Centauri Dreams
Imagining and Planning Interstellar Exploration
A White Dwarf Proposal for Kepler
With four years of collected data at hand, Kepler scientists will remain busy even with their spacecraft hobbled. We now know that we’re not going to get Kepler back to full working order following the degradation of two of its reaction wheels, but as this report noted on August 19, possibilities remain for scientific studies using the two remaining reaction wheels aided by thrusters to control the spacecraft’s attitude. And as we’re finding out, a ‘two-wheel’ Kepler mission may still offer opportunities, one of the more fascinating of which is our subject today.
The proposed target is white dwarf stars, the remnants of stars whose mass is not high enough to produce a neutron star as they evolve past the red giant phase. A typical white dwarf has a mass similar to that of the Sun, but a volume close to that of the Earth. While Sirius B, at 8.6 light years out, is the closest known white dwarf, eight white dwarfs are believed to be present among the one hundred closest star systems to the Sun. And while we don’t normally think of white dwarfs as capable of sustaining life-bearing planets, maybe we should take another look. A new paper points out that stars like these can provide an energy source for billions of years.
Image: A white dwarf as compared with the Earth. Credit: Ohio State University/Richard Pogge.
To orbit in a white dwarf’s habitable zone requires an orbit in the range of 0.01 AU for temperatures that could support liquid water on the surface to exist. This is a habitable zone that evolves with time, starting off too hot for liquid water and eventually becoming too cold to sustain it, but surprisingly, a white dwarf planet in this kind of orbit could have a maximum of eight billion years of habitability to support whatever life might form there. Lead author Mukremin Kilic (University of Oklahoma) and team calculate an overall habitable zone extending from 0.005 AU to 0.02 AU.
Could such planets exist? Clearly, an expanding red giant will consume its inner planets before contracting into a white dwarf, so planets within 1 AU or less will presumably have to arrive after the red giant phase. But possibilities exist: We’ve found planets orbiting close to the exposed core of a red giant (KOI 55.01 and KOI 55.02) and we’ve even found planets around pulsars. There are models that produce short period planets in billion-year timescales that seem to be applicable to white dwarfs, with planet formation from nearby gas being one scenario and the capture or migration of planets from much further out in the system being another.
Add delivery of water through cometary impacts and the presence of a habitable world in either scenario seems a bit less unlikely. We can also throw into the mix the fact that 30 percent of the white dwarfs near the Sun show metal-polluted atmospheres perhaps caused by the accretion of rocky debris. Indeed, some 4.3 percent have known debris disks, the latter a demonstration that interactions within the system can send asteroids, moons or small planets close to the white dwarf. But if short-period planets around these stars do exist, we have yet to find them, a fact the paper attributes to our lack of observational data for a sufficient number of stars.
Kilic and team argue that Kepler in its two-wheel mode offers an opportunity to run the kind of survey that would find the first exoplanets in a white dwarf habitable zone. From the paper:
If the history of exoplanet science has taught us anything, it is that planets are ubiquitous and they exist in the most unusual places, including very close to their host stars and even around pulsars (Wolszczan & Frail 1992). Currently there are no known planets around WDs, but we have never looked at a su?cient number of WDs at high cadence to ?nd them through transit observations. It is essentially impossible to ?nd Earth-Jupiter size planets around WDs by any other method (Gould & Kilic 2008). If habitable planets exist around WDs, the proposed Kepler imaging survey will ?nd them.
The proposed survey would require 200 total days of observing time examining 10000 white dwarfs in the Sloan Digital Sky Survey imaging area, the great benefit being that Kepler’s wide field of view would allow a large number of white dwarfs to be observed at the same time. The researchers believe up to 100 planets will be identified in the habitable zone, an extension of the Kepler planet-hunting charter extended to a new set of targets. The paper continues:
Biomarkers, including O2, on such planets can be detected with the JWST [James Webb Space Telescope]. Hence, even though this is a completely unexplored search area for transiting planets, the scienti?c yield of the proposed survey will be enormous.
Exactly so. Remember this about white dwarfs as transit targets. The stars are about the same size as the Earth, so Earth-sized and smaller planets should be easy to detect as they pass in front of the primary. And once a planet in the habitable zone has been identified, the high contrast ratio between the planet and the host white dwarf means that future telescopes should be able to run the biomarker searches mentioned above. Is it possible that the first evidence of life on an exoplanet may come not from a G- or even an M-class system, but a white dwarf?
The paper is Kilic et al., “Habitable Planets Around White Dwarfs: an Alternate Mission for the Kepler Spacecraft,” a Kepler white paper available as a preprint. For more on white dwarf planets, see Habitable Worlds around White Dwarf Stars. Thanks to Antonio Tavani for the pointer to this work.
Thoughts on Ceres (and Memories of Pohl)
Working on this entry last night, I found my thoughts turning inescapably to Frederick Pohl, the iconic science fiction writer and editor whose death was announced just hours ago. Most Centauri Dreams readers doubtless have their memories of Pohl’s work, perhaps from the great novels of the 1950s like The Space Merchants and Gladiator-at-Law or the striking Gateway of the late 1970’s that would spawn the Heechee series. As something of a bibliographer, I’m also fascinated with Pohl’s role as a youthful magazine editor. He was editing Astonishing Stories for the pulp house Popular Publications at the age of 20, an occupation that would deepen into lengthy runs at Galaxy and IF and later stints editing books for Bantam.
Pohl’s early days in science fiction are captured memorably in The Way the Future Was, a 1978 reminiscence that had me digging through my collection of old pulps to look up issues he had edited. Astonishing was always a favorite of mine, but I was surprised to realize how fond he must have been of Super Science Stories, which he oversaw from 1939 to 1943. In fact, one of Pohl’s last blog entries this July was an exhortation to bring back Super Science Stories in a new format, basing it on reprints much like the late Famous Fantastic Mysteries created by the Munsey group in the 1940s.
