Centauri Dreams
Imagining and Planning Interstellar Exploration
Pluto and How We See It
As I did after yesterday’s post, I occasionally get requests for pictures of objects in natural color, as opposed to significantly enhanced images (at various wavelengths) designed to tease out structure or detail. Here are Pluto and Charon as seen by New Horizons’ LORRI (Long Range Reconnaissance Imager), with color data supplied by the Ralph instrument. The images in this composite are from July 13 and 14 and according to JHU/APL, “…portray Pluto and Charon as an observer riding on the spacecraft would see them.”
For those interested, Jenna Garrett wrote a fine piece for WiReD last summer called What We’re Really Looking at When We Look at Pluto that goes into the instrumentation aboard New Horizons and discusses the philosophical issues separating what we see from what is really there. Let me quote briefly from this:
It’s not hard for a photographer to understand why you’d question actually seeing Pluto—the same question has nagged photographers since Nicéphore Niépce made View from the Window at Le Gras in 1826. A camera is a simple machine: A lens and a shutter that allows the passage of light, which hits the chemical emulsion of film or the pixels of a digital sensor. That intervening technology takes photons bouncing off an object and interpolates them into data. More technology turns that data into an image. And still more technology disseminates that image so you might see it.
I don’t want to get too far into philosophy, but just for fun, here’s the Niépce image.
Image: The first recorded photograph, taken from a window in his study by Joseph Nicéphore Niépce. For more, visit this University of Texas site.
It’s always good to ask how images are processed, especially when dealing with data being returned from the edge of the Solar system through a number of instruments. New Horizons carries three imagers: The aforementioned LORRI and Ralph, along with Alice, an ultraviolet imaging spectrometer. Ralph has ten times the resolution of the human eye, but we use data as needed from the instrument packages to ferret out what scientists are looking for.
I also like this quote by Jon Lomberg, a deeply felt ratification of New Horizons from Garrett’s piece:
“You don’t really have to understand a lot about astronomy to know how difficult this is,” says Lomberg. “Getting it there, having it work for nine years and having it do exactly what they’re telling it to do. You just want to applaud. It makes everybody think Goddamn! that was a good thing to do!“
I’m sure that most of the Centauri Dreams audience is with Jon on that sentiment. But let’s move on to further news about Pluto from the Division of Planetary Sciences meeting in Maryland. In analyzing the New Horizons data, we learn that Pluto’s upper atmosphere is a good deal more compact and significantly colder than we had thought based upon earlier models. Pluto’s atmosphere seems to escape more or less the same way that atmospheric gases do on Earth or Mars, rather than acting as we would expect from a cometary body. Here is the already famous image that showed us ‘blue skies’ (of a sort) on Pluto.
Image: Pluto’s haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC). The high-altitude haze is thought to be similar in nature to that seen at Saturn’s moon Titan. The source of both hazes likely involves sunlight-initiated chemical reactions of nitrogen and methane, leading to relatively small, soot-like particles (called tholins) that grow as they settle toward the surface. This image was generated by software that combines information from blue, red and near-infrared images to replicate the color a human eye would perceive as closely as possible. Credits: NASA/JHUAPL/SwRI.
Here again we’re aiming at something close to what the human eye would perceive.
We also learned at DPS that Pluto’s moons are unlike anything we’re familiar with in the rest of the Solar System. Most inner moons in the Solar System (including ours) move in synchronous rotation, with one face always toward the planet. But the small moons of Pluto do nothing of the kind. Hydra rotates 89 times during a single circuit of Pluto, while the rest of the small moons rotate faster than we would expect as well. Have a look at the chart that Mark Showalter (SETI Institute) prepared for presentation at DPS.
Image: Spin periods for the range of Pluto’s moons. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
We may well be looking at chaotic spin rates — variable over time — and likely the result of the torque Charon exerts, which would keep the moons from settling into synchronicity. Showalter characterized these wobbling moons as ‘spinning tops,’ and it also appears that several of them may have been formed by merger, with two or more former moons coming together following the event that created Charon. That would make sense — surely there were a large number of objects after a massive impact, with the present system having consolidated from these. Here’s the slick video illustrating the motion of these moons that NASA has produced.
