Archives

A Dark Matter Collapse near M87?

by Paul Gilster | May 22, 2009 | Deep Sky Astronomy & Telescopes | 8 Comments

When we talk about the diameter of the Milky Way, it's usual to cite a figure of about 100,000 light years. But the much more diffuse halo of stars surrounding the galaxy actually extends almost twice as far. You would expect to find more or less the same situation in other galaxies, but new observations of the giant galaxy M87 have turned up a surprising fact: Its halo of stars is much smaller than expected. It's true that the halo is three times the size of that around the Milky Way, but its diameter of a million light years is still much smaller than anticipated given the size of the parent galaxy. Mysteries like this seem just the thing for the weekend, so consider the possibility, raised in the paper on this work, that the truncated halo is the result of a collapse of dark matter in the Virgo Cluster, where M87 resides. The Virgo Cluster is approximately 50 million light years from us and contains hundreds of galaxies of all descriptions, including spirals like the Milky Way....

Life’s Persistence through the Bombardment

by Paul Gilster | May 21, 2009 | Asteroid and Comet Deflection | 12 Comments

None of us would have wanted to be around during the Late Heavy Bombardment, that frenetic bashing of our planet as the young Solar System worked out its debris problems between 4.1 and 3.8 billion years ago. The Hadean period was a time when enormous asteroids pummeled our world over a span lasting as long as 200 million years, an ongoing series of events one would have assumed lethal for whatever organisms may have evolved by then. But was the Late Heavy Bombardment really the deadly rain we've always assumed? A new paper in Nature questions the idea, basing its results on computer modeling of the Earth's heating during the bombardment. Oleg Abramov and Stephen J. Mojzsis (University of Colorado) argue that our planet's surface would likely have been sterilized during this period, but microbial life below the surface or in underwater conditions would almost certainly have survived. "Our new results point to the possibility life could have emerged about the same time that evidence...

The Hunt for Centauri Planets

by Paul Gilster | May 20, 2009 | Exoplanetary Science | 26 Comments

Finding Earth-like planets around any star would be a stunning feat, and either Kepler or CoRoT may deliver such news before too long. But how much more exciting still if we find a planet like this around a star as close as Centauri B? After all, the Centauri stars are our closest stellar neighbors, close enough (a mere 40 trillion kilometers!) to conjure up the possibility of a robotic mission there and, if we play our propulsion cards right in the future, perhaps a manned trip as well. A Radial Velocity Long Shot But can we pick up the faint signature of a terrestrial world in this system, given that it would be akin to 'detecting a bacterium orbiting a meter from a sand grain -- from a distance of 10 kilometers'? The phrase is Lee Billings', from his fine essay in SEED called The Long Shot, on an ongoing project to do just that. Most radial velocity surveys are spread out over numerous stars, picking off close-in worlds whose traces should be obvious in short periods of time....

Building the Interstellar Message

by Paul Gilster | May 19, 2009 | Astrobiology and SETI | 14 Comments

I'm glad to see the phrasing of the key question used in the SETI Institute's 'Earth Speaks' project. Assuming we one day detect a signal from an extraterrestrial civilization, the Institute asks, 'Should we reply, and if so, what should we say?' Given the apparent ease with which broadcasts to the stars have been made in the last few years, advertising everything from snack foods to movies, this question might easily have been 'What should we say when we respond to an extraterrestrial signal?' When or if? I come down on the side of the 'if' formulation, because the question deserves a global response, one reflecting a broad range of disciplines and perspectives. Such a response takes time to build. Another thing I like about 'Earth Speaks' is that it will give us an interesting take on our own species. The plan here is to encourage people to submit messages, pictures and sounds online, using the Internet to solicit ideas. Fine-Tuning an Interstellar Greeting The site is here, where...

Tau Zero Update

by Paul Gilster | May 18, 2009 | Tau Zero Foundation | 17 Comments

Tau Zero's Kelvin Long seems to be everywhere these days, his most recent publication being a summary of the interstellar sessions at the UK Space Conference, held in early April. You can read that one here, where you'll discover that Long also provides a thorough backgrounder on the Tau Zero Foundation, its goals and vision for the future. Some of these goals are much discussed in these pages -- to make incremental progress toward the robotic and human exploration of the stars by using philanthropic funding to support credible research by Tau Zero 'practitioner' scientists. Other goals include practical ways to expand the public perception of interstellar issues, including supporting students through scholarships, offering educational products, and organizing sessions at established conferences. Echoes naturally arise from the Breakthrough Propulsion Physics project that Marc Millis once managed for NASA, but in fact Tau Zero hopes to take a significantly different course, and one...

