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Human Compulsions Among the Stars

by Paul Gilster | Mar 3, 2010 | Astrobiology and SETI | 24 Comments

What are the odds for survival of a technological society? We don't know yet, having but one example to work with, but it's interesting to speculate, as Ray Villard does in a recent online post, about the kinds of intelligence that may evolve in the universe. All too often we equate technology with intelligence, which may skew our view of projects like SETI. Energized by the American Association for the Advancement of Science meeting in San Diego last week, Villard is thinking that intelligent life may have appeared on our planet not once but twice, and one of those life-forms is never going to be found by listening to radio wavelengths. The case for cetaceans seems strong. Here's Villard on the matter: Physiologically, dolphins have a brain architecture and brain mass-to-body mass ratio that is closer to that of humans than for any other species on Earth. Many years of experiments on captive dolphins show that they are self-aware, have a sense of self-identity, do detailed problem...

Gravitational Lensing Measures the Universe

by Paul Gilster | Mar 2, 2010 | Deep Sky Astronomy & Telescopes | 4 Comments

Data from the Keck telescope (Mauna Kea), the Hubble Space Telescope and the Very Large Array have been used in conjunction with the findings of the Wilkinson Microwave Anisotropy Probe to offer up a new way to measure the size of the universe, as well as how rapidly it is expanding and how old it is now. By determining a value for the Hubble constant, the work confirms the age of the universe within a span of 170 million years as 13.75 billion years old. I'm always fascinated with work involving gravitational lensing -- just yesterday we looked at using the Sun's lensing effects for potential SETI investigations -- and here we have a classic case of measuring how light traveled from a bright, active galaxy along different paths to reach the Earth. A strong gravitational lens like the one used in this study, called B1608+656, creates multiple images of the same galaxy lying behind the lensing object. Studying the time the light took along each path, it was possible to gather...

SETI: The Solar Sail Perspective

by Paul Gilster | Mar 1, 2010 | Missions | 14 Comments

I love what Dan Wertheimer, a Berkeley astronomer and one of the powers behind the SETI@Home distributed computing project, told a session at the recent AAAS meeting in San Diego. Wertheimer was talking about the possibility of using the Sun's gravitational lens for SETI purposes, and as quoted by Alan Boyle, said that such an observatory could "read the license plates on an extrasolar planet." That reminded me of Claudio Maccone's whimsical but mind-boggling remark at the interstellar conference in Aosta last July, which went in much the same direction. What could lensing do? "We could see the roads of their cities. We could see the cars they are driving." Drake has made the case for using the Sun's gravitational lens for SETI purposes for a long time now, and he repeated it at the TED 2010 conference in Long Beach. As to Maccone, he has long championed the FOCAL mission to the gravitational lens that would exploit the fantastic magnifications available at 550 AU and beyond. But it...

Enceladus Hotspots, and Memories of Orion

by Paul Gilster | Feb 26, 2010 | Outer Solar System | 18 Comments

Although we've been preoccupied largely with theoretical matters this week, I don't want it to close without reference to the new Cassini imagery of Enceladus. This shot was made at a phase angle of 145 degrees when Cassini was about 14,000 kilometers from Enceladus, during the flyby of November 21. The remarkable jets spraying from the fractured surface in the south polar region are clearly visible. Image: Dramatic plumes, both large and small, spray water ice out from many locations along the famed "tiger stripes" near the south pole of Saturn's moon Enceladus. The tiger stripes are fissures that spray icy particles, water vapor and organic compounds. More than 30 individual jets of different sizes can be seen in this image and more than 20 of them had not been identified before. At least one jet spouting prominently in previous images now appears less powerful. Credit: NASA/JPL/SSI. I keep thinking about Project Orion, back in the crazy days before the Test Ban Treaty of 1963...

Other Life in the Multiverse?

by Paul Gilster | Feb 25, 2010 | Exotic Physics | 68 Comments

What conditions would you say are 'congenial to life'? For physicist Robert Jaffe and colleagues at MIT, the phrase refers to places where stable forms of hydrogen, carbon and oxygen can exist. Jaffe explains why: "If you don't have a stable entity with the chemistry of hydrogen, you're not going to have hydrocarbons, or complex carbohydrates, and you're not going to have life. The same goes for carbon and oxygen. Beyond those three we felt the rest is detail." It's an important issue in Jaffe's work because he wants to see whether other universes could harbor life. We know that slight changes to the laws of physics would disrupt the evolution of the universe we live in. The strong nuclear force, for example, could have been just a bit stronger, or weaker, and stars would have been able to produce few of the elements needed to build planets. Remove the electromagnetic force and light would not exist, nor would atoms and chemical bonds. Nudging Nature's Parameters Run through the...