I love Showalter’s take on all this in a SETI Institute news release: “There’s clearly something fundamental about the dynamics of the system that we do not understand. We expected chaos, but this is pandemonium.”
Pluto’s Unexpected Complexities
Keeping up with a site like this can be a daunting task, especially when intriguing papers can pop up at any time and announcements of new finds by our spacecraft come in clusters. But site maintenance itself can be tricky. Recently Centauri Dreams regular Tom Mazanec wrote in with a project to be added to the links on the home page and before long, with my encouragement, he had sent a number of solid suggestions on exoplanet projects both Earth- and space-based, most of which have now been added. My thanks to Tom and all those who have at various times caught a broken link or added a suggestion for new links or stories.
We begin the week looking at work discussed at the Division for Planetary Sciences meeting in Maryland, starting with the continuing bounty coming in from New Horizons. I always like to quote Alan Stern, because as principal investigator for New Horizons, he is not only its chief spokesman but the guiding force that saw this mission become a reality. And I think he’s absolutely on target when he points to how fulsome a discovery Pluto is turning out to be:
“It’s hard to imagine how rapidly our view of Pluto and its moons are evolving as new data stream in each week,” says Stern. “As the discoveries pour in from those data, Pluto is becoming a star of the solar system. Moreover, I’d wager that for most planetary scientists, any one or two of our latest major findings on one world would be considered astounding. To have them all is simply incredible.”
Image: Pluto and Charon are revealing themselves as worlds of profound complexity. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
All this with a flyby, leading me to wonder what we might find with a Pluto orbiter.
Think about Voyager. It opened our eyes to new worlds for this first time. It flew by Io and gave us active volcanoes. It flew by Triton and we saw weird ‘cantaloupe terrain’ and nitrogen geysers. All these stay fixed in my mind as I remember first learning about them. But what New Horizons is showing us ranges from bizarre moons to possible ice volcanoes, the huge satellite Charon in a system that is practically a binary ‘planet,’ and surface features that tell us about an active world that was once thought to be inert. Who thought Pluto/Charon would be this complex!
Wright Mons and Piccard Mons, as it turns out, each appear to have a hole at their summit, the signature of a volcano, but one expected to cough up water ice, nitrogen, ammonia or methane in a melted slurry rather than lava. We can’t push this too far, because on a world about which we have so much to learn, we may be in for yet another surprise. And Oliver White, a postdoctoral researcher at NASA Ames, points out another of the unknowns:
“If they are volcanic, then the summit depression would likely have formed via collapse as material is erupted from underneath. The strange hummocky texture of the mountain flanks may represent volcanic flows of some sort that have travelled down from the summit region and onto the plains beyond, but why they are hummocky, and what they are made of, we don’t yet know.”
Image: Scientists using New Horizons images of Pluto’s surface to make 3-D topographic maps have discovered that two of Pluto’s mountains, informally named Wright Mons and Piccard Mons, could possibly be ice volcanoes. The color is shown to depict changes in elevation, with blue indicating lower terrain and brown showing higher elevation; green terrains are at intermediate heights. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
As this JHU/APL news release makes clear, Pluto’s surface is also showing us far more textures than we might have expected. Why do we see so few small craters? Neither Pluto nor Charon give us many of these, casting doubt on the older model of Kuiper Belt objects formed by the accumulation of small objects. Now you can see why 2014 MU69 is beginning to loom so large. This KBO may be a pristine primordial planetesimal, the first ever to be explored. Assuming the New Horizons mission is extended, a flyby of 2014 MU69 will give us another look at a class of objects that may have been formed quickly and at close to their current size.
But we still have a lot of explaining to do re Pluto’s surface itself. Trying to determine the age of a surface is often a matter of counting the crater impacts to see what has accumulated over time (think of the relatively smooth surface of Europa, which indicates continuing resurfacing that obscures impacts). On Pluto, we do find surfaces that point to the earliest era of the Solar System four billion years ago, but we also see things like Sputnik Planum, whose smooth and impact-free terrain looks to have been formed within the past ten million years, an eyeblink in astronomical time.
