Centauri Dreams
Imagining and Planning Interstellar Exploration
Iain Banks: An Appreciation
The all too early death of Iain Banks conjures up so many images from his books that I can’t begin to list them all here. Grant his sly word-play, his wit, his deft management of character and you’re still left with a sense of gratitude for the sheer poetry of his landscapes. In Look to Windward, a character named Kabe walks the streets of blacked out city, down along a dark canal whose quayside is softened by snow. Then he looks up and the universe rotates:
The snow was easing now. Spinwards, over the city center and the still more distant mountains, the clouds were parting, revealing a few of the brighter stars as the weather system cleared. A thin, dimly glowing line directly above — coming and going as the clouds moved slowly overhead — was far-side light. No aircraft or ships that he could see. Even the birds of the air seemed to have stayed in their roosts.
Spinwards… We’re on one of Banks’ ‘orbitals,’ space habitats formed as enormous rings millions of kilometers in diameter, its inhabitants living in an environment shaped by technology but fine-tuned to produce benign climates and often jaw-dropping visual juxtapositions. In the post-scarcity world of Banks’ Culture, Orbitals vie with Ships containing sentient minds, some utterly enormous, as are the General Systems Vehicles that can reach 200 kilometers in length. Here, too, we are dealing with artifacts that are entire worlds amidst a society in which the limits of material needs have been transcended and creative use of time is the imperative.
Anyone familiar with Banks knows he loved giving his ships absurd names, and thus we move among vehicles like ‘So Much for Subtlety’ (The Player of Games), ‘Very Little Gravitas Indeed’ (Use of Weapons) and ‘Just the Washing Instruction Chip in Life’s Rich Tapestry’ (The Hydrogen Sonata). Each of these ships, possessing an artificial intelligence of its own, becomes a character, and often a significant one, in the action.
If Banks had his playful side, he was often demanding, his wit leavening a style that could be tense and baroque. Here’s a passage from The Hydrogen Sonata that puts readers to work:
At sunset above the plains of Kwaalon, on a dark, high terrace balanced on a glittering black swirl of architecture forming a relatively microscopic part of the equatorial Girdlecity of Xown, Vyr Cossont — Lieutenant Commander (reserve) Vyr Cossont, to give her her full title — sat performing part of T. C. Vilabier’s 26th String-Specific Sonata For An Instrument Yet To Be Invented, catalogue number MW 1211, on one of the few surviving examples of the instrument developed specifically to play the piece, the notoriously difficult, temperamental and tonally challenged Antagonistic Undecagonstring — or elevenstring, as it was commonly known.
In this, a novel as dense with ideas as any Banks wrote, getting to know Vyr Cossont is only a small part of the challenge as the author describes space-faring species brought together in common interest over what could be described as the philosophical ‘suicide’ of an important fellow civilization. No more details — read the book and immerse yourself in a far future that’s as different from most such visualizations as it is possible to be. Remember, this is a universe without material want, but we certainly find out early that it is not one without conflict.
I have Centauri Dreams readers to thank for introducing me to Banks years ago, and I’ve worked my way through most of his science fiction, though not yet his well regarded mainstream work, novels like The Wasp Factory or Canal Dreams. If the dazzling inventions of an Arthur C. Clarke or Isaac Asimov were fuel for his imagination, I can also see why he listed Brian Aldiss and M. John Harrison as literary influences. The latter, in particular his Viriconium stories and novels, surely awakened Banks’ instincts. He found there an enigmatic, lush, highly textured prose that turned the remotest futurity plausible.
Thinking about Banks, as I did much of the weekend, I realized that the science fictional enterprise transcends the limits of what we’ve come to call ‘futurism.’ Self-styled futurists tend to get the facts wrong because they rely on something akin to prophecy. How could they do anything else? We cannot know what knowledge waits to be uncovered, and that makes projections of the future all too often pessimistic, based as they are on an extrapolation of current trends without any off-setting new information. Read David Deutsch for more on this. His The Beginning of Infinity is suffused with an innate optimism that draws on the fact that problems are solved through new knowledge in a process without foreseeable end.
Within the limitations of our own place in time, we cannot know what that new knowledge will be. Iain Banks, in the tradition of our best science fiction writers, takes us into futures that have already found it. His outcomes are rich because they challenge our understanding of ourselves. His is a future that is and is not familiar, one compounded of our aspirations and our fears. I’ll close with this fine passage from The Player of Games, a personal favorite. Again we’re on an orbital, at the close of a novel that has taken us all the way to the Magellanics:
He stood on the snow-covered balcony, gazing at the dark trees descending in uneven rows to the glittering black fjord. The mountains on the far side shone faintly, and above them in the crisp night dim areas of light moved on the darkness, occluding star-fields and the farside Plates. The clouds drifted slowly, and down at Ikroh there was no wind.
