Paul Gilster | Centauri Dreams

Eternal Monuments Among the Stars

by Paul Gilster | Jan 24, 2012 | Astrobiology and SETI | 93 Comments

Yesterday’s post looked at SETI and its assumptions, using the lens of a new paper on how the discipline might be enlarged. The paper’s authors, Robert Bradbury, Milan ?irkovi? and George Dvorsky, are not looking to supplant older SETI methods, but rather to broaden their scope by bringing into play what we are learning about astrobiology and artificial intelligence. It is perilous, obviously, to speculate on how an alien civilization might behave, yet to some extent we’re forced to do it in choosing SETI targets, and that being the case, why not add into the mix methods that go beyond our current radio and optical searches, methods that may have a better chance of success? The Engima of Contact A key to extending SETI’s reach is to question the very idea of contact. One assumption many of SETI’s pioneers had in common was that there was an inherent need to communicate with other species, and that this need would take the form of intentional radio beacons or optical messages. What...

Rethinking SETI’s Targets

by Paul Gilster | Jan 23, 2012 | Astrobiology and SETI | 51 Comments

Have you ever given any thought to intergalactic SETI? On the face of it, the idea seems absurd -- we have been doing SETI in one form or another since the days of Project Ozma and without result. If we can’t pick up radio signals from nearby stars that tell us of extraterrestrial civilizations, how could we expect to do so at distances like M31’s 2.573 million light years, not to mention even the closest galaxies beyond? Herein lies a tale, for what intergalactic SETI exposes us to is the baldness of our assumptions about the overall SETI attempt, that it is most likely to succeed using radio wavelengths, and that it may open up two-way communications with extraterrestrials. It’s the nature of these assumptions that we need to explore today. The Visibility of a Galactic Culture Let’s suppose, for example, that Nikolai Kardashev’s thoughts about types of civilizations are compelling enough to put to the test. A Kardashev Type III civilization is one that is able to exploit the energy...

Dawn Explores Vesta’s Chemistry

by Paul Gilster | Jan 20, 2012 | Asteroid and Comet Deflection | 30 Comments

The Dawn spacecraft, orbiting Vesta since July of last year, reached its lowest altitude orbit in December, now averaging 210 kilometers from the asteroid's surface. Ceres is Dawn's next stop, but that journey won't begin until the close-in work at Vesta is complete, with the craft in its low altitude mapping orbit for at least ten weeks and then another period at higher altitudes before Dawn leaves Vesta in late July. The spacecraft's Gamma Ray and Neutron Detector (GRaND) instrument is already telling us much about the giant asteroid's surface composition. In fact, the five weeks of mapping at low-altitude have provided the first look at global-scale variations on Vesta. GRaND measures the abundance of elements found in planetary surfaces, and while its investigations are still in the early stages of analysis, it's clear that Vesta's surface varies widely as opposed to the mostly uniform composition of smaller asteroids. We know that Vesta developed a core, mantle and crust, making...

A Comet Consumed by the Sun

by Paul Gilster | Jan 19, 2012 | Deep Sky Astronomy & Telescopes | 13 Comments

Imagine what we could do if we could attain speeds of 640 kilometers per second. That's the velocity of a comet recently tracked just before passing across the face of the Sun and apparently disintegrating in the low solar corona. I'm just musing here, but it's always fun to muse about such things. 640 kilometers per second drops the Alpha Centauri trip from 74,600 years-plus (Voyager-class speeds) to less than 2000 years. A long journey, to be sure, but moving in the right direction, and in any case, these are speeds that would allow exploration deep into the outer system. We're a long way from such capabilities, but they're a rational goal. But back to the comet. The object was discovered on July 4, 2011 and designated C/2011 N3 (SOHO), the latter a reference to the ESA/NASA Solar and Heliospheric Observatory, whose Large Angle and Spectrometric Coronagraph made the catch. On July 6, NASA's Solar Dynamics Observatory was able to pick up the comet some 0.2 solar radii off the Sun,...

NIAC Looking for New Proposals

by Paul Gilster | Jan 18, 2012 | Advanced Rocketry | 11 Comments

NASA’s Innovative Advanced Concepts program has issued a second call for proposals, following the selection of its first round of Phase I concepts in 2011. NIAC (formerly the NASA Institute for Advanced Concepts) ran from 1998 to 2007 in the capable hands of Robert Cassanova, who is now external council chair for the new organization. After a four year interregnum, the program returned in 2011 with the goal of funding “early studies of visionary, long term concepts – aerospace architectures, systems, or missions (not focused technologies).” The 2011 effort resulted in funding for 30 advanced technology proposals, each of them receiving $100,000 for one year of study. The new call for proposals continues the NIAC theme of looking for ideas that are both innovative and visionary, while remaining at an early stage of development, considered as being ten years or more from actual use on a mission. Approximately fifteen proposals are likely to win funding in the 2012 selection, with short...