Image: A slide from Oliver White’s presentation at DPS, showing crater densities on Pluto’s surface. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
Other terrains on Pluto look to be somewhere in between, with evidence of cratering extending back not nearly as far as the oldest areas. So is Sputnik Planum, which is on the left of Pluto’s heart-shaped feature, an anomaly, or a marker for a surface that has been geologically active for much of its history? We’re looking at evidence for how objects in the outer Solar System formed, again a splendid reason to back the extension of New Horizons to 2014 MU69.
More on Pluto/Charon and the findings discussed at the DPS meeting tomorrow.
The Initiative for Interstellar Studies: A Three Year Update
Kelvin Long is chief editor of the Journal of the British Interplanetary Society and the author of Deep Space Propulsion (Springer, 2011). A founder and first project leader of Project Icarus, the ongoing re-design of the Project Daedalus starship, Kelvin is also a co-founder of the non-profit Icarus Interstellar. He now serves as executive director of the Institute for Interstellar Studies, an organization whose mission (‘Scientia ad Sidera: Knowledge to the Stars’) he describes in the following essay.
by Kelvin F. Long
The Initiative for Interstellar Studies (i4is) is a not-for-profit foundational institute incorporated in the United Kingdom with the mandate to develop interstellar capabilities. We at the initiative just successfully passed our third anniversary since our founding. We began work in August 2012 and went live on the 12th September 2012. Shortly after, we ratified our purpose through our innovative logo, and our mission and vision statements. And today we are focused on the launch of our innovative new educational course titled ‘Starship Engineer’. We are piloting the first version of this in London during November, and we hope some of you will join us: http://i4is.org/news/starship_engineer
But first, it is worth just reminding the readers what we are really about. The mission of i4is is to foster and promote education, knowledge and technical capabilities which lead to designs, technologies or enterprise that will enable the construction and launch of interstellar spacecraft. The vision of i4is is to aspire towards an optimistic future for humans on Earth and in space. Our bold vision is to be an organisation that is central to catalysing the conditions in society over the next century to enable robotic and human exploration of the frontier beyond our Solar System and to other stars, as part of a long-term enduring strategy and towards a sustainable space-based economy. Our motto is “Scientia ad sidera” (knowledge to the stars) and our philosophy of approach is “Starships in our Lifetime”. In addition to this, we also spent weeks writing our own bespoke articles of association, which forms our effective constitution as a company limited by guarantee but not having a share capital – which means we are a not-for-profit entity. In addition, our team produced a ‘founding Declaration’ which sets out what we believe and are working towards. The full text of this can be read here: http://i4is.org/the-starship-log/foundations
So how far have we got in the constitution of the world’s first ever foundational institute dedicated to the goal of the stars? The Initiative for Interstellar Studies is led by a board of directors for which I serve as its Executive Director, supported by the Deputy Directors Rob Swinney and Andreas Hein. We are also supported by our international advisory committee which is chaired by Professor Gregory Matloff and deputy Professor Chris Welch. We have various committees, including a marketing committee and a finance committee, which ensures we are fiscally compliant and ethical? But our activity based committee’s number a few, and I shall give a brief synopsis of each in turn along with their achievements to date?
The Alpha Centauri Prize Committee has the purpose of rewarding success and incentivising progress in activities related to interstellar studies. So far the committee has given out several awards for University students associated with their thesis projects, or for internal members for work that they have done to assist our mission that goes above and beyond what is expected of them. We have received sponsorship from several external organisations to fund those awards. We seek to establish the Alpha Centauri Prize awards as the standard by which all of our progress is measured.
The Educational Academy Committee is chaired by Rob Swinney and has the purpose of fostering educational abilities to conduct research relating to a broad set of subjects pertaining to interstellar studies, associated sciences and the arts. The committee has undergone much public outreach work, working with schools and universities, particularly across the UK.
