Planetary Discovery around Ultracool Star

I have a special enthusiasm for microlensing as a means of exoplanet discovery. With microlensing, you never know what you’re going to come up with. Transits are easier to detect when the planet is close to its star, and hence transits more frequently. Radial velocity likewise sends its loudest signal when a planet is large and close. Microlensing, detecting the ‘bending’ of light from a background object as it is affected by a nearer star’s gravitational field, can turn up a planet whether near to its star or far, and in a wide range of masses. It can also be used to study planetary populations as distant as the galactic bulge and beyond. Now we have news of a cold planet about the size of the Earth orbiting what may turn out to be a brown dwarf, and is in any case no more than 7.8 percent the mass of our Sun. Is this an object like TRAPPIST-1, the ultra-cool dwarf star we’ve had so much to say about in recent days as investigations of its 7 planets continue? If so, the planet...

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Cassini Through the Gap

Sometimes it pays to step back and try to look at spaceflight with fresh eyes. Go out and find Saturn in the sky and consider it as the ancients did, a moving celestial ember. And as you stand there, realize all over again that we've built a spacecraft that has been operating around that world since 2004, feeding us a datastream as its path was tweaked to look at interesting targets. The sheer magnitude of this accomplishment -- Cassini is now operating between the planet and its rings! -- is cause for celebration even as the mission's end approaches. Image: Artist's concept of Cassini diving between Saturn and its innermost ring. Credit: NASA/JPL-Caltech/Space Science Institute. Today's good news is that controllers have reacquired Cassini's signals following its plunge through the ring/planet gap on April 26, a time during which its 4-meter high-gain antenna was re-oriented to serve as an ad hoc shield against whatever dust grains or particles might be in its path. Critical...

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Speculations on Habitable Zone Waterworlds

What to make of Fergus Simpson’s new paper on waterworlds, suggesting that most habitable zone planets are of this type? If such worlds are common, we may find that most planets in the habitable zones of their stars are capable of evolving life, but unlikely to host technological civilizations. An explanation for the so-called ‘Fermi Paradox’? Possibly, but there are all kinds of things that could account for our inability to see other civilizations, most of them covered by Stephen Webb in his If the Universe Is Teeming with Aliens … Where Is Everybody? (2nd ed., Springer 2015), which offers 75 solutions to the problem. Simpson (University of Barcelona) makes his case in the pages of Monthly Notices of the Royal Astronomical Society, arguing that the balance maintained by a planetary surface with large amounts of both land and water is delicate. The author’s Bayesian statistical analysis suggests that most planets are dominated either by water or land, most likely water. Earth may,...

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Further Work on TRAPPIST-1

A closely packed planetary system like the one we’ve found at TRAPPIST-1 offers intriguing SETI possibilities. Here a SETI search for directed radio transmissions aimed at the Earth gives way to an attempt to overhear ongoing activity within another stellar system. For it’s hard to conceive of any civilization developing technological skills that would turn away from the chance to make the comparatively short crossing from one of the TRAPPIST-1 worlds to another. Our more spread out system is challenging for a species at our level of technological development, but a colony on Mars or an outpost on Titan would surely produce intense radio traffic as it went about daily operations and reported back to Earth. Could TRAPPIST-1 be home to similar activities? The SETI Institute has continued to investigate the prospect, starting with ‘eavesdropping’ observations at 2.84 and 8.2 GHz in early April. Image: A size comparison of the planets of the TRAPPIST-1 system, lined up in order of...

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Breakthrough Listen Data Becoming Available

Andrew Siemion (Berkeley SETI Research Center) presented results from the first year of the Breakthrough Listen initiative last Thursday at the Breakthrough Discuss meetings in Palo Alto. The data can be acquired here, with the caveat that file sizes can be gigantic and the data formats demand specialized software. Background information and details are available on this BSRC page. Working with the Parkes instrument in New South Wales as well as the Green Bank telescope in West Virginia and Lick Observatory's Automated Planet Finder on Mt. Hamilton in California, the project is rapidly amassing petabytes of data. Image: The largest single-dish fully steerable radio telescope began operation in 2000 August in Green Bank, West Virginia, USA. Dedicated as the Robert C. Byrd Green Bank Telescope, the device weighs over 30 times more than the Statue of Liberty, and yet can point anywhere in the sky more precisely than one thousandth of a degree. The main dish is so large that it could...

