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Hayabusa2: Asteroid Touchdown

by Paul Gilster | Feb 25, 2019 | Asteroid and Comet Deflection | 19 Comments

For those of you who’ve been asking, I think the best way to keep up with the Hayabusa2 mission to asteroid Ryugu is via Twitter, @haya2e_jaxa. The news continues to percolate via websites and various publications, with a sustained ripple when the spacecraft successfully tested its sample mechanism and touched down on the asteroid. I’ll remind you too that the mission team now offers updated systems information in English on its Haya2NOW page for obsessives like me who want a really fine-grained look at what’s going on. Hayabusa 2 is once again at what JAXA calls its ‘home position’ about 20 kilometers above the asteroid as the multi-part sample selection process continues. JAXA’s news release on the touchdown was to the point: National Research and Development Agency Japan Aerospace Exploration Agency (JAXA) executed the asteroid explorer Hayabusa2 operation to touch down the surface of the target asteroid Ryugu for sample retrieval. Data analysis from Hayabusa2 confirms that the...

A White Dwarf with Puzzling Rings

by Paul Gilster | Feb 22, 2019 | Deep Sky Astronomy & Telescopes | 6 Comments

Backyard Worlds: Planet 9 is a project worth investigating. Using a database drawn from NASA's Wide-field Infrared Survey Explorer (WISE), Backyard Worlds: Planet 9 is probing the cosmos at infrared wavelengths. Volunteers search the WISE data in a 'citizen science' effort that has already discovered more than 1,000 likely brown dwarfs. Now we have news of an intriguing white dwarf showing apparently multiple rings of gas and dust. A ringed white dwarf isn't unique. In fact, dust and rings have been observed around white dwarfs that were considerably younger than the one in question, J0207. As described in a paper in Astrophysical Journal Letters, the object is about 145 light years away in the constellation Triangulum and is thought to be about 3 billion years old. With a temperature of 5,800 degrees Celsius (10,500 degrees Fahrenheit), J0207 produced a strong infrared signal. Bear in mind that a white dwarf is a remnant, a star left behind when its Sun-like predecessor, running out...

Finding Neptune’s Smallest Moon

by Paul Gilster | Feb 21, 2019 | Outer Solar System | 8 Comments

What a lively place Neptune used to be, at least back in the days when the planet captured Triton, doubtless a Kuiper Belt Object now in a retrograde orbit around the primary. Recent work led by Mark Showalter (SETI Institute) puts the Hubble Space Telescope to work in studying one result of the sudden acquisition of so massive an object. A first generation of small satellites was likely scattered and rearranged, its debris becoming the Neptunian moons we see today. Among them is Hippocamp, once known as S/2004 N 1, which appears to be a fragment from Neptune's second largest moon Proteus. What an interesting set of observations we have here. Discovered in 2013, Hippocamp is the outermost of the planet's inner moons, and it orbits a scant 12,000 kilometers from Proteus. We can relate the 2013 discovery with what Voyager 2 found at Neptune in 1989: A large impact crater on Proteus. "The first thing we realised was that you wouldn't expect to find such a tiny moon right next to...

Kepler 107: Collision of Worlds

by Paul Gilster | Feb 20, 2019 | Exoplanetary Science | 26 Comments

It seems increasingly clear that the factors that govern what kind of a planet emerges where in a given stellar system are numerous and not always well understood. Beyond the snowline, planets draw themselves together from the ice and other volatiles available in these cold regions, so that we wind up with low-density gas or ice-giants in the outer parts of a stellar system. Sometimes. Rocky worlds are made of silicates and iron, elements that, unlike ice, can withstand the much warmer temperatures inside the snowline. But consider: While we now have 2,000 confirmed exoplanets smaller than three Earth radii, the spread in their densities is all over the map. We’re finding that other processes must be in play, and at no insubstantial level. Low-density giant planets can turn up orbiting close to their stars. Planets not so dissimilar from Earth in terms of their radius may be found with strikingly different densities in the same system, and at no great distance from each other. Which...

Gravitational Wave Astronomy: Enter the ‘Standard Siren’

by Paul Gilster | Feb 19, 2019 | Deep Sky Astronomy & Telescopes | 29 Comments

Recently we've talked about 'standard candles,' these being understood as objects in the sky about which we know the total luminosity because of some innate characteristic. Thus the Type 1a supernova, produced in a binary star system as material from a red giant falls onto a white dwarf, causing the smaller star to reach a mass limit and explode. These explosions reach roughly the same peak brightness, allowing astronomers to calculate their distance. Even better known are Cepheid variables, stars whose luminosity and variable pulsation period are linked, so we can measure the pulsation and know the true luminosity. This in turn lets us calculate the distance to the star by comparing what we see against the known true luminosity. This is helpful stuff, and Edwin Hubble used Cepheids in making the calculations that helped him figure out the distance between the Milky Way and Andromeda, which in turn put us on the road to understanding that Andromeda was not a nebula but a galaxy....