Exoplanetary Ring Systems and Their Uses

by Paul Gilster | Jan 17, 2012 | Exoplanetary Science | 5 Comments

What to say about an extrasolar ring system that has already had its four distinct rings named? Rochester, Sutherland, Campanas and Tololo are the Earth-bound sites where the unusual system was first detected and analyzed, and the international team of researchers involved thought them suitable monickers for the four rings thus far detected. The light curve of the young, Sun-like star they’ve been studying in the Scorpius-Centaurus association -- a region of massive star formation -- shows what appears to be a dust ring system orbiting a smaller companion occulting the star. The data here come from SuperWASP (Wide Angle Search for Planets) and the All Sky Automated Survey (ASAS) project. The star in question is 1SWASP J140747.93-394542.6, which displays a complex eclipse event with, at some points, 95 percent of the light from the star being blocked by dust. Similar in mass to the Sun, the star is only about 16 million years old, and lies about 420 light years away from the Solar...

Circumbinary Planets: A New Class of Systems?

by Paul Gilster | Jan 16, 2012 | Exoplanetary Science | 9 Comments

Last week's meeting of the American Astronomical Society is still much in the news, and I want to cover several more stories from the Austin conclave this week, starting with yet another circumbinary planetary system, in which a planet orbits two stars. Not long ago we looked at Kepler-16b, a circumbinary planet orbiting two stars in this mode -- as opposed to a binary system where planets orbit one or the other of the two stars. Kepler-16b was interesting but perhaps unusual given the perceived difficulties in finding stable orbits around close binaries. But things are happening quickly on the exoplanet front. Needing more information about the prevalence of this kind of planet and the range of orbital and physical properties involved in such systems, we now get news of not one but two more, Kepler-34b and Kepler-35b. Note the nomenclature: We could as easily call these Kepler-34(AB)b and Kepler-35(AB)b. We confront the real possibility that 'two sun' systems are not necessarily...

New Exomoon Project Will Use Kepler Data

by Paul Gilster | Jan 13, 2012 | Exoplanetary Science | 6 Comments

Exomoons are drawing more interest all the time. It may seem fantastic that we should be able to find moons around planets circling other stars, but the methods are under active investigation and may well yield results soon. Now David Kipping (Harvard-Smithsonian Center for Astrophysics) and colleagues have formed a new project called HEK -- the Hunt for Exomoons with Kepler. We thus move into fertile hunting ground, for there has never been a systematic search for exomoons despite the work of ground-breaking researchers like Kipping, Gaspar Bakos (Princeton) and Jean Schneider (Paris Observatory). It’s definitely time for HEK as Kepler’s exoplanet candidate list grows. Kepler, of course, works with transit methods, noting the dip in starlight as an exoplanet passes in front of the star under observation. HEK will use Kepler photometry to look for perturbations in the motion of the host planet that could flag the presence of a moon. Variations in transit timing (TTV) and duration...

Three Exoplanets Smaller than Earth

by Paul Gilster | Jan 12, 2012 | Exoplanetary Science | 28 Comments

It’s always gratifying to note the contributions of amateur astronomers to front-line science. In the case of three small planets discovered around the Kepler star KOI-961, the kudos go to Kevin Apps, now a co-author of a paper on the new work. It was Apps who put postdoc Philip Muirhead (Caltech) on to the idea that KOI-961, a red dwarf, was quite similar to another red dwarf, the well-characterized Barnard’s Star, some six light years away in the constellation Ophiuchus. It was a useful idea, because we do have accurate estimates of Barnard Star’s size, and the size of the star becomes a key factor in exoplanet detections. For the depth of a light curve -- the dimming of the star over time due to the passage of planets across its surface as seen from Kepler -- reveals the size of the respective planets. Researchers from Vanderbilt University aided the Caltech team in determining KOI-961’s size, a difficult call because while Kepler offers data about a star’s diameter, that data is...

Planets by the Billions in Milky Way

by Paul Gilster | Jan 11, 2012 | Exoplanetary Science | 104 Comments

People sometimes ask why we are spending so much time searching for planets that are so far away. The question refers to the Kepler mission and the fact that the distance to its target stars is generally 600 to 3,000 light years. In fact, fewer than one percent of the stars Kepler is examining out along the Orion arm are closer than 600 light years. The reason: Kepler is all about statistics, and our ability to learn how common exoplanets and in particular terrestrial planets are in the aggregate. The last thing the Kepler team is thinking about is targets for a future interstellar probe. Studies of closer stars continue -- we have three ongoing searches for planets around the Alpha Centauri stars, for example. But there is so much we still have to learn about the overall disposition of planets in our galaxy. New work by an international team of astronomers involves gravitational microlensing to answer some of these questions, and the results suggest that planets -- even warm,...