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On Breakthrough Discuss

Although I hadn't thought I would get a post off today, I do want to get this Breakthrough Initiatives news release out about the upcoming Breakthrough Discuss meeting. Pay particular attention to the online options for participating. BREAKTHROUGH INITIATIVES TO HOST WORLD-RENOWNED SCIENTISTS AND SCHOLARS IN SUMMIT ON LIFE IN THE UNIVERSE AND SPACE EXPLORATION Second annual "Breakthrough Discuss" conference held April 20-21 and broadcast on Facebook Live San Francisco - April 18, 2017 - Breakthrough Initiatives today announced its second annual Breakthrough Discuss scientific conference, which will bring together leading astronomers, engineers, astrobiologists and astrophysicists to advance discussion surrounding recent discoveries of potentially habitable planets in nearby star systems. The conference will take place on Thursday, April 20 and Friday, April 21, at Stanford University. The two days of discussions will focus on newly discovered Earth-like "exoplanets" in the Alpha...

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Mission Concepts: Bound Orbits around Other Stars

Can we use a laser array to get a fast probe to another star? Breakthrough Starshot relies upon the notion, which was first advanced by Robert Forward all the way back in 1962, and subsequently considered by George Marx in 1966, along with hosts of researchers since. With beamed energy we leave the propellant behind, but as we’ve seen in our discussions of deceleration, there remains the problem of slowing down at the target. Breakthrough Starshot assumes a flyby, but the paper we looked at yesterday works out strategies for braking into orbit at the target star. Or more accurately, at the target stars, for multiple systems are assumed. Let’s dig back into that paper today, but first, let me make a brief administrative comment. The upcoming Breakthrough Discuss meeting in Palo Alto (I covered last year’s sessions) occurs at exactly the wrong time for me -- I’m locked into long-standing travel plans elsewhere. While I travel, there will be no Centauri Dreams posts for the rest of this...

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Proxima Mission: Fine-Tuning the Photogravitational Assist

Deceleration has always been problematic in projected schemes for interstellar travel. A flyby of a star at a substantial percentage of lightspeed yields a fraction of the data that would be obtainable by a probe slowed into orbit in the target system. But how to slow down? In particular, how do you slow down when your method of propulsion is beamed energy? The ideas have flowed over the years, ranging from Philip Norem’s ‘thrustless turning’ -- using interactions between the spacecraft and the interstellar magnetic field -- to Robert Forward’s ‘staged’ sail, in which the sail separates into separate components, with beamed laser light from Earth bouncing off one to the other to slow the payload. Norem’s notion, though, hugely lengthened trip times while taking the spacecraft far beyond the target before turning it back, while staged sails require a pointing accuracy in a laser array that is hard to imagine. Many other options have been advanced, including braking against a stellar...

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New Findings on Enceladus, Europa

Jim Green, who is director of the Planetary Science Division at NASA headquarters, clearly loves his job, and he got so excited during Thursday's news conference that he kept interchanging Enceladus with Europa in his remarks. Both were in play during the discussion, and the context made it clear what he intended, but I always get a kick out of seeing that kind of enthusiasm showing forth in scientists and academics. It's a reminder of why they got involved in the first place, and for that matter, what drew me into writing about the field myself. The news delivered in the press conference and through two new papers involves two older space missions that are driving planning for yet a third, the Europa Clipper mission, a Jupiter orbiter that is still in the design and planning stages. And with Cassini in its final months of operation, it's fitting that a Cassini flyby through the Enceladus plumes in 2015 should result in what Cassini project scientist Linda Spilker (JPL) called a...