My Own Private Star Trek

by Paul Gilster | May 15, 2009 | Culture and Society | 30 Comments

by Jon Lomberg I had no idea when the week started that I would be publishing not one but two essays on Star Trek. But Jon Lomberg was inspired by Athena Andreadis' take on the new movie to write down his own reflections on the series in its many forms. Lomberg's name should be instantly recognizable to this readership. Jon was Carl Sagan's principal artistic collaborator for many years, illustrating Sagan's books and serving as chief artist for COSMOS. He storyboarded many of CONTACT's astronomical animations and designed the cover for the Voyager Interstellar Record, which is now pushing into the heliosheath and bound for true interstellar space. In addition to regular lecturing, Jon is the creator of the remarkable Galaxy Garden in Kona, Hawaii and remains an active astronomical artist in many media. Herewith his thoughts and recollections of Star Trek, Sagan, Roddenberry and more. I wasn't a fan of the series when it first came out. The first episode I recall seeing was in the...

Kepler Observations Begin

by Paul Gilster | May 14, 2009 | Exoplanetary Science | 7 Comments

With the Herschel/Planck telescopes now on their way -- the successful launch took place at 1312 UTC from the European Space Agency's launch pad at Kourou, and the two spacecraft are now on separate trajectories -- we can take a breather to reflect on what a busy time it's been of late for space telescopes. The ongoing Hubble repairs are a fascinating story in and of themselves, but we've also got Kepler to think about as its hunt for Earth-like planets around other stars now gets underway. Shaking out the instrumentation has taken some time, but the Kepler operations team slowed the pace of communications about a week ago to eighteen hours per day, a number that will drop to six as science observations now proceed. For the balance of the mission, according to JPL project manager Jim Fanson, communications will occur only twice per week as Kepler sends home precious data. "Now the fun begins," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center,...

Reflections on the New Star Trek

by Paul Gilster | May 13, 2009 | Culture and Society | 44 Comments

by Athena Andreadis This morning I have the pleasure of introducing my friend Athena Andreadis, who will give us her thoughts on the recent Star Trek film. Dr. Andreadis is Associate Professor of Cell Biology at the University of Massachusetts Medical School, and the author of To Seek Out New Life: The Biology of Star Trek. In her basic molecular neurobiology research, she studies the fundamental gene regulatory mechanism known as alternative splicing. The long-term goal of her research is to understand how the brain works, and contribute to the struggle against mental retardation and dementia. When not conjuring in the lab, Athena writes essays on science and science fiction, while writing her own SF/F fiction, some of which appears at the site Starship Reckless, which she founded. We Now Interrupt Our Regular Programming… … so that, stepping into Paul's hospitable parlor, I can hold forth on the Star Trek reboot (henceforth ST||, for parallel timeline). I assume that...

Thursday Launch for Herschel and Planck

by Paul Gilster | May 12, 2009 | Deep Sky Astronomy & Telescopes | 6 Comments

While we're thinking about space telescopes like the aging but potentially repairable Hubble, let's not forget the launch now scheduled for Thursday from the Guiana Space Centre in Kourou. The European Space Agency's Herschel instrument will be lifted into an orbit 1.5 million kilometers from Earth, stationed at the second Lagrange point (L2) so that Sun, Moon and Earth can all be hidden behind a sunshade to afford the instrument a clear view without disturbance from its celestial neighbors. Image: About 0.5 hours after launch, Herschel separates from the launcher upper stage and starts its cruise to L2 (the second Lagrangian point), situated at about 1.5 million kilometers from Earth. Credit: ESA/D. Ducros, 2009. Along with Herschel goes Planck, also scheduled for the L2 point (the two satellites will separate shortly after launch and reach L2 independently). Herschel is the largest infrared telescope ever launched, with a 3.5-meter primary mirror made of silicon carbide that is...

New Missions for Hubble and Spitzer

by Paul Gilster | May 11, 2009 | Deep Sky Astronomy & Telescopes | 0 Comments

With all eyes on the mission to service the Hubble telescope, it's fascinating to see that technology created for the James Webb Space Telescope is going to be used to enhanced Hubble's Advanced Camera for Surveys (ACS). The particular Application-Specific Integrated Circuit, or ASIC, design in question mirrors that of the Webb instrument and also equipment recently installed at the 2.2-meter University of Hawaii telescope on Mauna Kea, where it is part of the Charge-Coupled Device (CCD) detection system. An ASIC is a small, specialized integrated circuit, and the one about to go into Hubble could be transformative. That's because new spectrographic instruments going into Hubble will work with the repaired and upgraded ACS instrument in the study of dark energy and distant galaxies, a truly enhanced imaging capability for the aging workhorse. The ASIC next goes into space on the Webb telescope, leading one to ponder what a repair mission to that instrument would look like. After all,...

