When you consider that age of the Universe – 13.8 billion years by our most recent counts – and that which is “observable” to us measures about 93 billion light-years in diameter, you begin to wonder why we haven’t found signs of extra-terrestrial intelligence (ETI) beyond our Solar System. To paraphrase Enrico Fermi, the 20th-century physicists who advanced the famous Fermi Paradox – “where the heck are all the aliens?”
It is no easy thing to search for signs of intelligent life beyond our Solar System. In addition to the incredible distances involved and the fact that we really only have indirect methods at our disposal, there is also the small problem of not knowing exactly what to look for. If intelligent life does exist beyond our Solar System, would they even communicate as we do, using radio transmitters and similar forms of technology?
First, some clarification should be made as to what SETI and METI are all about it and what sets them apart. The term METI was coined by Russian scientist Alexander Zaitsev, who sought to draw a distinction between SETI and METI. As he explained in a 2006 paper on the subject:
“The science known as SETI deals with searching for messages from aliens. METI science deals with the creation of messages to aliens. Thus, SETI and METI proponents have quite different perspectives. SETI scientists are in a position to address only the local question “does Active SETI make sense?” In other words, would it be reasonable, for SETI success, to transmit with the object of attracting ETI’s attention? In contrast to Active SETI, METI pursues not a local and lucrative impulse, but a more global and unselfish one – to overcome the Great Silence in the Universe, bringing to our extraterrestrial neighbors the long-expected annunciation ‘You are not alone!'”
In short, METI looks for ways in which we might be able to contact aliens instead of waiting to hear from them. However, this does not mean that organizations like METI International are without ideas on how me might better listen to our (potential) alien neighbors. After all, communication goes beyond mere messages, and also requires that a medium exist with which to convey the message.
Such is the recommendation put forth by Dr. Morris Jones, a space analyst and writer who serves on the METI advisory council. In a recent article published on METI International’s website, he addressed the two main challenges when it comes to looking for ETI. On the one hand, you have the need for multiple methodologies to increase the odds of finding something. But as he indicates, there’s also the problem of knowing what to look for:
“We are not really sure of how extraterrestrials would communicate with us. Would they use radio waves, lasers, or something more exotic? Perhaps the universe is awash in extraterrestrial signals that we cannot even receive. SETI and METI practitioners spend a lot of time wondering how a message would be encoded in terms of language and content. It’s also important to consider the medium of transmission.”
In the past, says Jones, SETI searches were based on radio astronomy because that was the only practical means of doing so. Since then, efforts have expanded to include optical telescopes and the search for laser signals. This is due to the fact that in the past few decades, human beings have developed the technology to use laser for the sake of communications.
In a 2016 SETI paper, Dr. Philip Lubin of the University of California, Santa Barbara, explained how the development of directed-energy propulsion could help us search for evidence of aliens. As one of the scientific minds behind Breakthrough Starshot – a laser-driven lightsail that would be fast enough to make the trip to Alpha Centauri in just 20 years – he believes it’s a safe bet that ETI could be using similar technology to travel or communicate.
In addition, Dr. Avi Loeb from the Harvard-Smithsonian Center for Astrophysics (also one of the minds behind Starshot) has also suggested that fast-radio bursts (FRBs) could be evidence of alien activity. FRBs have been a subject of fascination to scientists since they were first detected in 2007 (the “Lorimer Burst“), and could also be a sign of alien communications or a means of propulsion.
Another means involves searching for artefacts – i.e. looking for evidence of physical infrastructure in other star systems. Case in point, since 2015, astronomers have been seeking to determine what is responsible for the periodic dimming of KIC 8462852 (aka. Tabby’s Star). Whereas most studies have sought to explain this in terms of natural causes, others have suggested it could be evidence of an alien megastructure.
To this array of search methods, Dr. Jones offers a few other possibilities. One way is to look for neutrinos, a type of subatomic particle that is produced by the decay of radioactive elements and interacts with matter very weakly. This allows them to pass through solid matter and also makes them very difficult to detect. Neutrinos are produced in large quantities by our Sun and astronomical sources, but they can also be produced artificially by nuclear reactors.
