Yesterday's post about planets in red dwarf systems examined the idea that the slow formation rate of these small stars would have a huge impact on planets that are today in their habitable zone. We can come up with mechanisms that might keep a tidally locked planet habitable, but what do we do about the severe effects of water loss and runaway greenhouse events? Keeping such factors in mind plays into how we choose targets -- very carefully -- for future space telescope missions that will look for exoplanets and study their atmospheres. But the question of atmospheres on early worlds extends far beyond what happens on M-dwarf planets. At MIT, Hilke Schlichting has been working on what happened to our own Earth's atmosphere, which was evidently obliterated at least twice since the planet's formation four billion years ago. In an attempt to find out how such events could occur, Schlichting and colleagues at Caltech and Hebrew University have been modeling the effects of impactors that...

As the Thanksgiving holiday approaches here in the US, I'm looking at a new paper in the journal Anthropocene that calls the attention of those studying sustainability to the discipline of astrobiology. At work here is a long-term perspective on planetary life that takes into account what a robust technological society can do to affect it. Authors Woodruff Sullivan (University of Washington) and Adam Frank (University of Rochester) make the case that our era may not be the first time "...where the primary agent of causation is knowingly watching it all happen and pondering options for its own future." How so? The answer calls for a look at the Drake Equation, the well-known synthesis by Frank Drake of the factors that determine the number of intelligent civilizations in the galaxy. What exactly is the average lifetime of a technological civilization? 500 years? 50,000 years? Much depends upon the answer, for it helps us calculate the likelihood that other civilizations are out there,...

Last year the New Frontiers in Astronomy & Cosmology program, set up by the John Templeton Foundation as a grant-awarding organization, dispensed three grants with a bearing on what Clément Vidal calls 'Zen SETI.' The idea of looking into our astronomical data and making new observations to track possible signs of an extraterrestrial civilization at work is not new, and yesterday we looked at Freeman Dyson's early contribution. Carl Sagan and Josif Shklovskii are also among those in a lineage we can extend back at least to the early 20th Century. The recent grants show a gathering momentum for extending SETI in new directions. The team of Jason Wright (Pennsylvania State) and colleagues Steinn Sigurðsson and Matthew Povich is embarking on a hunt for Dyson spheres, which if observed in a distant galaxy colonized by a Kardashev Type III civilization, should throw an unmistakable signature in the infrared. Could we find such an object in our data from WISE, the Wide-field...

If we're trying to extend the boundaries of the search for extraterrestrial intelligence, how do we proceed? A speculative mind is essential, and one of the delights of science fiction is the ability to move through an unrestricted imaginative space, working out the ramifications of various scenarios. But we have to prioritize what we're doing, which is why Freeman Dyson settled on the idea of looking for conspicuous examples of intelligence using technology. It's no surprise that the term 'Dysonian SETI' has arisen to describe how such a search might proceed. The Dyson sphere is a case in point. We can imagine a civilization vastly more ancient and technologically adept than our own deciding to maximize the amount of power it can draw from a star. Although Dyson spheres are sometimes pictured as shells completely surrounding a star, Dyson's ideas are more readily thought of in terms of a 'swarm' of objects soaking up as much power as possible. Other configurations are in the mix,...

The SETI challenge has often been likened to archaeology, and for good reason. In both cases, we are trying to recover information about cultures from the past. When Heinrich Schliemann dug into the numerous layers of Troy -- and in the process inadvertently damaged precious remnants of later eras -- he and his team were exploring the heroic age of Homer. Any SETI detection will likewise deal with a signal from the past. Just how old it is will depend upon how far away the source world is, for this information travels at the speed of light. The archaeology analogy is hardly perfect, because on Earth we are dealing with artifacts of our own species and are often working with linguistic remains we can decipher to aid our understanding. Figuring out Egyptian hieroglyphs wasn’t easy, but the stele known as the Rosetta Stone gave us a text in three scripts that helped us make sense of them. Even Linear B, the script of the Mycenaean Greeks before the emergence of the Greek alphabet, can...

