Paul Gilster | Centauri Dreams

Pale Red Dot: Proxima Centauri Campaign Begins

by Paul Gilster | Jan 18, 2016 | Exoplanetary Science | 38 Comments

A new observational campaign for Proxima Centauri, coordinated by Guillem Anglada-Escudé (Queen Mary University, London), is about to begin, an effort operating under the name Pale Red Dot. You'll recall Dr. Anglada-Escudé's name from his essay Doppler Worlds and M-Dwarf Planets, which ran here in the spring of last year, as well as from Centauri Dreams reports on his work on Gliese 667C, among other exoplanet projects. Pale Red Dot is a unique undertaking that brings the public into an ongoing campaign from the outset, one whose observations at the European Southern Observatory's La Silla Observatory begin today. The closest star to our Sun, Proxima Centauri was discovered just over 100 years ago by the Scottish astronomer Robert Innes. A search through the archives here will reveal numerous articles about the red dwarf and the previous attempts to find planets orbiting it. I'll point you to a round-up of exoplanet work on Proxima thus far next week, when my essay...

KIC 8462852: A Century Long Fade?

by Paul Gilster | Jan 14, 2016 | Astrobiology and SETI | 273 Comments

I hadn’t expected a new paper on KIC 8462852 quite this fast, but hard on the heels of yesterday’s article on the star comes “KIC 8462852 Faded at an Average Rate of 0.165±0.013 Magnitudes Per Century From 1890 To 1989,” from Bradley Schaefer (Louisiana State University). Schaefer takes a hard look at this F3 main sequence star in the original Kepler field not only via the Kepler data but by using a collection of roughly 500,000 sky photographs in the archives of Harvard College Observatory, covering the period from 1890 to 1989. The Harvard collection is vast, but Schaefer could take advantage of a program called Digital Access to a Sky Century@Harvard (DASCH), which has currently digitized about 15 percent of the archives. Fortunately for us, this 15 percent covers all the plates containing the Cygnus/Lyra starfield, which is what the Kepler instrument focused on. Some 1581 of these plates cover the region of sky where KIC 8462852 is found. What Schaefer discovers is a secular...

Following Up KIC 8462852

by Paul Gilster | Jan 13, 2016 | Astrobiology and SETI | 42 Comments

As I sat down to write yesterday morning, I realized there was a natural segue between the 1977 ‘Wow!’ signal, and the idea that it had been caused by two comets, and KIC 8462852, the enigmatic star that has produced such an interesting series of light curves. What I had planned to start with today was: “Are comets becoming the explanation du jour for SETI?” But Centauri Dreams reader H. Floyd beat me to the punch, commenting yesterday: “Comets are quickly earning the David Drumlin Award for biggest SETI buzzkill.” As played by Tom Skeritt, David Drumlin is Ellie Arroway’s nemesis in the film Contact, willing to knock down the very notion of SETI and then, in a startling bit of reverse engineering, turning into its champion as he claims credit for a SETI detection. And of course you remember controversial KIC 8462852 as the subject of numerous media stories first playing up the idea of alien mega-engineering, and then as quickly declaring the problem solved by a disrupted family of...

Return to ‘Wow!’

by Paul Gilster | Jan 12, 2016 | Astrobiology and SETI | 27 Comments

The famous Wow! signal, picked up on August 15, 1977 at the Big Ear radio telescope (Ohio State University) is back in the news, with a new theory suggesting a source for the signal right here in the Solar System. Antonio Paris (St. Petersburg College, FL) asks us to consider a cometary origin for the signal, generated as two comets released hydrogen as they passed near the Big Ear's search field. The now-dismantled telescope had a fixed field of view, so a bright signature at 21 centimeters -- the hydrogen line -- would have appeared short-lived. Specifically, 21-cm refers to the line in the spectrum of neutral hydrogen atoms, a wavelength corresponding to 1420 megahertz associated with the most common element in the universe. It was back in 1959 that both Philip Morrison and Frank Drake fixed on the hydrogen line as a rational place to look for interstellar beacons, the assumption being that any civilization trying to reach another would choose a wavelength associated with some...

