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Wrestling with METI

by Paul Gilster | Jul 20, 2017 | Astrobiology and SETI | 91 Comments

If we were to send a message to an extraterrestrial civilization and make contact, should we assume it would be significantly more advanced than us? The odds say yes, and the thinking goes like this: We are young enough that we have only been using radio for a century or so. How likely is it that we would reach a civilization that has been using such technologies for an even shorter period of time? As assumptions go, this one seems sensible enough. But let's follow it up. In an interesting piece in the New York Times Magazine, Steven Johnson makes the case this way: Given the age of the universe, almost 14 billion years, that means it would have taken 13,999,999,900 years before radio communications became a factor here on Earth. Now let's imagine a civilization that deviates from our own timeline of development by just one tenth of one percent. If they are more advanced than us, they will have been using technologies like radio and its successors for 14 million years. Assumptions...

Keeping an Eye on Ross 128

by Paul Gilster | Jul 19, 2017 | Exoplanetary Science | 28 Comments

Frank Elmore Ross (1874-1960), an American astronomer and physicist, became the successor to E. E. Barnard at Yerkes Observatory. Barnard, of course, is the discoverer of the high proper motion of the star named after him, alerting us to its proximity. And as his successor, Ross would go on to catalog over 1000 stars with high proper motion, many of them nearby. Ross 128, now making news for what observers at the Arecibo Observatory are calling "broadband quasi-periodic non-polarized pulses with very strong dispersion-like features," is one of these, about 11 light years out in the direction of Virgo. Any nearby stars are of interest from the standpoint of exoplanet investigations, though thus far we've yet to discover any companions around Ross 128. An M4V dwarf, Ross 128 has about 15 percent of the Sun's mass. More significantly, it is an active flare star, capable of unpredictable changes in luminosity over short periods. Which leads me back to that unusual reception. The SETI...

Making Optical SETI Happen

by Paul Gilster | Jul 18, 2017 | Astrobiology and SETI | 6 Comments

Yesterday I made mention of the Schwartz and Townes paper "Interstellar and Interplanetary Communication by Optical Masers," which ran in Nature in 1961 (Vol. 190, Issue 4772, pp. 205-208). Whereas the famous Cocconi and Morrison paper that kicked off radio SETI quickly spawned an active search in the form of Project Ozma, optical SETI was much slower to develop. The first search I can find is a Russian project called MANIA, in the hands of V. F. Shvartsman and G. M. Beskin, who searched about 100 objects in the early 1970s, finding no significant brightness variations within the parameters of their search. If you want to track this one down, you'll need a good academic library, as it appears in the conference proceedings for the Third Decennial US-USSR Conference on SETI, published in 1993. Another Shvartsman investigation under the MANIA rubric occurred in 1978. Optical SETI did not seem to seize the public's imagination, perhaps partially because of the novelty of communications...

Detection Possibilities for Optical SETI

by Paul Gilster | Jul 17, 2017 | Astrobiology and SETI | 34 Comments

The Laser SETI campaign we looked at on Friday is one aspect of a search for intelligent life in the universe that is being addressed in many ways. In addition to optical methods, we look of course at radio wavelengths, and as we begin to characterize the atmospheres of rocky exoplanets, we'll also look for signs of atmospheric modification that could indicate industrial activity. But we have to be careful. Because SETI looks for evidence of alien technology, it is a search for civilizations about whose possible activities we know absolutely nothing. So we can't make assumptions that might blind us to a detection. Getting the blinders off also means extending our reach. If successful, the Laser SETI project will do two things we haven't been able to do before -- it will scan the entire sky and, because it is always on, it will catch optical transients we are missing today, and tell us whether any of these are repeating. In radio terms, think of the famous WOW! signal of 1977,...