These, claims Jones, could be used for the sake of communications. The only problem is that looking for them would require some specialized equipment. Currently, all means of detecting neutrinos involve expensive facilities that have to be built either underground or in extremely isolated locations to ensure that they are not subject to any kind of electromagnetic interference.
Another possibility is searching for evidence of communications that rely on gravitational waves. Predicted by Einstein’s Theory of General Relativity, the first detection of these mysterious waves was first made in February 2016. And in the coming years and decades, it is expected that gravitational wave observatories will be established so the presence of these “ripples” in spacetime can be visualized.
However, compared to neutrinos, Jones admits that this seems like a long shot. “It’s hard to conceive with our current grasp of physics,” he writes. “They are extremely difficult to generate at a detectable level. You would need abilities similar to those of superheroes, and be able to smash neutron stars and black holes together at will. There are probably easier ways to get a message across the stars.”
Beyond these, there is the even more exotic possibility of “Zeta Rays”, which Dr. Jones is not prepared to rule out. Basically, “Zeta Rays” is a term used by physicists to describe physics that go beyond the Standard Model. As scientists are currently looking for evidence of new particles with the Large Hadron Collider and other particle accelerators, it stands to reason that anything they discover will be the added to the SETI and METI search manifest.
But could such physics entail new forms of communication? Hard to say, but definitely worth considering. After all, the physics that power our current technology certainly existed before we did. Or as Jones put it:,
“Is it possible to transmit with something better than we already have? Until we know a lot more physics, we just won’t know. Humanity in the twenty-first century could be like an isolated tribe in the Amazon jungle a century ago, unaware that the air around them was filled with radio signals. SETI uses the science and technology provided to us by other disciplines. Thus, we must wait until physics itself makes some more major breakthroughs. Only then can we consider such exotic methods of searching. We think a lot about the message. But we should also think about the medium.”
Other projects that are dedicated to METI include Breakthrough Listen, a ten-year initiative launched by Breakthrough Initiatives to conduct the largest survey to date for extraterrestrial communications – encompassing the 1,000,000 closest stars and 100 closest galaxies. Back in April of 2017, the scientists behind this project shared their analysis of the first year of Listen data. No definitive results have been announced yet, but they are just getting started!
Ever since Drake proposed his famous equation, human beings have eagerly sought to find evidence of extra-terrestrial intelligence. Unfortunately, all of our efforts have been haunted by Fermi’s equally-famous paradox! But of course, as space exploration goes, we’ve really only begun to scratch the surface of our Universe. And the only way we can ever expect to find evidence of intelligent life out there is to keep looking.
And with greater knowledge and increasingly sophisticated methods at our disposal, we can be sure that if intelligent life is out there somewhere, we will find it eventually. One can always hope, right? And be sure to check out this video of Dr. Jones 2014 presentation at the SETI Institute, titled “A Journalistic Perspective on SETI-Related Message Composition“:
In September of 2015, scientists announced that the star known as KIC 8462852 (aka. “Tabby’s Star” or “Boyajian’s Star”) was experiencing a strange dip in luminosity. At the time, astronomers indicated that this mysterious behavior could be the result of comets transiting in front of the star, but other (perhaps more hopeful) individuals claimed that it could also be the result of an alien megastructure.
During the 1960s, Freeman Dyson and Nikolai Kardashev captured the imaginations of people everywhere by making some radical proposals. Whereas Dyson proposed that intelligent species could eventually create megastructures to harness the energy of their stars, Kardashev offered a three-tiered classification system for intelligent species based on their ability to harness the energy of their planet, solar system and galaxy, respectively.
Earlier this week, NASA hosted the “Planetary Science Vision 2050 Workshop” at their headquarters in Washington, DC. Running from Monday to Wednesday – February 27th to March 1st – the purpose of this workshop was to present NASA’s plans for the future of space exploration to the international community. In the course of the many presentations, speeches and panel discussions, many interesting proposals were shared.
Among them were two presentations that outlined NASA’s plan for the exploration of Jupiter’s moon Europa and other icy moons. In the coming decades, NASA hopes to send probes to these moons to investigate the oceans that lie beneath theirs surfaces, which many believe could be home to extra-terrestrial life. With missions to the “ocean worlds” of the Solar System, we may finally come to discover life beyond Earth.