Solid Results from ‘Second Light’

by Paul Gilster | Jan 11, 2016 | Exoplanetary Science | 17 Comments

If they did nothing else for us, space missions might be worth the cost purely for their role in tuning up human ingenuity. Think of rescues like Galileo, where the Jupiter-bound mission lost the use of its high-gain antenna and experienced numerous data recorder issues, yet still managed to return priceless data. Mariner 10 overcame gyroscope problems by using its solar panels for attitude control, as controllers tapped into the momentum imparted by sunlight. Overcoming obstacles is part of the game, and teasing out additional science through extended missions taps into the same creativity. Now we have news of how successful yet another mission re-purposing has been through results obtained from K2, the Kepler 'Second Light' mission that grew out of problems with the critical reaction wheels aboard the spacecraft. It was in November of 2013 that K2 was proposed, with NASA approval in May of the following year. Kepler needed its reaction wheels to hold it steady, but like Mariner 10,...

Space Habitats Beyond LEO: A Short Step Towards the Stars

by Paul Gilster | Jan 8, 2016 | Advanced Rocketry | 62 Comments

Building a space infrastructure is doubtless a prerequisite for interstellar flight. But the questions we need to answer in the near-term are vital. Even to get to Mars, we subject our astronauts to radiation and prolonged weightlessness. For that matter, can humans live in Mars' light gravity long enough to build sustainable colonies without suffering long-term physical problems? Gregory Matloff has some thoughts on how to get answers, involving the kind of space facility we can build with our current technologies. The author of The Starflight Handbook (Wiley, 1989) and numerous other books including Solar Sails (Copernicus 2008) and Deep Space Probes (Springer, 2005), Greg has played a major role in the development of interstellar propulsion concepts. His latest title is Starlight, Starbright (Curtis, 2015). by Gregory Matloff The recent demonstrations of successful rocket recovery by Blue Origin and SpaceX herald a new era of space exploration and development. We can expect, as...

HD 7449Ab: Choreography of a Planetary Dance

by Paul Gilster | Jan 7, 2016 | Exoplanetary Science | 3 Comments

Given this site’s predilections, it’s natural to think of Centauri A and B whenever the topic of planets around close binary stars comes up. But systems with somewhat similar configurations can produce equally interesting results. Take what we’re finding around the G-class star HD 7449, some 127 light years from our Sun. In 2011, a planet of roughly eight times Jupiter’s mass was found orbiting the star in an orbit so eccentric that it demanded explanation. A highly eccentric orbit can indicate another object in the system that is affecting the planet. Exactly what has now been determined. “The question was: is it a planet or a dwarf star?” says Timothy Rodigas (Carnegie Institution for Science), who led the work on the discovery. Rodigas’ team went to work using the Magellan adaptive optics system (MagAO) on the Magellan II (Clay) instrument at Las Campanas in Chile. MagAO allows sharp visible-light images to be acquired, with the instrument capable of resolving objects down to the...

Globular Clusters: Home to Intelligent Life?

by Paul Gilster | Jan 6, 2016 | Astrobiology and SETI | 26 Comments

I can think of few things as spectacular as a globular cluster. Messier 5 is a stunning example in Serpens. With a radius of some 200 light years, M5 shines by the light of half a million stars, and at 13 billion years old, it's one of the older globular clusters associated with our galaxy. Clusters like these orbit the galactic core, stunning chandeliers of light packed tightly with stars. The Milky Way has 158 known globulars, while M31, the Andromeda galaxy, boasts as many as 500. Giant elliptical galaxies like M87 can have thousands. Image: The globular cluster Messier 5, consisting of hundreds of thousands of stars. Credit: ESA/Hubble & NASA. Via Wikimedia Commons. Given the age of globular clusters (an average of ten billion years), it's a natural assumption that planets within them are going to be rare. We would expect their stars to contain few of the heavy elements demanded by planets, since elements like iron and silicon are created by earlier stellar generations. And...