Laser SETI: All Sky All the Time

by Paul Gilster | Jul 14, 2017 | Astrobiology and SETI | 22 Comments

The SETI Institute's just announced Laser SETI funding campaign intends to put into practice what SETI researchers have been anticipating for decades, an all-sky, all-the-time observing campaign. The Institute's Eliot Gillum and Gerry Harp are behind the project, backed by an impressive list of advisors, with the intention of using optical SETI methods to look for signs of extraterrestrial civilizations. In doing so, they're reminding us how we've done SETI, how we can surmount its current limitations, and what a SETI of the future will look like. Think about how SETI has evolved since the days when Frank Drake created Project Ozma at the National Radio Astronomy Observatory at Green Bank (WV). Fresh with the insights of Giuseppe Cocconi and Philip Morrison, who examined radio methods and suggested a search for signals near the 21 centimeter wavelength of neutral hydrogen, Drake turned a 26-meter radio telescope to examine the nearby Sun-like stars Tau Ceti and Epsilon Eridani. Would...

Citizen Scientist Imagery of the Great Red Spot

by Paul Gilster | Jul 13, 2017 | Outer Solar System | 8 Comments

All of the Juno spacecraft's instruments -- including JunoCam -- were operational during its July 10 flyby, giving us a close-up look at the Great Red Spot. Now 16,000 kilometers wide, the storm has been studied since 1830 and may be considerably older than that. Juno's orbit took it to perijove (closest to Jupiter's center) at 2155 EDT on the 10th (0155 UTC on the 11th), when it closed to about 3500 kilometers above the cloud tops. The passage across the Great Red Spot occurred eleven minutes later at some 9000 kilometers above the clouds. While the data are being unpacked and analyzed, we can enjoy the efforts of citizen scientists who went to work on the raw images posted on the JunoCam site and processed them, a procedure done in coordination with the Juno team. "These highly-anticipated images of Jupiter's Great Red Spot are the 'perfect storm' of art and science. With data from Voyager, Galileo, New Horizons, Hubble and now Juno, we have a better understanding of the...

A Binary ‘Rogue’ Planet?

by Paul Gilster | Jul 12, 2017 | Exoplanetary Science | 8 Comments

‘Planetary mass binary’ is an unusual term, but one that seems to fit new observations of what was thought to be a brown dwarf or free-floating large Jupiter analog, and now turns out to be two objects, each of about 3.7 Jupiter masses. That puts them into planet-range when it comes to mass, as the International Astronomical Union normally considers objects below the minimum mass to fuse deuterium (13 Jupiter masses) to be planets. This is the lowest mass binary yet discovered. A team led by William Best (Institute for Astronomy, University of Hawaii) went to work on the L7 dwarf 2MASS J11193254–1137466 with the idea of determining what they assumed to be the single object’s mass and age. It was through observations with the Keck II telescope in Hawaii that they discovered the binary nature of their target. The separation between the two objects is about 3.9 AU, based upon the assumption that the binary is around 160 light years away, the distance of the grouping of stars called the...

Terrain Clues to Ice in the Outer System

by Paul Gilster | Jul 11, 2017 | Outer Solar System | 11 Comments

The human expansion into the Solar System will demand our being able to identify sources of water, a skill we're honing as explorations continue. On Mars, for example, the study of so-called 'pitted craters' has been used as evidence that the low latitude regions of the planet, considered its driest, nonetheless have a layer of underlying ice. The Dawn spacecraft discovered similar pitted terrain on Vesta, as you can see in the image below. Image: These enhanced-color views from NASA's Dawn mission show an unusual "pitted terrain" on the floors of the craters named Marcia (left) and Cornelia (right) on the giant asteroid Vesta. The views show that the physical properties or composition of the material in which these pits form is different from crater to crater. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/JHUAPL. Vesta's Marcia crater contains the largest number of pits on the asteroid. The 70-kilometer feature is also one of the youngest craters found there. So what accounts for this...

