible—also increases the likelihood of extraterrestrial life. Researchers have found life in forms and locations that surprise us: in rocks far underground where no light ever shines, at high temperatures we once thought would cook any critter, and in very unfriendly locations such as in strong acid environments that would dissolve the skin of any human. If life is this tough, we've had to revise our estimates of the kinds of harsh environments in which life could thrive on other worlds.

So we now have greater expectations of finding life out there. Mars may have once been warm and wet, and thus conducive to life. Jupiter's moon Europa and Saturn's moon Enceladus have scientists excited about the possibility of life there. SETI (Search for Extraterrestrial Intelligence) telescopes constantly scan the skies, looking for electromagnetic signals that alien intelligent species may have transmitted into space. (We ourselves do it all the time—not intentionally as a signal, but via our constant radio and TV transmissions that escape into space.)

With these findings, our level of anticipation of life elsewhere has skyrocketed. We're gaining confidence that we may not be alone. There is still no direct evidence for life elsewhere, but its likelihood is greater, as our understanding of  conditions out there increase.

More on extraterrestrial life next time…

Goldilocks Globe—Part 2

[News flash! It was just announced by NASA on 2 February that the Kepler Space Telescope has discovered 1235 candidate exo-planets as of that date! Of those, some 68 are Earth size! NASA will be further examining these candidates over the next few months, to see which may really be planets. How timely! On to Goldilocks.]

A few months ago a so-called “Goldilocks” planet was found. It got tagged with the name Goldilocks, because its star had two previously-discovered planets that were either too hot or too cold to support life. But a little more analysis of the data revealed a smaller in-between planet, dubbed Goldilocks, and officially given the moniker “Gliese 581 g.” It’s far enough away from its star to be able to have water, rather than either ice (it’s too cold) or steam (it’s too hot). Furthermore, it’s not much larger than Earth, so even its gravity and atmosphere could be like ours. Gliese 581 g is the first planet that we have located that just might support life as we know it! It’s caused quite a buzz in the astronomical community.

Planet Gliese 581 g is orbiting a star some 20 light years (that’s about 120 trillion miles) away. The star itself is named Gliese 581 a—which is a naming system that gives stars and their planets a numerical moniker. This star is quite different from our sun—it’s a red dwarf, it’s about one-third the size of the sun, it’s much older, and it’s a little over half the temperature. That may seem to describe an unusual star, but red dwarfs (which are too dim to see with the human naked eye) constitute as many as 90% of all the many billions of stars in our Milky Way galaxy. So they’re very common, and if life really does exist out there (astronomers get more confident every day that we’re not alone), it likely is orbiting a red dwarf star.

So what more do we know about this Goldilocks Gliese 581 g? It’s probably a rocky planet (like Earth) with enough mass to hold onto an atmosphere, if it has one. It is about 1.5-2 times the size of Earth, so its gravity wouldn’t be so large as to crush life forms similar to Earth’s. Its orbital period (its year) is very short—only about 37 Earth days—because it’s very close to its little, cool star. That brings about the fascinating result that the planet would be tidally locked to its star (like our Moon is to Earth), so it presents just one face to the star. That means that its perpetually daylight face stays boiling hot, while its permanent night face is freezing cold.

So how could it foster life or have liquid water? Because the zone between night and day (Goldilocks’s “twilight zone”) could be just the right temperature for life. In fact, if the planet has an atmosphere, that twilight zone could be quite wide, due to winds blowing around and spreading out the habitable zone.

It would be a wild experience to stand on Gliese 581 g and gaze at its sun. Rather than appear yellow-white, it’d be orange-red. It would appear about twice the size of our sun (since it’s closer), but it would never roam across the sky. Just as if you were to stand on the Moon and watch Earth constantly hovering in the same spot, day after day, year after year, the star Gliese 581 a would be stuck in the same place, and it would remain near the horizon.

Goldilocks has astronomers pretty excited, but mostly its discovery is leading them to expect to locate more habitable planets soon. The race is on! Kepler is continuing to find more planets around neighboring stars (1235 and counting!). We are beginning to document the fact that planetary systems are quite common in our galaxy. Couple this fact with the robustness of life that we’re also discovering right here on Earth, and the probability of life existing on planets other than Earth grows ever higher. Just a couple of decades ago the question “Are we alone?” had to be answered with a high degree of speculation and doubt. It’s beginning to appear, however, that the answer might well be “Not at all.”

Goldilocks Globe—Part 1

The search is on for planets around nearby stars. In only the last decade or so have astronomers begun to find so-called extra-solar planets around other stars. Prior to that, they felt pretty confident that planets must be out there, but the difficulties of verifying their presence were beyond the tools at hand. More powerful telescopes and more powerful computers are now allowing these discoveries to be made.

How do astronomers detect planets circling other stars? There is as yet no telescope capable of adequately zeroing in on a planet in another solar system—a star is just too bright and the planets too small and dim to see them. But if the planets are there, they will exert the tiniest gravitational pull on their star, causing it to wobble a minute amount, as they circle. Today’s big telescopes, backed up by super computers, have the sensitivity to discern this miniscule quavering of a star and even infer what kinds of planets are causing the tremble. In fact, the planetary motion laws that Newton gave us can be used to determine how many planets are there, their masses, and the size of their orbits. It’s amazing what the laws of physics will allow us to discover indirectly!

So the search for extra-solar planets has kicked into high gear in the last several years. Different teams of astronomers using different facilities feed off of and compete with each other and keep the enthusiastic juices flowing. New telescopes and techniques are coming on line all the time and are racking up impressive findings.

Until a few years ago astronomers strongly suspected, but had no direct evidence of, planets beyond our solar system. The discoveries are now piling up quickly—on the order of 400 hundred planets or more have been found to date. (I give a rough number, because the tally mounts almost daily.) Last year NASA sent up the Kepler Space Telescope—especially designed to ferret out extra-solar planets. The Kepler team has already announced locating several more worlds out there. A formal NASA report is imminently due, that will likely add dramatically to the total.

So what has been found so far? The vast majority of recently discovered planets are huge—the size of Jupiter and more. The tools available thus far are not yet sensitive enough to find smaller worlds, like Earth, but Kepler will undoubtedly change that. Super Jupiters are nice to find, but they hold little chance of harboring life of a type anything like us—their gravity is too great, their atmosphere is too thick, and their temperatures are usually too high.

On to the Goldilocks planet next time…