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Upcoming Interstellar Sessions

by Paul Gilster | Mar 12, 2012 | Culture and Society | 3 Comments

It's shaping up to be an interesting week. I want to get to the recent Kepler data release, and also to the antimatter news from CERN, and I also want to talk about everything from decelerating an interstellar craft to models of expansion into the galaxy a la Frank Tipler. [And thanks to Centauri Dreams reader Eric Goldstein for reminding me of the upcoming WISE data release on the 14th!]. For today, though, let's look at two upcoming conferences, especially since I'm running behind in getting to the first of them, the CONTACT 2012 gathering, which is coming up right away. The full title of this one is CONTACT: Cultures of the Imagination, and it's a meeting with a rich history. Back in 1979, Jim Funaro was teaching a course in anthropology at Cabrillo College (Aptos, CA) that used science fiction as a vector into the scientific issues his course raised. The course allowed students to go to work creating cultures and, in a game-like simulation, to explore how the fictional societies...

Science Fiction and the Probe

by Paul Gilster | Mar 9, 2012 | Culture and Society | 30 Comments

Physicist Al Jackson, who is the world's greatest dinner companion, holds that title because amongst his scientific accomplishments, he is also a fountainhead of information about science fiction. No matter which writer you bring up, he knows something you never heard of that illuminates that writer's work. So it was no surprise that when the subject of self-replicating probes came up in these pages, Al would take note in the comments of Philip K. Dick's story "Autofac," which ran in the November, 1955 issue of H. L. Gold's Galaxy. A copy of that issue sits, I am happy to say, not six feet away from me on my shelves. This is actually the first time I ever anticipated Al -- like him, I had noticed "Autofac" as one of the earliest science fiction treatments of the ideas of self-replication and nanotechnology, and had written about it in my Centauri Dreams book back in 2004. If any readers know of earlier SF stories on the topic, please let me know in the comments. In the story, the two...

Intelligent Probes: The Spread-Spectrum Challenge

by Paul Gilster | Mar 8, 2012 | Astrobiology and SETI | 21 Comments

Let's imagine for a moment that John Mathews (Pennsylvania State University) is right in theorizing that space-faring civilizations will use self-reproducing probes to expand into the galaxy. We've been kicking the issues around most of this week, but the SETI question continues to hang in the background. For if there really are extraterrestrial civilizations in the nearby galaxy, how would we track down their signals if they used the kind of communications network Mathews envisions, one in which individual probes talked to each other through tight-beam laser communications designed only for reception by the network itself? One problem is that the evidence we're looking for would most likely come in the form of spread-spectrum signals, a fact Jim Benford pointed out in a comment to my original post on Mathews, and one that also pointed to recent work by David Messerschmitt (UC-Berkeley). The latter makes a compelling case for spread-spectrum methods as the basis for interstellar...

SETI and Self-Reproducing Probes

by Paul Gilster | Mar 7, 2012 | Astrobiology and SETI | 14 Comments

It was back in the 1980s when Robert Freitas came up with a self-reproducing probe concept based on the British Interplanetary Society's Project Daedalus, but extending it in completely new directions. Like Daedalus, Freitas' REPRO probe would be fusion-based and would mine the atmosphere of Jupiter to acquire the necessary helium-3. Unlike Daedalus, REPRO would devote half its payload to what Freitas called its SEED package, which would use resources in a target solar system to produce a new REPRO probe every 500 years. Probes like this could spread through the galaxy over the course of a million years without further human intervention. A Vision of Technological Propagation I leave to wiser heads than mine the question of whether self-reproducing technologies like these will ever be feasible, or when. My thought is that I wouldn't want to rule out the possibility for cultures significantly more advanced than ours, but the question is a lively one, as is the issue of whether...

Robotic Networks Among the Stars

by Paul Gilster | Mar 6, 2012 | Missions | 62 Comments

Imagine a future in which we manage to reach average speeds in the area of one percent of the speed of light. That would make for a 437-year one-way trip to the Alpha Centauri system, too long for anything manned other than generation ships or missions with crews in some kind of suspended animation. Although 0.01c is well beyond our current capabilities, there is absolutely nothing in the laws of physics that would prevent our attaining such velocities, assuming we can find the energy source to drive the vehicle. And because it seems an achievable goal, it's worth looking at what we might do with space probes and advanced robotics that can move at such velocities. How, in other words, would a spacefaring culture use artificial intelligence and fast probes to move beyond its parent solar system? John Mathews ( Pennyslvania State) looks at the issue in a new paper, with a nod to the work of John von Neumann on self-reproducing automata and the subsequent thoughts of Ronald Bracewell...