Toward a Planet Formation Model for Pulsars

by Paul Gilster | Jul 10, 2017 | Exoplanetary Science | 5 Comments

Our theories of planet formation grow more mature as the exoplanet census continues, but I've always speculated about the first planets discovered and how they could have possibly been where we found them. The discovery of the planets around the pulsar PSR B1257+12 occurred in 1992, the work of the Polish astronomer Aleksander Wolszczan. Anomalies in its pulsation period -- this is a millisecond pulsar with a period of 6.22 milliseconds -- led Wolszczan and Dale Frail to produce a paper on the first extrasolar planets ever found. We wouldn't find such planets at all if it were not for the effect of their gravitational pull on the otherwise regular pulses from the pulsar. But how could the planets now know as Draugr, Poltergeist and Phobetor, the latter found in 1994, possibly have formed in such an environment? After all, a dense neutron star (a pulsar is a highly magnetized, rotating neutron star) is the result of a supernova that should have destroyed any planets nearby, making it...

How Many Brown Dwarfs in the Milky Way?

by Paul Gilster | Jul 7, 2017 | Exoplanetary Science | 35 Comments

Interesting news keeps coming out of the National Astronomy Meeting in the UK. Today it involves brown dwarfs and their distribution throughout the galaxy, a lively question given how recently we’ve begun to study these ‘failed stars.’ Maybe we need a better name than ‘brown dwarfs,’ for that matter, since these objects are low enough in mass that they cannot sustain stable hydrogen fusion in their core. In a murky intermediary zone between planet and star, they can produce planets of their own but straddle all our contemporary definitions. At the NAS meeting, an international team led by Koraljka Muzic (University of Lisbon) has reported on its work on brown dwarfs in clusters. It seems a sensible approach -- go to the places where young stars are forming and try to figure out how many brown dwarfs emerge alongside them. That could help to give us an overview, because the brown dwarfs we’ve already found (beginning with the first, in 1995) are generally within 1500 light years of...

Juno’s Upcoming Run over the Great Red Spot

by Paul Gilster | Jul 6, 2017 | Outer Solar System | 10 Comments

I love the image of Jupiter below because of the detail -- a mosaic of 27 images taken on closest approach by Cassini in 2000, it shows visible features down to 60 kilometers across. Nine images covering the entire planet were acquired in red, green and blue to provide color much like what our eyes would see if we were there. The Great Red Spot, nestled among the clouds of ammonia, hydrogen sulfide and water, is obvious. But we'll soon learn much more, for the Juno spacecraft is scheduled to fly directly over the Great Red Spot on July 10. Image: This true color mosaic of Jupiter was constructed from images taken by the narrow angle camera onboard NASA's Cassini spacecraft on December 29, 2000, during its closest approach to the giant planet at a distance of approximately 10 million kilometers. Credit: NASA/JPL/Space Science Institute. Launched on August 5, 2011, Juno completed its first year in Jupiter orbit on July 4, a reminder of how well shielded its instruments are in this...

174P/Echeclus: Focus on an Unusual Centaur

by Paul Gilster | Jul 5, 2017 | Outer Solar System | 0 Comments

Centaurs are intriguing objects, and not just because of the problem in figuring out what they are. For one thing, the farthest points in their orbits take them between the orbits of the outer planets in our Solar System. That makes them unstable, yielding lifetimes on the order of a few million years. They also show characteristics of both asteroids and comets, which makes objects like 174P/Echeclus so intriguing. Discovered in 2000, it was classified as a minor planet before a cometary coma appeared. Thus its current cometary designation. So what exactly do we have here? In 2005, a large piece of 174P/Echeclus broke off, possibly the result of an impact or, despite a distance at the time of over 13 AU from the Sun, perhaps the release of volatiles. We saw another outburst in 2011 at a distance of 8.5 AU from the Sun. Maria Womack (University of South Florida), who is lead author of a new paper on Echeclus, calls it “a bizarre solar system object,” which sounds about right, though...

