Reykjavik is an old haunt of mine, a favorite place to which I have not returned in all too long. I was delighted, then, to hear from Angelle Tanner, who in August attended the Extreme Solar Systems IV conference there. I had the pleasure of getting to know Dr. Tanner in Knoxville when we both spoke at a biosignatures session at the 2017 symposium of the Tennessee Valley Interstellar Workshop. Dr. Tanner received her PhD at UCLA, did postdoc work at both Caltech and Georgia State, and is now an associate professor at Mississippi State University. Her work specializes in exoplanet detection and programs devoted to understanding the properties of stars that host planets, as well as the architecture of the systems that evolve around them. It's a pleasure to turn today's essay over to Dr. Tanner for a look at exoplanetary events in Iceland's capital. by Angelle Tanner Mid-August marked the fourth meeting of the Extreme Solar Systems conference -- this one in Reykjavik, Iceland - touted...

SETI, the Search for Extraterrestrial Intelligence, has kept its focus on the stars, through examination of electromagnetic wavelengths from optical to radio signals. But Jim Benford has been advocating that we consider near-Earth objects as potential SETI targets, prompted by Ronald Bracewell's thoughts in a 1960 paper advancing the 'sentinel hypothesis.' A Bracewell probe could linger in a target system for millions of years, monitoring developments on worlds with the potential for life. Couple that thought with the rarely studied co-orbital' objects that approach the Earth both frequently and closely and you have a map for a realm of SETI that is only now coming into investigation. What follows is a news release from The Astrophysical Journal covering Benford's new paper, one we discussed on Centauri Dreams back in March [see A SETI Search of Earth's Co-Orbitals]. I want to get this out now because Benford will be delivering the 2019 Eugene Shoemaker Memorial Lecture tomorrow,...

Centauri Dreams regular Alex Tolley here examines a new paper with a novel take on Saturn’s moon Enceladus. Tempting us with its geysers and the organic compounds Cassini detected in their spray, Enceladus offers the prospect of life within its internal ocean. But are there other explanations for what we see, pointing to what may be a prebiotic environment? For that matter, what features of life’s chemistry could emerge on such a world without yet maturing into what we would recognize as living organisms? The paper Alex examines offers us quite an interesting take on a possible origin for life not just on Enceladus but elsewhere in the universe. by Alex Tolley Image: "Snow on Enceladus.” Credit: David Hardy. The discovery of subsurface oceans in the icy moons of Europa and Enceladus has increased interest in the exploration of these moons. The logic of the mantra “Follow the water” implies that there may be extant life in these oceans, most excitingly from a unique genesis at...

Breakthrough Listen has just announced a new optical SETI effort in partnership with the VERITAS Collaboration. The news took me by surprise, for VERITAS (Very Energetic Radiation Imaging Telescope Array System) generally deals in high-energy astrophysics, with a focus on gamma rays, which signal their presence through flashes of Cherenkov radiation when they strike the Earth's atmosphere. Here, the array is being used to look for technosignatures, as Andrew Siemion (UC- Berkeley SETI Research Center) explains: "Breakthrough Listen is already the most powerful, comprehensive, and intensive search yet undertaken for signs of intelligent life beyond Earth. Now, with the addition of VERITAS, we're sensitive to an important new class of signals: fast optical pulses. Optical communication has already been used by NASA to transmit high definition images to Earth from the Moon, so there's reason to believe that an advanced civilization might use a scaled-up version of this technology for...

A useful exercise for learning how to look for life elsewhere is to try to find it right here on Earth. Thus Carl Sagan’s observations of our planet via data taken during the 1993 flyby of the Galileo spacecraft, which was doing a gravity assist maneuver enroute to Jupiter. Sagan and team found pigments on the Earth’s surface with a sharply defined edge in the red part of the spectrum. What he was looking at was the reflection of light off vegetation. The ‘red edge’ has become well known in astrobiology circles and is considered a potential biosignature. On Earth, vegetation is the most abundant reflecting surface indicating life (vegetation covers about 60% of present-day Earth’s land surface). The increase in reflectance shows up at about 700 nm, varying in strength depending upon the species of plant. But as Jack O’Malley-James and Lisa Kaltenegger (Cornell University/Carl Sagan Institute) point out, photosynthetic structures containing chlorophyll are found not just in vegetation...

