Archives

Starships, Pubs and Sir Arthur

by Paul Gilster | Mar 19, 2008 | Culture and Society | 13 Comments

I'm a great believer in getting back to work when bad news hits, and I suspect Arthur C. Clarke was as well. His almost 100 books surely attest to the fact. With intriguing exoplanet news about to be released, that is exactly what I've been doing this morning, with an article I'll post tomorrow. As I've been developing that story, I've kept pondering what to say about Clarke, working up a kind of reminiscence in the back of my mind, then deciding everything was happening too fast for that. Not that his death was a surprise, Sir Arthur having been ill for quite some time, but the thought of a world without Clarke in it takes a bit of getting used to. I'll need some time to take its measure. Oddly, my favorite of his books was the relatively obscure 1957 collection Tales from the White Hart. The yarns in this slim volume involve one Harry Purvis, like Clarke a polymath who deals knowledgeably on most any subject, and a man whose improbable accounts flummox the ready audience in the...

Arthur C. Clarke, R.I.P.

by Paul Gilster | Mar 18, 2008 | Culture and Society | 14 Comments

No time this evening to do anything more than pass along the sad news that we have lost one of our greatest visionaries. The BBC has the story, and the New York Times offers a lengthy obituary.

If the Phone Doesn’t Ring, It’s Me

by Paul Gilster | Mar 18, 2008 | Astrobiology and SETI | 58 Comments

The line in the title above is from a Jimmy Buffett song. A friend who knows all Buffett songs line by line uses it on his answering machine, invariably provoking a chuckle when I ponder the implications. If the phone doesn't ring, just what kind of message is being sent? Or is any message being sent at all? Thus does the singer capture the bewildered funk of romantic attachments, which can make hash out of all our logic. Like the dog that doesn't bark (think Sherlock Holmes), the phone that doesn't ring carries its own meaning, one we must now try to parse. For the SETI phone isn't ringing. If extraterrestrial civilizations are out there, is their silence a way of sending us a message? Alan Tough created a Web site with the express purpose of offering a communications venue to any nearby alien probes, spacecraft designed to study us and report home. The Invitation to ETI contains a number of essays explaining the project and more or less asking for participation by ET (Paul Davies'...

Organics, Water in Protoplanetary Disk

by Paul Gilster | Mar 17, 2008 | Exoplanetary Science | 17 Comments

We have interesting news coming up this week with regard to the first detection of methane in the atmosphere of an exoplanet, of significance because it demonstrates that we can detect organic molecules using spectroscopy in ways that will one day help us study the atmospheres of terrestrial worlds around other stars. More on this later in the week, after a NASA teleconference scheduled for the 19th. Today, though, let's talk about another kind of detection in the circumstellar disk of a young star. At work in the latter is the Spitzer Space Telescope's infrared spectrograph, which is being put to use to look at the composition of protoplanetary disks. Specifically, John Carr (Naval Research Laboratory) and Joan Najita (National Optical Astronomy Observatory, Tucson) have been examining gases in the planet forming region around the star AA Tauri, using refined methods that have allowed them to find the spectral signatures of three organic molecules: Hydrogen cyanide, acetylene and...

Human Outcomes Among the Stars

by Paul Gilster | Mar 15, 2008 | Culture and Society | 65 Comments

Does transhumanism have a serious objective? The question resonates oddly yet provocatively given the stakes being considered. Augmenting the human frame potentially expands our powers, while the goal of uploading consciousness seems to offer a kind of immortality. These are surely desirable steps, but some versions of a posthuman future seem to point toward triviality, an existence within a simulated reality within a computational matrix, an awareness that sees no need to explore when simulation and observation can suffice. Can we avoid such a result? I have a visceral, non-digital sense that a 'singularity,' if it occurs, will not include pushing minds evolved over eons to cope with a physical biosphere into digital frameworks. I doubt seriously that a human consciousness could make the adaptation -- madness is the likely result. Hardly an expert on any of the relevant disciplines, I could well be wrong, but I noted Athena Andreadis' thoughts on this issue in a recent entry on her...

Time, Tides and Habitability

by Paul Gilster | Mar 14, 2008 | Exoplanetary Science | 16 Comments

Keep your eye on Gliese 581. Not that the news is necessarily good for our hopes for habitability around that star -- in fact, a recent paper suggests quite the opposite. The red dwarf exploded into the public consciousness with the announcement that one of its planets -- Gl 581 c -- could conceivably support clement temperatures and water at the surface, at least in places. But in exploring that possibility, we're getting a case study of world-class science at work, analyzing data, offering hypotheses, broadening options. It's an exciting process to watch. Gl 581 d is now being analyzed for habitability, while Gl 581 c begins to appear less and less likely as a home to life. It may take decades and new space-based observatories for the issue to be resolved, but we now have a new take on Gl 581 c, embedded in a broader study of tidal evolution as planetary systems evolve. The study has implications not just for rocky worlds but for planetary formation in many scenarios. The work of...