M-Dwarf Habitability: New Work on Flares

by Paul Gilster | Jul 4, 2017 | Exoplanetary Science | 31 Comments

The prospects for life around M-dwarf stars, always waxing and waning depending on current research, have dimmed again with the release of new work from Christina Kay (NASA GSFC) and colleagues. As presented at the National Astronomy Meeting at the University of Hull (UK), the study takes on the question of space weather and its effect on habitability. We know that strong solar flares can disrupt satellites and ground equipment right here on Earth. But habitable planets around M-dwarfs -- with liquid water on the surface -- must orbit far closer to their star than we do. Proxima Centauri b, for example, is roughly 0.05 AU from its small red host (7,500,000 km), while all seven of the TRAPPIST-1 planets orbit much closer than Mercury orbits the Sun. What, then, could significant flare activity do to such vulnerable worlds? Image: Artist’s impression of HD 189733b, showing the planet’s atmosphere being stripped by the radiation from its parent star. Credit: Ron Miller. Working with...

‘Cosmic Modesty’ in a Fecund Universe

by Paul Gilster | Jun 30, 2017 | Astrobiology and SETI | 38 Comments

I came across the work of Chin-Fei Lee (Academia Sinica Institute of Astronomy and Astrophysics, Taiwan) when I had just read Avi Loeb's essay Cosmic Modesty. Loeb (Harvard University) is a well known astronomer, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics and a key player in Breakthrough Starshot. His 'cosmic modesty' implies we should accept the idea that humans are not intrinsically special. Indeed, given that the only planet we know that hosts life has both intelligent and primitive lifeforms on it, we should search widely, and not just around stars like our Sun. More on that in a moment, because I want to intertwine Loeb's thoughts with recent work by Chin-Fei Lee, whose team has used the Atacama Large Millimeter/submillimeter Array (ALMA) to detect organic molecules in an accretion disk around a young protostar. The star in question is Herbig-Haro (HH) 212, an infant system (about 40,000 years old) in Orion about 1300...

Magnetic Reconnection at the ‘Planet of Doubt’

by Paul Gilster | Jun 29, 2017 | Outer Solar System | 12 Comments

Perhaps the image of Uranus just below helps explain why the planet has been treated so sparsely in science fiction. Even this Voyager view shows us a featureless orb, and certainly in visible light the world has little to make it stand out other than its unusual axis of rotation, which is tilted so that its polar regions are where you would expect its equator to be. Geoff Landis' "Into the Blue Abyss" (2001) is the best fictional treatment I know, but the fog-shrouded Uranus of Stanley G. Weinbaum's "The Planet of Doubt" (1935) has its own charms, though obviously lacking the scientific verisimilitude of the Landis tale. My admiration for Gerald Nordley's "Into the Miranda Rift" (1993) is unabated, taking us into this strange world's most dramatic moon, while I should also mention Kim Stanley Robinson's visit to Uranus in Blue Mars (1997), where the moon is established as a protected wilderness site while the rest of the Uranian satellite system is under colonization. Fritz Leiber's...

Planet 9? Planet 10? Planet X?

by Paul Gilster | Jun 28, 2017 | Outer Solar System | 17 Comments

When you find a protoplanetary disk that displays unusual properties, the suspicion grows that an unseen planet is causing the phenomenon. The young Beta Pictoris is a classic case in point: Here we see disk asymmetry, with one side of the disk appearing longer and thinner than the other, and a warp that could be caused by the planet known as Beta Pictoris b. Or consider an extreme case, HD 142527. A T Tauri star in Lupus, HD 142527 displays an inner disk that is tilted by about 70 degrees (see HD 142527: Shadows of a Tilted Disk). Such a striking offset could be caused by an encounter with another star, though there no good candidates. Are we seeing the effects of proto-planets? All this comes to mind because of what Kat Volk (JPL) and Renu Malhotra (Lunar and Planetary Laboratory, University of Arizona) are seeing in our own Solar System. Their analysis of the more distant regions of the Kuiper Belt shows that objects there display an offset of about eight degrees from the...