This report was drafted by NASA’s Planetary Science Division (PSD) in response to a congressional directive to begin a pre-Phase A study to assess the scientific value and engineering design of a Europa lander mission. These studies, which are known as Science Definition Team (SDT) reports, are routinely conducted long before missions are mounted in order to gain an understanding of the types of challenges it will face, and what the payoffs will be.
In addition to being the co-chair of the Science Definition Team, Hand also served as head of the project science team, which included members from the JPL and the California Institute of Technology (Caltech). The report he and his colleagues prepared was finalized and issued to NASA on February 7th, 2017, and outlined several objectives for scientific study.
As was indicated during the course of the presentation, these objectives were threefold. The first would involve searching for biosignatures and signs of life through analyses of Europa’s surface and near-subsurface material. The second would be to conduct in-situ analyses to characterize the composition of non-ice near-subsurface material, and determine the proximity of liquid water and recently-erupted material near the lander’s location.
The third and final goal would be to characterize the surface and subsurface properties and what dynamic processes are responsible for shaping them, in support for future exploration missions. As Hand explained, these objectives are closely intertwined:
“Were biosignatures to be found in the surface material, direct access to, and exploration of, Europa’s ocean and liquid water environments would be a high priority goal for the astrobiological investigation of our Solar System. Europa’s ocean would harbor the potential for the study of an extant ecosystem, likely representing a second, independent origin of life in our own solar system. Subsequent exploration would require robotic vehicles and instrumentation capable of accessing the habitable liquid water regions in Europa to enable the study of the ecosystem and organisms.”
In other words, if the lander mission detected signs of life within Europa’s ice sheet, and from material churned up from beneath by resurfacing events, then future missions – most likely involving robotic submarines – would definitely be mounted. The report also states that any finds that are indicative of life would mean that planetary protections would be a major requirement for any future mission, to avoid the possibility of contamination.
But of course, Hand also admitted that there is a chance the lander will find no signs of life. If so, Hand indicated that future missions would be tasked with gaining “a better understanding of the fundamental geological and geophysical process on Europa, and how they modulate exchange of material with Europa’s ocean.” On the other hand, he claimed that even a null-result (i.e. no signs of life anywhere) would still be a major scientific find.
Ever since the Voyager probes first detected possible signs of an interior ocean on Europa, scientists have dreamed of the day when a mission might be possible to explore the interior of this mysterious moon. To be able to determine that life does not exist there could no less significant that finding life, in that both would help us learn more about life in our Solar System.
As a specialist in UV spectroscopy of planetary surfaces, Dr. Hendrix has collaborated with many NASA missions to explore icy bodies in the Solar System – including the Galileo and Cassini probes and the Lunar Reconnaissance Orbiter (LRO). Dr. Hurford, meanwhile, specializes in the geology and geophysics of icy satellites, as well as the effects orbital dynamics and tidal stresses have on their interior structures.
Founded in 2016 by NASA’s Outer Planets Assessment Group (OPAG), ROW was tasked with laying the groundwork for a mission that will explore “ocean worlds” in the search for life elsewhere in the Solar System. During the course of the presentation, Hendrix and Hurford laid out the findings from the ROW report, which was completed in January of 2017.
As they state in this report, “we define an ‘ocean world’ as a body with a current liquid ocean (not necessarily global). All bodies in our solar system that plausibly can have or are known to have an ocean will be considered as part of this document. The Earth is a well-studied ocean world that can be used as a reference (“ground truth”) and point of comparison.”
By this definition, bodies like Europa, Ganymede,Callisto, and Enceladus would all be viable targets for exploration. These worlds are all known to have subsurface oceans, and there has been compelling evidence in the past few decades that point towards the presence of organic molecules and prebiotic chemistry there as well. Triton, Pluto,Ceres and Dione are all mentioned as candidate ocean worlds based on what we know of them.
Titan also received special mention in the course of the presentation. In addition to having an interior ocean, it has even been ventured that extremophile methanogenic lifeforms could exist on its surface:
“Although Titan possesses a large subsurface ocean, it also has an abundant supply of a wide range of organic species and surface liquids, which are readily accessible and could harbor more exotic forms of life. Furthermore, Titan may have transient surface liquid water such as impact melt pools and fresh cryovolcanic flows in contact with both solid and liquid surface organics. These environments present unique and important locations for investigating prebiotic chemistry, and potentially, the first steps towards life.”