With one interstellar conference in the books for 2014, I'll be headed next for the Tennessee Valley Interstellar Workshop, whose upcoming gathering will be held in Oak Ridge this November. Last week's coverage of the 100 Year Starship Symposium in Houston has allowed several interesting stories to back up in the queue, and I'll spend the next few days going over some of the latest findings, starting with the discovery that a large fraction of the water in Earth's oceans may be substantially older than we think. The results make a strong case for water as a common ingredient in planet formation no matter where the planet forms or around what kind of star. Ilsedore Cleeves (University of Michigan) is lead author on the new paper in Science that argues the case. What Cleeves and colleagues have found is that up to half of the water in our Solar System formed before the Sun itself emerged from the primordial gas and dust cloud that gave it birth. That encompasses more than the Earth's...

Gatherings like the 100 Year Starship Symposium have tough organizational choices to make, and the solutions aren't always obvious. A good part of any aerospace conference is involved in presenting papers, but do you set up a multi-track system or take a single-track approach? In Houston, the 100 Year Starship organization chose multiple tracks: We had, for example, a track on Life Sciences, one on Data Communications, another on Propulsion & Energy, and there were several others including a useful track on Interstellar Education. The problem is that with all these tracks running at once, it was a matter of picking and choosing, and that often meant getting up after a presentation, switching rooms, and entering another track. I missed papers in Kathleen Toerpe's Education track that I wanted to hear because I needed to hear many of the Propulsion & Energy papers, and while I caught a paper in the Becoming an Interstellar Civilization track, it was at the expense of some promising...

I like George Johnson's approach toward SETI. In The Intelligent-Life Lottery, he talks about playing the odds in various ways, and that of course gets us into the subject of gambling. What are the odds you'll hit the right number combination when you buy a lottery ticket? Whenever I think about the topic, I always remember walking into a casino one long ago summer on the Côte d'Azur. I've never had the remotest interest in gambling, and neither did the couple we were with, but my friend pulled a single coin out of his pocket and said he was going to play the slots. "This is it," he said, holding up the coin, a simple 5 franc disk (this was before the conversion to the Euro). "No matter what happens, this is all I play." He went up to the nearest slot machine and dropped the coin in. Immediately lights flashed and bells rang, and what we later calculated as the equivalent of about $225 came pouring out. Surely, I thought, he'll take at least one of these coins and play it again --...

We tend to assume that our mistakes as a species flag us as immature, a young civilization blundering about with tools it is misusing on a course that may lead to extinction. But assume for a moment that an intelligent extraterrestrial civilization goes through phases more or less like our own. If we're sifting through radio signals and looking for optical flashes to find them, shouldn't we consider other ways such a civilization announces itself? What if we're not the only polluters in the universe, for example, and other cultures are making the same mistakes? In a 2010 paper, Jean Schneider (Observatoire de Paris-Meudon) and colleagues noted the possibility of using pollutants as a way of moving beyond biosignatures to find ETI. Let me quote from the paper: ...another type of far from equilibrium signals can be seen as techno-signatures, i.e., spectral features not explained by complex organic chemistry, like laser emissions. In the present state of our knowledge one cannot...

How do you produce life on an early Earth bathed in ultraviolet radiation? The presumption when I was growing up was that the combination of chemicals in ancient ponds, fed energy by lightning or ultraviolet light itself, would produce everything needed to start the process. Thus Stanley Miller and Harold Urey's experiments, beginning in 1953 at the University of Chicago, which simulated early Earth conditions to produce amino acids out of a sealed 'atmosphere' of water, ammonia, methane and hydrogen, with electrodes firing sparks to simulate lightning. But there are other ways of explaining life's origins, as a new study from the Jet Propulsion Laboratory and the Icy Worlds Team at the NASA Astrobiology Institute reminds us. Hydrothermal vents on the sea floor have been under consideration since the 1980s, with some researchers pointing to the 'black smokers' that produce hot, acidic fluids. The new NASA work looks at much cooler vents bubbling with alkaline solutions like those in...