Cassini: Close Pass Skirts Enceladus Plumes

by Paul Gilster | Mar 13, 2008 | Outer Solar System | 14 Comments

One question jumps out at me from the blog entries that Cassini team members have been posting on the probe's dazzling close pass by Enceladus. It's from deputy project scientist Linda Spilker, who says: "I am thinking about the two Voyager flybys of the Saturn system that took place over 25 years ago. How in the world did we miss the Enceladus plumes back then???" Indeed, but that's the nature of exploration, to learn something new each time you revisit a place, especially one that's fully 10 AU out. The process is addictive, and breathtaking. Do be aware of the flyby blog, offering an inside view of one of the most interesting of Cassini's encounters thus far (also be aware that the entries are oddly out of order, a problem apparently being fixed). With the data downlink now started (as of about 0201 UTC today) via the Deep Space Network's Goldstone station, we can ponder the chutzpah of taking a spacecraft so close to the huge geysers erupting out of the south pole of Enceladus....

Moving (and Saving) the Planet

by Paul Gilster | Mar 12, 2008 | Asteroid and Comet Deflection | 30 Comments

The ever reliable Dennis Overbye gives us a look at the Earth's fate in his most recent story for the New York Times. Citing the work of Klaus-Peter Schroeder (University of Guanajuato, Mexico) and Robert Connon Smith (University of Sussex), Overbye describes our planet's eventual engulfment by a red giant Sun. Earlier studies had questioned whether the Earth might survive this phase, but Smith and Schroeder say no. Their calculations show a red giant Sun 256 times as wide as today's star, and fully 2730 times more luminous. And it will swallow the Earth. I was interested to see Overbye's reference to a 2001 paper that, in the spirit of speculative jeu d'esprit familiar in good science fiction, looks at a way to save the planet. But first, let's run through where our star is heading. Burning through its hydrogen on the main sequence, the Sun should keep getting hotter and larger. Figure 1.1 billion years until you reach the point where it is 11 percent brighter than today, creating a...

In Praise of Ancient Light

by Paul Gilster | Mar 11, 2008 | Exotic Physics | 6 Comments

How things change over time has never been as strikingly demonstrated as in recent findings. If you go back to the distant era when the universe was only 380,000 years old, you find that neutrinos made up fully ten percent of the universe. Given that these sub-atomic particles moving at nearly the speed of light are so abundant today that millions of them pass through us every second, you'd think they compose a substantial portion of today's universe, but they actually account for less than one percent. And the change in neutrino ratio is only the beginning. For according to five years of recently released data from the Wilkinson Microwave Anisotropy Probe (WMAP), the early universe was composed of 12 percent atoms, 15 percent photons, almost no dark energy, and 63 percent dark matter. The contrast is stark, given WMAP estimates of the current cosmos: 4.6 percent atoms, 23 percent dark matter, 72 percent dark energy. And, of course, those greatly diminished neutrinos. Image: WMAP...

TEDI: Looking for Planets Around Small Stars

by Paul Gilster | Mar 10, 2008 | Exoplanetary Science | 6 Comments

A new observing program designed to study planets around small, cool stars is in the works. TEDI, the TripleSpec - Exoplanet Discovery Instrument, saw first light on the 200-inch Hale Telescope just before Christmas, and is now in its commissioning phase, with an observing program scheduled to begin this spring. And for those who occasionally wonder why we seldom discuss stars like Barnard's Star or Proxima Centauri in terms of the planet hunt, read on. For TEDI is the kind of program that should be able to survey not just M dwarfs but L and T class stars as well, opening exciting possibilities for discovery. Planets around Proxima Centauri? Perhaps, and extending all the way down to T-class brown dwarfs makes things interesting as well. But finding such planets is a challenge with conventional radial velocity methods. Here's why: Radial velocity searches are generally conducted in the optical band, and work well with stars, like the Sun, that are bright at these wavelengths. The...

Power Shortage in the Outer Solar System?

by Paul Gilster | Mar 8, 2008 | Outer Solar System | 23 Comments

As if we didn't have enough trouble getting to the outer Solar System, now comes word that the US inventory of plutonium-238 is diminishing. That's what NASA administrator Mike Griffin told a House appropriations subcommittee this past week, pointing out that after the Mars Science Laboratory launches in 2009, the agency will find itself running out of the plutonium needed to fuel radioisotope power systems. Even New Horizons, on the way to Pluto/Charon, is using Russian plutonium, the periodic purchase of which has been forced by NASA's dwindling supplies. New Horizons' principal investigator Alan Stern told the committee that beyond the Mars Science Laboratory, NASA probably has enough plutonium on hand or on order to fuel the outer planets flagship mission targeted at 2017 and an interim Discovery class mission scheduled to fly a few years earlier, the latter intended, ironically enough, to test more efficient radioisotope power systems now under development. Meanwhile, the outer...