Remember 'Nemesis'? The idea was that mass extinctions on Earth recur on a timescale of between 20 and 40 million years, and that this recurrence could be accounted for by the existence of a faint star in a highly elliptical orbit of the Sun. Put this object on a 26 million year orbit and it would, so the theory ran, destabilize Oort cloud comets, causing some to fall into the inner system at a rate matching the record of extinctions. Thus a cometary bombardment was to be expected on a regular basis, as were the mass extinctions that were its consequence. No one has found Nemesis, though other theories about recurring mass extinctions are in play, including recent work from Lisa Randall and Matthew Reece that explores dark matter as the trigger, with the Sun periodically passing through a disk of the stuff. Of course, finding dark matter itself continues to be a problem. Moreover, the wide range in the proposed recurrences gives rise to the possibility that these events are not...

A paper called “The Natural History of ‘Oumuamua,” just out in Nature Astronomy, puts the emphasis on the word ‘natural.’ We know how much of a stir in the media the interstellar visitor has made given its peculiarities, and the hypothesis put forward by Harvard’s Avi Loeb that it could be a technological object. Now we have a group of 14 astronomers, European as well as American, who have assessed the available data from all angles. This is a worthwhile effort, assembling a team at the International Space Science Institute (ISSI) in Bern, Switzerland that intends to meet once again later in the year. It considers the question of whether the extraterrestrial spacecraft hypothesis is supported by examination of all the peer-reviewed work that has thus far appeared. Matthew Knight (University of Maryland), working with Alan Fitzsimmons (Queen’s University Belfast) assembled the team. Knight believes that natural phenomena can explain ‘Oumuamua: "We put together a strong team of experts...

On Monday I was talking about the rise of open access scientific journals, using the European Space Agency's Acta Futura as just one example. The phenomenal arXiv service, not itself a journal but a repository for preprints of upcoming papers, is already well known in these pages. Now we have the largest public release of SETI data in the history of the field, a heartening follow-through on a trend that broadens the audience for scientific research. Breakthrough Listen is presenting two publications in the scientific literature (available as full text, citation below) describing the results of three years of radio and optical observations, along with the availability of a petabyte of data from its work at the Green Bank instrument in West Virginia and the Parkes Radio Telescope in Australia. This covers a sample of 1327 nearby stars (within 160 light years from Earth) and builds on the team's results on 692 stars as presented in 2017. No signs of extraterrestrial civilizations turn...

If you want to look for possible artifacts of advanced civilizations, as do those practicing what is now being called Dysonian SETI, then it pays to listen to the father of the field. My friend Al Jackson has done so and offers a Dyson quote to lead off his new paper: "So the first rule of my game is: think of the biggest possible artificial activities with limits set only by the laws of physics and look for those." Dyson wrote that in a 1966 paper that repays study today (citation below). Its title: The Search for Extraterrestrial Technology." Dysonian SETI is a big, brawny zone where speculation is coin of the realm and the imagination is encouraged to be pushed to the limit. Jackson is intrigued, as are so many of us, with the idea of using the Sun's gravitational lens to make observations of other stars and their planets. Our recent email conversation brought up the name of Von Eshleman, the Stanford electrical engineer and pioneer in planetary and radio sciences who died two...