Ultimately, the ROW’s pursuit of life on “ocean worlds” consists of four main goals. These include identifying ocean worlds in the solar system, which would mean determining which of the worlds and candidate worlds would be well-suited to study. The second is to characterize the nature of these oceans, which would include determining the properties of the ice shell and liquid ocean, and what drives fluid motion in them.
The third sub-goal involves determining if these oceans have the necessary energy and prebiotic chemistry to support life. And the fourth and final goal would be to determine how life might exist in them – i.e. whether it takes the form of extremophile bacteria and tiny organisms, or more complex creatures. Hendrix and Hurford also covered the kind of technological advances that will be needed for such missions to happen.
Naturally, any such mission would require the development of power sources and energy storage systems that would be suitable for cryogenic environments. Autonomous systems for pinpoint landing and technologies for aerial or landed mobility would also be needed. Planetary protection technologies would be necessary to prevent contamination, and electronic/mechanical systems that can survive in an ocean world environment too,
While these presentations are merely proposals of what could happen in the coming decades, they are still exciting to hear about. If nothing else, they show how NASA and other space agencies are actively collaborating with scientific institutions around the world to push the boundaries of knowledge and exploration. And in the coming decades, they hope to make some substantial leaps.
If all goes well, and exploration missions to Europa and other icy moons are allowed to go forward, the benefits could be immeasurable. In addition to the possibility of finding life beyond Earth, we will come to learn a great deal about our Solar System, and no doubt learn something more about humanity’s place in the cosmos.
NASA’s Dawn spacecraft has been poking around Ceres since it first established orbit in March of 2015. In that time, the mission has sent back a steam of images of the minor planet, and with a level of resolution that was previously impossible. Because of this, a lot of interesting revelations have been made about Ceres’ composition and surface features (like its many “bright spots“).
In what is sure to be the most surprising find yet, the Dawn spacecraft has revealed that Ceres may actually possess the ingredients for life. Using data from the Dawn spacecraft’s Visible and InfraRed Mapping Spectrometer (VIMS), an international team of scientists has confirmed the existence of organic molecules on Ceres – a find which could indicate that it has conditions favorable to life.
These findings – which were detailed in a study titled “Localized aliphatic organic material on the surface of Ceres” – appeared in the Feb. 17th, 2017, issue of Science. For the sake of their study, the international team of researchers – which was led by Maria Cristina de Sanctis from the National Institute of Astrophysics in Rome, Italy – showed how Dawn sensor data pointed towards the presence of aliphatic compounds on the surface.
Aliphatics are a type of organic compound where carbon atoms form open chains that are commonly bound with oxygen, nitrogen, sulfur and chlorine. The least complex aliphatic is methane, which has been detected in many locations across the Solar System – including in the Martian atmosphere and in both liquid and gaseous form on Saturn’s moon Titan.
From their study, Dr. de Sanctis and her colleagues determined that spectral data obtained by the VIMS instrument corresponded to the presence of these hydrocarbons in a region outside of the Ernutet crater. This crater, which is located in the northern hemisphere of Ceres, measures about 52 km (32 mi) in diameter. The aliphatic compounds which were detected were localized in a roughly 1000 square kilometers region around it.
The team ruled out the possibility that these organic molecules were deposited from an external source – such as a comet or carbonaceous chondrite asteroid. While both have been shown to contain organic molecules in their interior in the past, the largest concentrations on Ceres were distributed discontinuously across the southwest floor and rim of the Ernutet crater and onto an older, highly degraded crater.
In addition, other organic-rich areas were spotted being are scattered to the northwest of the crater. As Dr. Maria Cristina De Sanctis told Universe Today via email:
“The composition that we see on Ceres is similar to some meteorites that has organics and thus we searched for this material. We considered both endogenous and exogenous origin, but the last one seems less likely due to several reasons including the larger abundance observed on Ceres with respect the meteorites.”
