Heading for the hotel lobby the first night of the Breakthrough Discuss meeting, I thought about a major theme of the Breakthrough Starshot initiative: Making things smaller. Robert Forward wrote about sails hundreds of kilometers in diameter, and vast lenses deep in the Solar System to collimate a laser beam that would drive them. But Breakthrough Starshot is looking at a sail four meters across, carrying a payload more like a smartphone than a cargo ship. That big lens in the outer system? No longer needed if we can power up the sail close to home. How to Look at Alpha Centauri Digitization works wonders, and Moore’s Law takes us into ever smaller and more tightly packed realms on silicon chips. The trend affects every aspect of spaceflight and astronomy, as witness ACEsat, a small coronagraph mission with an explicit mission, the search for planets around Alpha Centauri A and B. Ruslan Belikov (NASA Ames), working with Northrop Grumman, led the team that conceived this mission,...

David Kipping and Alex Teachey have a new paper out on the possibility of ‘cloaking’ a planetary signature. The researchers, both at Columbia University, make the case that any civilization anxious to conceal its existence -- for whatever reason -- would surely become aware that all stars lying along its ecliptic plane would see transits of the home world, just as its own scientists pursued transit studies of planets around other stars. And it turns out there are ways to make sure this signal is masked by adjusting the shape of the planet’s transit light curves. Now this is a fascinating scenario as presented by the head of the Hunt for Exomoons with Kepler, whose business it is to know about the slightest of variations in light curves because they may contain information about exomoons or rings. Thus Kipping is a natural to look into the artificial manipulation of light curves, a study with definite SETI implications. Because methods like these work in two directions -- a...

When it comes to astrobiology, what we don't know dwarfs what we do. After all, despite all conjecture, we have yet to find proof that life exists anywhere else in the universe. SETI offers its own imponderables, adding on to the question of life's emergence. How often does intelligence arise, and if it does, how often does it produce civilizations capable of using technology? Even more to the point, how long do such civilizations last if they do appear? We keep asking the questions out of the conviction that one day we'll start retrieving data, perhaps in the form of a signal from another star. It's because of the lifetime-of-a-civilization question that I'm interested in a SETI search focused on red dwarf stars. True, M-dwarfs have a lot going against them, as Centauri Dreams readers know. A habitable planet around an M-dwarf may be tidally locked, which could be a showstopper except that some scientists believe global weather patterns may make at least part of such planets...

Given how powerful the transit method has proven for detecting exoplanets, we can assume great things are ahead. It won't be that many years before we're actually analyzing the atmospheric constituents of worlds much smaller than the gas giants for which we perform such studies now. That would make it possible for us to discover possible biosignatures. As I've speculated in these pages before, it may well be that we discover life on a planet around a distant star before we manage to discover it -- if it exists -- elsewhere in our Solar System. We're looking at worlds around other suns with something of the same spirit that Carl Sagan and the Voyager team looked back from the outer reaches and saw the Earth as a 'pale blue dot.' It's a comparison that René Heller and Ralph E. Pudritz draw in their recent paper on SETI strategy. Except here we're talking about extraterrestrial observers looking at our planet, the assumption being that if we can make these studies using our...

Running a site like Centauri Dreams means adapting and reconfiguring on a daily basis. The best laid plans and all that… When I wrote recently about the SETI efforts at KIC 8462852, my plan had been to follow up that discussion with a broader SETI issue -- where is the best place in the sky to search for a SETI signal? Then life intervened, first with my preparations to go to the Tennessee Valley Interstellar Workshop in Chattanooga, and then with the illness that cancelled those plans and left me with a thoroughly disrupted train of thought. I'm now ready to tackle that SETI question with particular reference to a new paper by René Heller and Ralph E. Pudritz, but I still want to put the discussion into context. With the KIC 8462852 SETI effort, we looked at a targeted observation campaign using the Allen Telescope Array to see if researchers could find any evidence of unusual activity associated with the star. As we saw in Jim and Dominic Benford's recent work (see...

