The thread on SETI's Paradox and the Great Silence has continued with considerable gusto, enough so that we're pushing the database limits on comments there. So I'm starting an overflow topic for those who want to keep the debate going. Please post any further responses to the SETI thread here, where we'll have plenty of room.
It's been some time since Centauri Dreams looked at the work Gregory Benford (University of California at Irvine) and his brother James (Microwave Sciences) are doing with solar sail concepts. But I just noted, in paging through a back issue of the Journal of the British Interplanetary Society, that their proposal for a microwave-beamed sail was written up there, based on a talk at the 2005 IAA symposium in Aosta, Italy. And because I want to keep sail concepts visible in a time when funding constraints have all but driven them from the news, let's revisit that work. What got the Benfords headlines not so long ago was the speeds they were proposing. Five years or less to Pluto? That's almost a halving of New Horizons' travel time, and it makes for some intriguing conjecture indeed. The Benfords learned from earlier laboratory experiments that heating up ultralight carbon sail materials causes accelerations greater than would be expected from the pressure of photons alone. Apparently...
The news about possible surface water on today's Mars points out how far we are from characterizing life's possibilities even in our own Solar System, much less around other stars. It may take boots on the ground on Mars to solve the question once and for all, but life in underground aquifers certainly is a plausible proposition, and the sooner we have proof (and samples to study), the better for astrobiology in general. Meanwhile, we push on with the very early wave of exoplanet studies, remembering that it's just over a decade since 51 Peg gave us the first confirmed detection around a main sequence star. I can't imagine a more fruitful field for a young astronomer to head for, with so many possibilities for study that you begin to wonder whether we'll have the human resources to keep up with the vast data inflow that's coming. Some of the more intriguing recent work concerns binaries and the planets around them. If we're getting fairly sanguine about the possibility of planets...
A note from Ian Jordan (Space Telescope Science Institute) passes along the welcome news that presentations and webcasts from last week's Astrophysics Enabled by the Return to the Moon 2006 workshop at STScI have been posted online (available here). There's plenty to dig into here, but of specific note for exoplanet research are the presentations by Webster Cash, Maggie Turnbull, Sara Seager and Peter McCullough. Centauri Dreams readers have read about all four of these scientists in the past year or so. Maggie Turnbull (Carnegie Institution of Washington) specializes in identifying stars that may have terrestrial planets around them. In an earlier post, we looked at some of her picks. Sara Seager (also at Carnegie) is particularly known for her work on HD 209458B, a hot Jupiter that transits its star and thus offers up much useful data. And Peter McCullough (Space Telescope Science Institute) is getting remarkable results from the XO telescope in Hawaii, collaborating with amateur...
The COROT satellite, slated for transit studies of nearby stars in search of exoplanets, has completed fueling up operations. Launch is scheduled for December 21 at the Baikonur cosmodrome in Kazakhstan. Nine days were required to top the satellite's tanks even though it is only carrying 40 litres of hydrazine, due to the highly poisonous nature of the fuel. A French project with ESA participation, COROT will be the first space misson specifically dedicated to finding extrasolar planets, and it may give us our first detection of rocky worlds only a few times larger than Earth.
One reason our SETI searches may be turning up nothing is that everywhere in the cosmos, civilizations exist that are much like ours. They may be, in other words, what Alexander Zaitsev calls 'dismally monotonous,' capable of being no more than passive when it comes to other living worlds. They are listening rather than transmitting. And Zaitzev is at the forefront of the movement to change all that, at least where Earth is concerned. Zaitsev's new paper lays out the basics of METI -- 'Messaging to ETI' -- the idea being to transmit purposely to likely stellar systems. The Russian scientist is fascinated by the question of consciousness. How widespread is it, and is it not the aim of SETI to find out whether it is a universal phenomenon or a singular one, isolated on our own world? On this score, all kinds of speculation are possible, and I rather like this Arthur C. Clarke quote cited by Zaitsev as one of various hypotheses: "...it is almost evident that biological intelligence is a...