The largest activity of this committee is in working with the International Space University in Strasbourg, and in particular with its Master’s Director Professor Chris Welch, who is a continued inspiration not just for the students but for all of us in his steadfast support of our ambitious efforts. Within this co-operative relationship, for which we have signed a Memorandum of Understanding, some of our projects have included “Autonomous Space Colony Construction” authored by Michio Hirai, which considered the manufacture of large structures in space; “Agriculture Design Trade-offs for Space Colony Feasibility“, authored by Erik Franks, which discussed farming methods in spaceflight; “Review of the Deceleration Options for a Robotic Interstellar Spacecraft Entering the System of Another Star“, authored by Wei Wang; “The Oculus Project: Solar Sailing to Discover Exoplanets at the Center of Our Galaxy“, authored by Piotr Murzionak, which looked at a gravitational lensing mission based on the ideas of the pioneer Claudio Maccone; “Jude: Solar Sailing A Low Mass Payload to Alpha Centauri-B“, authored by James Harpur, which considered an interstellar solar sail mission. The committee has also created a fun educational exam paper, which we call the ‘interstellar minimum’ – dare you have a go at it? http://i4is.org/the-starship-log/interstellar-minimum
Our biggest technical and educational accomplishment working with the International Space University has been the initiation and completion of a world ship project titled “Astra Planeta” and you can read a copy here: https://isulibrary.isunet.edu/opac/index.php?lvl=notice_display&id=9454].
This project was selected as one of the few team projects that the ISU runs each year and it involved over 20 Master’s students. The team also looked at the issues of creating a strategic and technological roadmap for a world ship. But the nice thing about this project, is that it also got supported by representatives from the Tennessee Valley Interstellar Workshop and Icarus Interstellar – so it may be one of the first successful pan-interstellar community projects, and is perhaps a model for the future.
The Technical Research Committee is chaired by Andreas Hein and has the purpose of conducting innovative theoretical and experimental research and development across the broad spectrum of issues relating to interstellar studies, associated sciences and the arts.
The committee’s flagship initiative is Project Dragonfly, which seeks to develop laser-sail propulsion capabilities based on the original ideas of Robert Forward. In the summer, the team ran a Kickstarter award and successfully won over $10,000.
This helped to fund a university affiliated design competition, which included participating teams from Cairo University, Egypt; University of California Santa Barbara, USA; Technical University of Munich, Germany and CranSEDS which involved students from Cranfield University in the UK, Skoltech in Russia and UPS in France. The University of Munich team won the competition with their innovative sail design. The four reports submitted by these teams were highly comprehensive and had to adhere to detailed competition requirements. To celebrate the award, the space artist David A Hardy was commissioned to produce an inspirational piece of art work of the winning design. The Technical Committee is now working on a technology roadmap focussed around the laser-sail technologies and this includes the consideration of actual space missions for the near future.
Image: Schematic of the winning Project Dragonfly design.
Image: David A Hardy commissioned art work of the winning laser-sail design for project Dragonfly.
The committee is also chairing several projects and this has already led to several reports. This includes “Project Sentinel” authored by Sissi Enestam, which described research into emission signals from different potential advanced space transportation systems as a contribution to SETI; “Space Eternal Memory” authored by Melissa Guzman which described methods of preserving and storing information on long duration deep space missions; “Project BAIR: the Black Hole Augmented Interstellar Rocket”, authored by Andrew Alexander, which discussed a black hole engine that utilised the Hawking radiation effect; “Program to Characterise the Local Stellar Environment” authored by Shambo Bhattacharjee. The committee is also currently launching a project relating to von Neumann machines and the Universal Constructor Project. The vision is to enable small interstellar probes to have the capability to build space infrastructures autonomously.
The Sustainability & Research Committee is chaired by Professor Rachel Armstrong and has the purpose of seeking space-based technological solutions to solving problems on Earth and in space, human made or environmental, and improving the human condition and harmonising cultural relations. Through this committee we have begun a relationship with a team of architects and initiated discussions on innovative technologies for the future that we can bring to our metropolis. The committee has also instigated the exciting ‘Starship Cities’ programmes, which seeks to develop the technologies for our society that can truly prepare us for the world ship journeys of the future. This includes looking at living architecture technologies such as protocells, and the ability to utilise them as a form of programmable matter and as a mechanism to simulate biological computing. In the last year the committee also completed a project with the International Space University titled “Biological Life Support Systems for Future Spaceflight Missions” authored by Brian Ramos. The committee is also looking at an innovative experimental architectural platform, upon which many types of experiments could be conducted on an iterative learning basis.