Gurgeh looked up and saw, among the clouds, the Clouds, their ancient light hardly waving in the cold, calm air. He watched his breath go out before him, like a damp smoke between him and those distant stars, and shoved his chilled hands into the jacket pockets for warmth. One touched something softer than the snow, and he brought it out; a little dust.
He looked up from it at the stars again, and the view was warped and distorted by something in his eyes, which at first he thought was rain.
Philosophy of the Starship: A Report
Stephen Ashworth’s April essay at Astronautical Evolution deals with a question of considerable scientific interest: When will Voyager 1 leave the Solar System? But writer, researcher and jazz saxophonist Ashworth also has a philosophical streak, writing articles so far this year on the prospects for a technological singularity, the role of space in a society threatened with ecological disruption, and the business model best suited for manned spaceflight. In this essay, Stephen brings us a report from a recent seminar that mixes philosophy and starships, with consequential questions about autonomous technology, the role of discovery in combating intellectual stagnation, and the geopolitics of deep space exploration.
by Stephen Ashworth
The Institute for Interstellar Studies plans to run a symposium annually at the British Interplanetary Society‘s headquarters in London. The first of these events took place on 29 May, dedicated to the philosophy of the starship, and was organized by Kelvin Long and Rob Swinney. It follows several interstellar meetings at the BIS in the past few years, including one on warp drive concepts, one in which the Icarus project was formally launched, and in 2011 a reopening of the case for worldships [see Colonizing the Galaxy Using World Ships].
The title of Wednesday’s meeting, the “philosophy” of the starship, was left as broad as possible, I think deliberately, in order to encourage a variety of different angles, which worked well. Long’s own talk focused on Leonardo da Vinci, the Italian Renaissance polymath and artist (1452-1519). Not normally regarded as an astronautical pioneer, his significance was that he developed ideas which were centuries ahead of their time, including designs for flying machines. We now find ourselves facing a similar leap into the future of imagination-driven technology, and Long sketched out possible technology roadmaps towards that future.
Image: Underway at the BIS. This and the other images in this essay courtesy of Stephen Ashworth and Kelvin Long.
Keith Cooper discussed how self-replicating Von Neumann probes spreading through the Galaxy might fit into a philosophy for interstellar exploration [see Robotic Replicators for more of Keith’s ideas on the subject] . He pointed out that autonomous probes, based on nanotechnology, 3D printing and artificial intelligence, would be very useful for creating industrial infrastructure in space. But their autonomy could lead to unpredictable evolutionary changes in their behaviour, and could also sour a first contact scenario with extraterrestrials if those probes trespassed on the aliens’ own resources.
Cooper linked this topic with Fermi’s infamous question, or paradox, about which everybody has strong views but minimal supporting observational evidence. The Fermi question inevitably captured the resulting debate. I quietly suggested that future symposia ought to have a ground rule that the words “Fermi” and “paradox” should not be allowed to appear in the same sentence, in order to avoid these fruitless arguments which have been going on for half a century now, but this did not strike the organisers as a very good idea.
Bob Parkinson, one of the original Daedalus team, revisited several of his papers from the 1974-1975 period. He described how social and technological conditions had changed in the four decades since Daedalus. One person was now able to do the work which then had required a large team, thanks to the power of the Internet, and to the calculating power of specialised software.
Image: Daedalus designer Bob Parkinson speaks, looking back on an earlier paper in which he examined starships as part of a continuum that began with Renaissance voyages of discovery.
While this may seem to be all to the good, I had a discussion with Richard Osborne about the prospects for the further global application of increasingly capable machines to routine work currently performed by people. Driving road vehicles is a case in point: a massive source of employment at present, yet crying out for automation, with cars, buses and trucks already increasingly computerised. The danger is of large-scale unemployment leading to social unrest. This problem has of course been seen before, but is set to become increasingly acute as computers running expert systems become able to take over intellectual work, such as that performed by the medical profession.
This question ought to be of increasing interest in interstellar research. One is prone to forget that the very technologies which we assume will be available for interstellar spaceflight imply massive social and economic changes, and these will need to be managed successfully if society is to continue to be able to advance further out into space.
Image: A break for lunch and discussion at the BIS.
After lunch, Ian Crawford discussed interstellar discovery as an antidote to intellectual stagnation, drawing on an article of his published in a special issue of JBIS entitled “The Impact of Space on Culture” (Nov. 1993). He was in fact responding to Francis Fukuyama’s notorious “end of history” thesis, in which the end of ideological conflict also entails an end to human creativity and achievement.
Crawford referred also to John Locke, who in his Essay Concerning Human Understanding argued that we cannot imagine genuinely new things, but must discover them. In order to avoid the fate which Fukuyama predicted, we therefore need to keep pressing outwards and discovering new things. But this was disputed by Martin Ciupa, who rejected Locke’s view. Quite a debate resulted on the relation between physical reality and the human mind.
