Paul Gilster | Centauri Dreams

SETI: Knowing Where to Look

by Paul Gilster | Mar 8, 2016 | Astrobiology and SETI | 22 Comments

Running a site like Centauri Dreams means adapting and reconfiguring on a daily basis. The best laid plans and all that… When I wrote recently about the SETI efforts at KIC 8462852, my plan had been to follow up that discussion with a broader SETI issue -- where is the best place in the sky to search for a SETI signal? Then life intervened, first with my preparations to go to the Tennessee Valley Interstellar Workshop in Chattanooga, and then with the illness that cancelled those plans and left me with a thoroughly disrupted train of thought. I'm now ready to tackle that SETI question with particular reference to a new paper by René Heller and Ralph E. Pudritz, but I still want to put the discussion into context. With the KIC 8462852 SETI effort, we looked at a targeted observation campaign using the Allen Telescope Array to see if researchers could find any evidence of unusual activity associated with the star. As we saw in Jim and Dominic Benford's recent work (see...

New Eyes on the Kuiper Belt

by Paul Gilster | Mar 7, 2016 | Deep Sky Astronomy & Telescopes | 3 Comments

You probably recall how tricky it was to find 2014 MU69, the small Kuiper Belt Object that will be the next destination for our New Horizons probe. The actual extended mission to 2014 MU69 awaits a summer 2016 review within NASA, but because trajectory changes to get there could not be delayed, the New Horizons craft performed four maneuvers late last year to set the course. The search for a suitable KBO began in 2011 and it was not until 2014, working with data from the Hubble Space Telescope, that scientists were able to find their best candidate. Now consider that 2014 MU69 has a diameter of about 45 kilometers, making it ten times larger than the average comet. How difficult, then, to assess the true population of smaller Kuiper Belt Objects. We'd like to know a lot more about much smaller KBOs, because assessing the abundance and collisional processes of these objects is way of understanding the debris disks we're seeing around other stars. Current theory suggests that KBOs...

A Transiting Jupiter Analog

by Paul Gilster | Mar 4, 2016 | Exoplanetary Science | 9 Comments

David Kipping and colleagues have discovered what they describe as ‘the first validated transiting Jupiter analog,’ a planet orbiting the K-class dwarf KIC-3239945. Kepler-167e is about 90 percent the size of Jupiter and orbits its star at about twice the distance that the Earth orbits the Sun. Given the fact that the star is cooler than the Sun -- an orange rather than a yellow dwarf -- temperature estimates for the planet are in the 130 K range, only about 20 K warmer than Jupiter. The discovery is discussed on the Cool Worlds YouTube channel, an outreach project launched by the Cool Worlds Lab at Columbia University, and is the subject of a paper submitted to The Astrophysical Journal (citation below). Kepler-167e isn’t just another ‘hot Jupiter’, a class of worlds that is well populated. ‘Hot Jupiters’ occupy orbits extremely close to the parent star. Finding a true Jupiter analog -- i.e., a planet in a close to circular orbit in a position roughly analogous to Jupiter’s in our...

A New Kind of ‘Fast Radio Burst’

by Paul Gilster | Mar 3, 2016 | Deep Sky Astronomy & Telescopes | 13 Comments

A new paper in Nature offers further information about Fast Radio Bursts (FRBs), which we last looked at only a few days back. The February 24 post examined work on FRBs that were consistent with what has been seen before -- transient pulses lasting mere milliseconds, while emitting huge amounts of energy (see Fast Radio Bursts: First Distance Measurement). Now we have further work out of the Max Planck Institute for Radio Astronomy (MPIfR) in Germany that describes the detection of the first source of repeating bursts, an object outside our own galaxy that is producing multiple short bursts. Lead author Laura Spitler (MPIfR) explains that a McGill University graduate student named Paul Scholz, using data from the Arecibo radio telescope in Puerto Rico, discovered the repeat signals last November. Scholz found a total of 10 new bursts. "Not only does this source repeat, but the brightness and spectra of the bursts also differs from those of other FRBs," adds Spitler. We may be...