Instead, they considered the possibility that they organic molecules were endogenous in origin. In the past, surveys have shown evidence of hydrothermal activity on Ceres, which included signs of surface renewal and fluid mobility. Combined with other surveys that have detected ammonia-bearing hydrated minerals, water ice, carbonates, and salts, this all points towards Ceres having an environment that can support prebiotic chemistry.
“The overall composition of Ceres can favor the pre-biotic chemistry,” said De Sanctis. “Ceres has water ice and minerals (carbonates and phyllosilicates) derived from pervasive aqueous alteration of rocks. It has also material that we think is formed in hydrothermal environments. All these information indicate condition not hostel to biotic molecules.”
These findings are certainly significant in helping to determine if life could exist on Ceres – in a way that is similar to Europa and Enceladus, locked away beneath its icy mantle. But given that Ceres is believed to have originated 4.5 billion years ago (when the Solar System was still in the process of formation), this study is also significant in that it can shed light on the origin, evolution, and distribution of organic life in our the Solar System.
There’s a remote chance that inexplicable light variations in a star in the Northern Cross may be caused by the works of an alien civilization.
1,480 light years from Earth twinkles one of the greatest mysteries of recent times. There in the constellation Cygnus the Swan, you’ll find a dim, ordinary-looking point of light with an innocent sounding name — Tabby’s Star. Named for Louisiana State University astronomer Tabetha Boyajian, who was the lead author on a paper about its behavior, this star has so confounded astronomers with its unpredictable ups and downs in its brightness, they’ve gone to war on the object, drilling down on it with everything from the Hubble to the monster 393.7-inch (10-meter) Keck Telescope in Hawaii. Continue reading “The Search Is On For Alien Signals Around Tabby’s Star”
Many years ago, Carl Sagan predicted there could be as many as 10,000 advanced extraterrestrial civilizations in our galaxy.
After nearly 60 years of searching without success, a growing list of scientists believe life on Earth only came about because of a lucky series of evolutionary accidents, a long list of improbable events that just happened to come together at the right time and will never be repeated.
Is it possible they are right and we are all there is?
Earth is a typical rocky planet, in an average solar system, nestled in the spiral arm of an ordinary galaxy. All the events and elements that came together to build our world could happen almost everywhere throughout the galaxy and there should be nothing unusual about the evolution of life on this planet or any others.
In a galaxy of hundreds of billions of stars, the law of averages dictates that intelligent life must exist somewhere.
So, why haven’t we found it yet?
There could be many reasons.
Looking for a radio signal in a galaxy of over 400 billion worlds across 100,000 light years and billions of radio frequencies makes the proverbial needle in a haystack sound easy. Imagine you are driving home, your spouse in one car and you in the other. There’s a thick fog making visual confirmation impossible and no cell phone reception. Luckily, a week ago you had a 250 channel CB installed in both cars. Unfortunately, you forgot to agree on a broadcast channel. To chat, the two CBs would have to be on at the same time and you’d need to independently search every channel, listen, broadcast, then move to the next, hoping to get lucky enough to land on the same channel.
What are the odds that would happen? Not very good. Multiply this scenario one hundred billion times and you have some idea of the challenges facing SETI. To add to that, advanced civilizations probably only stay radio active for a relatively short time in their development as they develop more sophisticated technology. Searching the radio spectrum would require looking at one frequency 24/7 for years to be sure you weren’t missing something and telescope time is far too expensive for that. While you were sitting on that single frequency, 20 extraterrestrial signals could have come in on other channels and you’d never know it.
The Fermi Paradox is used by many skeptics as the holy grail when trying to prove there is nobody out there. Fermi theorized that a galaxy with so much potential for life must be full of extraterrestrials. He noted that since the majority of stars are considerably older than our sun, extraterrestrials could be millions of years more advanced than us. Fermi calculated that even at sub light speed one of those civilizations should have colonized the galaxy by now and we would have seen evidence of it.
There is however a problem with that logic.
In 50,000 years, humans will probably look a little different than people do now. In 10 million years, considerably different. Imagine a civilization completely different from us from the start and 10 million years more advanced. We might not even be able to recognize them as life forms, let alone see any evidence of their existence.
Arthur C. Clarke once said advanced extraterrestrials would probably be indistinguishable to us from magic. Their communications would be like listening for an answer to drumbeats and getting only silence while the ether around you is filled with more information in a second than one could utter in a lifetime. There could be the alien equivalent of the super bowl going on a few light years away and we would probably not even have a clue.