Millis: Approaches to Interstellar Flight

by Paul Gilster | Feb 24, 2010 | Tau Zero Foundation | 31 Comments

How do you go about pushing the frontiers of propulsion science? Tau Zero Foundation founder Marc Millis discussed the question in a just published interview with h+ Magazine. One aspect of the question is to recognize where we are today. Millis is on record as saying that it may be two to four centuries before we're ready to launch an Alpha Centauri mission. Why the delay? The problem is not so much high-tech savvy as it is available energy, and Millis evaluates it by comparing the energy we use for rocketry today vs. the entire Earth's consumption of energy. The question is how much energy we produce and how much we consume, and what percentage of that is devoted to spaceflight. You can see and hear Millis discussing his calculations on the matter in a presentation he made at the TEDx Brussels 2009 session, one that is linked to from the interview. Obviously, the time to the Centauri stars decreases if we decide to put ten times more energy into the space program than we have...

Missions Cometary and Otherwise

by Paul Gilster | Feb 23, 2010 | Outer Solar System | 2 Comments

The Stardust spacecraft recently completed a course adjustment maneuver as it continues on its way to comet Tempel 1. The burn began at 2221 UTC on February 17 and lasted 22 minutes and 53 seconds. The net result: A change of the spacecraft's speed by 24 meters per second. That may not sound like much, but it has big ramifications for this interesting mission. Tempel 1 is a rotating object, and mission scientists want to have a look at places previously imaged by the Deep Impact mission of 2005 (and yes, this is the first time we've revisited a comet). An adjustment to Stardust's encounter time of eight hours and 20 minutes should maximize the chances of seeing the right surface features on the 2.99-kilometer wide potato-shaped mass. The burn took place almost exactly a year before the spacecraft will reach Tempel 1. You may remember Stardust as the first spacecraft to collect cometary samples and return them to Earth for study. After the sample return capsule was retrieved in 2006,...

Relativistic Rockets, Antimatter and More

by Paul Gilster | Feb 22, 2010 | Antimatter | 28 Comments

Interstellar theorist Richard Obousy (Baylor University) has some thoughts about William and Arthur Edelstein's ideas on flight near the speed of light. As discussed in these pages on Friday, the Edelsteins, in a presentation delivered at the American Physical Society, had argued that a relativistic rocket would encounter interstellar hydrogen in such compressed form that its crew would be exposed to huge radiation doses, up to 10,000 sieverts in the first second. Because even a 10-centimeter layer of aluminum shielding would stop only a tiny fraction of this energy, the Edelsteins concluded that travel near lightspeed would be all but impossible. Obousy, who handles the Project Icarus Web site, has his own credentials related to high speed travel, authoring a number of papers like the recent "Casimir energy and the possibility of higher dimensional manipulation" (abstract) that press for continued work into breakthrough propulsion. And when he talked to astrophysicist Ian O'Neill...

FOCAL: Last Call for IAC Papers

by Paul Gilster | Feb 20, 2010 | Missions | 3 Comments

Every few weekends as we move toward the March 5 deadline for submission of abstracts to the next International Astronautical Congress, I'll re-run this call for papers that I originally published in December. The Tau Zero Foundation hopes to energize discussion of FOCAL in the astronautical community and create a growing set of papers analyzing aspects of the mission from propulsion to communications, leading to a formal mission proposal. We hope anyone interested in furthering this work at the coming IAC in Prague will consider submitting a paper. The Tau Zero Foundation is announcing a call for papers related to the FOCAL mission. The venue: The 61st International Astronautical Congress in Prague, which convenes on the 27th of September, 2010 and runs to October 1. Specifically, we are looking for papers for session D4.2, "Interstellar Precursor Missions," whose focus is "...missions that significantly expand science -- using existing and emerging power and propulsion...

Pushing Up Against Lightspeed

by Paul Gilster | Feb 19, 2010 | Exotic Physics, Interstellar Medium | 91 Comments

Time dilation has long been understood, even if its effects are still mind-numbing. It was in 1963 that Carl Sagan laid out the idea of exploiting relativistic effects for reaching other civilizations. In a paper called "Direct Contact Among Galactic Civilizations by Relativistic Interstellar Flight," Sagan speculated on how humans could travel vast distances, reaching beyond the Milky Way in a single lifetime by traveling close to the speed of light. At such speeds, time for the crew slows even as the millennia pass on Earth. No going home after a journey like this, unless you want to see what happened to your remote descendants in an unimaginable future. Before Sagan's paper appeared (Planetary and Space Science 11, pp. 485-98), he sent a copy to Soviet astronomer and astrophysicist Iosif Shklovskii, whose book Universe, Life, Mind had been published in Moscow the previous year. The two men found much common ground in their thinking, and went on to collaborate on a translation and...