A Triple Asteroid Occultation

by Paul Gilster | Mar 7, 2008 | Outer Solar System | 3 Comments

Sometimes nature does what huge telescopes can't manage. Tomorrow night, a careful amateur astronomer may be able to provide information not only about the tiny asteroid 45 Eugenia but also about the two moons that orbit it. At play is an occultation, in which these moons and Eugenia itself helpfully occlude a star for observers in various parts of the southern US and Mexico. Sky & Telescope is reporting the relevant times to be 5:42 to 5:45 UTC on March 9. Image: Eugenia and its larger moon, Petit-Prince. With a density only 20 percent greater than water, this main belt asteroid is either a loose pile of rubble or an icy object with sparse rocky materials. Petit-Prince orbits it at a radius of 1,190 kilometers. Not shown here is the smaller moon, Petite-Princesse. The animation was assembled from infrared images of the objects. Credit: William Merline (SwRI), Laird Close (ESO), et al., CFHT. Moons have been discovered in their dozens around asteroids ever since 1994, when the...

Dreaming of von Neumann

by Paul Gilster | Mar 6, 2008 | Culture and Society | 38 Comments

Science fiction has brought us so many concepts for colonizing the stars over the last hundred years, everything from interstellar arks loading thousands of colonists (the sea-faring metaphor) to worldships that see generations of crewmembers live and die during their long joiurney. Suspended animation can get people through a trip that takes centuries, while robotic wardens might oversee the safe passage of human genetic material that could be converted into a colony upon arrival. If you want to be on the cutting edge today, though, better look toward what George Dvorsky talks about in Seven ways to control the Galaxy with self-replicating probes. Here's a novel way to colonize a distant star system: Let a von Neumann probe find a promising planet and use the matter it finds there to establish a colony and fill it with settlers. Not the kind of settler that gets out of a suspended animation tank, yawns, stretches, and then walks out onto an alien landscape, but an uploaded...

Exoplanets Aloft: Affordable Mission Concepts

by Paul Gilster | Mar 5, 2008 | Exoplanetary Science | 4 Comments

In today's world, one of the more useful gifts for a scientist to have is the ability to save money. Enter the Jet Propulsion Laboratory's Wesley Traub, who copes with problems like NASA's indefinite hold on Terrestrial Planet Finder with a low-cost alternative of his own. Last year, Traub and crew experimented with the Solar Bolometric Imager, an observatory lofted by a balloon to altitudes of 35 kilometers and more. Their study of air distortions at those altitudes convinced Traub that the balloon's movements through the stratosphere would not distort received images, and that led to speculation about doing exoplanet science close to home. A balloon-based TPF? Hardly, but Traub does talk about imaging perhaps twenty exoplanets, according to a recent story in New Scientist. The method: A coronagraph teamed with a one to two-meter mirror. The so-called Planetscope weighs in at $10 million, making it a bargain when compared to space-based observatories, and cheap enough to tempt...

Arecibo Watches the Skies for Space Rocks

by Paul Gilster | Mar 4, 2008 | Asteroid and Comet Deflection | 11 Comments

By Larry Klaes Tau Zero journalist Larry Klaes now looks at recent activity in near-Earth space, where a variety of objects have turned up just this year to remind us of the potential danger of impacts on our planet. With good connections at Cornell University, Larry is our point man for Arecibo information, the more of which the better as we assess the near-Earth asteroid issue and what can be done if one of these rogue objects is found to be on a collision course. The last two months have seen a fair number of objects from space making rather close encounters with the terrestrial worlds of our Solar System. In late January, a small planetoid designated 2007 WD5 made a relatively close pass of the planet Mars. Astronomers had earlier projected the planetoid might actually strike the Red Planet and hoped that one of the robotic spacecraft currently in Mars orbit would be able to record the 164-foot wide rock's impact on the planet's surface. However, as the scientists made...