Stellar Age: Recalibrating Our Tools

by Paul Gilster | Jan 5, 2016 | Deep Sky Astronomy & Telescopes | 5 Comments

Making the call on the age of a star is tricky business. Yet we need to master the technique, for stellar age is a window into a star's astrophysical properties, important in themselves and for understanding the star in the context of its interstellar environment. And for those of us who look at SETI and related issues, the age of a star can be a key factor -- is the star old enough to have produced life on its planets, and perhaps a technological civilization? Until recently, luminosity and surface temperature were the properties that helped us make a rough estimate of a star's age, which gives insight into how challenging the problem is. These are factors that, while they do change over time, give us only approximations of age. More recently, researchers have learned to study sound waves deep in the stellar interior, a method that is confined to bright targets and cannot help us with vast numbers of dimmer stars. Called asteroseismology, this method has helped our estimates of...

‘A City Near Centaurus’

by Paul Gilster | Jan 4, 2016 | Culture and Society | 8 Comments

Let's start the year off with a reflection on things past. Specifically, a story called "A City Near Centaurus," set on a planet circling one of the Alpha Centauri stars. Just which star is problematic, because our author, Bill Doede, describes it as a planet circling 'Alpha Centaurus II.' I'm sure he means Centauri B, but the story, which appeared in Galaxy at the end of Frederick Pohl's first year as editor, is less concerned about nomenclature and setting than the conflict between a humanoid alien called Maota and the timeless city he lives in. Michaelson, our human protagonist, looks out upon this long deserted metropolis: He gazed out from his position at the complex variety of buildings before him. Some were small, obviously homes. Others were huge with tall, frail spires standing against the pale blue sky. Square buildings, ellipsoid, spheroid. Beautiful, dream-stuff bridges connected tall, conical towers, bridges that still swung in the wind after half a million years. Late...

Can Social Insects Have a Civilization?

by Paul Gilster | Dec 31, 2015 | Culture and Society | 91 Comments

I first encountered Michael Chorost in his fine book World Wide Mind (Free Press, 2011), which looks at the relationship between biology and the machine tools that can enhance it. Mike's thinking on SETI has already produced rich discussion in these pages (see, for example, SETI: Contact and Enigma). In today's essay, he's asking for reader reactions to the provocative ideas on insect memory and intelligence that will inform his next book. While it does not happen on Earth, can evolution invent -- somewhere -- a social insect society capable of long-term memory and civilization? A nearby planet evidently hostile to our kind of life offers fertile ground for speculation. by Michael Chorost I've admired Paul Gilster's Centauri Dreams for many months and I've always been impressed by the quality of the comments. Paul graciously allowed me to write a guest entry to test one of my book-in-progress's ideas on a smart audience -- you. This book-in-progress will be my third book. My first...

‘Time Delays’ and Exploding Stars

by Paul Gilster | Dec 30, 2015 | Deep Sky Astronomy & Telescopes | 4 Comments

With our focus on nearby stars for both exoplanet detection and SETI work, I don't often find the time to talk about cosmology and 'deep sky' observations, although galaxy structure and formation are an interest of mine. But today I have a story too good to pass up, involving using gravitational lensing and time delays in how light reaches us to investigate events at the edge of the visible universe. In such work, the curvature of spacetime itself is part of our toolkit. Consider four images found around a foreground galaxy that were created by a background supernova. Here celestial alignments lead us to successful prediction, and for the first time, a supernova appears where astronomers have said it would. Or I should say, 're-appears.' The elliptical galaxy in question is located within the galaxy cluster MACS J1149+2223, which since 2012 has been known to lie between us and a background galaxy whose light is being magnified by the lens of the cluster. In November of 2014,...