In his own presentation, Martin Ciupa focused on science fictional representations of contact between humans and intelligent aliens. A selection of posters from 1950s movies demonstrated the obsession at the time with aliens carrying off our womenfolk. The theme of using interstellar travel to illustrate our unconscious fears in the present was continued in Forbidden Planet. Ciupa then considered the Star Trek Prime Directive, representing what some would now regard as an ethical approach to managing our relations with aliens, and contrasted it with the interventionism shown by the Monolith in 2001, and by Klaatu in The Day the Earth Stood Still.
This ethical choice is no theoretical abstraction, but a future version of a choice which is with us today: should the developed countries of the world intervene in cases such as the civil war in Syria?
Frederik Ceyssens offered his thoughts on geopolitical scenarios relevant to deep space exploration. Three broad futures were sketched out: one in which world governments tended to integrate into a unified global governing institution, one in which the current situation of several major power blocs continued, and one where political institutions were eclipsed by non-state actors such as multinational corporations, and the implications of these alternative scenarios were discussed.
As it would entail less short term competition and conflict, the former scenario was seen as more beneficial for government backing of long-term visionary projects such as launching an interstellar probe, but could also entail stagnation and complacency. The other scenarios would entail a more dynamic world, in which there could be actors sponsoring such projects albeit with a lower amount of resources. In any case, advocacy of a scientifically credible project was seen as important.
Image: Stephen Ashworth, standing at right, addresses the symposium.
My own contribution during the morning session took a broader philosophical approach: what are the key features of a social philosophy conducive to large-scale civil space engineering up to and including starships? I demonstrated that in every case, a philosophical stance which the interstellar community regards as true or virtuous is regarded by other groups in society as false or damaging. Even within the sphere of interstellar thought, there are several points of fundamental disagreement (the answer to Fermi’s question being a case in point).
Three years ago the BIS was in fact treated to a debate with two Marxist academic sociologists who rejected the propositions that space exploration as currently practised was beneficial or that it ought to be accelerated. I believe that we need to keep in mind views that contrast strongly with our own, and engage with them where possible.
The day wound up with a discussion, led by Kelvin Long, of possible ways to demonstrate laser-sail propulsion in space on a low budget. It is planned to pursue this further under the title Project Dragonfly, intended to complement the existing work (Project Forward) being led by James Benford into microwave beam-sail propulsion.
In the best BIS tradition, many of the 30 participants afterwards adjourned to a local pub to continue discussions over a pint or two.
Exoplanet Science Beyond JWST
Thinking as we have been about exoplanet detection, and in particular about taking the next steps beyond the James Webb Space Telescope, I’m intrigued to see what has happened with the WFIRST mission. After all, despite the successes of Kepler and ESA’s CoRoT, we live in an era when mission cancellation is not uncommon. The Space Interferometry Mission was canceled outright, while Terrestrial Planet Finder, long touted as the way we would home in on nearby planets like our own, has been put into indefinite suspension. The JWST is on the horizon, but interesting new possibilities are now bubbling up around WFIRST, the Wide Field Infrared Survey Telescope. A mission with a dark energy pedigree could now have serious exoplanet implications.
In Exoplanet Capabilities of WFIRST-2.4, Philip Horzempa looks at the latest design to emerge for this mission, one that takes us much deeper into exoplanet country than I had thought the mission could. After all, WFIRST was conceived as a way of studying dark energy and the universe at the largest scale, using what had been 1.2-meter optics. But Horzempa points out that the National Reconnaissance Office (NRO) has now given NASA two Hubble-class 2.4-meter telescope mirrors, a gift that will boost the mission’s capabilities dramatically.
Image: As envisaged by the Astro2010 Decadal Study, WFIRST will be a wide-field-of-view near-infrared-imaging and low-resolution-spectroscopy space telescope. WFIRST will address two of the most fundamental questions in astrophysics: Why is the expansion rate of the universe accelerating? And are there other solar systems like ours, with worlds like Earth? Credit: NASA GSFC.
Evolution of a Mission
My recent post on using gravitational lensing to search for planets around Proxima Centauri reminded me that microlensing was folded into WFIRST from the start, but boosting the optics with a 2.4-meter mirror means that three times as much light will be collectable by the space observatory. The WFIRST exoplanet program centers on 500 days of observation time spread over five years, observing a set of adjacent fields in the galactic bulge. The information thus gathered, because it is not weighted (like radial velocity methods) to large, close-in planets, will help us understand more about solar system structure around a wide variety of stars.