Oxygen Detected at Saturn’s Moon Dione

by Paul Gilster | Mar 5, 2012 | Uncategorized | 7 Comments

We recently looked at biosignatures as part of a discussion about using polarized light to examine exoplanet atmospheres. As if on cue, we now get a reminder of how carefully the biosignature hunt must proceed. It's not enough, for example, to find one or two interesting gases in a distant atmosphere, for natural processes can account for potential biomarkers, which is why we need to find gases like ozone and methane, oxygen and carbon dioxide existing simultaneously. The most recent discovery from Cassini data puts an exclamation point on the matter with the discovery of molecular oxygen ions in the thin atmosphere of Dione, one of Saturn's 62 moons. With a radius of no more than 560 kilometers, Dione is evidently composed of a layer of water ice surrounding a rocky core. We are not, obviously, talking about a thick atmosphere around a world this small. Cassini and its CAPS instrument (Cassini Plasma Spectrometer) closed to within 503 kilometers of the surface in April of 2010,...

A New Take on Planet Formation

by Paul Gilster | Mar 2, 2012 | Exoplanetary Science | 10 Comments

Figuring out how planets form is an old occupation, with the basic ideas of planetary accretion going back several centuries, though tuned up, to be sure, in the 1970s and tweaked ever since. In a disk of gas and dust orbiting a young central star, dust grains begin to clump together, eventually forming planetesimals. Accretion models assume that these small planetesimals bang into each other and gradually grow. The assumption is that in the inner system at least temperatures are hot and the era of planet formation occurs well after the central star has formed. Image: Artist's conception of a protoplanetary disk. Credit: NASA/JPL-Caltech/T. Pyle. Adjust for distance from the star and subsequent planetary migration in the gas/dust disk and you can come up with a system more or less like ours, with rocky inner worlds and gas giants out beyond the snow line, the latter being the distance from the star where it is cool enough for volatile icy compounds to remain solid. But Anne...

Finding Life Through Polarized Light

by Paul Gilster | Mar 1, 2012 | Exoplanetary Science | 16 Comments

One of these days we're going to have a new generation of telescopes, some in space and some on the Earth, that can analyze the atmosphere of a terrestrial world around another star. It's not enough to find individual gases like oxygen and ozone, carbon dioxide or methane. Any of these can occur naturally without ramifications for life. But finding all of these gases in the same atmosphere is telling, because without life to replenish them, some would disappear. Getting the data is going to be hard, which is why new work using the European Southern Observatory's Very Large Telescope is so interesting. The work involves 'Earthshine,' the reflection of sunlight off the Earth that is in turn reflected off the surface of the Moon. It's faint, to be sure, but Earthshine is visible in a crescent Moon when the light of the entire lunar disc is visible although only the crescent is brightly lit. Michael Sterzik (ESO) and team have used Earthshine to analyze our own planet's biosignature, and...

Remembering an Astronautical Pioneer

by Paul Gilster | Feb 29, 2012 | Culture and Society | 6 Comments

by Claudio Maccone Physicist Les Shepherd, whose funeral is today, left friends throughout the astronautical community. Claudio Maccone, who worked with Shepherd on many occasions, was quick to offer his recollections of this remarkable man whose standards of excellence and unflagging support helped many young scientists as they embarked on careers in space science. A young guy (44 years old, i.e. "young" by IAA standards) joins the IAA Interstellar Space Exploration Committee (ISEC) headed by Les Shepherd and Giovanni Vulpetti: that happened at the World Space Congress in Washington, D.C., USA, also known as the 43rd IAC, August 28 - September 5, 1992). I was then working at Alenia Spazio SpA in Torino (Turin), Italy, and I had this secret love for future interstellar space missions ("secret" since at my space company nobody was interested, of course). So, I consulted with my good old friend and "teacher" (he is senior than I) Giovanni Vulpetti, who was in a similar position at...

Les Shepherd, RIP

by Paul Gilster | Feb 28, 2012 | Culture and Society | 5 Comments

There are so many things to say about Les Shepherd, who died on Saturday, February 18, that I scarcely know where to begin. Born in 1918, Leslie Robert Shepherd was a key player in the creation of the International Astronautical Federation (IAF), becoming its third president in 1957 -- this was at the 8th Congress in Barcelona just a week after the launch of Sputnik -- and in 1962 he would be called upon to serve as its president for a second time. A specialist in nuclear fission who became deeply involved in nuclear reactor technology, Shepherd was one of the founding members of the International Academy of Astronautics (IAA), and served as chairman of the Interstellar Space Exploration Committee, which met for the first time at the 1984 IAF Congress in Lausanne, Switzerland. The IAF Congress in Stockholm the following year was the scene of the first ISEC symposium on interstellar flight, one whose papers were subsequently collected in one of the famous 'red cover' issues of the...