The distances in our galaxy are incredibly vast. Current spacecraft travel about 20 times faster than the speed of a bullet. While that sounds fast, at that speed it would take a spacecraft 75,000 years to travel to our nearest star only 4 light years away. Light years are a measure of distance so if we could speed that ship up to 186,000 miles per second (300,000 km/second), it would take 4 years to reach that same star.
Looking at a star 1,000 light years away is like being in a time machine. You are not seeing it as it is now, but one thousand years ago. Our galaxy is about 100,000 light years across with over 200 billion stars. Current theory suggests there may be as many as one billion earth-like planets in our galaxy. If just one tenth of those had some kind of life, that would leave us with about 100 million worlds harboring one celled creatures or better.
If just the tiniest fraction of them, (one one hundred thousandth) managed to spawn an advanced race of beings, there could be as many as 1,000 extraterrestrial civilizations in our galaxy. Regardless of whether you consider that a lot or a little, that would mean one technically advanced alien society exists for every hundred million stars. Our nearest extraterrestrial neighbor might be very, very far away. In the movies, the speculative fiction of warp speed, hyper drive and worm holes enable spaceships to travel faster than the speed of light and breach those distances fairly easily. But if the physics of this turn out to be impossible, then even the nearest alien civilizations may find interstellar travel very difficult and quite undesirable.
Another reason extraterrestrials may have made themselves scarce could be that the galaxy is jam packed with all sorts of weird beings and wondrous destinations. In this scenario why would advanced forms of life want to come here? There are probably so many more interesting places to visit. It would be like hunting for an exotic bird and not even giving the ant hill below your feet a second look.
Stephen Hawking has said, “I believe extraterrestrial life is quite common in the universe, although intelligent life less so. Some say it has yet to appear on Earth.”
Many think once a civilization achieves radio, it has a short window of but a few hundred years before it starts to integrate artificial intelligence into its own biology. Machines do everything so much easier, with far less risk and are immortal. It is entirely possible any aliens we hear from will have morphed into something more machine like than biological.
There has been a push lately for SETI to expand its operations from just passively listening, to actively broadcasting messages into the cosmos. One of the smartest men on the planet, Stephen Hawking, doesn’t think that’s a good idea. He believes that our messages might attract unwanted attention from unsavory creatures looking to blast us back into the stone age. He uses what happened to the Native Americans when they first encountered Columbus as an example. Alien races may have had to endure the same aggressive survival of the fittest culture. If they are at least as smart as Stephen Hawking, then everyone out there could be listening and nobody is broadcasting for fear of attracting the equivalent of Darth Vader and the Evil Empire to their shores.
Or, maybe there is a signal on its way right now, having traveled thousand of years, arriving next week, month or year.
Many scientists like Paul Davies, think SETI needs to start thinking more out of the box in its search methods. He advocates analyzing places in our own solar system like the moon, planets, asteroids and the Earth for evidence that aliens have passed this way. We should also be open to the possibility that we have already received a message from the stars and don’t recognize it because it arrived by something other than radio. Physist Vladimir Charbak thinks that life may have been spread throughout the galaxy by intelligent design and there may actually be evidence of this within our own DNA just waiting to be discovered.
Another reason we have yet to detect alien life could be there is nothing out there to find. Or to put it another way, we are the only game in town. To best answer that question, ask yourself, does this seem logical? There is a very good chance that one or more worlds just in our own solar system harbor some form of life. In a galaxy with as many as one billion or more potentially habitable planets, one could almost guarantee many of them will host life. There may potentially be hundreds of millions of worlds with living things on them. Does it make sense that in all that habitable real estate we are the only race to evolve into an intelligent species?
We humans tend to think of things with a distinctly anthropomorphic spin. Notions like, life needs water, oxygen and is based on carbon. Or, an advanced alien race would use radio and their signals should repeat. In popular culture, extraterrestrials portrayed in movies look remotely like us. This is done so we can recognize emotions and that fills movie theaters. I can remember aliens portrayed in the classic science fiction television show, “The Outer Limits” as energy balls, dust motes and tumbleweeds. They weren’t the most popular episodes, but the reality is that those portrayals are probably closer to the truth than ET and his heart lamp. Extraterrestrials will probably be as different from us as we are from a blade of grass and their motivations a complete mystery. It is very possible that the reason we haven’t found them yet is one that completely eludes our understanding at this point.