False Positives in the Search for Extraterrestrial Life

by Paul Gilster | Mar 2, 2016 | Astrobiology and SETI | 26 Comments

I'm still smarting about having to cancel my travel plans for the Tennessee Valley Interstellar Workshop in Chattanooga, particularly since the Tau Zero Foundation was one of the sponsors of the event. But fortunately, I do have people offering to write up the workshop for Centauri Dreams, so we'll have some coverage and photos soon. Onward… Hunting for Biosignatures We only have two years before the James Webb Space Telescope is scheduled to launch. Assuming all goes well, JWST should help ease us into the era of biosignature detection, as we look for the characteristic signs of living organisms in the atmospheres of their worlds. But just how definitive are such signatures? A new paper from the University of Washington digs into potential false positives and offers specifics on the signatures that could fool us. One way to study biosignatures is by transit spectroscopy, using data gathered from starlight as it passes through a planet's atmosphere during a transit. This...

Administrivia: Disrupted Schedule, Server Upgrade

by Paul Gilster | Mar 1, 2016 | Administrative | 21 Comments

My plan to attend the Tennessee Valley Interstellar Workshop this week fell through when I became ill two days before departure date. Talk about bad timing. TVIW is a wonderful conference, and not only was my son Miles flying in for the event, but I had planned many good conversations with friends in the interstellar community. I was also looking forward to the Homo Stellaris working track led by Robert Hampson. I've been at all previous TVIWs and deeply regret having missed this one. I'm hoping for a less foggy mind by tomorrow, at which point I'll resume the schedule here, which is four or five posts per week unless interrupted by travel. Complicating this past few days has been a server migration which apparently went well (this, thankfully, was out of my hands), and the need for a PHP upgrade, which should be occurring by the end of the week. Fingers crossed, I am hoping for no disruption. I'll hope to get some reports from TVIW and pass along links to presentations from the...

Power Beaming Parameters & SETI re KIC 8462852

by Paul Gilster | Feb 26, 2016 | Astrobiology and SETI | 111 Comments

When I first got interested in SETI, I naively assumed that we would get a detection fairly soon, and that we would detect not a directed beacon but simple background traffic in a remote civilization. I had no idea at the time how difficult it would be to pick up the kind of radio traffic we routinely generate on Earth from a distant star, and as a matter of fact, my interest in shortwave radio led me to assume that, just as I enjoyed the sport of DX -- listening for distant signals -- so SETI would simply be an offshoot of this, with a harder-to-get QSL card. Some time in the mid-1980s I wrote a piece called “Where the Real DX Is” for Glenn Hauser’s Review of International Broadcasting, running through a list of the nearest stars and talking about SETI projects that had been tried up to then. I haven’t gone back to read that article in years and would probably find it an embarrassing chore. But it’s interesting to me that the idea of leakage radiation does have its place,...

SETI: Power Beaming in Context

by Paul Gilster | Feb 25, 2016 | Astrobiology and SETI | 18 Comments

Thinking that we can understand the motivations of an extraterrestrial civilization seems like a fool's gambit, but we have to try. The reason is obvious: We have exactly one technological society to work with -- we're all we have -- and if we want to look for SETI signals, we have to interpolate as best we can. An alien culture, it is assumed, will do the same. This was the procedure outlined by Giuseppe Cocconi and Philip Morrison in their classic 1959 paper "Searching for Interstellar Communications," that began the modern era of SETI. If there are civilizations around stars like the Sun, the paper reasons, then some will be motivated to reach out elsewhere. From the paper: To the beings of such a society, our Sun must appear as a likely site for the evolution of a new society. It is highly probable that for a long time they will have been expecting the development of science near the Sun. We shall assume that long ago they established a channel of communication that would one day...