“I know I shouldn’t give it a thought, but if an offer got real, how could I say no?” Pohl wrote, not six weeks before his death. I would have loved to have seen that revived magazine in his hands.
But back to business. I learned of Pohl’s death while drawing up some notes on the asteroid belt, with which Pohl will always be associated in my mind because of the Heechee novels, in which some asteroids turn out to have been the site of an incomprehensible alien technology. The juxtaposition seemed utterly appropriate, for I remember reading Gateway in 1980 and thinking that Pohl had deftly sidestepped the interstellar propulsion conundrum. Rather than spending centuries developing the technologies to make a star mission happen, maybe we just run across an artifact that does things we can’t explain and makes such journeys possible. A thousand starships are at Gateway for the asking, though how they work is a mystery. I wouldn’t dream of throwing in any spoilers here, so you’ll have to go to the novels for more.
Ceres Inside and Out
What a grand notion the Heechee novels represented. It’s a shame Pohl won’t be here two years from now when the Dawn mission finally reaches the dwarf planet Ceres, which may hold a few surprises of its own. Orbiting in the main asteroid belt between Mars and Jupiter, Ceres is nonetheless much closer in composition to Jupiter’s moon Europa than to the rocky debris around it, particularly from the standpoint of astrobiology. Is it in fact a closer, easier Europa? This article in Astrobiology Magazine offers some thoughts on what Dawn mission science team liaison Britney Schmidt calls “a game changer in the Solar System.”
The change in nomenclature from asteroid to dwarf planet is indicative of the changes in our view of this object over the decades. When astronomer Giuseppe Piazzi discovered it in 1801, the object seemed inevitable, for as early as 1596 Johannes Kepler had noted the gap between Mars and Jupiter, and Johann Bode would later point to the probability of finding a planet there. The hypothesis of a pattern in planetary orbits like this has now been discredited, but the discovery of Uranus in 1781 seemed to confirm it and Ceres would be found shortly thereafter. As more and more asteroids began to be discovered and the true size of Ceres was realized, it lost the planetary status it had been assigned for almost half a century in astronomy books.
There’s no need to go back into the 2006 debate about what constitutes a planet other than to say that Ceres has now emerged as a ‘dwarf planet,’ joining Eris, Haumea, Makemake and Pluto in the designation. Confusingly enough, Ceres is still referred to as an asteroid in many quarters, though its unique status is conveyed in its round shape, an indication of formation in the early Solar System. The wild card, of course, is that there is the potential for a layer of water ice under the surface. Twice the size of Enceladus, Ceres is less than three times as far from the Sun as the Earth, making it a tempting target for studying water’s history as our system evolved.
Given the surface of objects like our own Moon, we can assume that Ceres has withstood its share of impact events in the early days of the Solar System, but an icy surface could have simply erased the evidence. Spectral evidence is also informative. From the article:
“The spectrum is telling you that water has been involved in the creation of materials on the surface,” Schmidt said.
The spectrum indicates that water is bound up in the material on the surface of Ceres, forming a clay. Schmidt compared it to the recent talk of minerals found by NASA’s Curiosity on the surface of Mars.
“[Water is] literally bathing the surface of Ceres,” she said.
In addition, astronomers have found evidence of carbonates, minerals that form in a process involving water and heat. Carbonates are often produced by living processes.
The original material formed with Ceres has mixed with impacting material over the last 4.5 billion years, creating what Schmidt calls “this mixture of water-rich materials that we find on habitable planets like the Earth and potentially habitable planets like Mars.”
I think Schmidt makes a good point, too, in going on to argue that Ceres may be just as interesting as more distant moons like Europa and Enceladus. For one thing, while Europa taps tidal interactions with Jupiter as a source of heat, Ceres draws on the Sun. For another, it’s considerably warmer than Europa, and unlike the latter, is not bathed in Jupiter’s deadly bands of radiation. Orbital or lander operations on Ceres should pose fewer challenges than Europa. What sets Europa apart, though, is the probability of a liquid ocean, while Ceres’ water is most likely in the form of water ice located in the mantle that wraps around its solid core.
Image: Scientists using the Hubble Space Telescope found Ceres was more like a planet than an asteroid — information that eventually led to a change in its categorization from asteroid to dwarf planet. Ceres’ mantle, which wraps around the asteroid’s core, may even be composed of water ice. The observations by NASA’s Hubble Space Telescope also show that the asteroid has a nearly round shape like Earth’s and may have a rocky inner core and a thin, dusty outer crust. Credit: NASA/ESA/SWRI/Cornell University/University of Maryland/STSci.
I’ll return to the science fiction theme by mentioning that Larry Niven’s Known Space stories posit an asteroidal government based on Ceres, while the dwarf planet also appears in various roles in the hands of writers from Alfred Bester to Robert Heinlein and, in recent days, James S. A. Corey. The Dawn mission will presumably not find any Pohl-style gateways among the asteroids, but what an opportunity Ceres presents. In 2015, five months of Dawn’s orbital operations there will turn a fuzzy image into sharply resolved surface features in the same year that New Horizons does the same for Pluto/Charon. Ceres may reshuffle our thinking if we learn that it once had the potential for habitability. What we won’t have, alas, is Frederick Pohl’s fictional take on what a human mission to Ceres might look like and the wonders it might find.
Upcoming Interstellar Events
The quickening pace of interstellar conferences in the past couple of years has been an encouraging surprise. If one necessary goal is to energize the public about the human future in space, then these meetings and their media coverage are surely part of the picture. I’m thinking about adding a calendar feature for conferences and other interstellar events to Centauri Dreams. Until then, here are some upcoming items, presented in chronological order.