It's always good to see Green Bank in the news. The West Virginia facility was the site of Frank Drake's pioneering SETI attempt called Project Ozma back in 1960. Now Green Bank's newest dish has been used to discover the first negatively charged molecule in space, a useful building block in our understanding of how interstellar matter turns into planets that can eventually produce life. The molecule in question is called C6H-, described as a chain of six carbon atoms with one hydrogen atom at the end and an extra electron. That makes it a molecular 'anion' -- a molecule with a negative charge because of the extra electron -- and it's a bit of an anomaly. You would think that ultraviolet light would dislodge that spare electron, but this molecule survives. In fact, it's larger than most neutral and all positive molecules known in space. Image: The Green Bank Telescope at dusk. Courtesy of NRAO/AUI. Astronomer Michael McCarthy (Harvard-Smithsonian Center for Astrophysics) calls it 'a...
Because it's hard to argue with people once involved in Nobel Prize-winning work, I take Warren Nagourney (University of Washington) at his word. At one time Nagourney assisted Hans Dehmelt, the UW scientist who won the 1989 Nobel Prize in physics. Now he's working with John Cramer on a project so bizarre that, as this Seattle Post-Intelligencer story reports, he understands it only faintly. That makes Centauri Dreams' chances of understanding it all but infinitesimal. And because the work involves the paradoxical quantum behavior called 'entanglement' and implies communicating information backwards in time, it also conjures up memories of another man one hesitates to challenge. It was Einstein who called certain weird quantum behaviors 'spooky action at a distance' and cultivated a continuing distaste for the paradoxes of quantum mechanics. These are formidable scientists, but then so is Cramer, and in a way he seeks to confirm something Einstein said a long time ago. Einstein...
The evidence for dark matter keeps piling up, even if we still don't know what it is. Back in the 1930s, Fritz Zwicky noted that the galaxies he was observing weren't massive enough to account for the way they cohered into clusters. Vera Rubin later took the idea of missing mass further, seeing that stars in the outer parts of galaxies rotated too quickly for the presumed mass of the galaxy. So we've known for a long time that something mysterious is out there. Groups studying the phenomenon focus on odd, hypothetical particles called WIMPS -- Weakly Interacting Massive Particles. To make them fit a theoretical model of how dark matter works, scientists assume WIMPS are neutral in charge and about 100 times more massive than a proton. The problem is that they don't interact with most matter. If they're to be found, they'll have to be detected in a rare collision within extremely sensitive detectors. Image: The CDMS II detectors (hexagons) are stacked in an icebox with six insulating...
About to receive the Royal Society's Copley Medal, Britain's highest scientific award, Stephen Hawking told a BBC radio audience that if the human race were to survive, it would be necessary to go to another star. Here's a quote from a story on this in the Daily Mail: "The long-term survival of the human race is at risk as long as it is confined to a single planet... Sooner or later, disasters such as an asteroid collision or nuclear war could wipe us all out. But once we spread out into space and establish independent colonies, our future should be safe. There isn't anywhere like the Earth in the solar system, so we would have to go to another star." Hawking acknowledges the immense problems, telling his interviewer that chemical rockets like the Saturn V used on Apollo would require tens of thousands of years to reach Alpha Centauri. And while he has an admiration for Star Trek's warp drive (and is quite a fan of the series, as Trekkies know), Hawking pins his hopes on antimatter,...