The Business Enterprise Committee is chaired by myself and has the purpose of encouraging entrepreneurship and business innovation initiatives related to the objects. We are currently exploring models for nurturing start-ups and aiming to develop a facilitation scheme over the next year. In addition, the committee is also in discussions with various private inventors about bringing potential products to market to benefit the community. One new company for which we have helped to nurture to fruition is Nebula Sciences (www.nebulasciences.com). This is a company led by Sam Harrison, who also serves on our Enterprise Committee, and conducts high altitude balloon launches into the upper stratosphere. That company is now working with multiple aerospace and marketing ventures throughout the world. The same team earlier placed the i4is logo at 89,000 ft, which was a milestone achievement for us, and demonstrates we are not just talking about theoretical developments.
Image: The i4is Logo at 89,000 ft in the stratosphere
As of our three year anniversary, our team has published over 100 papers, reports, articles and essays, has given over 50 presentations, has produced nearly 100 external and internal blog articles, has held over 30 formal team meetings and around 100 informal team meetings, has been involved with over 50 other external organisations, has participated in over 40 different international events, and today has around 70 people directly involved in our activities in one form or another. We have had media articles in multiple international publications and have participated in online podcasts and radio shows. We have attended or presented at events across the globe, throughout the United Kingdom, Europe and the United States. As a part of our participating in the London World Science Fiction convention 2014, our team also built a 4 m tall monolith in what may be a world record (anyone?). Our packed out session at this exciting venue included talks from the world renowned science fiction authors Gregory Benford, Stephen Baxter and Alastair Reynolds.
Image: Our Monolith displayed at Loncon3.
We have produced much of our own merchandise including t-shirts, post-cards and a calendar. One of our proudest and longest running achievement is the publication of our popular magazine Principium, and we are currently working on our twelfth issue. This is a popular publication for the community, and we always try to have an article on other organisations activities to help promote their work.
Image: Principium, the popular magazine of i4is.
We also have published our very own book “Beyond the Boundary” which had contributions from other 20 different authors associated with our subject [http://www.lulu.com/shop/http://www.lulu.com/shop/kelvin-long/beyond-the-boundary/hardcover/product-22028046.html]. And just to show that we are technologically minded, we have also developed our very own educational iPhone app. We have also been working with the inspirational artist and musician Alex Storer, and we are now on our fourth interstellar themed music album. This all proves we are engaging the both the arts and the sciences as we attempt to communicate the vision of interstellar travel. We have also recently just launched our own academic journal, Axiom, and we are now working on our second issue.
Image: Music albums, a journal and smartphone app of i4is.
So what about the future? Well, we are currently looking at facilities to host our Head Quarters and our team has visited many locations over the last couple of years and we are excited about the prospect of hosting interstellar events from such a facility. We are also working on another volume of the “Beyond the Boundary” book, as well as more issues of Principium and Axiom. We continue to attend events and this month we are attending Novacon, a science fiction convention held in Nottingham, UK, every year. Our team are busy working on papers for journals and various research projects from which we hope to see progress towards our goal made. We have also recently launched our supporting membership scheme (get in touch if you want to join) and we are planning to extend this in 2016. We are also keen to recruit more active volunteers to help out with our many activities.
One of the things I am personally keen to do in the future is to address how we can take this interstellar community onto the next level. That is, towards a path of constructive co-operation, resource sharing, and more focussed goal setting through inspirational leadership. One proposal I have made towards this, is the formation of an International Interstellar Committee, which would hold a bi-annual interstellar conference for which all of the community would help organise and participate in. Such a body would contain individual organisational membership, preserving their individual identifies and self-autonomy, whilst facilitating a global voice and finding synergies in strategies. It is my opinion, that such an entity may be needed if we are to find ways of harmonising relationships among different groups, but for all have their hearts set on the same goal.