The Science Definition Team commissioned by NASA to study the enhanced WFIRST design talks about finding in the range of 300 Earth-mass planets and 40 Mars-sized worlds using microlensing, with as many as 1000 super-Earths also likely to be found, for a grand total of perhaps 3000 exoplanets of all kinds emerging from the mission. Moreover, these methods would allow WFIRST to detect orphan planets ejected from their solar systems, galactic wanderers we are unable to detect with other methods. These worlds would be interesting not only in themselves but also as statistical fodder for planet formation theories.
Image: A microlensing light curve (left) produced by the relative movement of a star-planet system with respect to a background source (right). Image Credit: Dave Bennett (Notre Dame).
WFIRST’s continual evolution is also leading to the addition of a coronagraph that can block out the light of a central star to make it possible to image the planets around that star directly. So now we’re talking about a plan that, unlike Kepler, can go to work on the closest planets to our own system. Perhaps hundreds of new worlds could emerge from this work, all of them relatively nearby (the thinking in the current WFIRST report from the Science Definition Team is to look at the brightest 200 stars within 30 parsecs with these methods). Terrestrial worlds are beyond the capabilities of a WFIRST-2.4 coronagraph, but Neptunes and Jupiters should be well within its reach.
And here we come to one of the main points I wanted to make with this post, keying off Lee Billings’ concerns, discussed yesterday, about how and when we would start to get exoplanet spectra for worlds in the habitable zone. WFIRST can’t manage that feat, but it’s a step in the right direction. From Horzempa’s article:
The new WFIRST telescope will be also be able to obtain spectra of those planets, telling us something about their nature. As mentioned above, this will be the next crucial step in exoplanet exploration. We now know something about the sizes and masses of exoplanets. However, knowledge of surface composition is sorely lacking. Spectra obtained by WFIRST will help remedy this. Then, scientists will have data to help answer the questions raised by these worlds. Are they rocky planets? Gas giants? Are they ocean worlds? Are they covered in clouds? Are they worlds with compositions not found in our solar system? Some of the top targets for WFIRST will be the exoplanets discovered by the ground-based Doppler method. It will be able to confirm their existence, as well as tell us something about their personalities.
Current thinking is that WFIRST would be placed in a geosynchronous orbit, for reasons explained in the SDT report:
The primary factor that drove the selection of this orbit is the ability to continuously downlink data to the ground and obtain a much higher science data rate. The SDT weighed these benefits against the higher radiation environment and slightly less stable thermal environment versus the Sun-Earth L2 orbit chosen by the previous WFIRST SDT.
Servicing issues are also an obvious benefit of GEO. But a geosynchronous orbit rules out the use of a starshade, which may be the most potent way to block starlight and thus explore the habitable zone around target stars. There continues to be talk of using a starshade with the James Webb instrument and later missions, but it’s unlikely that WFIRST will one day be moved into position at L2 after fulfilling its earlier mission at GEO, as Horzempa suggests. Even so, WFIRST at GEO would still be able to home in on Kepler discoveries, along with whatever the Transiting Exoplanet Survey Satellite (TESS) comes up with.
Recovering Lost Mission Capabilities
A great deal of work was expended in the Terrestrial Planet Finder days to develop our coronagraph technology. So will that work now turn around to feed into WFIRST-2.4? For that matter, asks Horzempa, can WFIRST recover some of what we lost with the cancellation of the Space Interferometry Mission? The right technology could make this happen:
This could be accomplished by an ingenious method of adding a grid of micro-dots to the primary mirror. As with the other mechanical obstructions in the optical path, these dots would not interfere with images formed by the telescope. However, those dots would produce diffraction spikes that would serve as a tool for astrometry: measuring, with exquisite detail, the positions and motions of stars. What it translates to in practice is a powerful exoplanet discovery method for WFIRST-2.4. The astrometric dots would allow the telescope to measure the masses of exoplanets, even those that do not exhibit TTVs [Transit Timing Variations].
Astrometry is a powerful tool, one that could deepen our understanding of the Kepler discoveries, conceivably detecting non-transiting planets around some of these stars. Will such an astrometry option make its way into the final WFIRST design? If so, we could say a little bit of the SIM mission survives.
A fully enhanced WFIRST opens up other exoplanet possibilities as well. Adding the larger mirror would mean that WFIRST could detect TTVs several times smaller than Kepler. That should get the attention of David Kipping (Harvard-Smithsonian Center for Astrophysics), whose continuing work on exomoons relies partly on the precise detection of these kinds of variations. Could it be that WFIRST will detect our first exomoon, conceivably a large world orbiting a gas giant?
So at least one path forward after the James Webb Space Telescope begins to become apparent, in the form of a WFIRST mission enhanced with larger mirror and coronagraph and, perhaps, the grid of micro-dots discussed above. Is this the final precursor to the terrestrial planet imager we’re aiming for, the observatory capable of taking those critical spectra in the search for biosignatures? It might be if NASA decides to proceed with the WFIRST-2.4 design, a decision that should take place this month before further SDT meetings in September.