Fast Radio Bursts: First Distance Measurement

by Paul Gilster | Feb 24, 2016 | Deep Sky Astronomy & Telescopes | 11 Comments

Have we finally traced a Fast Radio Burst to its place of origin? News from the CSIRO (Commonwealth Scientific and Industrial Research Organisation) radio telescopes in eastern Australia, along with confirming data from the Japanese Subaru instrument in Hawaii, suggests the answer is yes. Fast Radio Bursts (FRBs) are transient radio pulses that last scant milliseconds. In that amount of time, they have been known to emit as much energy as the Sun emits in 10,000 years. And exactly what causes FRBs is still a mystery. Take the so-called 'Lorimer Burst' ( FRB 010724) which was discovered in archival data from 2001 at the Parkes radio telescope in New South Wales. Here we're dealing with a 30-jansky dispersed burst that was less than 5 milliseconds in duration. Although the burst appeared roughly in the direction of the Small Magellanic Cloud, the FRB is not thought to be associated with our galaxy at all. A 2015 event, FRB 110523, was discovered in data from the Green Bank dish in West...

An Exoplanet Changing Over Time

by Paul Gilster | Feb 23, 2016 | Exoplanetary Science | 15 Comments

Keep your eye on a program called the Hubble Cloud Atlas. This is a collaboration between fourteen exoplanet researchers around the globe that is intent on creating images of exoplanets using the Hubble Space Telescope. But while we've been able to directly image a small number of planets before now, the Cloud Atlas project brings a new twist. The plan is to create time-resolved images that can tease out details about planetary atmospheres. The test case is the planet 2M1207b, about 160 light years out in the constellation Centaurus. Infrared imaging made it possible to directly observe this planet in April of 2004, a task accomplished by researchers from the European Southern Observatory using data from the Very Large Telescope at Paranal (Chile). What we know about this planet makes it a formidable -- and definitely uninhabitable -- object, one with a surface temperature in the 1700 K range. Image: The 2M1207 star system, showing the faint red object 2M1207b, a planet four times...

SETI: Upcoming Talk of Interest

by Paul Gilster | Feb 22, 2016 | Astrobiology and SETI | 13 Comments

Given the interest the unusual star KIC 8462852 has generated here and elsewhere, I want to be sure those of you in California are aware of an upcoming talk that touches on the matter, as well as broader SETI issues. Titled "The Breakthrough Initiative - Listen and Megastructures at KIC 8463," the talk will be delivered by Andrew Siemion (UC-Berkeley). The venue is 1065 La Avenida Street, Mountain View, CA 94043. The time: Tuesday, February 23, 2016 from 12:00 PM to 1:00 PM (PST). More at this web page, from which the description that follows: Dr. Andrew Siemion, Director of the Berkeley SETI Research Center (BSRC) at the University of California, Berkeley, will present an overview of the Breakthrough Listen Initiative, 100-million-dollar, 10-year search for extraterrestrial intelligence. Dr. Siemion will also discuss other SETI efforts ongoing at the BSRC, including the successful citizen science project SETI@Home, as well as a concerted effort to undertake panchromatic observations...

Charon: Evidence of an Ancient Ocean

by Paul Gilster | Feb 22, 2016 | Outer Solar System | 12 Comments

I will admit to a fascination with Pluto's moon Charon that began even before it was discovered. Intrigued by the most distant places in the Solar System, I had always imagined what the view would be like from a tiny moon circling Pluto. At the time, we didn't know about Charon, so my vantage point was more like what we now know Kerberos or Styx to be. Then my interest tripled when the sheer size of Charon became known. A large moon was truly a world of its own, and Charon rose in my estimation to rival my other most intriguing moon, Neptune's Triton. Now we have word that Charon may once have had an internal ocean, still further evidence of the intricacy of objects in or near the Kuiper Belt. In Charon's case, something intriguing is shown by a study of the surface, one side of which New Horizons saw during the July 2015 flyby. What appears to be a series of tectonic faults that show up in the form of ridges, scarps and valleys reveals a surface that has to have been stretched over...