Some still view our endeavours as premature, given the state of human space exploration to date. But I rather believe that now more than ever, there is the need for a visionary stretch goal to focus the energies of our fragmented civilisation. The vision of the stars gives us such promise, about the discovery of other worlds or new life forms. Its such an exciting journey to be a part of and it also has transformation potential for human civilisation, so that we can start to address the universe on its own terms, whether we live in a crowded galaxy, or if we are the only intelligent life out there. I for sure, would like to find out – so let’s build those starships in our lifetime, and go forth with less of our weaknesses and more of our strengths, as a unified people, embracing discovery and adventure as a primary goal. Personally, I can’t think of anything more fulfilling to dedicate one’s life too. At the Initiative for Interstellar Studies, we are making some progress towards that goal.
The Most Distant Dwarf Planet Yet
Back in the days when Clyde Tombaugh was using a blink comparator to search for ‘Planet X,’ finding a new object in the outer Solar System was highly unusual. Uranus had been found in 1781, Neptune in 1846, and I suppose I should add Ceres in 1801, although it’s a good deal closer than the other two. The real point is that the Solar System seemed straightforward in Clyde Tombaugh’s day. There were eight planets and an asteroid belt. It wouldn’t be until 1943 that Kenneth Edgeworth argued that the outer system might have ‘a very large number of comparatively small bodies,’ with Gerard Kuiper publishing his own speculations in 1951.
Estonian astronomer Ernst Öpik first described what we now know as the Oort Cloud in 1932, with Jan Oort, a Dutch astronomer, reviving the idea in 1950. The Oort Cloud was a way to explain why comets behave the way they do. Oort believed that there must be a cometary ‘reservoir’ far away from the Sun — he chose 20,000 AU as a likely range because of the number of long period comets with aphelia at approximately that distance. Moreover, long-period comets seemed to come from all directions of the sky. As we’ve refined the idea and the numbers, we’ve begun to see just how vast the Solar System really is.
None of this is to take anything away from the discovery of the small world called V774104, announced yesterday at the Division for Planetary Sciences meeting in Washington, DC. Astronomer Scott Sheppard (Carnegie Institution for Science) and Chad Trujillo (Gemini Observatory, HI) have found a world 15.4 billion kilometers out, which works out to 103 AU and makes V774104 the most distant dwarf planet known, fully three times further from the Sun than Pluto. In Tombaugh’s day, such a discovery would have been front page news. Today we’ve come to assume that there are a lot of dwarf worlds out there, and expectations are that as our equipment improves, we’ll find plenty more.
Image: A dot moving (slowly) across background stars, V774104 was found about 15 degrees off the ecliptic. Credit: Subaru Telescope by Scott Sheppard, Chad Trujillo, and David Tholen.
V774104 is currently estimated to be between 500 and 1000 kilometers in diameter, less than half Pluto’s size. Just how significant it is in the larger scheme of things has yet to be determined because we’re not yet sure about the parameters of its orbit. Is it, at 103 AU, close to aphelion, and will it eventually swing back toward Neptune, making its orbit the likely result of a gravitational encounter with that planet? Or is V774104 actually something far more unusual, a world similar to Sedna and VP113 in being a possible member of the inner Oort Cloud?
Neither Sedna nor VP113 comes close enough to the Sun to experience gravitational effects from the giant planets. In fact, both stay outside 50 AU, thought to be the outer edge of the Kuiper Belt, and have aphelia as distant as 1000 AU. Colin at the Armagh Planetarium site notes the problem in V774104: Could a Dark World Put a New Light on Solar System History?:
…the current highly elliptical orbits of Sednoids cannot be their original orbits, the chance of smaller bodies in such eccentric paths accreting into objects hundreds of kilometres across is fantastically low. Sednoids must have originally formed in relatively circular orbits, possibly in the Oort Cloud.
So how did they get where they are today? One possibility to explain their orbits is that they reflect conditions in the Solar System’s infancy, when the young Sun was in a local environment rich in nearby stars. The other possibility is one that Percival Lowell would have loved. There may be a large, rocky planet out there that has elongated previously circular orbits.
The data from the 8-meter Subaru instrument in Hawaii that produced V774104 have also yielded a number of other objects roughly 80 to 90 AU from the Sun, all of which will need lengthy follow-up study to clarify the nature of their orbits. Like V774104, any of these might join Sedna and VP113 in never coming closer to the Sun than 50 AU. We may be about to see a surge in the numbers of dwarf worlds in this unusual category. Explaining why a region once thought to be empty is not should occupy astronomers and theorists for years to come.