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Investigation of a Possible Dwarf Planet

Astronomical investigations can overlap in extremely helpful ways. Consider the Dark Energy Survey, which examines some 12 percent of the sky in an attempt to learn more about whatever force is accelerating the expansion of the universe. DES is trying to map hundreds of millions of galaxies and identify thousands of supernovae while looking for patterns in cosmic structure, using a 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory (Chile). What DES produces are thousands of images -- its initial search uncovered 1.1 billion candidate objects, most of which are galaxies or background stars. But among the objects are some that move in successive observations, the signature of objects in our Solar System. David Gerdes (University of Michigan) was able to find what appears to be a dwarf planet within the dataset. Called 2014 UZ224 and informally known as DeeDee (for Distant Dwarf), the object has now been characterized...

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NIAC 2017: Interstellar Implications

I always look at the NASA Innovative Advanced Concepts (NIAC) awards with interest as well as a bit of nostalgia. When I began researching the book that would become Centauri Dreams, NIAC was an early incentive. Then known as the NASA Institute for Advanced Concepts, it was under the direction of Robert Cassanova (this was back around 2002), and its archive of funded studies was a treasure house of deep space ideas, from antimatter extraction in planetary magnetic fields to exoplanet imaging through starshades. I spent days going through any number of reports and interviewed many NIAC study authors. You can still see the NIAC reports from that era on the older site (go to NIAC Funded Studies). The current NIAC site makes the point that the program looks for "non-traditional sources of innovation that study technically credible, advanced concepts that could one day 'change the possible' in aerospace." And it's here that we get the 2017 Phase 1 proposals, a $125,000 award for a nine...

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Outer System News

NASA is to discuss new findings about ocean worlds in our Solar System in a news conference at 1400 EDT (1800 UTC) on Thursday. The prospects for oceans in the outer system are surprisingly varied, ranging from the strong evidence of a subsurface, salty ocean on Europa to other Jovian moons like Ganymede and Callisto, and of course, Saturn's intriguing moon Enceladus. Titan is thought to have a salty ocean perhaps 50 kilometers below its ice shell, while there are also possible ocean venues on Mimas, Triton and even Pluto. The news briefing participants will be: Thomas Zurbuchen, associate administrator, Science Mission Directorate at NASA Headquarters in Washington Jim Green, director, Planetary Science Division at NASA Headquarters Mary Voytek, astrobiology senior scientist at NASA Headquarters Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California Hunter Waite, Cassini Ion and Neutral Mass Spectrometer (INMS) team lead at the Southwest...

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The Value of an Exo-Venus

Looking back at science fiction's treatment of Venus, you can see a complete reversal by the 1960s, at which time we had learned enough about the planet to render earlier depictions invalid, and even quaint. Think back to the inundated surface of Venus in Bradbury's "Death by Rain" (1950) or Henry Kuttner and C. L. Moore's Clash by Night (1943), where humans live under water and the land surfaces are carpeted with jungle. Heinlein's Space Cadet is another example of a fecund Venus much like an Earthly rain forest. But by 1965, Larry Niven would be writing "Becalmed in Hell," about a nightmare Venus based on our insights into its intolerable surface. I should also mention a prescient tale by a writer who is a personal favorite of mine, James Gunn. It's "The Naked Sky" (1955), which shows us a desert Venus with hydrochloric acid clouds and huge atmospheric pressure, a land Gunn described as "embalmed at birth." As far as I know, this was the first SF tale that began to get Venus...

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Atmosphere Detected around Super-Earth GJ 1132b

There's interesting news this morning about planets around M-dwarfs. A team of astronomers led by John Southworth (Keele University, UK) has detected an atmosphere around the transiting super-Earth GJ 1132b. While we've examined the atmospheres of gas giants and have detected atmospheres on the super-Earths 55 Cancri e and GJ 3470 b, GJ 1132b is the smallest world yet where we've detected one. 39 light years from Earth in the constellation Vela, the transiting planet is 1.4 Earth radii in size, with a mass 1.6 times that of our world. We're continuing to move, in other words, into the realm of lower-mass planets when we study planetary atmospheres, an investigation that will be crucial as we look for biosignatures in distant solar systems. With GJ 1132b, we're dealing with a planet too close to its star to be habitable (it receives 19 times more stellar radiation than the Earth does, and has an equilibrium temperature of 650 K, or 377° C). But finding a thick atmosphere here is...