Breakthrough Propulsion Study

by Paul Gilster | Feb 15, 2019 | Breakthrough Propulsion | 69 Comments

Ideas on interstellar propulsion are legion, from fusion drives to antimatter engines, beamed lightsails and deep space ramjets, not to mention Orion-class fusion-bomb devices. We're starting to experiment with sails, though beaming energy to a space sail is still an unrealized, though near-term, project. But given the sheer range of concepts out there and the fact that almost all are at the earliest stages of research, how do we prioritize our work so as to move toward a true interstellar capability? Marc Millis, former head of NASA's Breakthrough Propulsion Physics project and founder of the Tau Zero Foundation, has been delving into the question in new work for NASA. In the essay below, Marc describes a developing methodology for making decisions and allocating resources wisely. by Marc G Millis In February 2017, NASA awarded a grant to the Tau Zero Foundation to compare propulsion options for interstellar flight. To be clear, this is not about picking a mission and its technology...

Planet Formation: How Ocean Worlds Happen

by Paul Gilster | Feb 14, 2019 | Exoplanetary Science | 98 Comments

It's hard to fathom when we look at a globe, but our planet Earth's substantial covering of ocean is relatively modest. Alternative scenarios involving 'water worlds' include rocky planets whose silicate mantle is covered in a deep, global ocean, with no land in sight. Kilometer after kilometer of water covers a layer of ice on the ocean floor in these models, making it unlikely that the processes that sustain life here could develop -- how likely is a carbon cycle in such a scenario, and without it, how do we stabilize climate and make an inhabitable world? These are challenging issues as we build the catalog of exoplanets and try to figure out local conditions. But it's also intriguing to ask what made Earth turn out as dry as it is. Tim Lichtenberg developed a theory while doing his thesis at the Eidgenössische Technische Hochschule in Zürich (he is now at Oxford), and now presents it in a paper in collaboration with colleagues at Bayreuth and Bern, as well as the University of...

Looking Back from System’s Edge

by Paul Gilster | Feb 13, 2019 | Outer Solar System | 14 Comments

Sometimes the way we discover new things is by looking back, as witness the blue haze of Pluto. The image below comes, of course, from New Horizons, taken after the flyby and looking back in the direction of the Sun. Here we're looking at a mosaic combining black and white LORRI images (Long Range Reconnaissance Imager) and enhancing them with lower-resolution color data from the Ralph/Multispectral Visible Imaging Camera (MVIC). The result, taken about 3.5 hours after closest approach, is in approximately true color. Image: Pluto as seen by New Horizons from 200,000 kilometers after the flyby. The spectacular blue haze, extending to over 200 kilometers in altitude, is the result of sunlight acting on methane and other molecules in Pluto's atmosphere to produce a photochemical haze. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. Ultima Thule likewise yields more of its secrets as we look at data from beyond the closest encounter. New...

2019 Symposium Call for Papers

by Paul Gilster | Feb 12, 2019 | Administrative | 18 Comments

6th Interstellar Symposium and Interstellar Propulsion Workshop - TVIW 2019 In collaboration with the National Aeronautics and Space Administration (NASA), the Tennessee Valley Interstellar Workshop (TVIW) hereby invites participation in its 6th Interstellar Symposium and Interstellar Propulsion Workshop -hosted by Wichita State University (WSU) and Ad Astra Kansas Foundation - to be held from Sunday, November 10 through Friday, November 15, 2019, in Wichita, Kansas. The 2019 TVIW has the following elements: The NASA Workshop on Interstellar Propulsion will focus solely on physics-based propulsion technologies that have the potential to meet the goal of launching an interstellar probe within the next century and achieving .1c transit velocity: Beamed Energy Propulsion, Fusion, and Antimatter. At this meeting, the state-of-the-art of each will be examined, competing approaches to advancing the Technology Readiness Level (TRL) of each will be presented by advocates and assessed by...

SETI’s Charismatic Megafauna

by Paul Gilster | Feb 8, 2019 | Astrobiology and SETI | 205 Comments

The search for technosignatures that could flag the presence of extraterrestrial cultures has accelerated in recent times with projects like Glimpsing Heat from Alien Technologies at Penn State and numerous papers. Or is the better term not 'cultures' but 'societies,' or 'civilizations'? SETI's funding challenges, at least from government agencies, point to the need for defining its terms in ways that NASA, for example, can live with. Nick Nielsen examines the question in today's essay, probing the issue of terminology in relation to public support, and noting the ongoing effort to evaluate and revise how SETI is described. Nielsen, a frequent Centauri Dreams contributor and a member of the board of directors for Icarus Interstellar, is a prolific writer who tracks these and other space-related issues in Grand Strategy: The View from Oregon, and Grand Strategy Annex. by J. N. Nielsen Recently there have been some signs that NASA may consider a rapprochement with SETI and SETI...