A Relatively Nearby Earth-Sized Planet
Given my abiding interest in red dwarf stars and the planets that circle them, I always keep an eye on what’s happening with the MEarth project. Two arrays of robotically controlled telescopes are involved in MEarth (pronounced ‘mirth’), one at the Fred Lawrence Whipple Observatory on Mt. Hopkins (AZ), the other a cluster of eight at the Cerro Tololo Inter-American Observatory in Chile. Both these arrays are controlled from MEarth’s offices in Cambridge (MA). MEarth is all about observing nearby M-dwarfs in the hunt for Earth-class planets.
My fascination in these stars is simply a result of the numbers. We’ve learned that M-dwarfs comprise as much as 80 percent of the stars in the Milky Way. Earth is not, in other words, orbiting the most common type of star out there. We also know that M-dwarfs host planets. If we learn that conditions on such worlds can support life, then we’ve dramatically expanded the search space for astrobiology. The prospect of a living world, probably tidally locked to its star, conjures images strange and wonderful, a world where shadows are permanent and half of the planet is an ice-covered waste, as Stephen Baxter recently portrayed in a planet called ‘Per Ardua’ that circles Proxima Centauri in his novel Ultima (Roc, 2015).
The latest news from MEarth comes out of MEarth-South, whose 40-centimeter instruments have detected an interesting light curve around the star GJ 1132, finding a dip of approximately 0.3 percent in the starlight. The signal, confirmed by other instruments in Chile, flags a planet that is roughly 1.2 times the size of the Earth, in a tight 1.6-day orbit. Given the star’s radius and the amount of light it blocks, researchers led by Zachory Berta-Thompson (MIT) calculate this is a planet with about 1.6 times Earth’s mass, a world that may well be rocky.
Image: In this artist’s rendering of GJ 1132b, a rocky exoplanet very similar to Earth in size and mass, circles a red dwarf star. GJ 1132b is relatively cool (about 226 degrees C) and could potentially host an atmosphere. At a distance of only 39 light-years, it will be a prime target for additional study with Hubble and future observatories like the Giant Magellan Telescope. Credit: Dana Berry.
The world is probably tidally locked. And life on GJ 1132b looks to be unlikely, given an estimated average temperature of 500 K (226 degrees Celsius). Says Berta-Thompson:
“The temperature of the planet is about as hot as your oven will go, so it’s like burnt-cookie hot. It’s too hot to be habitable — there’s no way there’s liquid water on the surface. But it is a lot cooler than the other rocky planets that we know of.”
That’s a useful fact because while surface conditions appear inimical to life, the planet is cool enough to retain a substantial atmosphere. GJ 1132 is a mere 39 light years from Earth, making it the closest Earth-sized exoplanet yet discovered. Recently we’ve been discussing the next generation of space telescopes, and now we find a world that will surely be a target for scrutiny, especially by the James Webb Space Telescope, which should be able to analyze the chemical constituents of the planet’s atmosphere and even detect the patterns of its winds.
“If we find this pretty hot planet has managed to hang onto its atmosphere over the billions of years it’s been around, that bodes well for the long-term goal of studying cooler planets that could have life,” adds Berta-Thompson. “We finally have a target to point our telescopes at, and [can] dig much deeper into the workings of a rocky exoplanet, and what makes it tick.”
Berta-Thompson points out that some 500 star systems are known to be closer to us than GJ 1132, and instruments like TESS (Transiting Exoplanet Survey Satellite) and CHEOPS (Characterizing Exoplanets Satellite), both scheduled for launch in 2017, will help us study many more targets. Learning how to analyze the atmospheres of nearby worlds is critical for our investigations into exoplanetary life. Planets like GJ 1132b will be useful in refining our tools as we begin to turn them to worlds with better prospects for living things.
The paper is Berta-Thompson et al., “A rocky planet transiting a nearby low-mass star,” Nature 527 (12 November 2015), 204-207 (abstract).