I'll wrap up this three-part series on 'lurker' probes and ways of finding them with Keith Cooper's provocative take on the matter. A contributor to Centauri Dreams whose far-ranging ideas have fueled a number of dialogues here (see the archives), Keith is editor of Astronomy Now and the author of the upcoming book The Contact Paradox: Challenging Assumptions in the Search for Extraterrestrial Intelligence. I've read the manuscript and can tell you that you're going to want this one on your shelves. Today, Keith takes us into the practical realm. If we were to find a Bracewell probe in our Solar System, what would we do with it? Who might discover it, who would claim its technologies, and what, under international law, would be its legal status? Plenty of material for science fiction plots here as we embark on the search to see what's out there among Earth's co-orbitals. by Keith Cooper It's enough to keep me awake at night. Suppose that an extraterrestrial probe is discovered in our...

One objection to SETI is that it is not falsifiable -- there is no point at which a lack of signals can prove that extraterrestrial civilizations do not exist. But there are some aspects of SETI that can be falsifiable. Consider a class of objects near enough for us to investigate not only with listening efforts but with probes, one small enough to be thoroughly covered, and one most people know almost nothing about. Could these offer a listening post for 'Bracewell probes,' a way of watching the development of our culture and reporting home to ETI? And if so, could we combine SETI with METI to advance both disciplines without compromising our own security? If the idea of nearby probes seems far-fetched today, it was even more so when Ronald Bracewell advanced his 'sentinel hypothesis.' Bracewell took the question of SETI and stood it on its ear. That was no mean feat in 1960, for SETI was just being born in that year through the efforts of Frank Drake at the Green Bank instrument in...

The question of whether or not we would recognize extraterrestrial life if we encountered it used to occupy mathematician and historian Jacob Bronowski (1908-1974), who commented on the matter in a memorable episode of his 1973 BBC documentary The Ascent of Man. "Were the chemicals here on Earth at the time when life began unique to us? We used to think so. But the most recent evidence is different. Within the last few years there have been found in the interstellar spaces the spectral traces of molecules which we never thought could be formed out in those frigid regions: hydrogen cyanide, cyano acetylene, formaldehyde. These are molecules which we had not supposed to exist elsewhere than on Earth. It may turn out that life had more varied beginnings and has more varied forms. And it does not at all follow that the evolutionary path which life (if we discover it) took elsewhere must resemble ours. It does not even follow that we shall recognise it as life — or that it will...

The search for technosignatures that could flag the presence of extraterrestrial cultures has accelerated in recent times with projects like Glimpsing Heat from Alien Technologies at Penn State and numerous papers. Or is the better term not 'cultures' but 'societies,' or 'civilizations'? SETI's funding challenges, at least from government agencies, point to the need for defining its terms in ways that NASA, for example, can live with. Nick Nielsen examines the question in today's essay, probing the issue of terminology in relation to public support, and noting the ongoing effort to evaluate and revise how SETI is described. Nielsen, a frequent Centauri Dreams contributor and a member of the board of directors for Icarus Interstellar, is a prolific writer who tracks these and other space-related issues in Grand Strategy: The View from Oregon, and Grand Strategy Annex. by J. N. Nielsen Recently there have been some signs that NASA may consider a rapprochement with SETI and SETI...

One of the more important things about the interstellar object called 'Oumuamua is the nature of the debate it has engendered. Harvard astronomer Avi Loeb's paper examining it as a possible technology has provoked comment throughout the scientific community, as witness Jason Wright's essay below. Dr. Wright (Penn State) heads the Glimpsing Heat from Alien Techologies (G-HAT) project, which he described in these pages, and is a key player in the rapidly developing field of Dysonian SETI, the study of possible artifacts as opposed to deliberate communications from extraterrestrial civilizations. Here he looks at the debate Loeb's work has engendered and its implications not only for how we do science but how we teach its values to those just coming into the field. Jason's essay was originally posted several days ago on his Astrowright blog, which should be a regular stop for Centauri Dreams readers. by Jason T. Wright Avi Loeb is the chair of the astronomy department at Harvard, a...