“The Starships ARE Coming”
Peter Schwartz, writer, futurist and co-founder of the Global Business Network, will present a talk about starships and the scenarios that could lead to them on September 17th at 7:30 in San Francisco. Coordinated by the Long Now Foundation, the talk will track Schwartz’ presentation at the recent Starship Century conference in San Diego. From the Long Now site:
Participants included scientists such as Freeman Dyson and Martin Rees and writers such as Gregory Benford and Neal Stephenson. The professional futurist in the group was Peter Schwartz, who contributed scenarios playing out four futures of starship ambitions. To his surprise, exploring the scenarios suggested that getting effective star travel over the coming century or two is not a long shot. Even by widely divergent paths, it looks like a near certainty.
Schwartz’ talk “The Starships ARE Coming” will be presented at the SF Jazz Center in San Francisco. For more, click here.
100 Year Starship 2013 Public Symposium
The Orlando conference that kicked off the DARPA solicitation in 2011 is fondly remembered for its scope and depth, not to mention its sheer size. Now that the Dorothy Jemison Foundation for Excellence has formed the 100 Year Starship organization, we’ve had last year’s conference in Houston and anticipate an upcoming event in the same city. From the symposium website:
Across the globe, calls are being made for bolder human expansion into space beyond earth orbit. Achieving the interstellar journey in many ways must build upon, promote and establish fundamental research, technology development, societal systems and capacities that facilitate ready access to our inner solar system and which will leave an indelible mark upon life on earth. 100YSS is working to create new avenues to foster such innovative, robust collaborative, Transdisciplinary research, project design and technological development. The 100YSS 2013 Public Symposium—Pathway to the Stars, Footprints on Earth—seeks to highlight both the small incremental steps and radical leaps required to make significant progress on the way to interstellar space.
The 2013 Public Symposium runs from September 19-22 at the Hyatt Regency Downtown Houston. For details and registration, go here.
Conversation with Gregory Benford
Physicist and science fiction writer Gregory Benford will appear at the Crawford Family Forum for a public conversation with KPCC’s Mat Kaplan, host of a science series called “NEXT: People | Science | Tomorrow.” Kaplan is also a host for the Planetary Society’s Planetary Radio. From the KPCC website:
Our ancestors gazed at a night sky filled from horizon to horizon with brilliant stars. Were they dreaming of reaching for the cosmos even before they were fully human? Regrettably, interstellar voyages with today’s technology would take thousands or even tens of thousands of years. We’re not there yet, but some of the smartest people on our planet are working on ways we can conquer the final frontier. Propulsion by energy beam, warp drive and other technologies are being researched with encouragement from NASA and other organizations.
“NEXT: Is This the Starship Century?” will take place on Wednesday September 25 from 7:00 to 8:30. For more information, click here. The Crawford Family Forum is at 474 South Raymond Avenue, Pasadena, CA 91105.
Second Starship Century Symposium in London
The second Starship Century Symposium will be held Monday October 21 at the Royal Astronomical Society on Piccadilly in London, with Royal Astronomer Martin Rees as a featured speaker. Including talks and a panel, the event will feature both James and Gregory Benford, editors of the recently published Starship Century anthology, which will be sold on the premises (proceeds going toward interstellar research). I should also mention that those of you who have asked about ebook editions of Starship Century can now find it online with color illustrations at Amazon, Smashwords and Barnes & Noble. Admission to the symposium is free.
The schedule for this event is still being firmed up, but speakers will include astronomer Ian Crawford and Stephen Baxter (tentative), with a starting time of 10:00 AM.
Gravity Design Challenge
And although it’s not interstellar in nature, I do want to mention a competition of the sort I hope we’ll see more of in relation to space themes. Science education non-profit Iridescent is partnering with Warner Bros. Pictures in what is called the Gravity Design Challenge, based on the upcoming George Clooney/Sandra Bullock film Gravity. The film, due out in October, is a survival tale set in low-Earth orbit. Iridescent is hosting the Gravity Design Challenge on Curiosity Machine, its online science studio. The idea is that teenagers will work with their parents to create what Iridescent calls a ‘Rube Goldberg Machine rocket’ that simulates a space mission.
The month long contest is ongoing and ends September 10. The grand prize winner receives a trip to New York and four tickets to the premiere of Gravity. From an Iridescent news release:
Volunteer mentors, including professional engineers, faculty and students from a variety of organizations, including Boeing, Columbia University, Stanford University, UC Berkeley, USC, and University of San Francisco, will provide feedback to Gravity Design Challenge participants through the submission period. A panel of experts from the astrophysics field will judge the final entries.
The idea of leveraging popular entertainment in the direction of science education is one that could prove fruitful as a way of nudging young minds toward careers in aerospace, just as science fiction itself does. There are all kinds of creative ways this might be accomplished on the Net, and we’ll see whether future media events can tap into a similar educational impulse.
Existential Risk and Far Future Civilization
How do we ensure the survival of our civilization over future millennia? Yesterday Heath Rezabek discussed installations called Vessels that would contain both archives and habitats to offset existential risk. Today Rezabek’s collaborator, author Nick Nielsen, broadens the view with an examination of risk itself and three possible responses for protecting our culture. Nick is the author of two books, The Political Economy of Globalization (Palgrave Macmillan, 2000) and Variations on the Theme of Life (Trafford, 2007). In addition to his recent talk at Starship Congress in Dallas, he presented “The Moral Imperative of Human Spaceflight” in 2011 at the 100 Year Starship Symposium in Orlando, and “The Large Scale Structure of Spacefaring Civilization” at the 2012 100YSS conference. In addition, he authors two blogs: Grand Strategy: The View from Oregon and Grand Strategy Annex, focusing on the future of civilization and the philosophical implications of contemporary events. Mr. Nielsen is a contributing analyst with Wikistrat, an online strategic consulting firm.
by J. N. Nielsen
To see our world as a pale blue dot barely visible in the vastness of space graphically shows Earth’s place in the universe, and if we could continue to expand our scope for several more orders of magnitude while remaining focused on our pale blue dot, we would perceive our Earth in the full magnitude of its cosmological context. Just as Earth is placed in cosmological context in its appearance as a pale blue dot, we must similarly place earth-originating life, intelligence, and civilization in its cosmological context, and we can do so by way of astrobiology. Astrobiology can be considered an extrapolation and extension of terrestrial biology, or as biology in a cosmological context.