WFIRST: Moving Closer to a Mission

by Paul Gilster | Feb 19, 2016 | Exoplanetary Science | 27 Comments

We learned on Wednesday that the Agency Program Management Council, which works under the aegis of NASA, has made the decision to proceed with the Wide Field Infrared Survey Telescope. WFIRST is the next step in major astrophysical observatories after the launch of the James Webb Space Telescope in 2018, an instrument that will work at near-infrared wavelengths to study dark matter and dark energy, with a significant exoplanet component. All these issues are relevant to what we do here at Centauri Dreams, but the exoplanet aspect of the mission, which includes a coronagraph to allow the close inspection of distant solar systems, is particularly interesting. Blocking the otherwise overwhelming glare of a host star (even at these wavelengths), the WFIRST coronagraph should help to reveal the planets around it, a crucial separation that will allow us to make spectrographic measurements of the chemical makeup of planetary atmospheres. Paul Hertz, director of NASA's astrophysics division...

Tracking the Chelyabinsk Impactor

by Paul Gilster | Feb 18, 2016 | Asteroid and Comet Deflection | 11 Comments

Yesterday's post on the distribution of asteroid populations inevitably had me thinking about the Chelyabinsk event on February 15, 2013, and about the concurrent flyby of the asteroid (367943) Duende, which took place on the same day. A scant sixteen hours after the explosion of the Chelyabinsk bolide and the fall of five tons of meteoritic material to the ground in Siberia, (367943) Duende passed by at about 27,700 kilometers above the surface of the Earth. We talked yesterday about learning more about asteroid distributions, so we could understand where they come from and what to expect as we assess their trajectories. In the case of Chelyabinsk, it was originally thought that both events were related, with the Chelyabinsk impactor associated with (367943) Duende in the form of a companion object, or perhaps as material that broke away from the parent asteroid. But an analysis of the orbits of both objects as well as spectroscopic analysis of Duende and the Chelyabinsk material...

A New Look at Asteroid Distribution

by Paul Gilster | Feb 17, 2016 | Asteroid and Comet Deflection | 10 Comments

We know that understanding Near-Earth Objects is vital not only for assessing future asteroid surveys and spacecraft missions, but also for tracking potential impactors on Earth. Projects like the Catalina Sky Survey and its now defunct southern hemisphere counterpart, the Siding Spring Survey, are all about asteroid and comet discovery, with a more specific goal of looking for objects posing a potential hazard to our planet. We lost the Siding Spring effort in 2013 due to funding problems, but the Catalina Sky Survey (CSS) is still in robust operation. The survey draws data from a 1.5 meter telescope on the peak of Mt. Lemmon (Arizona) and a 68 centimeter instrument nearby at Mt. Bigelow. Now we have word that Mikael Granvik (University of Helsinki) and an international team of researchers have drawn on about 100,000 images acquired by the Catalina Sky Survey to study the properties of some 9000 NEOs detected in an eight-year period. The goal is to construct a model for the...

Light, Dry Atmosphere of a ‘Super-Earth’

by Paul Gilster | Feb 16, 2016 | Exoplanetary Science | 31 Comments

We’re probing the atmospheres of exoplanets both from the Earth and from space. Transmission spectroscopy allows us to look at the spectra of starlight at various wavelengths as a transiting planet passes first in front of its host star, and then moves behind it. Now we have news of a successful detection of gases in the atmosphere of a super-Earth, using data from the Hubble Space Telescope. The team, made up of researchers at University College London and Catholic University of Leuven (Belgium) calls this a significant first. “This is a very exciting result because it’s the first time that we have been able to find the spectral fingerprints that show the gases present in the atmosphere of a super-Earth,” said Angelos Tsiaras, a PhD student at UCL, who developed the analysis technique along with colleagues Dr. Ingo Waldmann and Marco Rocchetto in UCL Physics & Astronomy. “Our analysis of 55 Cancri e’s atmosphere suggests that the planet has managed to cling on to a significant...