Of Islands and the Imagination

by Paul Gilster | Mar 3, 2008 | Culture and Society | 9 Comments

Ever since I was a kid watching Adventures in Paradise on TV, I've had a yen for islands, the more remote the better. The show had quite a pull on a young imagination, as skipper Gardner McKay sailed the waters of French Polynesia in his schooner, turning up beautiful women and adventure at most every port. The thought of someday threading through the Tuamotus or setting out for Nuku Hiva and the Marquesas made my spirit soar, and to this day my fascination with maps is undiminished. So you can imagine how I studied the image below, and the kind of speculations it triggered. Because when you look at a map, you try to put yourself there in your mind, and perhaps no islands are more challenging to imagine than the ones pictured here. The work of San Diego middle school teacher Peter Minton (and thanks to Frank Taylor for the pointer), they're based on Cassini imagery peering through the murk of Titan's atmosphere at what seems to be an island group in a methane sea. Assuming, of...

Dark Energy: Dimming a Standard Candle?

by Paul Gilster | Mar 1, 2008 | Deep Sky Astronomy & Telescopes | 13 Comments

How light travels through various media can tell us volumes. Take the phenomenon called 'extinction,' which describes what happens to light as it encounters dust and gas between the original object and our position on Earth. Studying this effect led to our earliest understanding of interstellar dust as a factor to be taken into account of when discussing the space between the stars. And because we have much to learn about what is in that space, a new observation proves useful indeed, adding to our options for the study of 'dark energy,' the mysterious repulsive force that seems to account for the accelerating expansion of the universe. Examining what they describe as a new form of carbon found within minerals in meteorites, Andrew Steele and Marc Fries (Carnegie Institution) examine the question of how these so-called 'graphite whiskers' might affect astronomical observations. The going theory is that the whiskers may have formed near the Sun early in our Solar System's life, being...

43rd Carnival of Space Online

by Paul Gilster | Mar 1, 2008 | Culture and Society | 2 Comments

The 43rd Carnival of Space is now available on Ethan Siegel's Starts with a Bang site, entertainingly offered in an 'Oscar winner' format that highlights an impressive array of contributions this week. The one I'll send you to first from an outer planets perspective is Bruce Irving's story on Music of the Spheres about robotic operations in extreme environments. Think Antarctica for upcoming tests, and Europa for long-term uses of this promising technology. The helpful video that accompanies the piece features Bill Stone (Stone Aerospace), whose underwater vehicle Endurance is now undergoing tests in Wisconsin.

Toscanini Through the Light Years

by Paul Gilster | Feb 29, 2008 | Culture and Society | 22 Comments

A friend of mine who knows more about classical music than anyone I've ever met, and who has turned his passion for it into a second career, asked me a question a few years ago that stays with me. A great admirer of Toscanini, he wondered whether some of the the conductor's prodigious output was in some sense still 'out there.' For Toscanini went to work in New York after he left Italy, conducting the first broadcast concert of the NBC Symphony Orchestra in 1937. His NBC broadcasts were, of course, recorded, but my friend's thoughts had turned interstellar and he wondered where those radio signals were now. We discussed radio signals propagating outwards at the speed of light, so that a 1937 broadcast would now be 71 light years out, and in answer to his query, I said yes, if you could somehow position yourself through superluminal means 71 light years from here, you would be on the wavefront as the initial Toscanini broadcast swept over you. But, I assured him, you wouldn't be able...

The Sun’s Exotic Neighborhood

by Paul Gilster | Feb 28, 2008 | Interstellar Medium | 13 Comments

We think about our interstellar neighborhood in terms of stars, like Alpha Centauri and Tau Ceti, but the medium through which our relative systems move is itself a dynamic and interesting place. The Sun is currently passing through a shell of material known as the Local Interstellar Cloud. And that cloud is, in turn, located at the edge of a vast region known as the Local Bubble, scoured of material by supernova explosions in the nearby Scorpius-Centaurus and Orion Association star-forming regions. Within the past 105 years, the Sun emerged from the interior of the Local Bubble; it now moves obliquely in the direction of the high-density molecular clouds of the Aquila Rift, a star-forming region that itself reminds us how energetic 'empty' space really is. If we're ever going to send fast missions outside the Solar System, we're going to need plenty of data about the materials through which our vehicles move, particular as velocities mount to the point where collision with even...

« Older Entries

Next Entries »

Charter

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).

Now Reading

On Comments

If you'd like to submit a comment for possible publication on Centauri Dreams, I will be glad to consider it. The primary criterion is that comments contribute meaningfully to the debate. Among other criteria for selection: Comments must be on topic, directly related to the post in question, must use appropriate language, and must not be abusive to others. Civility counts. In addition, a valid email address is required for a comment to be considered. Centauri Dreams is emphatically not a soapbox for political or religious views submitted by individuals or organizations. A long form of the policy can be viewed on the Administrative page. The short form is this: If your comment is not on topic and respectful to others, I'm probably not going to run it.

Follow by E-Mail

Advanced Propulsion Research