Tau Boötis, a billion year old star some 50 light years from Earth, would be a fascinating place to see up close. The star is orbited by a gas giant some 4.4 times Jupiter's mass, one of those 'hot Jupiters' that close to improbably tight distances with the primary. In this case, the planet/star separation is a mere 0.049 AU, making it about 5 percent of the distance between the Earth and the Sun. 'Hot Jupiters' are bound to be dramatic objects anyway, but this one has other attributes. A team of French astronomers has been able to measure the magnetic field of Tau Boötis itself, finding it just slightly larger than the Sun's. That's the first direct measurement of the magnetic field of a star hosting an exoplanet, and it sets up interesting studies of the interactions between the two bodies as the planet moves so breathtakingly close to its star. Image: An artist's conception of the giant exoplanet orbiting Tau Boötis through the star's magnetic archs. Credit David Aguilar, CfA. In...
We seem to have accepted in our time the notion that technology always moves forward. But a key factor in the Drake Equation, that long and interesting conjecture that parses the possibilities for extraterrestrial life, is the question of whether technological societies have an average lifetime. Do they invariably survive to reach the stars, or do they destroy themselves before this is possible? Listen to something Fred Hoyle said back in 1964: It has often been said, if the human species fails to make a go of it here on Earth, some other species will take over the running. In a sense of developing high intelligence, this is not correct. We have, or will have, exhausted the necessary physical prerequisites so far as this planet is concerned. With coal gone, oil gone, high-grade metallic ores gone, no species however competent can make the long climb from primitive conditions to high-level technology. This is a one-shot affair. If we fail, this planetary system fails so far as...
We've identified over 200 planets around other stars, but in many ways we know little about other solar systems. The problem is in extrapolating from our knowledge of one or two planets to an entire planetary system, much of which we cannot detect. Can we expect to find gas giants mixed with small terrestrial worlds around most Sun-like stars? And what about the smaller and far fainter red dwarfs? Clearly, the job of characterizing not just planets but entire systems is going to occupy astronomers for many a decade. A new paper from the California & Carnegie team takes helpful steps in that direction. New planet finds are always fascinating, and the team does have four of them, the highlight being the pair orbiting the Sun-like star HIP 14810. Greg Laughlin (UC-SC) writes about that system on the systemic site, noting this: The fact that the orbit is clearly non-circular would be strong evidence for the presence of planet c, even if there weren't enough data to detect c directly. If...
It's a gorgeous day in the mid-Atlantic states following one of the most colorful autumns in memory. Most of the leaves are down now, which gives me plenty to do. I had intended to look at the new paper from the California & Carnegie planet finder team, but the great outdoors beckons. Instead, we'll examine their latest next week, along with more on interstellar flight scheduling with reference to Marc Millis' recent presentation at Princeton and an intriguing Fred Hoyle insight. For today, here's a quick post on how adaptive optics can sharpen a telescope's view. In the image below, you're seeing two views of the part of the Orion Nebula known as the Trapezium. The Subaru telescope on Mauna Kea (Hawaii), working without adaptive optics, obtained the image on the right back in 1999. The image on the left shows the effect of a new laser guide star system and enhanced AO, and as you can see, the difference in detail is remarkable. Be sure to click to enlarge both views. Image: The...
When do you decide to launch a starship? It's a question based as much on cultural assumptions as technology. Start with the premise that we can ratchet up today's velocities to 150 kilometers per second, roughly ten times the speed at which New Horizons will cross Pluto's orbit. If we want to send a probe six light years to Barnard's Star at that speed, we would be looking at a travel time of 12,000 years. That's a lot of time, but better than Voyager's 70,000-year plus travel time to the Centauri stars (if either Voyager were pointed in their direction). Clearly, 12,000 years is too many, especially in an age that regards maximum mission time as the lifetime of a researcher working on the project. Besides, if we did launch that kind of mission, it would inevitably be passed enroute by a faster spacecraft. And that's the conundrum: does there ever come a time when you do launch, or are you always waiting for better propulsion systems and faster travel times? As Andrew Kennedy...