The Science Definition Team’s final report is “Wide-Field InfraRed Survey Telescope – Astrophysics Focused Telescope Assets,” available online.
Deeper Into the Golden Age
The golden age of exoplanets? I’ve often described our time as such, referring to the fact that we’re finding planets at such a fast clip and learning so quickly about the wide range of planetary systems out there, including those with ‘hot Jupiters’ and ‘super-Earths.’ But the next step in the discovery process is a bit murkier. If we’re learning how exoplanets are distributed — and even with a hobbled Kepler, we still have a great deal of data still to be analyzed — we’re not yet ready to take the spectra of exoplanet atmospheres on conceivably habitable worlds.
This is important, because light scattering off an atmosphere bears the signature of things like water vapor, oxygen, methane and carbon dioxide, the right combination of which could signal life. And just as Kepler is useful at developing a statistical read on the distribution of smaller planets, so we’ll want to have a way to measure the frequency of worlds that actually do bear life. It’s a problem Lee Billings notes in How We Could Find Alien Life Soon — and Why We Probably Won’t, an essay in Nautilus. After touching on the technologies of spectrum gathering, Lee says this:
The bigger, more fundamental problem is that obtaining the spectrum from just one potentially habitable exoplanet is unlikely to be enough; satisfying our search for life, gaining some inkling of our cosmic context, will probably require surveying hundreds or thousands of worlds in the relatively short timespan of one space-telescope mission. To quickly, efficiently perform such a search requires one or more very large, very sophisticated starlight-suppressing space telescopes—telescopes that currently have no funding and very little public awareness.
Billings’ take is that a fully developed space telescope capable of taking atmospheric spectra of Earth-like worlds would cost in the range of $5 billion, a step up from the $600 million Kepler and higher than the $3.6 billion Cassini. He’s quick to point out that the cost is substantially lower than Americans pay per year for chocolate candy — Neil deGrasse Tyson makes this same point using lip balm as a cost per year comparison to the Cassini orbiter. And even though I think Lee’s $5 billion figure is optimistically low, it’s hard to deny his point: Finding life signatures on habitable zone planets is within our grasp if we have the will to make it happen.
Image: Orbis Terrarum, a world map published by the Dutch astronomer, cartographer and clergyman Petrus Plancius in 1594, charting a century of European exploration. Filling in the gaps in maps like this took centuries. How long will it be before we begin building a cartography of terrestrial worlds around other stars?
For his part, Seth Shostak calls this enterprise, and Kepler in particular, “the most exciting research experiment going.” In How Ordinary Are We?, Shostak runs through the current woes, centering on the failure of a reaction wheel used to point the telescope. A command sequence to torque the wheels may eventually clear the material causing the friction, or perhaps not. But with two years of Kepler data still in the pipeline, we’re going to get an important read on the fraction of Sun-like stars that have Earth-sized planets in the habitable zone no matter what.
Fix the reaction wheel and another year of data gathering could occur. But without it, we still get an answer, although one, as the SETI Institute’s Jon Jenkins tells Shostak, with slightly larger error bars. Both results may well act as a spur to public interest in the question of what we do next, relating the statistical Kepler findings to the stars closer to our own Sun. Missions like TESS (Transiting Exoplanet Survey Satellite) will help us find some of these potentially habitable worlds, but until we have spectral information about their atmospheres, we’ll be left to wonder the age-old question of Earth’s place in the cosmos and the frequency of life elsewhere.
Gravitational Lensing in Proxima Planet Hunt
I normally think about gravitational lensing as a way of finding planets that are a long way from home. That’s just the nature of the beast: Lensing as an exoplanet detection tool depends upon a star with planets moving in front of a background object, its mass ‘bending’ space enough to cause slight changes to the image of the farther star. Monitor those changes closely enough and you may see the signature of a second disruption, flagging the presence of a planet around the closer star. Occultations like these are rare enough and more likely to be found in a crowded starfield, such as looking toward galactic center.
It’s a remarkable fact that instruments like the Hubble Space Telescope can make measurements down to 0.2 milliarcseconds, a milliarcsecond being (as this Space Telescope Science Institute news release notes) the angular width of a nickel in Honolulu when viewed from New York City. Comparable measurements, within range of the European Southern Observatory’s Very Large Telescope (Chile) and ESA’s Gaia space telescope, may be able to offer confirmation of what we find when we study two upcoming occultation opportunities involving not a distant star but the closest one.
Image: Proxima Centauri (Alpha Centauri C). Credit: NASA, ESA, K. Sahu and J. Anderson (STScI), H. Bond (STScI and Pennsylvania State University), M. Dominik (University of St. Andrews).