There are many definitions of astrobiology, some quite detailed and others quite concise. The NASA strategic plan of 1996 (quoted in Steven J. Dick and James E. Strick, The Living Universe: NASA and the Development of Astrobiology, 2005) gives this definition of astrobiology:
“The study of the living universe. This field provides a scientific foundation for a multidisciplinary study of (1) the origin and distribution of life in the universe, (2) an understanding of the role of gravity in living systems, and (3) the study of the Earth’s atmospheres and ecosystems.”
The NASA astrobiology website characterizes astrobiology as follows:
“Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This multidisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry and life on Mars and other bodies in our Solar System, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in space.”
More briefly, astrobiology has been called, “The study of life in space” (Mix, Life in Space: Astrobiology for Everyone, 2009) and that, “Astrobiology… removes the distinction between life on our planet and life elsewhere.” (Plaxco and Gross, Astrobiology: A Brief Introduction, 2006). Taking these sententious formulations of astrobiology as the study of life in space, which removes the distinction between life on our planet and life elsewhere, gives us a new perspective with which to view life on Earth.
With earth-originating life, intelligence, and civilization placed in cosmological context, we ourselves and our civilization can be understood in terms of the Fermi paradox. Fermi asked, if the universe is filled with life, “Where is everybody?” The universe is billions of years old, demonstrably compatible with the existence of intelligent life, and yet we find no evidence of highly advanced civilizations. The paradox has only been sharpened by recent scientific discoveries of exoplanets, including small, rocky planets in the habitable zones of stars, some of them relatively nearby in cosmological terms.
Once we remove the distinction between life on earth and life elsewhere we see that the idea of an “alien” is an anthropocentric concept, and a Copernican conception such as astrobiology must do away with the idea of “aliens” as constituting all life other than earth-originating life. So when we ask, “Where are all the aliens?” We must answer, “Right here, on earth; we are the aliens.”
A conception of intelligence and civilization as comprehensive as astrobiology would place these phenomena in cosmological context, and drawing on the insights of astrobiology we can see that an anthropocentric conception of alien intelligence as all intelligence other than earth-originating intelligence limits our conception of intelligence, as an anthropocentric conception of alien civilization as all civilization other than earth-originating civilization limits our conception of civilization. A Copernican conception will be concerned with the fate of life, intelligence, and civilization as such, but we must also acknowledge that we are all that is known so far of life as such, uncopernican though that sounds.
We are the only known “aliens” to pass through the Great Filter – which is what we call whatever it is that has filtered out other possible civilizations in the universe and left us only with our own civilization on Earth – and the development of astrobiology has directed our attention to the many near disasters we have experienced in the past – disasters that have shaped the surface of our planet and the history of life on Earth. The emergence of a single hominid species from several branches of hominid evolution makes homo sapiens a kind of existential choke point or bottleneck in the history of intelligent life, so that there is a sense in which we are the great filter. And this life, which is itself a marvelous and meaningless accident of the cosmos, is vulnerable at any moment to being annihilated by another meaningless accident of the cosmos.
Through the ages of cosmological and geological time our homeworld has been subject to massive volcanism, asteroid impacts, solar flares, gamma ray bursts, and the extensive glaciation that characterizes the present Quaternary glaciation, with its warmer inter-glacial periods such as the Holocene, during which the whole of human civilization has emerged. These natural forces of the Earth, the solar system, and the cosmos at large have shaped terrestrial life, humanity, and human civilization; we have been hammered on the anvil of a violent and dynamic universe. And we have survived thus far, but our survival is not guaranteed.
Earth-originating life has now given rise to industrial-technological civilization, which continues in its development to this day. What follows planet-bound industrial-technological civilization is the process of extraterrestrialization – the movement of the infrastructure of terrestrial civilization off the surface of the Earth and into space – which places earth-originating civilization in cosmological context, just as the pale blue dot places Earth in cosmological context and astrobiology places life in cosmological context. The process of extraterrestrialization, should it come to pass, furnishes us with a more comprehensive conception of civilization that begins to transcend our anthropic bias.
The resources of industrial-technological civilization hold the promise that life, intelligence, and civilization can spread beyond our terrestrial homeworld. Each stage in the development of a civilization capable of harnessing the energy resources required to expand beyond exclusively planet-bound conditions represents passing through further layers of the Great Filter. The gravitational thresholds of our home world, our local solar system, our local galaxy, and our local universe are each of them existential risks and existential opportunities for the future development of earth-originating life, intelligence, and civilization. With the passage beyond one gravitational threshold to another, existential risk is mitigated but not eliminated; the mitigation of one level of existential risk means ascending to a more comprehensive level of existential risk.
The technology that our civilization develops will influence the structure of extraterrestrialized civilization. If the settlement of the universe is parallel to the settlement of our planet, each gravitational threshold will first be passed by an initial slow wave, only to much later be filled in by faster waves of expansion resulting from later, higher technology. But in the event of a disruptive technological breakthrough, as, for example, any of the technologies based on the Alcubierre drive concept, there could be an initial fast wave of expansion only later filled in by slower and more thorough later waves filling in the gaps.
Given extraterrestrialized civilization in its cosmological context, we can approach existential risk mitigation through three principles: knowledge, which transforms unknown uncertainties into quantifiable risks that admit of calculation and mitigation, redundancy, which means multiple self-sufficient centers for Earth-originating intelligent life, and autonomy, which assures the independence of each self-sufficient center to seek its own strategies for survival.
What does knowledge have to do with risk? Following economist Frank Knight, what we call Knightian risk distinguishes between predictability, risk, and uncertainty, with predictability implying total knowledge, risk implying partial knowledge, and uncertainty implying the absence of knowledge. These are simplified and idealized categories; no risk is entirely free of uncertainty, and even uncertainty must lie within what is possible within our universe, and in that sense is predictable. But Knightian risk offers a framework to think about the dynamic nature of risk, which changes over time. The growth of knowledge moves the boundary of risk outward, meaning less uncertainty and more predictability.