More on growth scenarios for interstellar flight soon. But I don't want to let the recent dark matter news get past us, so a quick nod to the University of California at Santa Cruz, where researchers have run a powerful computer simulation to probe the dark matter halo that evidently surrounds our Milky Way. It's a further step toward understanding the stuff that makes up 82 percent of the matter in the universe, and that in turns helps us see how the large scale structure of the cosmos has evolved. Image: Density map of dark matter in a halo the size of the Milky Way galaxy's dark matter halo. Credit: J. Diemand, UC-SC. I grew up in a time when it was thought that everything in the cosmos was explicable through gravitational forces produced by objects we could see. From solar systems on up to galaxies, it made sense -- and the textbooks did this quite neatly with colorful diagrams -- to show how matter found its way into configurations that would turn into celestial objects visible...
In a book so stuffed with insights and quirky oddments that it belongs on the shelf of anyone interested in interstellar flight, Carl Sagan and I.S. Shklovskii once made a stunning calculation. Their 1966 volume Intelligent Life in the Universe (San Francisco: Holden-Day) presents the argument that with an average annual growth rate of just 1/3 of one percent, energy demand will outstrip the total solar radiation falling on the Earth by a factor of 100,000 within 2500 years. The re-building of the Solar System into something like a Dyson sphere may be inevitable. But isn't it a pipe dream to assume that growth will continue at even these modest levels? That was certainly my initial response, for so many things can throw a spanner into a civilization's works. But Andrew Kennedy (The Chronolith Project, Seville Spain) takes a hard look at growth issues in a recent paper with interesting results. Kennedy believes that growth is far more tenacious than generally accepted. Economic...
Those who ponder the Fermi Paradox might want to consider Myrhaf's solution, one based on economics. If advanced technolgical civilizations really are out there, maybe they simply can't afford to build interstellar spacecraft. Myrhaf assumes that the only realistic way to travel between the stars is via a slow generation ship, what Isaac Asimov once called a 'spome' or 'space home.' And he doubts anyone would attempt it. Expensive? You bet. And maybe there's no one with the deep pockets to build it. Governments are too inefficient, while capital investment is unlikely because interstellar travel has such a long timeline. Corporate heads looking for return on their investments aren't likely to have enough patience for a slow boat to Centauri. Charity? Perhaps there's a hope through what Myrhaf calls 'committed visionaries,' but we're talking investment over the course of generations. Does any culture have that kind of long-term vision once it develops the technologies that could build...
If we're lucky, the COROT mission, to be launched December 21, will be the first to detect rocky planets not much larger than the Earth around other stars. We've looked at COROT recently, and discussed how it and the Kepler space telescope will use transit methods to find these distant worlds. But as you go beyond Kepler (to be launched in 2008), the need for new technologies becomes apparent, which is why planet-finder designs like New Worlds are so significant. Now I see that Claude Catala (Observatoire de Paris-Meudon) is proposing a new take on space-borne telescopes for this purpose. Catala suggests a survey that would gather light from literally hundreds of 10-centimeter telescopes working in tandem (COROT itself is built around a single 27-centimeter telescope). These are small instruments, to be sure, and in some ways less impressive than high-end amateur equipment now on the market. But each boasts a wide field of view, roughly 60 times that of the full Moon. And that helps,...
The recent National Science Foundation report recommending scaling back support for the Arecibo radio telescope raises eyebrows here. Arecibo has just been instrumental in identifying the near-Earth asteroid 1999 KW4 as a binary, one that provides useful information about the mass, shape and density of its components and hence about near-Earth asteroids in general. That's the kind of knowledge we need as we ponder how to analyze Earth-crossing objects to prevent future planetary disasters. But while focusing on ongoing radio astronomy work, the report gives short shrift to Arecibo's radar capabilities, which make this kind of investigation possible. In a letter to the NSF's Division of Astronomical Sciences, Guy Consolmagno SJ, who is head of the Department for Planetary Sciences of the American Astronomical Society, had this to say: There is in fact only one reference to radar in the entire 78 page document, and no mention at all of asteroids. But the Arecibo radar results are key...