Quantifying KIC 8462852 Power Beaming
Plasma physicist James Benford, CEO of Microwave Sciences, is well known here on Centauri Dreams. Today he is joined by his son Dominic, whose work focuses on the development of ultrasensitive technologies for far-infrared through millimeter-wave astronomy. The younger Dr. Benford is Program Scientist for NASA’s WFIRST mission, which is designed to conduct major surveys in the near-infrared to answer fundamental questions on the nature of dark energy, the distribution of dark matter, the occurrence of planets around other stars, and even to enable the direct imaging of planetary systems. Previously, Dominic was Chief Scientist for the Cosmic Origins Program Office, as well as Deputy Mission Scientist for WISE, the Wide-field Infrared Survey Explorer. In today’s entry, the Benfords look at the SETI Institute’s recent observations of KIC 8462852 and analyze the detectability of power beaming at these distances.
by James and Dominic Benford
The recent report from the SETI Institute of radio observations of the anomalous star KIC 8462852 has immediate implications. That report concluded that, using the Allen Array, no narrowband radio signals were found above a few hundred Janskys in 1 Hz channels and no “wideband” signals above 100 Janskys are seen in 100 kHz channels. This is for observations taking place for 2 weeks, observing half the time. This implies about 180 hours of observations, although only about 1% of the time is spent at any individual frequency.
The purpose of the observations is to see whether the anomalous star is the site of a super-civilization that might be incidentally radiating sufficient power that we can observe, i.e., leakage radiation. They might even be intentionally producing signals for us to detect. The easiest way to do that is to ‘piggyback’, to put a message onto the power beams.
The thresholds they have reported, above which no signals are present, have implications for the presence of power beams in the anomalous star system. Beaming power on astronomical scales has been a frequent topic on this site and it has long been pointed out that the beaming of power for various purposes could be observable at astronomical distances.
The missions suggested for power beaming involve Earth-to-space applications such as launching spacecraft to orbit or raising satellites from a lower orbit to a higher one. Several workers have studied interplanetary missions, meaning space-to-space transfers of cargo. Finally, launch into the outer solar system and for interstellar precursors and ultimately for starships has also been quantified.
We have examined the thresholds in light of concepts proposed for beaming power in and around our solar system. By comparing the reported thresholds set by the SETI Institute, the non-observation of leakage signals at their stated thresholds implies the following:
- Orbit raising missions, which require lower power, are not detectable at the thresholds of the Allen Array.
- Launch from a planetary surface into orbits would be bright enough to be seen by the 100 kHz observations. However, the narrow bandwidth 1 Hz survey would not see them.
- Interplanetary transfers by beam-driven sails should be detectable in their observations, but are not seen. This is for both the narrow 1 Hz and for the “wideband” 100 kHz observations.
- Starships launched by power beams with beamwidths that we happen to fall within would be detectable, but are not seen.
These results must be qualified by noting:
- Power beaming is not an isotropic endeavor, and so the geometry of the transmitter and the intended recipient will produce a conjunction from our point of view only episodically. The observations were conducted for only a limited time and further observations would provide a more stringent constraint.
- Even the “wideband” observation is actually quite narrow compared with the kinds of sources that would be used in power beams, based on our current understanding of microwave physics. For the applications discussed here, the 100 kHz bandwidth observed would be about 10 to 100 millionths of the center frequency of the Beamer. But high-power devices are inherently not designed for such narrow bandwidths.
- The frequencies we would use for power beaming are in the millimeter band, so are outside the microwave range the Allen Array observed.
Therefore the observations by the Allen Array are not sufficiently broad to produce firm conclusions about realistic Beamers.
Readers are encouraged to consult the original paper: Harp et al., “Radio SETI Observations of the Anomalous Star KIC 8462852” (preprint). Previous discussions on this matter can be found in the following reports:
“A Path Forward for Beamed Sails”: https://centauri-dreams.org/?p=20962
“Seeing Alien Power Beaming”: https://centauri-dreams.org/?p=34133
“Microwave Beaming: A Fast Sail to Mars”: https://centauri-dreams.org/?p=1176
“The Case for Beamed Sails”: https://centauri-dreams.org/?p=20924
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