Freezing Out the Dark Energy Field

by Paul Gilster | May 9, 2009 | Exotic Physics | 19 Comments

A testable prediction about dark energy? Such is the promise of a new formulation from Sourish Dutta and Robert Scherrer (Vanderbilt University), whose dark energy model interacts with normal matter and has observable results, including a prediction about the expansion rate of the universe. Astronomical surveys in the next decade should be able to detect the slowdown in the expansion rate predicted by this model, if it exists. Think 'quintessence,' a new field with the unique property that it can act like antigravity, forcing nearby objects to move away from each other rather than pulling them together. The quintessence field as developed by Dutta and Scherer likely went through a phase transition somewhere around 2.2 billion years after the Big Bang. 'Freezing out' as the universe cooled creates a scenario where the energy density of the field remained high until, with the phase transition, it dropped abruptly to a level it retains to this day. Another result: The release of some of...

A Look Back at Star Trek’s Biology

by Paul Gilster | May 8, 2009 | Culture and Society | 21 Comments

The appearance of the new Star Trek film has inspired Athena Andreadis to revisit the epilogue of her 1998 book To Seek Out New Life: The Biology of Star Trek (Random House). Andreadis (University of Massachusetts) is a frequent commenter on issues of space exploration on this and other sites, including her own Astrogator's Logs, where you'll find the updated epilogue. It's well worth reading in the context of how and why we explore. Sharply critical of the Star Trek franchise, Andreadis nonetheless commends its celebration of the human thirst for knowledge, something she believes may be the one thing we have in common with whatever extraterrestrial beings we find out there. This is bracing stuff, even for those of us who leaned more toward Heinlein than Star Trek in our youths. Here, the author speaks about dreaming of possibilities and making them accessible: Scientific understanding does not strip away the mystery and grandeur of the universe; the intricate patterns only become...

New Title on Gravitational Focus Mission

by Paul Gilster | May 7, 2009 | Missions, Research Tools | 14 Comments

Claudio Maccone's new book is out, an extension and re-analysis of the material in two earlier titles that examined the author's innovative ideas on deep space systems. Maccone is best known to Centauri Dreams readers as the major proponent of a mission to the Sun's gravitational focus where, at 550 AU and beyond, a spacecraft could take advantage of lensing properties that would allow detailed observations of distant stars and their planets. The Italian physicist, formerly associated with Alenia Spazio and now working independently on deep space matters, has developed the idea as an interstellar precursor mission loaded with good science. But in the second part of Deep Space Flight and Communications: Exploiting the Sun as a Gravitational Lens (Springer, 2009), he also examines the mathematics of what is known as the Karhunen-Loève Transform (KLT), analyzing the tools that seem to offer the best choices for optimized communications as we eventually develop star-faring capabilities....

EGR: A ‘Hail Mary’ Pass to the Stars

by Paul Gilster | May 6, 2009 | Missions | 30 Comments

EGR, standing for Embryo/Gestation/Rearing, is the name of a mission presented by John Hunt on Tibor Pacher's PI Club site, where Tibor encourages the development of what he calls 'crazy ideas.' Crazy, that is, in terms of brainstorming, getting concepts out there for comment and growth. Hunt's is likely to be controversial on several levels, although its goal -- an insurance policy for the species -- is one this site can endorse. Why an insurance policy? As we've discussed recently, the number of existential threats facing our species makes the Fermi question pointed. Self-destruction would be an ignominious end for any culture, but one not inconsistent with factors as diverse as incoming asteroids, nuclear war or biological weaponry run amok. Hunt prefers to focus on a specific threat: Advances in the area of biotech, nanotech, and artificial intelligence are accelerating. Molecular manufacturing will also bring us the ability to produce chemicals which are entirely novel and...

Wired Looks at Advanced Propulsion

by Paul Gilster | May 5, 2009 | Breakthrough Propulsion | 26 Comments

Wired has picked up on our Frontiers of Propulsion Science book with just published interviews of Marc Millis and Eric Davis, co-editors of the volume. Interviewer Sharon Weinberger had a tough assignment, dealing with a 739 page collection of technical and scientific papers aimed, as she notes, at scientists and university students. But her questions were well chosen, particularly in drawing out why a book like this was necessary. Defining the Terms Marc Millis, founder of the Tau Zero Foundation, noted the need for a single, defining reference point outlining the current status of research and the opportunities presented. Thus the motivation: To clear the way for progress, my colleagues and I decided to compile this one document covering the status, issues, and unresolved questions behind a variety of known concepts, and to link the ideal goals back to real physics details. To the extent possible, we endeavored to treat these subjects impartially; showing both their visionary...