A big reason why the Fermi paradox has punch is the matter of time. Max Tegmark gets into this in his excellent new book Our Mathematical Universe: My Quest for the Ultimate Nature of Reality (Knopf, 2014), where he runs through what many thinkers on the subject have noted: Our Sun is young enough that countless stars and the planets that orbit them must have offered homes for life long before we ever appeared. With at least a several billion year head start, wouldn't intelligent life have had time to spread, and shouldn't its existence be perfectly obvious by now? Tegmark's book is fascinating, and if you're interested in learning why this dazzling theorist thinks it likely we are the only intelligent life not just in our galaxy but in our universe, I commend it to you (although Fermi issues play only the tiniest of roles in its overall themes). I'll have plenty of occasion to get into Tegmark's ideas about what he believes to be not just a multiverse but a multiply-staged...

I see a lot to like about Abraham Loeb’s new paper “The Habitable Epoch of the Early Universe,” available as a preprint and now going through the submission process at Astrobiology. Not that it isn’t controversial, and for reasons that are patently obvious as soon as one digs into it. But the sheer chutzpah of postulating that microbial life might have started up no more than ten or fifteen million years after the Big Bang takes the breath away. This is a notion that extends life so far back that it defies our conventional models of how it formed. Temperatures aren’t the problem, given that radiation in the early universe would have produced cozy conditions for a multi-million year window of time as what is now called the cosmic microwave background (CMB) continued to cool. The problem is that we have to get from hydrogen and the helium created by fusion in the Big Bang furnace to heavy elements that are usually explained by large stars seeding the cosmos with supernovae explosions....

I first ran across David Messerschmitt's work in his paper "Interstellar Communication: The Case for Spread Spectrum," and was delighted to meet him in person at Starship Congress in Dallas last summer. Dr. Messerschmitt has been working on communications methods designed for interstellar distances for some time now, with results that are changing the paradigm for how such signals would be transmitted, and hence what SETI scientists should be looking for. At the SETI Institute he is proposing the expansion of the types of signals being searched for in the new Allen Telescope Array. His rich discussion on these matters follows. By way of background, Messerschmitt is the Roger A. Strauch Professor Emeritus of Electrical Engineering and Computer Sciences at the University of California at Berkeley. For the past five years he has collaborated with the SETI institute and other SETI researchers in the study of the new domain of "broadband SETI", hoping to influence the direction of SETI...

Although I didn’t write about the so-called ‘Shkadov thruster’ yesterday, it has been on my mind as one mega-engineering project that an advanced civilization might attempt. The most recent post was all about moving entire stars to travel the galaxy, with reference to Gregory Benford and Larry Niven’s Bowl of Heaven (Tor, 2012), where humans encounter an object that extends and modifies Shkadov’s ideas in mind-boggling ways. I also turned to a recent Keith Cooper article on Fritz Zwicky, who speculated on how inducing asymmetrical flares on the Sun could put the whole Solar System into new motion, putting our star under our directional control. The physicist Leonid Shkadov described a Shkadov thruster in a 1987 paper called “Possibility of Controlling Solar System Motion in the Galaxy” (reference at the end). Imagine an enormous mirror constructed in space so as to reflect a fraction of the star’s radiation pressure. You wind up with an asymmetrical force that exerts a thrust upon...

David Brin is a familiar name to science fiction readers worldwide, the award-winning author of the highly regarded 'uplift' novels that include Startide Rising (1983), The Uplift War (1987) and Brightness Reef (1995). Among his numerous other titles are The Postman (1985), Kiln People (2002) and Existence (2012). But Brin is also known as a futurist whose scientific work ranges over topics in astronautics and astronomy to forms of dispute resolution and the role of neoteny in human evolution. His Ph.D in Physics from the University of California at San Diego followed a masters in optics and an undergraduate degree in astrophysics from Caltech. He was a postdoctoral fellow at the California Space Institute and the Jet Propulsion Laboratory. Brin has served on advisory committees dealing with subjects as diverse as national defense, space exploration, SETI and nanotechnology, future/prediction and philanthropy. His essay The Great Silence (available here) is but one of his many...