Outstanding Early Imagery from WISE

by Paul Gilster | Feb 18, 2010 | Deep Sky Astronomy & Telescopes | 9 Comments

We're keeping a close eye on the WISE mission (Wide-field Infrared Survey Explorer) and the possibility of identifying brown dwarfs closer to our Sun than the Centauri stars. But WISE's targets are numerous, and the early imagery coming back from the mission is promising indeed. To check out the capabilities of this space-based observatory, have a look at some of the new photos, which show M31, the Andromeda galaxy, at a variety of wavelengths. The first image was made with all four of WISE's infrared detectors -- the caption describes the color coding. Image: The immense Andromeda galaxy, also known as Messier 31 or simply M31, is captured in full in this new image from NASA's Wide-field Infrared Survey Explorer, or WISE. The mosaic covers an area equivalent to more than 100 full moons, or five degrees across the sky. WISE used all four of its infrared detectors to capture this picture (3.4- and 4.6-micron light is colored blue; 12-micron light is green; and 22-micron light is red)....

Star Formation in the Early Universe

by Paul Gilster | Feb 17, 2010 | Deep Sky Astronomy & Telescopes | 6 Comments

We know that new stars form out of cold gas and dust that are present in galaxies, but what accounts for the fact that star formation is slower than in earlier eras? Three to five billion years after the Big Bang, galaxies turned out stars at a much faster clip than they do today. The Milky Way seems to produce stars at a rate equaling about ten times the mass of our Sun each year, whereas similar galaxies earlier in their lives featured star formation rates that were up to ten times higher. Michael Cooper (University of Arizona) and colleagues have gone to work on this question by studying data from the DEEP2 survey of 50,000 galaxies, picking a sample of one dozen massive galaxies to represent the average population. Working with the Hubble and Spitzer space telescopes as well as radio telescope arrays in France and California, the team then observed the selected galaxies in the infrared and measured their radio frequency emissions, making cold gas clouds visible. Cooper and...

‘Smart Dust’ and Solar Sails

by Paul Gilster | Feb 16, 2010 | Sail Concepts | 9 Comments

My interest in solar sail concepts goes back to the days of Cordwainer Smith's "The Lady Who Sailed the Soul," a science fiction tale (Galaxy, April 1960) whose evocative conjuring of a fantastic future has always stayed with me despite far more realistic sail concepts from the pen of Arthur C. Clarke and Poul Anderson, to name but a few. But magsails -- craft that operate by creating a magnetic field that can interact with the solar wind -- offer possibilities just as robust, provided we can tame the propulsive effects of that wind. And this may not be easy, given the changing speed and strength of this stream of charged particles outbound from the Sun. Moving in some cases faster than 400 kilometers per second, the solar wind seems to offer a clear path to the outer system, but we know all too little about it. That's why I always keep an eye on attempts to measure the solar wind, including the IBEX (Interstellar Boundary Explorer) mission that examines the interactions between the...

Space: ‘Let’s Just Do It’

by Paul Gilster | Feb 15, 2010 | Culture and Society | 77 Comments

When Peter Diamandis talks about the emergence of a 'let's just do it' mentality about spaceflight, anyone interested in getting our species off-planet will listen up. Diamandis, after all, as chief executive of the X Prize Foundation, has been a major force in making commercial space ventures newsworthy. Who can forget the first flight of Scaled Composites' SpaceShipOne? Diamandis firmly believes we are no longer content to watch government astronauts work in space. It's time for the commercial sector to take off. In a new article in the Wall Street Journal (thanks to Erik Anderson for the heads-up), Diamandis lays out our biggest challenge in getting a space-based infrastructure into operation: The cost. Ponder the fact that as the US space shuttle fleet is closed down, American astronauts will need to hitch rides on the Russian Soyuz at a cost of over $50 million per person. That sounds high, and it is, but compare it to shuttle costs of between $750 to $2 billion per flight,...