Perspectives Beyond the Moon

by Paul Gilster | Feb 7, 2019 | Culture and Society | 9 Comments

Today we re-enter the realm of perspective-altering photographs, images that open new vistas in our early reconnaissance of the Solar System. Before October 7, 1959, we had little knowledge of the far side of the Moon, even though librations allowed the occasional glimpse at extremely low angles of a small part of it. The Soviet moon probe Luna 3 took the first photographs of the far side, and was followed by the much better imagery of Zond 3 in 1965. NASA's Lunar Orbiter program would continue the mapping as the 1960s progressed. Image: First glimpse. The view of the Moon's far side from Luna 3. The far side would swim into vivid focus, of course, when Apollo 8 and subsequent missions took astronauts to the Moon, but it was up to the China National Space Administration to make the first soft landing there on January 3 of this year (Ranger 4 had impacted on the far side in 1962, but without returning data before impact). Working in this environment demanded a relay satellite to...

Refining the Shape of the Milky Way

by Paul Gilster | Feb 6, 2019 | Deep Sky Astronomy & Telescopes | 15 Comments

Figuring out the shape of things -- where to place what we see in the sky in a 3-D representation -- has always been challenging. We're looking out at a disk of stars from well within it, and it wasn't until the 1920s and the work of Edwin Hubble that we began to see there were other such disks, not nebulae at all but galaxies in their own right, some bigger than ours. Interestingly, Immanuel Kant had speculated about this as far back as 1755. About our own galaxy, we still have much to learn, as I am once again reminded by a paper by authors from Macquarie University (Australia) and the Chinese Academy of Sciences. The Milky Way turns out to be not as flat as many depictions would have us believe. In fact, our galaxy shows distinct signs of warping, a spiral pattern that appears to be the result of torque produced by the Milky Way's massive inner disk of closely packed stars. In the outer regions of the galaxy's neutral hydrogen disk, the warp becomes readily apparent. We wind up...

Cassini Data on Saturn’s Rings, Clouds

by Paul Gilster | Feb 5, 2019 | Outer Solar System | 9 Comments

Larry Klaes' article on the film Silent Running, with its images of Saturn originally intended for 2001: A Space Odyssey, makes today's story the obvious segue, and thus gives me the chance to catch up with some work I've been wanting to write about. For scientists using Cassini data have been able to zero in on the age of Saturn's rings, an always lively area of controversy, with evidence that the rings formed between 10 million and 100 million years ago. The new analysis is discussed in the journal Science. How to make such a call? Everything depends on getting a firmer fix on the mass of the rings, which in turn would tell us something about how bright individual ring particles must be. The brightness of the rings should have been affected by soot-like darkening inevitable over time. Fortunately, we had Cassini at Saturn to perform its so-called Grand Finale orbits, 22 dives between the planet and the rings. The gravitational effect of the rings went from being noise in data about...

In Wildness is the Preservation of the World: ‘Silent Running’ and Our Choice of Futures

by Paul Gilster | Feb 1, 2019 | Uncategorized | 99 Comments

Centauri Dreams' resident film critic Larry Klaes continues his in-depth look at science fiction movies with 1972's Silent Running, whose protagonist is faced with a stark choice far from home. The film rode the era's surging interest in environmentalism, and while overshadowed in the memory of many of us by 1968's 2001: A Space Odyssey (and what SF film isn't?), it has interesting connections with that film. Douglas Trumbull, who handled special effects for 2001, was the force behind Silent Running, and concepts originally envisioned for the former turned up in the latter, especially in the depiction of Saturn. How Saturn might have played into the earlier film -- and why Jupiter took its place there -- is just one of the historical avenues Larry explores in this wide-ranging essay. By Larry Klaes "On this first day of a new century, we humbly beg forgiveness and dedicate these last forests of our once beautiful nation to the hope that they will one day return and grace our foul...

AI Colonization: The Founder and the Ambassador

by Paul Gilster | Jan 31, 2019 | Autonomy and Robotics | 61 Comments

As we look toward future space missions using advanced artificial intelligence, when can we expect to have probes with cognitive capabilities similar to humans? Andreas Hein and Stephen Baxter consider the issue in their paper “Artificial Intelligence for Interstellar Travel” (citation below), working out mass estimates for the spacecraft and its subsystems and applying assumptions about the increase in computer power per payload mass. By 2050 we reach onboard data handling systems with a processing power of 15 million DMIPS per kg. As DMIPS and flops are different performance measures [the computing power of the human brain is estimated at 1020 flops], we use a value for flops per kg from an existing supercomputer (MareNostrum) and extrapolate this value (0.025?1012 flops/kg) into the future (2050). By 2050, we assume an improvement of computational power by a factor 105 , which yields 0.025?1017 flops/kg. In order to achieve 1020 flops, a mass of dozens to a hundred tons is needed....