I'm still smarting about having to cancel my travel plans for the Tennessee Valley Interstellar Workshop in Chattanooga, particularly since the Tau Zero Foundation was one of the sponsors of the event. But fortunately, I do have people offering to write up the workshop for Centauri Dreams, so we'll have some coverage and photos soon. Onward… Hunting for Biosignatures We only have two years before the James Webb Space Telescope is scheduled to launch. Assuming all goes well, JWST should help ease us into the era of biosignature detection, as we look for the characteristic signs of living organisms in the atmospheres of their worlds. But just how definitive are such signatures? A new paper from the University of Washington digs into potential false positives and offers specifics on the signatures that could fool us. One way to study biosignatures is by transit spectroscopy, using data gathered from starlight as it passes through a planet's atmosphere during a transit. This...

When I first got interested in SETI, I naively assumed that we would get a detection fairly soon, and that we would detect not a directed beacon but simple background traffic in a remote civilization. I had no idea at the time how difficult it would be to pick up the kind of radio traffic we routinely generate on Earth from a distant star, and as a matter of fact, my interest in shortwave radio led me to assume that, just as I enjoyed the sport of DX -- listening for distant signals -- so SETI would simply be an offshoot of this, with a harder-to-get QSL card. Some time in the mid-1980s I wrote a piece called “Where the Real DX Is” for Glenn Hauser’s Review of International Broadcasting, running through a list of the nearest stars and talking about SETI projects that had been tried up to then. I haven’t gone back to read that article in years and would probably find it an embarrassing chore. But it’s interesting to me that the idea of leakage radiation does have its place,...

Thinking that we can understand the motivations of an extraterrestrial civilization seems like a fool's gambit, but we have to try. The reason is obvious: We have exactly one technological society to work with -- we're all we have -- and if we want to look for SETI signals, we have to interpolate as best we can. An alien culture, it is assumed, will do the same. This was the procedure outlined by Giuseppe Cocconi and Philip Morrison in their classic 1959 paper "Searching for Interstellar Communications," that began the modern era of SETI. If there are civilizations around stars like the Sun, the paper reasons, then some will be motivated to reach out elsewhere. From the paper: To the beings of such a society, our Sun must appear as a likely site for the evolution of a new society. It is highly probable that for a long time they will have been expecting the development of science near the Sun. We shall assume that long ago they established a channel of communication that would one day...

Given the interest the unusual star KIC 8462852 has generated here and elsewhere, I want to be sure those of you in California are aware of an upcoming talk that touches on the matter, as well as broader SETI issues. Titled "The Breakthrough Initiative - Listen and Megastructures at KIC 8463," the talk will be delivered by Andrew Siemion (UC-Berkeley). The venue is 1065 La Avenida Street, Mountain View, CA 94043. The time: Tuesday, February 23, 2016 from 12:00 PM to 1:00 PM (PST). More at this web page, from which the description that follows: Dr. Andrew Siemion, Director of the Berkeley SETI Research Center (BSRC) at the University of California, Berkeley, will present an overview of the Breakthrough Listen Initiative, 100-million-dollar, 10-year search for extraterrestrial intelligence. Dr. Siemion will also discuss other SETI efforts ongoing at the BSRC, including the successful citizen science project SETI@Home, as well as a concerted effort to undertake panchromatic observations...

The question of a gradual dimming of KIC 8462852 continues to make waves, the most recent response being Michael Hippke's preprint on the arXiv site, discussed in the post immediately below. Bradley Schaefer (Lousiana State University), who published his work on the dimming he found in now digitized photographs in the archives of Harvard College Observatory, disagrees strongly with Hippke's findings and is concerned that the paper impugns the solid work being performed by DASCH (Digital Access to a Sky Century@Harvard). Below is Dr. Schaefer's response with details on the astrophotographic photometry at the heart of the issue. by Bradley E. Schaefer A few hours ago, Michael Hippke posted a manuscript to arXiv (http://arxiv.org/abs/1601.07314), and submitted the same manuscript to the Astrophysical Journal Letters (ApJLett). This manuscript claims to have found that the DASCH data produces light curves with secular trends (both systematic dimmings and brightenings) over the...