Directed Panspermia: Seeding the Galaxy

by Paul Gilster | Feb 12, 2010 | Astrobiology and SETI | 58 Comments

Panspermia, the idea that life might travel through space to seed other planets and even other star systems, is a fascinating topic for conjecture, and our understanding of the survival of various forms of life in extreme environments only adds to its appeal. But just as SETI has an active counterpart that seeks to send rather than simply receive interstellar messages, so panspermia has its own advocates for a new kind of mission: To seed the stars from Earth. A group called SOLIS (Society for Life in Space) has sprung up around the notion. Its goal: To propagate our family of organic Life throughout the Milky Way Galaxy and beyond. We propose to seed young planetary systems in star-forming interstellar clouds. We shall design and launch directed panspermia missions carrying the microbial representatives of Life by the year 2050. So says the SOLIS Web site and so says society coordinator Michael Mautner, who is a research professor in chemistry at Virginia Commonwealth University....

Dark Energy: Calibrating Standard Candles

by Paul Gilster | Feb 11, 2010 | Deep Sky Astronomy & Telescopes | 6 Comments

To measure the brightness of a star, astronomers compare it to standard reference stars. You would think measurements of the latter would be highly refined by now, but as this New Scientist story points out, the bright star Vega's most accurate measurements date back to the 1970s. That puts the focus on a new space telescope, or maybe New Scientist's term 'rocket-borne' is better here, because the ACCESS experiment will actually not go into orbit, but will make four suborbital flights to make measurements lasting only minutes. ACCESS (Absolute Color Calibration Experiment for Standard Stars) will look at four common reference stars: Sirius, Vega, and two much fainter objects, HD 37725 and BD+17?4708, with observing time limited to about 400 seconds. That's not much time, but it's enough for ACCESS to gauge the brightness of the four reference stars to a precision of one percent and perhaps better, twice the precision of today's measurements. Image: Standard Candles are used to...

Mapping the Interstellar Medium

by Paul Gilster | Feb 10, 2010 | Interstellar Medium | 6 Comments

We've long known that the spaces between the stars are not empty, but are pervaded by a highly dilute mix of gas and dust. Now we're getting maps that show the presence of large cavities in this interstellar medium, created by supernova events as well as outflowing solar winds from clusters of hot, young stars. The Sun resides in the so-called Local Cavity, a low-density area of neutral gas that is about 80 parsecs in radius. The Local Cavity is, in turn, surrounded by a 'wall' of dense, neutral gas, with gaps in the wall -- 'interstellar tunnels' -- that are low-density pathways to surrounding cavities. We study the interstellar medium by looking at the light produced by stars and using absorption line spectroscopy to see how that light is affected by gases between us and the stars in question. Johannes Hartmann's classic study of the spectrum of Delta Orionis in 1904 was a huge advance, looking at absorption from the 'K' line of calcium and concluding that the gas was not present...

New Evidence for Water on Enceladus

by Paul Gilster | Feb 9, 2010 | Outer Solar System | 11 Comments

New measurements from Cassini, made on a flyby through the plume of Enceladus on March 12, 2008, bolster the case for liquid water in the Saturnian moon. Cassini found negatively charged water ions in the plume, and its plasma spectrometer also traced other kinds of negatively charged ions including hydrocarbons. That adds Enceladus to a fairly select list -- the Earth, Titan and the comets -- where negatively charged ions are known to exist in the Solar System. They're found in Earth's ionosphere, and also in places at the surface where liquid water is in motion, such as waterfalls. Image: Is there liquid water beneath this surface? Portions of the tiger stripe fractures, or sulci, are visible along the terminator at lower right, surrounded by a circumpolar belt of mountains. The icy moon's famed jets emanate from at least eight distinct source regions, which lie on or near the tiger stripes. However, in this view, the most prominent feature is Labtayt Sulci, the approximately...

Notes & Queries 2/8/10

by Paul Gilster | Feb 8, 2010 | Culture and Society | 21 Comments

Prospects for Interstellar Travel Be aware of Paul Titze's continuing exegesis of John Mauldin's book Prospects for Interstellar Travel (Univelt, 1992). I used Mauldin again and again as I developed my Centauri Dreams book, finding the dense and lengthy volume covered every conceivable aspect of interstellar flight as understood by current physics. But the book was published in a small press run and is hard to track down, although Amazon usually has a few copies from independent resellers available. Paul is doing the community a service by going through Mauldin chapter by chapter, highlighting the salient points with commentary. A quote from an early chapter: Relativity makes energy a serious problem through the limits imposed to prevent speeds greater than light. Relativity also offers tantalizing solutions: the slowing of time and Total Conversion of mass to energy. How closely propulsion might approach TC is explored in Chapter 4. One could hope to find a way to travel without the...

FOCAL: Renewed Call for Papers

by Paul Gilster | Feb 6, 2010 | Missions | 17 Comments

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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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