Kepler-16b: Inside a Chilly Habitable Zone?

by Paul Gilster | Jan 10, 2012 | Exoplanetary Science | 15 Comments

The annual meeting of the American Astronomical Society is now in session in Austin, sure to provide us with interesting fodder for discussion in coming days. Just coming off embargo yesterday was news of further study of the interesting Kepler-16 system. This one made quite a splash last fall when the planet known as Kepler-16b was discovered to orbit two stars, with the inevitable echoes of Star Wars and the twin suns that warmed the planet Tatooine. This planet, though, was a gas giant more reminiscent of chilly Saturn than a cozily terrestrial world. Image: An artist's conception of the Kepler-16 system (white) from an overhead view, showing the planet Kepler-16b and the eccentric orbits of the two stars it circles (labeled A and B). For reference, the orbits of our own solar system's planets Mercury and Earth are shown in blue. New work out of the University of Texas at Arlington explores the question of habitability in a system like this. Credit: NASA/Ames/JPL-Caltech. You'll...

Innovative Interstellar Explorer: A Response to Questions

by Paul Gilster | Jan 9, 2012 | Missions | 18 Comments

Ralph McNutt's recent update on the progress of the Innovative Interstellar Explorer concept elicited plenty of comments, enough that Dr. McNutt wanted to answer them in a new post. Now at Johns Hopkins University Applied Physics Laboratory, McNutt is Project Scientist and a Co-Investigator on NASA's MESSENGER mission to Mercury, Co-Investigator on NASA's Solar Probe Plus mission to the solar corona, Principal Investigator on the PEPSSI investigation on the New Horizons mission to Pluto, a Co-Investigator for the Voyager PLS and LECP instruments, and a Member of the Ion Neutral Mass Spectrometer Team on the Cassini Orbiter spacecraft. With all that on his plate, it's hard to see how he has time for anything else, but McNutt also continues his work as a consultant on the Project Icarus interstellar design study. His Innovative Interstellar Explorer is a precursor mission designed to push our technologies hard. by Ralph McNutt I typically do not get involved with commenting on comments...

Our Meaning-Stuffed Dreams

by Paul Gilster | Jan 6, 2012 | Culture and Society | 20 Comments

Gregory Benford's work is so widely known that it almost seems absurd to introduce him, but for any Centauri Dreams readers who have somehow missed it, I challenge you to read In the Ocean of Night and not become obsessed with reading this author's entire output. This week has been a science fictional time for Centauri Dreams, with discussion of SF precedents to modern discoveries in the comments for stories like Marc Millis' 'Future History.' So it seems appropriate to end the week with an essay Greg published yesterday on his own site, one that appealed to me so much that I immediately asked him for permission to run it again here. In the essay, Greg takes a look at science fiction writer Thomas Disch and in particular the way his thoughts on SF illuminate not just the genre but the world we live in. It's insightful stuff, and makes me reflect on how our ideas of the future shape our upcoming realities. I will also admit to a fascination with science fiction's history that never...

100 Year Starship Winner Announced

by Paul Gilster | Jan 6, 2012 | Culture and Society | 11 Comments

These are good times for Icarus Interstellar, which teamed with the Dorothy Jemison Foundation and the Foundation for Enterprise Development to win the 100 Year Starship proposal grant. Mae Jemison, the first female African-American astronaut to fly into space, founded DJF in honor of her late mother. As lead on the proposal, her organization now takes on the challenge of building a program that can last 100 years, and might one day result in a starship. Centauri Dreams congratulates the winning trio, and especially Kelvin Long, Richard Obousy and Andreas Tziolas, whose labors in reworking the Project Daedalus design at Icarus Interstellar have paid off. While the award was announced to the winners at the end of last week, I held up the news here while the three parties involved coordinated their own announcement. But I see that other venues are picking up the story, as in this Sharon Weinberger piece for the BBC and now a similar article in Popular Science, so it seems time to go...

Resolving the Mysteries of Titan’s Weather

by Paul Gilster | Jan 5, 2012 | Outer Solar System | 7 Comments

A robust new computer model that couples the atmosphere of Titan to a methane reservoir on the surface goes a long way toward explaining not just how methane is transported on the distant moon, but also why the various anomalies of Titan's weather operate the way they do. The model comes out of Caltech under the guidance of Tapio Schneider, working with, among others, outer system researcher extraordinaire Mike Brown. It gives us new insights into a place where the average surface temperature hovers around a chilly -185 degrees Celsius (-300 F). Image: NASA's Cassini spacecraft chronicles the change of seasons as it captures clouds concentrated near the equator of Saturn's largest moon, Titan. (Credit: NASA/JPL/SSI). Titan can a frustrating place for meteorologists to understand because during the course of a year some things happen that, in the early days of research, didn't make a lot of sense. The moon's equator, for example, is an area where little rain is supposed to fall, but...