Project Icarus: Contemplating Starship Design

by Paul Gilster | Feb 27, 2012 | Missions | 68 Comments

Andreas Tziolas, current leader of Project Icarus, gave a lengthy interview recently to The Atlantic's Ross Andersen, who writes about starship design in Project Icarus: Laying the Plans for Interstellar Travel. Icarus encounters continuing controversy over its name, despite the fact that the Icarus team has gone to some lengths to explain the choice. Tziolas notes the nod to Project Daedalus leader Alan Bond, who once referred to "the sons of Daedalus, perhaps an Icarus, that will have to come through and make this a much more feasible design." I like that sense of continuity -- after all, Icarus is the follow-on to the British Interplanetary Society's Project Daedalus of the 1970s, the first serious attempt to engineer a starship. I also appreciate the Icarus' team's imaginative re-casting of the Icarus myth, which imagines a chastened Icarus washed up on a desert island planning to forge wings out of new materials so he can make the attempt again. But what I always fall back on is...

FTL Neutrinos: Closing In on a Solution

by Paul Gilster | Feb 24, 2012 | Exotic Physics | 56 Comments

The news that the faster-than-light neutrino results announced to such widespread interest by the OPERA collaboration have now been explained has been spreading irresistibly around the Internet. But the brief piece in ScienceInsider that broke the news was stretching a point with a lead reading "Error Undoes Faster-Then-Light Neutrino Results." For when you read the story, you see that a fiber optic cable connection is a possible culprit, though as yet an unconfirmed one. Sean Carroll (Caltech) blogged on Cosmic Variance that while he wanted to pass the news along, he was reserving judgment until a better-sourced statement came to hand. I've thought since the beginning that a systematic error would explain the 'FTL neutrino' story, but I still was waiting for something with more meat on it than the ScienceInsider news. It came later in the day with an official CERN news release, and this certainly bears quoting: The OPERA collaboration has informed its funding agencies and host...

M-Dwarfs: A New and Wider Habitable Zone

by Paul Gilster | Feb 23, 2012 | Exoplanetary Science | 18 Comments

I want to work a new paper on red dwarf habitability in here because it fits in so well with yesterday's discussion of the super-Earth GJ1214b. The latter orbits an M-dwarf in Ophiuchus that yields a hefty 1.4 percent transit depth, meaning scientists have a strong lightcurve to work with as they examine this potential 'waterworld.' In transit terms, red dwarfs, much smaller and cooler than the Sun, are compelling exoplanet hosts because any habitable worlds around them would orbit close to their star, making transits frequent. When I first wrote about red dwarfs and habitability in my Centauri Dreams book, it was in connection with the possibilities around Proxima Centauri, but of course we can extend the discussion to M-dwarfs anywhere, this being the most common type of star in the galaxy (leaving brown dwarfs out of the equation until we have a better idea of their prevalence). Manoj Joshi and Robert Haberle had published a paper in 1997 that described their simulations for...

A Waterworld Around GJ1214

by Paul Gilster | Feb 22, 2012 | Exoplanetary Science | 42 Comments

I love the way Zachory Berta (Harvard-Smithsonian Center for Astrophysics) describes his studies of the transiting super-Earth GJ1214b. Referring to his team's analysis of the planet's atmosphere, Berta says "We're using Hubble to measure the infrared color of sunset on this world." And indeed they have done just this, discovering a spectrum that is featureless over a wide range of wavelengths, allowing them to deduce that the planet's atmosphere is thick and steamy. The conclusion most consistent with the data is a dense atmosphere of water vapor. Discovered in 2009 by the MEarth project, GJ1214b has a radius 2.7 times Earth's and a mass 6.5 times that of our planet. It's proven to be a great catch, because its host star, an M-dwarf in the constellation Ophiuchus, offers up a large 1.4 percent transit depth -- this refers to the fractional change in brightness as the planet transits its star. Transiting gas giants, for example, usually have transit depths somewhere around 1 percent,...

Black Hole Flags Galactic Collision

by Paul Gilster | Feb 21, 2012 | Deep Sky Astronomy & Telescopes | 8 Comments

HLX-1 (Hyper-Luminous X-ray source 1) is thought to be a black hole, one that's a welcome discovery for astronomers trying to puzzle out the mysteries of black hole formation. Located roughly 290 million light years from Earth and situated toward the edge of a galaxy called ESO 243-49, this black hole looks to be some 20,000 times the mass of the Sun, which makes it mid-sized when compared with the supermassive black holes at the center of many galaxies. The latter can have masses up to billions of times more than the Sun -- the black hole at the center of our own galaxy is thought to comprise about four million solar masses. Just how a supermassive black hole forms remains a subject for speculation, but study of HLX-1 is giving us clues that point in the direction of a series of mergers of small and mid-sized black holes. For it turns out that HLX-1, discovered by Sean Farrell (Sydney Institute for Astronomy in Australia and University of Leicester, UK) and team at X-ray...