For example, even if we have done very little in the past forty years in terms of human space exploration and extraterrestrial settlement, and we are still accessing earth orbit with disposable chemical rockets, space science has made enormous progress during this period of time, and this knowledge has transformed our understanding of our universe and our place within it. This growth of our knowledge of the universe has made the universe a little less uncertain and a little more predictable for us, suggesting clear paths for the management and mitigation of existential risk.
Knowledge alone is not enough. Without redundancy of earth-originating life, intelligence, and civilization we still face the possibility of a terrestrial single-point failure. Existential risk mitigation ultimately means multiple self-sufficient centers for Earth-originating intelligent life. These distinct centers of earth-originating life, intelligence, and civilization will be subject to distinct risks and distinct opportunities, and these distinct populations of Earth-originating life, intelligence, and civilization will be subject to distinct selection pressures, so that they will evolve into unique forms.
Knowledge of risks and redundant centers of earth-originating life together are not yet enough to secure on the long-term viability of Earth-originating life, intelligence, and civilization. Redundancy without diversity incurs the risk of homogeneity and monoculture. Existential risk mitigation also points to the necessity of the independence of each self-sufficient center to seek its own strategies of survival. The mutual independence of self-sufficient centers means the possibility of continued social and technological experimentation, which will in turn lead to the realization of distinct forms of civilization.
Autonomy seems like a simple enough condition, but it may be more difficult to achieve than we suppose. If we look around the planet today, with all its ethnic and cultural diversity, we see that there is, for all practical purposes, only one viable form of political organization – the nation-state – and again, for all practical purposes, only one viable form of civilization – industrial-technological civilization. We need to proactively seek to transcend social and technological monoculture to arrive at a civilizational pluralism from which social and technological experimentation flows naturally.
Taking existential risk seriously means that certain moral imperatives follow from this perspective, but who would possibly object to preventing human extinction? Of course, it is not as simple as that. It might be more difficult than we suppose to define human extinction, because to do so we would need to agree upon what constitutes human viability in the long term. Additionally, there are vastly different conceptions of what constitutes a viable civilization and of what constitutes the good for civilization. What is stagnation? What is flawed realization? What exactly is subsequent ruination, when achievement is followed by failure? What constitutes a civilizational failure? What exactly would constitute the “drastic failure of… life to realise its potential for desirable development”? What is human potential? Does it include transhumanism? For some, transhumanism is a moral horror, and a future of transhumanism would be a paradigm case of flawed realization, while for others a human future without transhumanism would constitute permanent stagnation. These are difficult questions that cannot be wished away; to pretend that they are not contentious is to fail to do justice to the complexity of the human condition.
These different conceptions of human potential and desirable outcomes for civilization will issue in different ideals, different aspirations, and different actions, but if we can continue to increase knowledge, establish redundancy and assure autonomy there is reason to hope that existential catastrophe can be avoided and an OK outcome realized, which is the point of what Nick Bostrom calls the maxipok rule – maximizing the probability of an OK outcome, where an OK outcome is defined as an outcome that avoids existential catastrophe.
If we do nothing, we will have on our conscience the extinction of all earth-originating life, intelligence and civilization. In the long term, our survival is only to be had through the extraterrestrialization of our civilization. But survival is not salvation. Survival often simply means that we will have the opportunity to go on to make later mistakes on a larger scale, which constitutes an OK outcome that is better than the alternative.
Deep Time: The Nature of Existential Risk
At the recent Starship Congress in Dallas, writer, librarian and futurist Heath Rezabek discussed the Vessel Archives proposal — a strategy for sustaining and conveying Earth’s cultural and biological heritage — which was directly inspired by Gregory Benford’s idea of a Library of Life. Working with author Nick Nielsen, Rezabek is concerned with existential risk — Xrisk — and the need to ensure the survival of our species and its creations in the event of catastrophe. Rezabek and Nielsen’s presentation was the runner up for the Alpha Centauri Prize awarded at the Congress, and it was so compelling that I asked the two authors to offer a version of it on Centauri Dreams. Heath’s work follows below, while we’ll look at Nick’s in tomorrow’s post. Both writers will be returning on a regular basis for updates and further thoughts on their work.
by Heath Rezabek
Some challenges are too daunting to approach alone.
Existential risk is certainly one; bringing a comprehensive strategy to a room full of seasoned interstellar advocates is another. Collaboration can sometimes be a greater challenge than solo work, but often it yields rewards far greater than the sum of their parts. I met Nick Nielsen through his asking an audience question of me, after my first presentation of the Vessel proposal at the 100 Year Starship Symposium in September 2012. My work with Nick has been a continuing process of encountering unexpected ideas in unexpected combinations, and this collaboration led us to propose and present a combined session on our work since 2012: ‘Xrisk 101: Existential Risk for Interstellar Advocates’, at the first Starship Congress, organized by Icarus Interstellar, in August 2013.
I have felt the importance of answering the challenge of existential risk (put simply, risks to our existence) since the moment my own sense of this subject achieved critical mass and began drawing all other related ideas into its orbit — which I can, amazingly, pin to the reading of a key article in io9 on June 18 of 2012. This reading began a process of nearly frenzied integration and streamlining, which culminated in a draft proposal for very long term archives and habitats as a means of mitigating long term risk, presented at 100YSS 2012. My preprint of that first, sprawling, 52 page paper emerged from a month of intense creation. It is still available on figshare.
I call these proposed installations Vessels. While this is a discussion for later, I deliberately invoke that term as the best and most descriptive one available, for something which includes all senses of the word that I can find: not only the sense of a craft, but of a receptacle, a conduit, a medium. If an eventual interstellar vessel does not contain a Vessel, then it may be incomplete.