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New Horizons: Star Fields Beyond

The attitude you bring to a star field changes everything. When I was a kid trying to figure out how to use a small telescope, I scanned the usual suspects -- the Moon, Saturn and its rings, the Galilean satellites of Jupiter -- all the while planning to branch out into major wonders like M31 or the Ring Nebula in Lyra. But when I turned to deep sky objects, what I discovered was that I could see little more than faint smudges -- I was using no more than a 3-inch reflector. It was a disappointment for a while, until I accepted the limitations of my equipment. And then I became a cataloger of faint smudges, as avidly tracking down celestial objects as any stamp collector sorting through new finds. A patient uncle showed me how to look slightly away from the object I sought, to pick it up in peripheral vision. I began keeping notebooks listing my first glimpses of various nebulae and clusters. So many celestial objects were out of reach, but somehow a field of stars became wondrous not...

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‘Blue Binaries’ Argue for Smooth Neptune Migration

We’re getting a few clues about the nature of planet migration in the early Solar System thanks to a class of objects being described as ‘blue binaries.’ Cold Classical Kuiper Belt Objects (CCKBOs) are generally reddish, but a population of widely separated binaries has now been identified that is thought to have originated in the inner edges of the Kuiper Belt. The paper reporting on this work argues that these objects were pushed out a distance of over 4 AU to their present location among the CCKBOs as the result of gravitational interactions with Neptune billions of years ago, a movement induced by the migration of the planet from 20 to 30 AU. If so, we can draw some conclusions about that migration, and we’re reminded in the process of how rich the Kuiper Belt is in objects of different origins. Led by Wes Fraser (Queen’s University, Belfast), the study used data drawn from the Gemini North instrument and the Canada-France-Hawaii Telescope, both on Mauna Kea, as part of a project...

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New Options for Locating Fast Radio Bursts

Our catalog of distant, highly energetic events continues to grow. On the Fast Radio Burst (FRB) front, we have the welcome news that the Molonglo radio telescope some 40 kilometers from Canberra, Australia has undergone extensive re-engineering, a project that is paying off with the detection of three new FRBs. The telescope's collecting area of 18,000 square meters and an eight square degree field of view make it ideal for such work. Image: Artist's impression shows three bright red flashes depicting Fast Radio Bursts far beyond the Milky Way, appearing in the constellations Puppis and Hydra. Credit: James Josephides/Mike Dalley. You'll recall that Fast Radio Bursts are millisecond long, intense pulses that can appear out of nowhere with a luminosity a billion times greater than anything we have observed in the Milky Way. The phenomenon was noted for the first time a decade ago at the Parkes radio telescope in New South Wales. The sources remain enigmatic, but Manisha Caleb, a PhD...

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Building the Tools for Icy Moons

With my own memories of the July 4, 1997 landing of Mars Pathfinder at Chryse Planitia as fresh as yesterday, it's hard to believe that we are looking at the 20th anniversary of rover operations on the planet. But as the Curiosity rover continues its travels and we look toward the Mars 2020 rover mission, we're also taking a much longer look ahead at the worlds where life may be more likely to be found, the icy moons of Jupiter and Saturn. Ponder this: Testing at the Jet Propulsion Laboratory is showing that ice grains in conditions like we will encounter on places like Enceladus or Europa can behave like sand dunes. That means fine grains that could stall an improperly designed rover, leading NASA engineers to begin rethinking designs harking back to the early days of Moon exploration, lightweight commercial wheels attached to a flexible chassis, a system that has worked for a variety of missions but will need adjustment for future work. The rovers that use these systems will, in...

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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).

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