New Horizons: Occultations in Preparation for MU69

by Paul Gilster | Jun 27, 2017 | Outer Solar System | 16 Comments

Our spacecraft have never encountered an object as far from Earth as 2014 MU69, but New Horizons will change all that when it races past the Kuiper Belt object on New Year's Day of 2019. This summer is an interesting part of the project because planners will use it to gather as much information as possible about what they'll find at the target. We have three occultations to work with, one of them just past, and they are as tricky as it gets. But before I get to the occultations, let me offer condolences to the family and many New Horizons friends of Lisa Hardaway, who died in January at age 50. Hardaway helped to develop the LEISA (Linear Etalon Imaging Spectral Array) spectrometer that brought us such spectacular results during the Pluto/Charon flyby. She was program manager at Ball Aerospace for the Ralph instrument that contains LEISA. Mission scientists used data from the instrument package to make geological, color and composition maps of Pluto and its moons. The mission team...

Beam-Riding and Sail Stability

by Paul Gilster | Jun 23, 2017 | Sail Concepts | 31 Comments

Breakthrough Starshot, the ambitious 30-year plan for launching small interstellar craft to a nearby star, depends critically on the sails that will ride a laser beam to 20 percent of lightspeed. In the essay below, James Benford takes a hard look at where we are now in the matter of sail stability, a subject he and brother Gregory have analyzed in their laboratory work. But as Jim points out, there is a great deal we still don't know, emphasizing the need for a dedicated test facility in which deep analysis and experimentation can proceed. The Chairman of the Sail Subcommittee for Breakthrough Starshot, Dr. Benford gives us insight into the magnitude of the challenge, and the possible solutions now being considered. By James Benford Riding on the beam, i.e., stable flight of a sail propelled by beam momentum, is an essential requirement of beam-driven propulsion. It places considerable demand upon the shape of the sail and beam. Some amount of beam jitter, oscillations in the...

DSTART: Imagining Interstellar Futures

by Paul Gilster | Jun 22, 2017 | Missions | 10 Comments

Back in the 1970s, the British Interplanetary Society conceived the idea of designing a starship. The notion grew into Project Daedalus, often discussed in these pages, producing a final report that summed up what was then known about interstellar possibilities, from fusion propulsion to destination stars. Barnard's Star, 6 light years out, became the target because at the time, it was the only star for which evidence of planets existed, though that evidence later turned out to be the result of error in the instrument being used for the observations (more on this soon, in an essay I've written for the Red Dots campaign. I'll link to it as soon as it runs). The designing of Daedalus, much of it done in London pubs, was a highly significant event. What Alan Bond, Anthony Martin, Bob Parkinson and the rest were doing was not so much putting forth something that our civilization would build as sending us a clear message. Even at this stage of our development, humans could conceive of...

PLATO: Planet Hunting Mission Officially Adopted

by Paul Gilster | Jun 21, 2017 | Exoplanetary Science | 4 Comments

The European Space Agency has just announced the official adoption of the PLATO mission. The untangled acronym -- PLAnetary Transits and Oscillations of stars -- tells us that, like Kepler and CoRoT, this is a planet hunting mission with asteroseismological implications. Photometric monitoring of nearby bright stars for planetary transits and determination of planetary radii should help build our target list for spectroscopic follow-up as we delve into planetary atmospheres looking for biosignatures. Launch is scheduled for 2026. Asteroseismology studies how stars oscillate, giving us information about the internal structure of the star that would not be available through properties like brightness and surface temperature. PLATO will be carrying out high precision photometric monitoring at visible wavelengths, targeting bright stars (mV ? 11), though with capabilities for fainter stars down to magnitude 16. Several hundred thousand stars will ultimately be characterized in the search...

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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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