'Oumuamua continues to inspire questions and provoke media attention, not only because of its unusual characteristics, but because of the discussion that has emerged on whether it may be a derelict (or active) technology. Harvard's Avi Loeb examined the interstellar object in these terms in a paper with Shmuel Bialy, one we talked about at length in these pages (see 'Oumuamua, Thin Films and Lightsails). The paper would quickly go viral. Those who have been following his work on 'Oumuamua will want to know about two articles in the popular press in which Loeb answers questions. From the Israeli newspaper Ha'aretz comes an interview conducted by Oded Carmeli, while at Der Spiegel Johann Grolle asks the questions. From the latter, a snippet, in which Grolle asks Loeb what the moment would be like if and when humanity discovers an extraterrestrial intelligence. Loeb's answer raises intriguing questions: I can't tell you what this moment will look like. But it will be shocking. Because...

Seeking life on other worlds necessarily makes us examine our assumptions about the detectability of living things in extreme environments. We're learning that our own planet supports life in regions we once would have ruled out for survival, and as we examine such extremophiles, it makes sense to wonder how similar organisms might have emerged elsewhere. Pondering these questions in today's essay, Centauri Dreams regular Alex Tolley asks whether we are failing to consider possibly rich biospheres that could thrive without the need for surface water. By Alex Tolley Image: An endolithic lifeform showing as a green layer a few millimeters inside a clear rock. The rock has been split open. Antarctica. Credit: https://en.wikipedia.org/wiki/Endolith#/media/File:Cryptoendolith.jpg, Creative Commons). A policeman sees a drunk man searching for something under a streetlight and asks what the drunk has lost. He says he lost his keys and they both look under the streetlight together. After a...

Jill Tarter, an all but iconic figure in SETI, has just launched Technosearch, an Internet tool that includes all published SETI searches from 1960 to the present. A co-founder of the SETI Institute well known for her own research as well as her advocacy on behalf of the field, Tarter presents scientists with a way to track and update all SETI searches that have been conducted, allowing users to submit their own searches and keep the database current. The tool grows out of needs she identified in her own early research, as Tarter acknowledges: "I started keeping this search archive when I was a graduate student. Some of the original papers were presented at conferences, or appear in obscure journals that are difficult for newcomers to the SETI field to access. I'm delighted that we now have a tool that can be used by the entire community and a methodology for keeping it current." Image: Screenshot of the Radio List on https://technosearch.seti.org/. Among the materials included in...

One of the problems with optical SETI is interstellar extinction, the absorption and scattering of electromagnetic radiation. Extinction can play havoc with astronomical observations coping with gas and dust between the stars. The NIROSETI project (Near-Infrared Optical SETI) run by Shelley Wright (UC-San Diego) and team is a way around this problem. The NIROSETI instrument works at near-infrared wavelengths (1000 - 3500 nm), where extinction is far less of a problem. Consider infrared a 'window' through dust that would otherwise obscure the view, an advantage of particular interest for studies in the galactic plane. Would an extraterrestrial civilization hoping to communicate with us choose infrared as the wavelength of choice? We can't know, but considering its advantages, NIROSETI's instrument, mounted on the Nickel 1-m telescope at Lick Observatory, is helping us gain coverage in this otherwise neglected (for SETI purposes) band. I had the chance to talk to Dr. Wright at one of...

A new paper from Jason Wright (Penn State) and colleagues Shubham Kanodia and Emily Lubar deals with SETI and the 'parameter space' within which we search, with interesting implications. For the researchers show that despite searching for decades through a variety of projects and surveys, SETI is in early days indeed. Those who would draw conclusions about its lack of success to this point fail to understand the true dimensions of the challenge. But before getting into the meat of the paper, let's talk about a few items in its introduction. For Wright and team contextualize SETI in relation to broader statements about our place in the cosmos. We can ask questions about what we see and what we don't see, but we have to avoid being too facile in our interpretation of what some consider to be an 'eerie silence' (the reference is to a wonderful book by Paul Davies of the same name). Image: Penn State's Jason Wright. Credit: Jody Barshinger. Back in the 1970s, Michael Hart argued that...