I had no idea, going into 100YSS 2012, whether this proposal had any merit or use whatsoever. Being a librarian by career and calling, it certainly felt right, as the first and last and best I could do. Yet meeting Nick Nielsen was pivotal: his patient unpacking of the implications of mitigating Xrisk for the future of civilization has been crucial to my own optimism over humanity’s prospects, should we fulfill our full potential.
Offered here is a post which casts our Starship Congress 2013 session into blog format. The content can be found in much the same form in our video and slides, but I still encourage you to view them both if you connect with any of these ideas whatsoever. For links to video and slides, go to http://labs.vessel.cc/.
Though the concept stands for risks to our very existence, existential risk or Xrisk is far from intractable or imponderable. Because of the subtypes described in our session below (Permanent Stagnation and Flawed Realization), we can do much to improve the prospects for Earth-originating intelligent life tomorrow by working to improve its prospects today.
This begins with directly mitigating the extinction risks that we can, and with safeguarding — to the best of our abilities — our scientific, cultural, and biological record so that future recoveries are possible if needed; and the Vessel proposal attempts a unified approach to this work.
“Build as if your ancestors crossed over your bridges.”
— Proverbial
Xrisk 101: Existential Risk for Interstellar Advocates (Part 1)
(Xrisk 101) is divided into two parts. In the first, I will cover the fundamentals of Xrisk, and update on the Vessel project, a framework for preserving the cultural, scientific, and biological record. In the second, Nick Nielsen will explore the longer term implications of overcoming Xrisk for the future of civilization.
Though discussed in other terms, Xrisk was a key concern and priority for the DARPA 2011 starship workshop. In its January 2011 report, that workshop prioritized “creating a legacy for the human species, backing up the Earth’s biosphere, and enabling long-term survival in the face of catastrophic disasters on Earth.” [1]
At the 100YSS 2012 Symposium, I presented a synthesis of strategies to address all three of these goals at once, called Vessel. Before updating on the Vessel project, I want to talk first about Existential Risk, what it includes, and why we should prioritize finding ways to meet its challenge.
Existential Risk denotes, simply enough, risks to our existence. Existential Risk encompasses both Extinction Risk and Global Catastrophic Risk.
Nick Bostrom, Director for the Future of Humanity Institute, defines Existential Risk this way in a key paper we’ll cover throughout, Existential Risk Prevention as Global Priority : “An existential risk is one that threatens the premature extinction of Earth-originating intelligent life, or the permanent and drastic destruction of its potential for desirable future development.” [2] In an array of possible risks presented in the paper, small personal risks are down in the lower left, while situations of widespread suffering such as global tyranny are in the middle as Global Catastrophic Risks. Finally, the destruction of life’s long term potential defines Existential Risk, in the upper right.
Xrisk has become a popular shorthand for this whole spectrum of risks. We can see signs of it emerging as a priority for various space-related efforts. One of the most popular images of Xrisk today is that of a sterilizing asteroid strike. And asteroids play a big role in some of the most visible efforts in space industry today, such as the ARKYD telescope or NASA’s asteroid initiative. Specialists sometimes see unpredicted cultural or technological Xrisks as even more urgent.
Starship Congress had its eye on some pretty long-term goals, and Earth provides our only space and time to work towards them. On that basis alone, the challenge of Xrisk must be answered.
But setting aside our own goals, what are the stakes? How many lives have there been, or could yet be if extinction is avoided? Nick Bostrom has run some interesting numbers.
“To calculate the loss associated with an existential catastrophe, we must consider how much value would come to exist in its absence. It turns out that the ultimate potential for Earth-originating intelligent life is literally astronomical.” [2]
How so? First we need a standard for measurement. Let’s start with the total number of humans ever to have lived on Earth. Wolfram Alpha lists the total world population as 107.6 billion people over time. The current global population is 7.13 billion. If we leave out the current population, we get 100 billion — About the number of neurons in a single human brain.
100 billion lives.
One Pale Blue Dot.
Here’s an excerpt of Carl Sagan’s thoughts on that famous image of Earth from afar:
Consider again that dot.
That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
In … all this vastness … there is no hint that help will come from elsewhere to save us from ourselves. The Earth is the only world known, so far, to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment, the Earth is where we make our stand.
100 billion lives is our basic unit of measure.
Now; How much value would come to exist if our future potential is never cut short?
1016 — 10 million billion — is one estimate of the potential number of future lives on Earth alone, if only 1 billion lived on it sustainably for the 1 billion years it’s projected to remain habitable.
But if we consider the possibility of the spread of life beyond Earth, or synthetic minds and lives yet to come, Bostrom’s estimate [2] grows vast:
1052 potential lives to come. 100 million x 100 billion x 100 billion x 100 billion x 100 billion
This means that reducing the chances of Xrisk by a mere 1 billionth of 1 billionth of 1 percent…
is worth 100 billion billion lives.
With just a slight shift in priorities, we can hugely boost the chances of life achieving its full future potential by working to enhance its prospects today.
Let’s look at Bostrom’s definition again: “An existential risk is one that threatens the premature extinction of Earth-originating intelligent life, or the permanent and drastic destruction of its potential for desirable future development.”
Notice that fragment – “… destruction of its potential for desirable future development.” Survival alone is not enough. In some cases, a surviving society may be brutalized, stagnant, or diminished irreparably, unable to aspire or to build itself anew. This brings us to two subtypes of Xrisk as crucial as extinction itself, and both fall into the realm of Global Catastrophic Risks.
- Permanent Stagnation – Humanity survives but never reaches technological maturity or interstellar civilization.
- Flawed Realization – Humanity reaches technological maturity but in a way that is irredeemably flawed.
Pop culture has a working knowledge of them both, in different terms. Nick and I joke that it’s a bit like: Zombies vs Vampires.
Permanent Stagnation and Flawed Realization. Losing our capability as a civilization, or enduring only in a deeply flawed form. These two risks fill our dystopian movies. But because popular culture understands them, we can learn valuable lessons about our messaging and priorities by understanding them too.