Pardon this extended introduction to Jim Benford's response to Nick Nielsen's Friday essay, but it comes at a serendipitous time. Jim's recent online work has reminded me that we in the interstellar community need to work to see that as many resources as possible are made available online. In the absence of specialized bibliographies, useful information can be hard to find in more general indices. And it's always dismaying to read an intriguing abstract only to realize that the paper itself is behind a pricey firewall. Access to academic libraries certainly helps, but online databases still vary in what they make available, which is why I always check the home pages of the authors of a given paper to see if they have posted a copy of their work themselves. Scientists can do much to get the word out, as Jim's new site attests. You'll find it at http://jamesbenford.com/. Over the weekend, after Nick had discussed METI (Messaging to Extraterrestrial Intelligence) on Friday, I resorted...

To broadcast or not to broadcast? The debate over sending intentional signals to other stars continues to simmer even as various messages are sent, with no international policy in place to govern them. Writer Nick Nielsen looks at METI afresh today, placing it in the context of existential risk and pondering the implications of what David Brin has dubbed the 'Great Silence.' If risk aversion is our primary goal, do we open ourselves to a future of permanent stagnation? Or is announcing ourselves to the universe something we have any real control over, given the ability of an advanced civilization to detect our presence whether we send messages or not? Mr. Nielsen, a contributing analyst with online strategic consulting firm Wikistrat, wonders whether our counterparts around other stars aren't wrestling with the same issues. by J. N. Nielsen At the Icarus Interstellar Starship Congress in Dallas last August I had the good fortune to be present for James Benford's talk about METI,...

In a recent paper outlining a novel strategy for SETI, Michael Gillon (Université de Liège) makes a statement that summarizes what Robert Forward began saying back in the 1970s and even earlier. Interstellar flight is extraordinarily difficult, but not beyond the laws of physics: Our technology is certainly not yet mature enough to build a probe able to reach one of the nearest stars in a decent time (i.e. within a few decades), but nothing in our physical theories precludes such a project. On the contrary, the constant progress in the fields of space exploration, nanotechnology, robotics and electronics, combined with the development of new possible energy sources like fusion reactors or solar sails, indicate that interstellar exploration could become a technological possibility in the future, provided that our civilization persists long enough. That last issue about the survival of our society is the L variable in the Drake equation, referring to the lifespan of any...

It was back in 2010 that Nir Goldman (Lawrence Livermore National Laboratory) first predicted that the impact of a comet on the early Earth could produce potential life-building compounds like amino acids. Goldman was using computer simulations to make the call, studying molecular dynamics under the conditions of such impacts. He found that the shock of impact itself should produce amino acids and other prebiotic compounds, regardless of conditions on the planet. It was intriguing work because it suggested that impacts in the outer system (think Enceladus, for example) could produce enough energy to create the shock synthesis of prebiotics there. Now Goldman, working with collaborators from Imperial College London and the University of Kent, has gone beyond the simulations to test the process in the laboratory. By firing a projectile into a mixture comparable to the material found on a comet -- water, ammonia, methanol and carbon dioxide -- the team was able to produce several...

Michael Michaud is no stranger to these pages, with a number of prior contributions and a reputation that precedes him in the field of SETI and interstellar research at large. Among his accomplishments are a lengthy career in the U.S. Foreign Service, where he served as Counselor for Science, Technology and Environment at U.S. embassies in Paris and Tokyo, and Director of the State Department's Office of Advanced Technology. His involvement with SETI is lengthy and includes chairing working groups at the International Academy of Astronautics and numerous articles and papers. His book Contact with Alien Civilizations: Our Hopes and Fears about Encountering Extraterrestrials (Springer, 2007) is an indispensable contribution to the growing body of SETI literature. Today Michael reflects on the life of his friend and colleague John Billingham, who died on August 4 at the age of 83. by Michael Michaud One of the true pioneers of SETI has left us. John Billingham played a major role in...