Future AI: The Explorer and the Philosopher

by Paul Gilster | Jan 29, 2019 | Autonomy and Robotics | 29 Comments

Robert Bradbury had interesting thoughts about how humans would one day travel to the stars, although whether we could at this point call them human remains a moot point. Bradbury, who died in 2011 at the age of 54, reacted at one point to an article I wrote about Ben Finney and Eric Jones’ book Interstellar Migration and the Human Experience (1985). In a comment to that post, the theorist on SETI and artificial intelligence wrote this: Statements such as “Finney believes that the early pioneers … will have so thoroughly adapted to the space environment” make sense only once you realize that the only “thoroughly adapted” pioneers will be pure information (i.e. artificial intelligences or mind uploaded humans) because only they can have sufficient redundancy that they will be able to tolerate the hazards that space imposes and exist there with minimal costs in terms of matter and energy. Note Bradbury’s reference to the hazards of space, and the reasonable supposition -- or at least...

Artificial Intelligence and the Starship

by Paul Gilster | Jan 28, 2019 | Autonomy and Robotics | 45 Comments

The imperative of developing artificial intelligence (AI) could not be more clear when it comes to exploring space beyond the Solar System. Even today, when working with unmanned probes like New Horizons and the Voyagers that preceded it, we are dealing with long communication times, making probes that can adapt to situations without assistance from controllers a necessity. Increasing autonomy promises challenges of its own, but given the length of the journeys involved, earlier interstellar efforts will almost certainly be unmanned and rely on AI. The field has been rife with speculation by science fiction writers as well as scientists thinking about future missions. When the British Interplanetary Society set about putting together the first serious design for an interstellar vehicle -- Project Daedalus in the 1970s -- self-repair and autonomous operation were a given. The mission would operate far from home, performing a flyby of Barnard's Star and the presumed planets there with...

The Next Steps in Space

by Paul Gilster | Jan 25, 2019 | Advanced Rocketry | 131 Comments

Most of my research for Centauri Dreams involves looking at papers and presentations on matters involving deep space, whether propulsion systems, closed loop life support, or even possible destinations. That's why it's a huge help to get an article like the one below, giving us an overview of current thinking and an analysis of what is either in the pipeline or under consideration for the near-term. How do we get from here to the kind of Solar System infrastructure we'll need to go interstellar? Ioannis Kokkinidis has an impressive background: He holds a Master of Science in Agricultural Engineering from the Department of Natural Resources Management and Agricultural Engineering of the Agricultural University of Athens. He went on to obtain a Mastère Spécialisé Systèmes d'informations localisées pour l'aménagement des territoires (SILAT) from AgroParisTech and AgroMontpellier and a PhD in Geospatial and Environmental Analysis from Virginia Tech. Today...

What’s Next for New Horizons?

by Paul Gilster | Jan 23, 2019 | Missions | 29 Comments

The exuberance of images like the one below captures the drama of Solar System exploration. Scenes like this are emblematic of the early reconnaissance of the Solar System. We saw similar enthusiasm with missions near and far -- I'm thinking back, for example, not just to Voyager, but the Viking landings on Mars, and I'm sure Russian controllers were equally jubilant when their Venera craft touched down on Venus. Space is indeed the 'final frontier,' as James T. Kirk reminded us on Star Trek, and it's a frontier that goes on without end. Image: Celebration in full swing as scientists react to the view from New Horizons after the Ultima Thule flyby. Credit: NASA / JHUAPL / SwRI / Henry Throop. Let's keep in mind, then, that New Horizons is not just returning Ultima Thule data, but continuing to push into the Kuiper Belt doing good science. In terms of future missions, we need to learn as much as we can about radiation, gas and dust as we assess the environment. New Horizons will get...

‘Oumuamua, SETI and the Media

by Paul Gilster | Jan 21, 2019 | Astrobiology and SETI | 99 Comments

One of the more important things about the interstellar object called 'Oumuamua is the nature of the debate it has engendered. Harvard astronomer Avi Loeb's paper examining it as a possible technology has provoked comment throughout the scientific community, as witness Jason Wright's essay below. Dr. Wright (Penn State) heads the Glimpsing Heat from Alien Techologies (G-HAT) project, which he described in these pages, and is a key player in the rapidly developing field of Dysonian SETI, the study of possible artifacts as opposed to deliberate communications from extraterrestrial civilizations. Here he looks at the debate Loeb's work has engendered and its implications not only for how we do science but how we teach its values to those just coming into the field. Jason's essay was originally posted several days ago on his Astrowright blog, which should be a regular stop for Centauri Dreams readers. by Jason T. Wright Avi Loeb is the chair of the astronomy department at Harvard, a...

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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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