Saying Goodbye to Philae

by Paul Gilster | Feb 15, 2016 | Outer Solar System | 9 Comments

Landing on a small object in the Solar System isn't easy. Witness the Philae lander, which traveled to Comet 67P/Churyumov-Gerasimenko as part of the European Space Agency's Rosetta mission. Philae 'landed' on November 12, 2014, having to deal with a malfunctioning thruster along the way. Upon arrival at the surface of the comet, Philae was to have fired anchoring harpoons to steady itself on the surface, but after a dramatic seven-hour descent, the harpoons failed to fire. Thus the lander did touch down at the initial landing site, called Agilkia, but then bounced to a new site -- Abydos -- about a kilometer away. Even now, we're not sure just where Philae is despite imagery from the orbiting Rosetta. What ESA has told us, however, is that the lander evidently made contact with the comet four times during an unplanned for two-hour additional flight across the surface. During the process it grazed the rim of a depression called Hatmehit on its way to its resting place at Abydos....

Pondering Gravitational Waves

by Paul Gilster | Feb 11, 2016 | Deep Sky Astronomy & Telescopes | 157 Comments

“Einstein would be beaming,” said National Science Foundation director France Córdova as she began this morning’s news conference announcing the discovery of gravitational waves. I can hardly disagree, because we have in this discovery yet another confirmation of the reality of General Relativity. Caltech’s Kip Thorne, who discussed black hole mergers way back in 1994 in his book Black Holes and Time Warps, said at the same news conference that Einstein must have been frustrated by the lack of available technologies to detect the gravitational waves his theory predicted, a lack that it took a century to remedy with the LIGO collaboration. Thorne believes that if he had been armed with the right tools, Einstein himself would have made the detection. But of course the tools weren’t there. Somehow that thought produced an odd echo of the very decade of General Relativity’s emergence, one that shows how much GR changed the nature of our view of the universe. It was in 1911, just four...

A Future We Can Choose

by Paul Gilster | Feb 10, 2016 | Culture and Society | 81 Comments

The very small may lead us to the very large. Payload sizes, for one thing, can be shrunk as we increasingly master the art of miniaturization, giving us far more bang for the buck. In that sense, we can think about tiny interstellar probes that may one day be sent, as Robert Freitas has envisioned, in waves of exploration, each of them no larger than a sewing needle, but armed with artificial intelligence and capable of swarm-like behavior. Mastering the tiny thus enables the longest of all journeys. But thinking about small payloads also makes me ponder much larger constructs. Suppose in a hundred years we can work at the atomic level to build structures out of the abundant raw material available in the asteroid or Kuiper belts. It's possible to imagine enormous arcologies of the kind discussed by Gerard O'Neill that may one day house substantial human populations. In this way nanotech opens the door to renovation in the realm of gigantic colony worlds. And if one of these colony...

Inside Rocky Exoplanets

by Paul Gilster | Feb 9, 2016 | Exoplanetary Science | 3 Comments

We’ve gone from discovering the presence of exoplanets to studying their atmospheres by analyzing the spectra produced when a planet transits in front of its star. We’re even in the early stages of deducing weather patterns on some distant worlds. Now we’re looking at probing the inside of planets to learn whether their internal structure is something like that of the Earth. The work is led by Li Zeng (Harvard-Smithsonian Center for Astrophysics), whose team developed a computer model based on the Preliminary Reference Earth Model (PREM), the standard model for the Earth’s interior. Developed by Adam Dziewonski and Don L. Anderson for the International Association of Geodesy, PREM attempts to model average Earth properties as a function of radius. Zeng adjusted the model for differing masses and compositions and applied the revised version to six known rocky exoplanets with well understood characteristics. The work shows that rocky worlds should have a nickel/iron core that houses...

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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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