For STScI’s Kailash Sahu has gone to work on stars that have a high angular motion across the sky, reasoning that we might be able to find a nearby star on which to make microlensing observations. In Proxima Centauri, Sahu hit the jackpot, a star that crosses a stretch of sky with the apparent width of the full Moon every 500 years. Not one but two occultation events loom in Proxima’s near-future, the first being its passage in front of a 20th-magnitude background star in October of 2014, the second an occultation of a 19.5-magnitude star in February of 2016.
Reading about this induced one of those ‘slap yourself on the forehead’ moments when I realized how prescient it was of Sahu and team to use Hubble to plot Proxima’s trajectory, looking for precisely this kind of event. And if the instruments above can measure down to 0.2 milliarcseconds, this method could pay off, for the displacement of the background stars induced by Proxima’s mass is estimated at 0.5 milliarcseconds and 1.5 milliarcseconds respectively. If there are planets around Proxima Centauri, this method may find them.
Image: This plot shows the projected motion of the red dwarf star Proxima Centauri (green line) over the next decade, as plotted from Hubble Space Telescope observations. Because of parallax due to Earth’s motion around the Sun, the path appears scalloped. Because Proxima Centauri is the closest star to our Sun (distance, 4.2 light-years), its angular motion across the sky is relatively fast compared to much more distant background stars. This means that in 2014 and 2016 Proxima Centauri will pass in front of two background stars that are along its path. This affords astronomers a rare opportunity to study warping of space by Proxima’s gravity, as will be evident in the apparent displacement of the two stars in sky photographs. This effect is called gravitational lensing. The amount of warping will be used to calculate a precise mass for Proxima Centauri and look for the gravitational footprint and any planets orbiting the star. The background image shows a wider view of the region of sky in the southern constellation Centaurus that Proxima is traversing. Credit: NASA, ESA, K. Sahu and J. Anderson (STScI), H. Bond (STScI and Pennsylvania State University), M. Dominik (University of St. Andrews), and Digitized Sky Survey (STScI/AURA/UKSTU/AAO).
Earlier efforts to find planets around Proxima have been intensive. Work with the UVES spectrograph at the European Southern Observatory, coupled with radial velocity studies of the star from the 1990s, helps us understand what we won’t find around Proxima. No planet of Neptune mass or larger is detectable there out to a distance of 1 AU. And we can go further: No super-Earths larger than 8.5 Earth masses have been found. Within Proxima’s habitable zone (assuming roughly 0.022 to 0.054 AU, which corresponds to an orbital period ranging from 3.6 to 13.8 days), no planets larger than 2-3 Earth masses have been detected in circular orbits.
You can see how much we leave out with this description, including planets of Earth mass or smaller in the habitable zone. And we always have to contend with the limitations of radial velocity work, which is sensitive to the orientation of the planetary system to us — in other words, we don’t know the angle at which we are observing the system, so we wind up with the still faint possibility of larger planets if we are seeing the Proxima system face-on. We do know that no transits have been found, indicative of an edge-on orientation, and the upcoming microlensing study coupled with ever more precise radial velocity measurements may help unlock the puzzle.
For more on recent Proxima Centauri work, see Endl and Kürster, “Toward Detection of Terrestrial Planets in the Habitable Zone of Our Closest Neighbor: Proxima Centauri,” Astronomy and Astrophysics, Volume 488, Issue 3, 2008, pp.1149-1153 (abstract). Kailash Sahu will be presenting his findings at the meeting of the American Astronomical Society in Indianapolis, with a paper already submitted to the Astrophysical Journal.
Civilizations Beyond Earth: A Different Angle
What kind of assumptions do we bring to SETI, and how are those assumptions changing? Tau Zero’s Larry Klaes has some thoughts on that, along with suggestions about what a new book on the subject may want to include in its second edition.
By Larry Klaes
SETI, the Search for Extraterrestrial Intelligence, has traditionally operated on the premise that there may be beings in the Milky Way galaxy and beyond who are smart, aware, and interested enough to deliberately attempt to contact other similarly advanced societies in the Universe.
The primary purpose for such an effort would be to alert any potential celestial neighbors to their presence for the exchange of information and ideas about themselves, their home world, and their take on existence. Their methods of transmission would include certain forms of electromagnetic radiation which the various parties should have in common, such as radio and light waves. This Messaging to Extraterrestrial Intelligences, or METI, is considered to be not only less complex and faster than sending a robotic or crewed vessel from one star system to another – barring the discovery of a way to move faster than light (FTL) – but also far less expensive and much safer for both sides.
The alien version of METI is presumed to be conducted by scientists using not their native language but rather some form of basic mathematics for the initial efforts at getting our attention and conducting basic conversations. This remedial arithmetic would serve as the assumed common key to eventually allow both species to use their own conventional languages to exchange more detailed information.