As if the Kepler star KIC 8462852 weren't interesting enough, Bradley Schaefer (Louisiana State) added to the controversy when he discovered what appeared to be a steady dimming of the star over the past century. Schaefer called the result "completely unprecedented for any F-type main sequence star," and given the discussion about KIC 8462852 as a SETI target, this raised the stakes. Something just as odd as the object's strange lightcurves was going on here, and it seemed natural to think that the dimming and the lightcurves were related. But Michael Hippke now begs to disagree. An old friend of Centauri Dreams (see, for example, his Exomoons: A Data Search for the Orbital Sampling Effect and the Scatter Peak), Hippke takes a close look at Schaefer's work and reaches a different conclusion. As he sees it, the 'dimming' of up 0.165 ± 0.013 magnitudes per century in this F3 star may actually be the result of imperfect calibration on the Harvard plates. In other words, while the...

How do we make out the odds on our survival as a species? Philosopher Nick Bostrom (University of Oxford) ponders questions of human extinction in terms of a so-called Great Filter. It's one that gives us a certain insight into the workings of the universe, in Bostrom's view, because it seems to keep the galaxy from being positively filled with civilizations. Somewhere along the road between inert matter and transcendent intelligence would be a filter that screens out the vast majority of life-forms, keeping the population of the galaxy low, and offering us a way to gauge our own chances for survival. Think of it this way. Perhaps the Great Filter has to do with the formation of life itself. If that is the case, then we have already made it through the filter and can go about exploring the universe. But if the Great Filter is in our future, then we can't know exactly what it will be, and neither can we know whether we will survive it. Here the final term in Frank Drake's equation...

I hadn’t expected a new paper on KIC 8462852 quite this fast, but hard on the heels of yesterday’s article on the star comes “KIC 8462852 Faded at an Average Rate of 0.165±0.013 Magnitudes Per Century From 1890 To 1989,” from Bradley Schaefer (Louisiana State University). Schaefer takes a hard look at this F3 main sequence star in the original Kepler field not only via the Kepler data but by using a collection of roughly 500,000 sky photographs in the archives of Harvard College Observatory, covering the period from 1890 to 1989. The Harvard collection is vast, but Schaefer could take advantage of a program called Digital Access to a Sky Century@Harvard (DASCH), which has currently digitized about 15 percent of the archives. Fortunately for us, this 15 percent covers all the plates containing the Cygnus/Lyra starfield, which is what the Kepler instrument focused on. Some 1581 of these plates cover the region of sky where KIC 8462852 is found. What Schaefer discovers is a secular...

As I sat down to write yesterday morning, I realized there was a natural segue between the 1977 ‘Wow!’ signal, and the idea that it had been caused by two comets, and KIC 8462852, the enigmatic star that has produced such an interesting series of light curves. What I had planned to start with today was: “Are comets becoming the explanation du jour for SETI?” But Centauri Dreams reader H. Floyd beat me to the punch, commenting yesterday: “Comets are quickly earning the David Drumlin Award for biggest SETI buzzkill.” As played by Tom Skeritt, David Drumlin is Ellie Arroway’s nemesis in the film Contact, willing to knock down the very notion of SETI and then, in a startling bit of reverse engineering, turning into its champion as he claims credit for a SETI detection. And of course you remember controversial KIC 8462852 as the subject of numerous media stories first playing up the idea of alien mega-engineering, and then as quickly declaring the problem solved by a disrupted family of...

The famous Wow! signal, picked up on August 15, 1977 at the Big Ear radio telescope (Ohio State University) is back in the news, with a new theory suggesting a source for the signal right here in the Solar System. Antonio Paris (St. Petersburg College, FL) asks us to consider a cometary origin for the signal, generated as two comets released hydrogen as they passed near the Big Ear's search field. The now-dismantled telescope had a fixed field of view, so a bright signature at 21 centimeters -- the hydrogen line -- would have appeared short-lived. Specifically, 21-cm refers to the line in the spectrum of neutral hydrogen atoms, a wavelength corresponding to 1420 megahertz associated with the most common element in the universe. It was back in 1959 that both Philip Morrison and Frank Drake fixed on the hydrogen line as a rational place to look for interstellar beacons, the assumption being that any civilization trying to reach another would choose a wavelength associated with some...