So where does that leave us?
Time and patience.
If you compare the 4.5 billion year old earth to a 24 hour clock, mankind doesn’t appear until a little over a minute before midnight. Take the almost sixty years we have been looking for extraterrestrials and project that on the same clock, it probably represents only about 20 or 30 seconds worth of searching for intelligent beings who may have been around millions and perhaps billions of years longer than we have. Our passage through time is just a tiny almost imperceptible blip when compared to the evolution of our galaxy.
New, very powerful listening devices will be coming into operation soon as well as sophisticated instruments that will be able to analyze exoplanets atmospheres to look for hints of life. SETI will expand into new areas and scientists will be able to devote a lot more telescope time to the search as the newly funded (100MM) Project Breakthough Listen kicks into high gear. It will cover 10 times more of the sky and the entire 1-10GHz radio spectrum. There will be more powerful optical and infrared searches and it is estimated the project will generate in a day as much data as SETI produced in an entire year. Recently, Project Breakthrough Starshot was announced as well. Seeded by another 100MM by Russian Billionaire, Yuri Milner, this ambitious project seeks to send a tiny light propelled robotic spacecraft to our nearest star system, Alpha Centauri. Stephen Hawking thinks this can be accomplished within the next generation and that new technology would allow a journey of only 20 years.
SETI scientist Nathalie Cabrol thinks its also time for a new approach to SETI’s search, a reboot if you will. She feels that “SETI’s vision has been constrained by whether ET has technology that resembles or thinks like us. She feels that the search, so far, has in essence been a search for ourselves. Electromagnetic fingerprints of radio transmitions carry a strong like us assumption”. She proposes involving a lot more disciplines in a redesign of the search. Astrobiology, life sciences, geoscience, cognitive science and mathematics among others. Her plan is to invite the research community to help craft a new scientific roadmap for SETI that very well may redefine the meaning of life and the cosmic search for new forms of it.
Some experts say we won’t see evidence of extraterrestrials for another 1500 years. That’s the time it will take for our TV and radio signals to have reached enough stars and have the best chance to be discovered.
In my opinion, I think highly advanced extraterrestrial societies already know we’re here and in about 10-15 years we’ll start getting some of the answers we’ve been looking for.
Last fall, astronomers were surprised when the Kepler mission reported some anomalous readings from KIC 8462852 (aka. Tabby’s Star). After noticing a strange and sudden drop in brightness, speculation began as to what could be causing it – with some going so far as to suggest that it was an alien megastructure. Naturally, the speculation didn’t last long, as further observations revealed no signs of intelligent life or artificial structures.
But the mystery of the strange dimming has not gone away. What’s more, in a paper posted this past Friday to arXiv, Benjamin T. Montet and Joshua D. Simon (astronomers from the Cahill Center for Astronomy and Astrophysics at Caltech and the Carnegie Institute of Science, respectively) have shown how an analysis of the star’s long-term behavior has only deepened the mystery further.
To recap, dips in brightness are quite common when observing distant stars. In fact, this is one of the primary techniques employed by the Kepler mission and other telescopes to determine if planets are orbiting a star (known as Transit Method). However, the “light curve” of Tabby’s Star – named after the lead author of the study that first detailed the phenomena (Tabetha S. Boyajian) – was particularly pronounced and unusual.
According to the study, the star would experience a ~20% dip in brightness, which would last for between 5 and 80 days. This was not consistent with a transitting planet, and Boyajian and her colleagues hypothesized that it was due to a swarm of cold, dusty comet fragments in a highly eccentric orbit accounted for the dimming.
However, others speculated that it could be the result of an alien megastructure known as Dyson Sphere (or Swarm), a series of structures that encompass a star in whole or in part. However, the SETI Institute quickly weighed in and indicated that radio reconnaissance of KIC 8462852 found no evidence of technology-related radio signals from the star.