This thinking is strongly reflected in the 1985 novel Contact (and the 1997 film version), the only major work of science fiction produced by astronomer, science popularizer, and SETI/METI pioneer Carl Sagan. In his story, Sagan envisioned a highly advanced, vast, and ancient alien technological civilization which transmits an initial message via radio waves to species they deem potentially worthy of dealing with. One day humanity receives this opening greeting from them in the form of the first one hundred prime numbers, which are digits divisible only by themselves and one. Prime numbers are a pattern produced by no known natural phenomenon.
On SETI Assumptions
If the bipedal residents of the planet Earth can detect and recognize the artificial nature of the primes being sent (“mathematics [is] the only truly universal language” declares the main character Ellie Arroway at one point in response to a visiting senator who wanted to know why the aliens didn’t just speak English) along with the subsequently more complex information which then follows, then one day we might be able join an entire galactic community of civilizations. This society would be similar to the United Nations, only on a celestial scale and with members of many different species from a diversity of alien worlds across space and time, yet somehow all managing to work together for the common cosmic good.
These assumptions, while not implausible, do reflect a particular scientific take regarding SETI, METI, and the nature and behavior of technological alien beings. The question is, does the fact that we have yet to confirm a recognizably artificial signal of extraterrestrial origin after six decades of modern SETI (and a handful of METI) activities mean that our scientific assumptions about intelligent aliens need to be revised, or have we just not been searching long and hard enough? Or perhaps both?
Since astronomer Frank Drake performed the first modern extraterrestrial hunt program in 1960 with a radio telescope search he called Ozma, SETI has traditionally been dominated by radio (and later optical) astronomers, as they are the ones who have conducted the majority of the searches for alien signals to the present era. Their parameters were and are still dictated by the contemporary limitations of what humanity can accomplish when it comes to interstellar distances and the paradigms of their fields and views on intelligent life elsewhere.
As for relevant disciplines outside of astronomy involved in SETI, there have been token representatives present going back to the first modern era SETI conferences, thanks in large part to Sagan. But usually the conferences and the projects were dominated by astronomers, who focused heavily on radio SETI and the technical details of such interstellar communications. Often they would use the famous Drake Equation (N = R* x fp x ne x fl x fi x fc x L) as their template but tend to gloss over the parts of that linear equation which were hard to quantify, which included most of it. This was especially done with fc and L, the fraction of civilizations that develop the means to let others in the galaxy know they exist and the overall lifetime of such technological societies, respectively.
Like most scientists, they felt comfortable with numbers, tangible facts, and mechanics. Why would an alien signal us? Well, because they could, so they would. They wanted to exchange knowledge because the operators had to be fellow scientists, which meant that even though they were alien, they had to think similarly to us, otherwise they would not be conducting METI/SETI. We were looking for versions of us, very specific versions if truth be told.
The accuracy of the statements is attested by Mark A. Sheriden’s excellent and insightful work titled SETI: A Critical History. From Chapter 10, Sheriden gives this quote from Dr. Jill C. Tarter, the recently retired director of the Center for SETI Research at the SETI Institute in Mountain View, California:
Not long after the [1979 NASA Life in the Universe] conference Jill Tarter, a key member of SETI’s second-generation leadership team, acknowledged that SETI was, indeed, “tuned” to find humanoids. “Those forms that we do find in this manner [i.e., a SETI-style search] will be more similar to life as we understand it than other forms that may exist. We put a filter on the problem.”
When asked what she would do differently if starting over again to study ETIs, Tarter responded with an echo of Shklovskii’s complaint prior to Byurakan-II, that the American SETI scientists failed to acknowledge the “complexity” of the problem they faced and, in particular, were ignoring the “humanities and biological aspects.” Tarter said, “I neglected biology, and civilizations, and paleontology.” In other words, she would have paid more attention to the “nature” aspects of the opportunity SETI represented.
Puzzling Out Alien Motivations
Why would an alien intelligence want to contact the stars? The possible motivations for such actions – or lack thereof – are just as important for the success of SETI and METI as figuring out how beings from another world (assuming the majority live on a planet or moon in the first place; another paradigm, perhaps?) might go about sending out signals into the galaxy.
Anthropologists, sociologists, biologists, and historians might have a clue in this area. At present they may have the native dwellers of only one planet to base their research and ideas upon, but at least it is a world with a very wide variety of life and an ancestry dating back at least 3.8 billion years.
These fields and their practitioners are given their due in the book Civilizations Beyond Earth: Extraterrestrial Life and Society, edited by Douglas A. Vakoch and Albert A. Harrison and published by Berghahn Books (New York, 2011). Vakoch, who also edited the book Communication with Extraterrestrial Intelligence (SUNY Press, New York, 2011) is the Director of Interstellar Message Composition at the SETI Institute and Professor of Clinical Psychology at the California Institute of Integral Studies. Harrison is Professor Emeritus in the Department of Psychology at the University of California, Davis.