Jupiter’s Protective Role Questioned

by Paul Gilster | Feb 20, 2012 | Outer Solar System | 24 Comments

How likely are we to find other planets in the universe that are as habitable as Earth? One key to the puzzle has long been thought to be the presence of Jupiter in our own Solar System. In fact, the presence of the giant planet has become a player in the so-called 'rare Earth' argument that sees Jupiter as just one factor that makes our Solar System unique. Put a gas giant in the proper position in any solar system and, so the argument goes, dangerous objects from the outer system will be deflected, protecting the inner planets and allowing life to flourish. The issue gets a hard look from Jonathan Horner (University of New South Wales) and Barrie Jones (The Open University, UK) in a paper delivered in Canberra in September of 2011. Jupiter as protector has a certain appeal. Voyager, Galileo and other probes have shown us a massive planet that is otherwise cold and forbidding, but a world with enough mass to have huge effects on other objects in the Solar System. Horner and Jones...

Alpha Centauri B: A Close Look at the Habitable Zone

by Paul Gilster | Feb 17, 2012 | Exoplanetary Science | 68 Comments

The dreams of Alpha Centauri I used to have as a boy all focused on visual effects. After all, the distance between Centauri A and B ranges from 11.4 to 36.0 AU. What would it be like to have a second star in our Solar System, one that occasionally closed to a little more than Saturn’s distance from the Sun? What would a day be like with two stars, and even more, what would night be like with a star that close lighting up the landscape? I also wondered about how much effect a second star would have on the planets in our system, curious as I was about gravitational effects and even the possible repercussions for weather and seasonal change. Image: The Alpha Centauri star system and other objects near it in the sky. Image copyright Akira Fujii / David Malin Images. You can imagine, then, that Duncan Forgan’s new paper hit close to home. Forgan (University of Edinburgh) has taken discussions of habitability around Centauri B to a new level by analyzing the effect of Centauri A on...

‘Light Echo’ Reveals Eta Carinae Puzzle

by Paul Gilster | Feb 16, 2012 | Deep Sky Astronomy & Telescopes | 2 Comments

Luminous Blue Variables are large, bright stars that give rise to periodic eruptions, like the so-called “Great Eruption” of Eta Carinae that was first noted in 1837 and continued to be observed for an additional 21 years. Things must have been lively around the companion star thought to orbit in the nebula around Eta Carinae, for the LBV blew off about 20 solar masses in this era, mimicking a supernova as it became the second brightest star in the sky. We’ve witnessed similar ‘supernova impostor’ events in other galaxies, but at 7500 light years, the Eta Carinae system is relatively nearby, allowing close study by Hubble and other telescopes. What brings Eta Carinae’s 1837 event back into the news is the use of so-called ‘light echoes’ to study what happened at a time when astronomy was in a much earlier state. Armin Rest (Space Telescope Science Institute) notes how useful the work is turning out to be: "When the eruption was seen on Earth 170 years ago, there were no cameras...

A Haze at Galactic Center

by Paul Gilster | Feb 15, 2012 | Deep Sky Astronomy & Telescopes | 3 Comments

The Planck mission continues to peel the layers off the onion as it probes the early universe. Planck is all about the Cosmic Microwave Background (CMB), that radiation left over from the era of recombination around 380,000 years after the Big Bang. As electrons and protons began to form neutral atoms, light was freed to stream through the universe, an afterglow of the Big Bang that missions like the Wilkinson Microwave Anisotropy Probe have studied in detail, and which Planck will now observe at still better sensitivity, angular resolution and frequency range. But the initial job for researchers is to remove sources of foreground emission to reveal the CMB itself, and that process is turning up interesting findings in its own right. The latest announcement from the European Space Agency involves a haze of microwaves that is not yet understood. Coming from the region around galactic center, the haze appears to be synchrotron emission, produced as electrons accelerated in supernovae...

KBOs: Surveying the Southern Skies

by Paul Gilster | Feb 14, 2012 | Deep Sky Astronomy & Telescopes | 13 Comments

Given yesterday's post on wandering planets, otherwise known as 'rogue' planets or 'nomads,' today's topic falls easily into place. For even as we ponder the possibility of 105 rogue planets at Pluto's mass or above for every main sequence star in the galaxy, we confront the fact that we still have much to learn about objects much closer to home in our own Kuiper Belt. We have yet, for example, to have a flyby, although it's possible the New Horizons spacecraft will line up on a useful target after its encounter with Pluto/Charon (and yes, it's conceivable that Triton is a captured KBO, and thus we have had a Voyager flyby). The discovery of objects like Sedna, Makemake and Eris makes it clear how much we may yet uncover. We can think of the broader category of Trans-Neptunian Objects (TNOs) in terms of potential mission targets, but we should also ponder the fact that their strong dynamical connection with the planets can help us gain insight into the mechanics of Solar System and...

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In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).

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