I can think of few things as spectacular as a globular cluster. Messier 5 is a stunning example in Serpens. With a radius of some 200 light years, M5 shines by the light of half a million stars, and at 13 billion years old, it's one of the older globular clusters associated with our galaxy. Clusters like these orbit the galactic core, stunning chandeliers of light packed tightly with stars. The Milky Way has 158 known globulars, while M31, the Andromeda galaxy, boasts as many as 500. Giant elliptical galaxies like M87 can have thousands. Image: The globular cluster Messier 5, consisting of hundreds of thousands of stars. Credit: ESA/Hubble & NASA. Via Wikimedia Commons. Given the age of globular clusters (an average of ten billion years), it's a natural assumption that planets within them are going to be rare. We would expect their stars to contain few of the heavy elements demanded by planets, since elements like iron and silicon are created by earlier stellar generations. And...

The vast changes our planet has undergone since formation add a real sense of humility to the exoplanet hunt. It's the humility that comes with exposure to deep time, reminding us that worlds like ours have developed through phases wildly different than the conditions we experience today. As we tune up our techniques for studying rocky worlds, we'll find planets in entirely different states of their own evolution, perhaps some with life, and some young enough to be life's future home. Perhaps some will be worlds where life has come, and gone. We have much to learn about how our own planet developed life, and new work from an international team led by Philip Pogge von Strandmann (University College London) gives us insight into a key issue: How long did it take for oxygen levels in the oceans and atmosphere to increase to the point that animal life could take off some 600 million years ago? Underlying the question is how the evolution of life ties in to changes in climate. For it...

I think you'll find Jon Lomberg's new essay in Slate as interesting as I do. We Need a World Cup for SETI uses a familiar figure at many sports events -- the guy in the stands holding up a Biblical reference on a poster -- to dig into a far more interesting issue. How does one go about maximizing visibility? The guy with the sign knows how to do it and if we think about his methods, we can better understand SETI. For as we think about radio and optical SETI, we're usually looking for signals that have been intentionally sent. Here we run into the particularly tricky business of trying to understand the thinking of an alien being, but there are certain principles that may apply to any civilization trying to send out a beacon-like message. The message needs to be short, cheap, easy to find, and in a place where it's likely to be seen. So what kind of beacon is this going to be? We've discussed 'Benford beacons' in these pages before (see, among others in the archive, Detecting a...

Last week I mentioned that I wanted to get into Massimo Marengo’s new paper on KIC 8462852, the interesting star that, when studied by the Kepler instrument, revealed an intriguing light curve. I’ve written this object up numerous times now, so if you’re coming into the discussion for the first time, plug KIC 8462852 into the archive search engine to get up to speed. Marengo (Iowa State) is himself well represented in the archives. In fact, I began writing about him back in 2005, when he was working on planetary companions to Epsilon Eridani. In the new paper, Marengo moves the ball forward in our quest to understand why the star I’ll abbreviate as KIC 8462 poses such problems. The F3-class star doesn’t give us the infrared signature we’d expect from a debris disk, yet the light curves we see suggest objects of various sizes (and shapes) transiting across its surface. What we lacked from Tabetha Boyajian’s earlier paper (and it was Boyajian, working with the Planet Hunters group,...

KIC 8462852 is back in the news. And despite a new paper dealing with the unusual star, I suspect it will be in the news for some time to come, for we’re a long way from finding out what is causing the unusual light curves the Planet Hunters group found in Kepler data. KIC 8462, you’ll recall, clearly showed something moving between us and the star, with options explored by Tabetha Boyajian, a Yale University postdoc, in a paper we examined here in October (see KIC 8462852: Cometary Origin of an Unusual Light Curve? and a series of follow-up articles). To recap, we’re seeing a light curve around this F3-class star that doesn’t look anything like a planetary transit, but is much more suggestive of debris. Finding a debris disk around a star is not in itself unusual, since we’ve found many such around young stars, but KIC 8462 doesn’t appear to be a young star when looked at kinematically. In other words, it’s not moving the way we would expect from a star that has recently formed....