Looking Ahead to OSIRIS-REx

by Paul Gilster | Dec 29, 2015 | Asteroid and Comet Deflection | 2 Comments

Back when I was in grade school, we put in several months studying ancient Egyptian culture. I can remember becoming fascinated with the pyramid builders and wanting to immerse myself in the world that produced them. But I don't think I ever reached the multidisciplinary level of a third-grader named Michael Puzio, who named the asteroid now called Bennu. The sharp-eyed Puzio entered a contest to name the asteroid that the OSIRIS-REx mission will fly to, choosing the Egyptian deity Bennu because he thought the spacecraft resembled the mythological bird. I call Michael Puzio one smart third-grader, and I'm happy that yesterday's post, on the near-Earth asteroid 2003 SD220, brought him to mind. The close pass by 2003 SD220 on Christmas Eve prompted a series of radar studies that we'll now use to help refine its orbit. Bennu is likewise nearby, though at about 500 meters a bit smaller than 2003 SD220, and it too has been the object of study by the planetary radars at Arecibo and...

‘Centaurs’ as Potential Impactors

by Paul Gilster | Dec 28, 2015 | Asteroid and Comet Deflection | 16 Comments

An asteroid shaped something like a sweet potato swept by the Earth on December 24, though at a sufficient distance (28 times further away than the Moon) to pose no hazard to our planet. 2003 SD220 was making the first of five predicted encounters within the next twelve years, and the measurements made by the planetary radar system at Arecibo on the asteroid's shape, rotation and other properties will now be useful in refining its orbit. The Jet Propulsion Laboratory's Goldstone Solar System Radar and the National Radio Astronomy Observatory's Green Bank Telescope and Very Long Baseline Array also contributed data on the asteroid. Highly elongated and more than 2 kilometers long, 2003 SD220 is of interest as a possible target for a future space mission, not only because asteroids should give us clues about conditions in the early Solar System, but also because near-Earth asteroids need to be well understood in case we one day find ourselves dealing with a potential impactor. Image:...

Voyager to a Star

by Paul Gilster | Dec 24, 2015 | Culture and Society | 43 Comments

The essay that follows is a much expanded version of a brief post that ran here last April, the idea being to give our Voyager spacecraft one last (symbolic) mission. It will run later this year in a publication called 'Handbook of the Unknowable,' produced by Espen Gangvik (Director Trondheim Biennale, Norway) and edited by Rachel Armstrong (Newcastle University, UK) and Rolf Hughes (Stockholm University of the Arts). The book will appear in conjunction with Meta.Morf 2016, a recurring Scandinavian festival dedicated to art and technology, which convenes this year in Trondheim. Armstrong, a familiar figure here on Centauri Dreams, tells me that the Handbook will use its essays, poetry, fiction and art to explore our engagement with space and our future among the stars. Meta.Morf 2016 will take place on March 10-11, and I commend both it and the Handbook to you. More on the event as we get closer. Let me also take this opportunity to wish all my readers the very best for the...

Dawn at Ceres: ‘Down Among Them’

by Paul Gilster | Dec 23, 2015 | Outer Solar System | 8 Comments

The new images just in from Dawn at Ceres unexpectedly evoke a much earlier mission, the Apollo 10 precursor to the lunar landing. This was the second manned mission to orbit the Moon, one that saw the lunar module drop to just over 15 kilometers from the surface in a rehearsal for the Apollo 11 landing. Just for fun, I've been looking through the Apollo 10 transcripts for day 5, when the LM ('Snoopy') had already separated from the command module. John Young was in the command module as Gene Cernan and Tom Stafford put Snoopy through its paces. Nobody had ever been this close to the Moon before. You probably remember or else have read about Snoopy's descent toward the lunar peaks: 100:25:43 Young: ...at 6 miles, he was doing 65 feet a second (20 m/s) on my - 6 miles (9.6 km) from me, he was doing 65 feet per second (20 m/s). At 3.8 miles (6.1 km) he was doing 73 feet per second (22 m/s). I think that confirms this burn. They are down there among the rocks… As Cernan quickly...