These two types of Xrisk cut to the heart of what it means to achieve our full potential. There is a vast opportunity between these risks, because of the many advances needed to achieve an interstellar future – and because of the benefits such advances could have for life on Earth — in areas such as habitat design, energy infrastructure, biotechnology, as well as advanced computing, networking, and archival.
If we work to prototype here and now, solving real-world problems along the way, all will benefit. If we make advances open and adaptable to humanity’s best minds, we will gain allies in our effort to uplift Earth and thrive beyond it. Perhaps advanced, resilient technologies could carry a seal standing for the dual design goals of uplifting life on Earth while advancing our reach towards the stars. Like LEED certification for an infinite future. What would such projects be like?
Last year, I proposed the Vessel project as a means to safeguard cultural potential on Earth and beyond. I’ll close with a brief update on this approach to advanced computing, compact habitat design, and long-term archival. With deep appreciation to Paul, I’ll continue in future guest entries by updating on the progress of the Vessel project, as I’ve continued to connect with interested specialists in several areas crucial to its implementation as a concrete strategy for Xrisk mitigation.
Image: Vessel Installation Symbol.
Vessel, as a design solution, begins with a simple premise: Capability lost before advanced goals are reached will be very difficult to recover, without a means of setting a baseline for civilization’s capabilities.
A Vessel is an installation, facility, or habitat that serves as a reservoir for Earth’s biological, scientific, and cultural record. Into a Vessel is poured what must be remembered for humanity’s potential to be maintained. On Earth or beyond, a Vessel habitat is designed to carry forth the sum of all we’ve been. In 2012, Vessel was pictured as the Lilypad seasteading habitat.
But different Vessels would have different designs based on their needs and settings. These traits remain key in each case:
At a Vessel’s core would lie biological archives, meant to preserve key traces of Earth’s biodiversity. Here the primary model is Gregory Benford’s groundbreaking 1992 Library of Life proposal. Benford details a program for freezing and preservation of endangered biomass for possible future recovery. [4]
Also crucial would be core archives for cultural and scientific knowledge, both physical and digital. I’m working with Icarus Interstellar to make sure the Vessel framework is compatible with Icarus projects. Several examples exist of information storage technologies engineered to endure the passage of time, such as the digital DNA encoding strategies of George Church’s team as well as Ewan Birney and Nick Goldman’s approach, the fused quartz technologies of Hitachi or Jingyu Zhang, and the Rosetta Disk project of the Long Now Foundation, which is the first deliverable for their Library of the Long Now. As yet I have not seen it proposed that such initiatives could or should be brought together in the service of a unified goal or project. Throughout 2014, I will be surveying these proposed strategies, as well as interviewing (when possible) their inventors and project leads on potential implementations.
Surrounding these archives would be Research Labs, where specialists could collaborate on advanced technologies, seeking critical paths which avoid and mitigate Xrisk. Or, in a time of recovery, sealed labs could be the birthplace of new beginnings. Research Labs would open inwards to draw upon the Core Cache. Experts in their relevant fields could be both stewards and users of the core archives.
But in the near term, through an outer ring of Learning Labs, Vessel facilities could welcome the curious, and give visitors an inspiring glimpse at advanced studies. Immersive labs could be catalysts for change, helping people understand the arc of history in nature, culture and science, the common risks ahead, and the limitless possibilities if Earth achieves its full potential. This function, familiar in one form to any who have visited a nature & science museum and seen paleontologists at work, hints at a pathway towards actual present-day implementations of the Vessel project as popular, well-attended, comprehensive exhibitions for a public trying to make sense of the patterns of our present day.
Built around these three roles — of Learning, Research, and Archival — the Vessel framework is designed to adapt to any setting or situation. What all Vessels would have in common is a dedication to preserving cultural capability, and a layered, approachable presence adapted to its setting. Many should be built, using many approaches. Some could be public, while mission critical Vessels may be as remote as the Svalbard Seed Vault, or even secret.
Some may be massive as habitats, with others more like sculptures, compact and dense as a room. At the recent Starship Century conference in May, Freeman Dyson envisioned terrarium-like habitats which could seed the vast reaches of space with life. This egg-like approach is hugely inspiring to ponder from the perspective of the Vessel project. Whether urban or remote, extreme habitats or modules on a starship, Vessel is offered as a flexible framework for the long term survival of life’s capabilities.
The Vessel project has several routes forwards. Plans for 2014 include the previously mentioned global survey of existing long-term archival projects, an open design document to help others adapt and evolve the Vessel framework (on which I am already working with a small team of interested artists and specialists), and a Kickstarter for a Vessel- related art project. And, at the invitation of Paul Gilster, we can add to these plans our regular updates on the Vessel project’s progress to the readers of Centauri Dreams. While I explore the nuts and bolts of Vessel’s critical path to an implementation, Nick will help deepen our grasp of the long term potential for a civilization that has chosen to mitigate Xrisk.
Right before Starship Congress, I began an Internship with the Long Now Foundation, working on a project called the Manual for Civilization (See here and here). As the first core collection for their planned Library of the Long Now, a 10,000 year archive, this work will overlap deeply with the Vessel project. So, my own timeline for Vessel is in flux. But if you’d like to collaborate, discuss ways of applying Xrisk mitigation to your own work, or want to help accelerate these efforts, please get in touch. You can register for updates on the Vessel project at vessel.cc.launchrock.com.
And, you can ask questions in the comments; both I and Nick will do our best to answer.
Our discussion of Xrisk continues tomorrow with Nick Nielsen.
——-
[1] 100 Year Starship. 2011. “The 100-Year Starship Study: Strategy Planning Workshop Synthesis & Discussions” (http://100yearstarshipstudy.com/100YSS_January_Synopsis.pdf). Accessed August 2012.