Other suggestions were made as well, but as Dr. Simon of the Carnegie Institute of Science explained via email, they fell short. “Because the brief dimming events identified by Boyajian et al. were unprecedented, they sparked a wide range of ideas to explain them,” he said. “So far, none of the proposals have been very compelling – in general, they can explain some of the behavior of KIC 8462852, but not all of it.”
To put the observations made last Fall into a larger context, Montet and Simon decided to examine the full-frame photometeric images of KIC 8462852 obtained by Kepler over the last four years. What they found was that the total brightness of the star had been diminishing quite astonishingly during that time, a fact which only deepens the mystery of the star’s light curve.
As Dr. Montet told Universe Today via email:
“Every 30 minutes, Kepler measures the brightness of 160,000 stars in its field of view (100 square degrees, or approximately as big as your hand at arm’s length). The Kepler data processing pipeline intentionally removes long-term trends, because they are hard to separate from instrumental effects and they make the search for planets harder. Once a month though, they download the full frame, so the brightness of every object in the field can be measured. From this data, we can separate the instrumental effects from astrophysical effects by seeing how the brightness of any particular star changes relative to all its neighboring stars.”
Specifically, they found that over the course of the first 1000 days of observation, the star experienced a relatively consistent drop in brightness of 0.341% ± 0.041%, which worked out to a total dimming of 0.9%. However, during the next 200 days, the star dimmed much more rapidly, with its total stellar flux dropping by more than 2%.
For the final 200 days, the star’s magnitude once again consistent and similar to what it was during the first 1000 – roughly equivalent to 0.341%. What is impressive about this is the highly anomalous nature of it, and how it only makes the star seem stranger. As Simon put it:
“Our results show that over the four years KIC 8462852 was observed by Kepler, it steadily dimmed. For the first 2.7 years of the Kepler mission the star faded by about 0.9%. Its brightness then decreased much faster for the next six months, declining by almost 2.5% more, for a total brightness change of around 3%. We haven’t yet found any other Kepler stars that faded by that much over the four-year mission, or that decreased by 2.5% in six months.”
Of the over 150,000 stars monitored by the Kepler mission, Tabby’s Starr is the only one known to exhibit this type of behavior. In addition, Monetet and Cahill compared the results they obtained to data from 193 nearby stars that had been observed by Kepler, as well as data obtained on 355 stars with similar stellar parameters.
From this rather large sampling, they found that a 0.6% change in luminosity over a four year period – which worked out to about 0.341% per year – was quite common. But none ever experienced the rapid decline of more than 2% that KIC 8462852 experienced during that 200 days interval, or the cumulative fading of 3% that it experienced overall.
Montet and Cahill looked for possible explanations, considering whether the rapid decline could be caused by a cloud of transiting circumstellar material. But whereas some phenomena can explain the long-term trend, and other the short-term trend, no one explanation can account for it all. As Montet explained:
“We propose in our paper that a cloud of gas and dust from the remnants of a planetesimal after a collision in the outer solar system of this star could explain the 2.5% dip of the star (as it passes along our line of sight). Additionally, if some clumps of matter from this collision were collided into high-eccentricity comet-like orbits, they could explain the flickering from Boyajian et al., but this model doesn’t do a nice job of explaining the long-term dimming. Other researchers are working to develop different models to explain what we see, but they’re still working on these models and haven’t submitted them for publication yet. Broadly speaking, all three effects we observe cannot be explained by any known stellar phenomenon, so it’s almost certainly the result of some material along our line of sight passing between us and the star. We just have to figure out what!”
So the question remains, what accounts for this strange dimming effect around this star? Is there yet some singular stellar phenomena that could account for it all? Or is this just the result of good timing, with astronomers being fortunate enough to see a combination of a things at work in the same period? Hard to say, and the only way we will know for sure is to keep our eye on this strangely dimming star.
And in the meantime, will the alien enthusiasts not see this as a possible resolution to the Fermi Paradox? Most likely!
The Fermi Paradox essentially states that given the age of the Universe, and the sheer number of stars in it, there really ought to be evidence of intelligent life out there. This argument is based in part on the fact that there is a large gap between the age of the Universe (13.8 billion years) and the age of our Solar System (4.5 billion years ago). Surely, in that intervening 9.3 billion years, life has had plenty of time to evolve in other star system!