Wolf 1061c: A Nearby Habitable Zone Planet?

by Paul Gilster | Dec 22, 2015 | Exoplanetary Science | 28 Comments

At no more than 14 light years away, Wolf 1061 gains our attention with the discovery that this small red dwarf hosts three planets, in orbits of 4.9, 17.9 and 67.2 days respectively. Of particular interest is Wolf 1061c, which appears to be within the habitable zone, defined here as the region in which it would be possible for liquid water to exist on the surface, and potentially life. Wolf 1061c has a mass at least 4.3 times that of Earth, with inner planet Wolf 1061b coming in at 1.4 times that mass. Wolf 1061d is calculated to be at least 5.2 times Earth's mass. Image: The Wolf 1061 system, with the habitable zone depicted in green. Credit: University of New South Wales. One thing Wolf 1061 reminds us is that red dwarf stars are good targets for radial velocity studies. For one thing, such stars have low levels of luminosity, which means their habitable zones are small and planets within them are in close orbits. Such planets create a stronger, more detectable signature for...

Oxygenation: Gradual Process, Profound Results

by Paul Gilster | Dec 21, 2015 | Astrobiology and SETI | 41 Comments

The vast changes our planet has undergone since formation add a real sense of humility to the exoplanet hunt. It's the humility that comes with exposure to deep time, reminding us that worlds like ours have developed through phases wildly different than the conditions we experience today. As we tune up our techniques for studying rocky worlds, we'll find planets in entirely different states of their own evolution, perhaps some with life, and some young enough to be life's future home. Perhaps some will be worlds where life has come, and gone. We have much to learn about how our own planet developed life, and new work from an international team led by Philip Pogge von Strandmann (University College London) gives us insight into a key issue: How long did it take for oxygen levels in the oceans and atmosphere to increase to the point that animal life could take off some 600 million years ago? Underlying the question is how the evolution of life ties in to changes in climate. For it...

Where Are the Jupiter Analogs?

by Paul Gilster | Dec 18, 2015 | Exoplanetary Science | 44 Comments

Are Solar Systems like ours commonplace? One way of answering this is to look at the role of planets like Jupiter, which may have helped to determine the habitability of the inner planets. But worlds like Jupiter in orbits around 5 AU do not appear to be the norm, as Andrew LePage points out in this discussion of a new exoplanet find. LePage, publisher of an essential site on exoplanet detection (www.DrewExMachina.com) is also a Senior Project Scientist at Visidyne, Inc. in Boston. Today he shows us what we know and just how much we still need to clarify about the occurence of planets like Jupiter and their role in system habitability. By Andrew J. LePage A couple of decades ago, astronomers thought they had planetary systems figured out: they consisted of a more or less orderly set of worlds orbiting in the same plane with small rocky worlds close in and much larger, volatile-rich planets orbiting farther out beyond the "snow line" where plentiful water freezes into solid ice. Along...

E-22: The Last Hurrah at Enceladus

by Paul Gilster | Dec 17, 2015 | Outer Solar System | 9 Comments

It's the end of an era. On Saturday December 19, the Cassini Saturn orbiter will make its final close pass by Enceladus. This doesn't mark the end of Cassini itself, which still has work to do especially with regard to Titan, but it does mean the end, at least for now, of our close-up study of a remarkable phenomenon: The plumes of Enceladus, which Cassini itself discovered. We've gained priceless data through its flybys, helping us make the case for an internal ocean. Cassini will continue to observe Enceladus until mission's end, but only from much greater distances. In fact, as this JPL news release explains, the closest Cassini will come to Enceladus after Saturday is about four times the distance of the upcoming flyby. Nor will the Saturday event be as close a pass as Cassini's dive through the south polar plume on October 28. That one took the spacecraft within a scant 49 kilometers of the surface, returning data that is still undergoing analysis as we probe the plume's...

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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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