Cosmic Inflation: Evidence and Perspective

by Paul Gilster | May 4, 2009 | Deep Sky Astronomy & Telescopes, Exotic Physics | 7 Comments

I want to talk about an exciting project to find traces of cosmic inflation today, but first, a bit of housekeeping. Regulars will know that server issues a couple of weekends ago caused me to change the software this site uses to a temporary Wordpress theme while I worked to install a more permanent solution. The new look is now in place, with a wider page, changes in fonts and, behind the scenes, all kinds of useful tools that will make maintaining and upgrading Centauri Dreams a far less arduous proposition. The new server configuation seems stable as well, so I'm hopeful that those recent issues are past us. No Web site is ever complete, and I have numerous tweaks to phase in over the coming months, but having a stable platform is obviously the first task. Now, to that inflation story. Over the weekend at the American Physical Society meeting in Denver, Ki Won Yoon (National Institute of Standards and Technology) described an experimental collaboration that is using incredibly...

Black Holes Wandering the Galaxy?

by Paul Gilster | May 1, 2009 | Deep Sky Astronomy & Telescopes | 14 Comments

Do rogue black holes wander through the distant outskirts of the Milky Way? A new theory suggests one way to find out: Look for small clusters of stars that should accompany such objects. The idea is that low-mass proto-galaxies with black holes at their center would have merged, creating a gravitational kick that would send the now larger black hole outward fast enough to escape the host dwarf galaxy, but not fast enough to leave the overall galactic halo. Image: This artist's conception shows a rogue black hole floating near a globular star cluster on the outskirts of the Milky Way. New calculations by Ryan O'Leary and Avi Loeb suggest that hundreds of massive black holes, left over from the galaxy-building days of the early universe, may wander the Milky Way. Fortunately, the closest rogue black hole should reside thousands of light-years from Earth. Credit: David A. Aguilar (CfA). The 'kick' comes from the emission of gravitational waves as the black holes merge, carrying away...

A Solar Sail Manifesto

by Paul Gilster | Apr 30, 2009 | Sail Concepts | 23 Comments

I was startled to see the Breakthrough Propulsion Physics project make the pages of The Atlantic in its current issue. Novelist Thomas Mallon, in an essay largely devoted to solar sailing and The Planetary Society's efforts in that direction, gives vent to some of the frustration, if not exasperation, many of us feel as we see basic research losing out to short-term missions whose purpose is by no means clear. "American politicians now mostly avoid the old conditional trope 'If we can put a man on the moon' — because we can't, not anymore," writes Mallon, who goes on to lament the passage of the BPP project and, five years later, NASA's Institute for Advanced Concepts. Questioning Why We Explore In Mallon's view, the sense of exploration is itself under attack: Even the most spectacular unmanned successes of the American space program — from the Voyager probes of the '70s to the Galileo and Cassini missions of the '90s — seem to belong to a fading worldview. A...

Renewed Challenge to the Dinosaur Killer

by Paul Gilster | Apr 29, 2009 | Asteroid and Comet Deflection | 10 Comments

Some scientific hypotheses seem too perfect to be anything but true. Long before we understood the processes behind plate tectonics, the natural fit between the coasts of Africa and South America made the notion of their original linkage seem obvious. Although dismissed in many quarters as mere coincidence, the piecing together of earlier continents would follow. The hypothesis of continental movement, whatever the cause, was almost too obvious not to be true. But does science really work so neatly? Writing about his work on the evident 'dinosaur killer' event at the Cretaceous/Tertiary boundary, Walter Alvarez once said: "Much of the work we do as scientists involves filling in the details about matters that are basically understood already, or applying standard techniques to new specific cases. But occasionally there is a question that offers an opportunity for a really major discovery." And the K/T impact seemed, like the continental coastlines, to be an obvious fit, a...

Eccentric Orbits and Bold Predictions

by Paul Gilster | Apr 28, 2009 | Culture and Society | 18 Comments

The 100th edition of the Carnival of Space is now up at the One-Minute Astronomer site, where I learned of the existence of Christopher Crockett's Innumerable Worlds blog. Christopher's story on two gas giants around subgiant stars is well worth reading. He's a UCLA graduate student now working at Lowell Observatory who offers a good deal of background material in his posts, as in this comment on the new planets' unusually eccentric orbits: How planets end up on such crazy orbits is a matter that is currently being researched. These two worlds aren't alone; many of the new worlds we're finding sit on highly eccentric orbits. The leading hypothesis is that interactions between closely spaced planets might affect their orbits. If two planets get too close, the lighter one can get ejected from the planetary system entirely while the remaining, more massive, world is left behind on a very elliptical orbit. This is the same principle we use to slingshot probes out into deep space by...

« 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