Unseen Planets Around a Young Star?

by Paul Gilster | Jan 4, 2012 | Exoplanetary Science | 2 Comments

If you want a glimpse of how remarkable technology continues to transform the exoplanet hunt, look no further than the Subaru telescope and its SEEDS project. SEEDS (Strategic Exploration of Exoplanets and Disks with Subaru Telescope/HiCIAO) works with data from the 8.2-meter telescope that the National Observatory of Japan runs on Mauna Kea (Hawaii). In its most recent finding, Subaru was used with the adaptive optics system HiCIAO (High Contrast Instrument for the Subaru Next Generation Adaptive Optics) to image the dust ring around HR 4796 A, a relatively young star (8-10 million years old) some 240 light years from Earth. Working with evanescent clouds of dust and debris over these distances is no easy matter, but adaptive optics can correct for atmospheric blurring to produce images that rival the Hubble Space Telescope's in terms of clarity. Add to that an advanced image processing technique called angular differential imaging, which suppresses the glare of the central star and...

A Future History

by Paul Gilster | Jan 3, 2012 | Culture and Society | 80 Comments

Predictions about the future of technology are so often wide of the mark, yet for many of us they're irresistible. They fuel our passion for science fiction and the expansive philosophy of thinkers like Olaf Stapledon. To begin 2012, Tau Zero founder Marc Millis offers up a set of musings about where we may be going, a scenario that, given the alternatives, sounds about as upbeat as we're likely to get. by Marc Millis "If we have learned one thing from the history of invention and discovery, it is that, in the long run - and often in the short one - the most daring prophecies seem laughably conservative." ~ Arthur C. Clarke In the 'new year' spirit of looking ahead, I offer now my personal views of 'a' possible future. These predictions are based first on trend extrapolations, include intersections from other disciplines, and work in the wildcard possibility of breakthrough propulsion physics. Consider this a science fictional offering intended to provoke thought rather than a...

Prior Visions of Star Flight

by Paul Gilster | Dec 29, 2011 | Culture and Society | 41 Comments

by Marc Millis Here is a holiday gift from Tau Zero as compiled by TZF's founding architect Marc Millis. It's part of Marc's continuing effort to find earlier references to the interstellar concepts -- many of them in fiction -- that we routinely ponder today. Some of these go back to the early 20th Century and in some cases the 19th. Compilations like this are always works in progress, as we found when putting together a list of interstellar propulsion concepts for the first chapter of the book Marc and Eric Davis edited, Frontiers of Propulsion Science, where one memory triggered another and the list kept growing. Readers are encouraged, then, to add other references to older material, as those of us who delight in prowling through old science fiction magazines have access to a mother lode of fictional precedents. I'll also mention that this post will be the last of 2011 -- as I did last week, I'll skip the Friday and Monday posts in honor of the holiday, with the next post...

New Work on FTL Neutrinos

by Paul Gilster | Dec 28, 2011 | Exotic Physics | 27 Comments

A paper in the December 24 issue of Physical Review Letters goes to work on the finding of supposed faster-than-light neutrinos by the OPERA experiment. The FTL story has been popping up ever since OPERA -- a collaboration between the Laboratori Nazionali del Gran Sasso (LNGS) in Gran Sasso, Italy and the CERN physics laboratory in Geneva -- reported last September that neutrinos from CERN had arrived at Gran Sasso's underground facilities 60 nanoseconds sooner than they would have been expected to arrive if travelling at the speed of light. The resultant explosion of interest was understandable. Because neutrinos are now thought to have a non-zero mass, an FTL neutrino would be in direct violation of the theory of special relativity, which says that no object with mass can attain the speed of light. Now Ramanath Cowsik (Washington University, St. Louis) and collaborators have examined whether an FTL result was possible. Neutrinos in the experiment were produced by particle...

Complex Molecules on Pluto

by Paul Gilster | Dec 27, 2011 | Outer Solar System | 6 Comments

I hope everyone is having a happy holiday season and looking forward to the upcoming New Year's festivities. In the intervening window, let's look at the outer Solar System. No other spacecraft has ever come as close to Pluto as New Horizons now has, already halfway between the Earth and the distant dwarf planet. It's also worth mentioning that New Horizons is only the fifth spacecraft to venture so deep into the Solar System, following the two Voyagers and the Pioneer spacecraft. July of 2015 will be an extraordinary time as we wait for data return from the mission and begin to find answers to some of the many questions that await us there. But studies from closer to home are continuing to reveal more about Pluto/Charon as well. The Cosmic Origins Spectrograph aboard the Hubble Space Telescope has found evidence for complex hydrocarbon and/or nitrile molecules on the planetary surface. Alan Stern, principal investigator for New Horizons, is behind the study, whose work was recently...

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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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