[2] Bostrom, N. “Existential Risk Reduction as Global Priority” (http://www.existential-risk.org/concept.pdf). Accessed August 2013.
[3] Sagan, C. Pale Blue Dot: A Vision of the Human Future in Space (Random House, 1997).
[4] Benford, G. “Saving the library of life,” Proceedings of the National Academy of Sciences 89, 11098-11101 (1992).
Sun-Skimming Planets (and a Riff on Brown Dwarfs)
It’s time to catch up with recent exoplanet finds out of MIT as I start weaving in recent news with conference notes and ideas from other reading. Kepler 78b is much in the news because of its orbit, which takes it around its star in a breathtaking 8.5 hours, so that you can cram almost three Kepler 78b years into a single Earth day. That means, of course, that this is a planet that all but skims its star, with an orbital radius about three times the radius of the star. In Solar System terms, we’re talking about a world forty times closer to its star than Mercury is to the Sun.
Image: A scorched Kepler 78b may have yet more to tell us, as the article below explains. Credit: NASA/JPL-Caltech.
With temperatures somewhere between 2300 K and 3100 K on the bright side (and I would assume this is a tidally locked world), we would be looking at a veritable ocean of lava on the surface. This MIT news release points out that because the researchers were able to detect the light emitted from the planet, we should be able to parse out further information about the composition of that surface and its reflective properties. From the paper on this work:
The robust detections of the occultations of the planet by the star, and of the time-variable illuminated fraction of the planet as it orbits around the star, make the system important for future observational and theoretical work. Observations with finer time sampling could better pin down the transit parameters. This in turn would clarify the equilibrium temperature of the planet’s dayside… It is unclear at this point if the occultations would be large enough in any band to be detected with any telescope besides Kepler, but the prospect of studying the surface or atmosphere of an Earth-sized exoplanet may be attractive enough to justify a large investment of telescope time.
Kepler 78b orbits a late G-class star and has, according to the paper, the shortest orbital period among all planets yet found transiting a main sequence star. The researchers, led by Roberto Sanchis-Ojeda (M.I.T. Kavli Institute for Astrophysics and Space Research) note that the rarity of giant planets in orbits this tight may be the result of smaller rocky worlds being less vulnerable to tidally-induced decay of their orbits. Among the other Kepler Objects of Interest (KOI) are 17 exoplanet candidates with orbital periods of less than 16 hours and inferred planetary sizes smaller than that of Neptune.
All this intrigues me especially because of my interest in brown dwarfs, dim and cool enough that a planet needing warmth for habitability would have to orbit exceedingly close to the object. Then we come to work on KOI 1843.03, a still unconfirmed candidate whose transit period is a mere 4.5 hours. The MIT team involved with this one, led by Saul Rappaport, finds that for a planet to orbit its star this closely, it must be extremely dense to prevent tidal forces from disrupting it.
The paper on this candidate argues that while planets with masses from 0.1 to 8 Earth masses can exist with orbital periods as low as 3.5 hours, they must be composed largely of iron with silicate mantles. “A number of planets with very short orbital periods are starting to be found,” the paper adds, “and a continuing search for them is likely to prove fruitful.” And later:
We find it interesting that constraints on the composition of close-in terrestrial planets can be obtained from such elementary considerations. There remain, of course, profound questions about why planets actually exist in such close-in orbits, which we will leave for another day.
The Rappaport work is interesting because of its methodology. The Roche limit is the distance from the star where its tidal forces would disrupt the planet and cause it to disintegrate. Even a small planet has to orbit outside that limit. Rappaport’s team argues that these ultra-short period candidates can be studied by using the Roche calculations to set limits on the planet’s mean density. If the planet’s radius can be measured by studying its transits (this contrasts transit depth with measured stellar radius) then the composition of the planet can be inferred.
Musing on Close Planets and Brown Dwarfs
Neither Kepler 78b (a G-class primary) nor KOI 1843.03 orbits a star anywhere as faint as a brown dwarf, but let’s extend our speculations to these dim objects. Nature seems to be telling us to expect planets just about everywhere we look. It will be fascinating to learn whether or not brown dwarfs can sustain planets pushing up against the Roche limit and thus remaining warm enough to sustain some kind of life. Gregory Benford’s story “The Man Who Sold the Stars” explores at its conclusion what a planet orbiting a dim Y-class brown dwarf might look like. Imagine, then, being on the surface of a planet circling the brown dwarf called Redstar:
Even though their helmets amped the visible spectrum, the effect was eerie. Stars shone in pale gray here against the inky black. The huge hull of Redstar hung as a burgundy disk cut off by the sea. Here and there across the long panorama of perpetual twilight, slanting rays of a deep Indian red showed floating plants, lapping on the waves in a somber sprawl. Everything glowed with infernal incandescence…. Down from the desolate slope to his left came an echoing cry, long and slow. In the thick air a thing like a huge orange gossamer butterfly fluttered on a thin wind. It swooped across a sky peppered with amber clouds and vanished with deliberate, long flaps of its enormous wings, vanishing behind a low eroded hill.
Image: Can a brown dwarf produce planets close enough to the object to be habitable? Credit: NASA, ESA, and JPL-Caltech.
A place like this is worth looking for, which is why brown dwarfs have such a large place in my imagination. Whether or not a Y-class dwarf could produce planets in such a configuration is something that only future observation will tell us. We are, though, beginning to learn the tricks of observing planets moving incredibly close to their parent star.
The paper on Kepler 78b is Sanchis-Ojeda et al., “Transits and Occultations of an Earth-Sized Planet in an 8.5 hr Orbit,” Astrophysical Journal Vol. 774, No. 1, p. 54 (abstract). The paper on KOI 1843.03 is Rappaport et al., “The Roche limit for close-orbiting planets: Minimum density, composition constraints, and application to the 4.2-hour planet KOI 1843.03,” Astrophysical Journal Vol. 773, No. 1, L15 (abstract). Greg Benford’s story is available in the Starship Century anthology.
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