Reading through the collected papers in Civilizations Beyond Earth reminded me of one of the first works I came across that was directly critical of the parameters modern SETI had laid down in its milestone years of 1959 and 1960, The Inner Limits of Outer Space by Dartmouth professor John C. Baird (Hanover, New Hampshire: University Press of New England, 1987). The author of the first major book on SETI by a professional psychologist, Baird was also part of Project Oasis, a NASA plan in 1979 to help design the multi-channel spectrum analyzer to be used in the space agency’s own burgeoning SETI project.
Baird pointed out how those involved in searching for extraterrestrial intelligences were spending a great deal of their time and resources in designing and building the instruments they planned to use, but not nearly as much in turn when it came to really thinking about what kind of beings might be out there and why they might want to conduct METI at all. Baird’s words and thoughts throughout The Inner Limits of Outer Space mirror what one finds twenty-four years later in Civilizations Beyond Earth. Neither work wants to do away with SETI so much as redefine it to improve the chances for success based on a more realistic or at least more open approach to alien life. The similarities also include the conclusion that even though current SETI is problematical in terms of detecting an actual extraterrestrial signal, it cannot hurt to keep trying for, to quote the current advertising motto of the New York State Lottery: “You never know.”
Among the highlights of Civilizations Beyond Earth which take it beyond the usual examinations of SETI and its related fields is the focus on what the general public, or laypersons, think and say about extraterrestrial life, in particular the intelligent kind.
Public Perceptions of ETI
Professional SETI researchers and other scientists tend to avoid the public perceptions about aliens, which they find to be full of undisciplined ideas and a tendency to buy into stories and reports about sightings of alien spaceships and their occupants. A fear of being lumped into the fringe realm of pseudoscience is among the top reasons why SETI has stuck with remote searches of distant star systems. However, there is a slowly opening acceptance that some ETI might send probes to our Sol system to observe us discreetly, perhaps in the Main Planetoid Belt or using nanotech devices or even smaller observing and data collecting technology scattered across Earth.
Several chapters of the book are devoted to polling the general public on the subject of alien life. Unrestrained by scientific parameters and paradigms, their theories and beliefs range from having aliens be the saviors of humanity to our destroyers. They also tend to be much more accepting of the idea that many ETI may already be here monitoring us.
In an ironic twist, the public often thinks of the physical appearance of alien beings as essentially humanoids with a large head and eyes, no visible ears, and slim bodies. On the other hand, scientists who focus on exobiology see life taking on many different forms on different worlds due to evolution. Nevertheless, because we know so little about life beyond Earth, a wide variety of viewpoints can be a welcome thing, as there are times when a different perspective on such a subject could be the key to discovery.
Among the most interesting papers in this collection were the ones where different human cultures interact with each other in space and time. In “Encountering Alternative Intelligences: Cognitive Archaeology and SETI”, Paul K. Wason looks at one of the fifteen humanoid species which have shared this planet with us, namely the Neanderthals. Although they existed in Europe around the same time with modern humans and even interbred with each other, their branch of the family tree died out roughly thirty thousand years ago. Clues from the archaeological record indicate that Neanderthals were quite different in many fundamental ways from current humanity despite being hominids which evolved on Earth. Even though their brains were a bit larger than ours, Neanderthal was not as sophisticated in many ways if we go by the evidence that has survived the ages. Regarding how scientists have learned as much as they do know about Neanderthals, Wason said: “Could it be also that one of the best ways of preparing for interstellar communication with other intelligences would be to engage in more study of how human intelligence works?”
Several centuries ago, there were two genetically related but otherwise very different human cultures which did interact with each other and for which we have extensive records of those encounters. In “The Inscrutable Names of God: The Jesuit Missions of New France as a Model for SETI-Related Spiritual Questions,” Jason T. Kuznicki, a research fellow at the Cato Institute, describes what happened when a group of Roman Catholic Jesuits sailed to North America starting in the Seventeenth Century to convert the native tribes living around the Canadian side of the Great Lakes region.
Armed with the tools of their religion, which included the presumptions of French philosopher Rene Descartes and Saint Thomas Aquinas that reason would inevitably bring everyone to the conclusion that the Christian God and souls exist, the Jesuit missionaries soon discovered that the Native Americans they met did not share these views or come to any of the same conclusions as the Jesuits thought would happen in matters of deities and the afterlife.
Here were fellow humans separated by a few thousand miles of ocean and yet the two cultures not only had wildly different views on many things, they also lacked the words of their languages to clearly get across their ideas on spiritual and religious matters. Now imagine what might take place between two entirely different species from separate worlds light years apart. Would an alien species even have a religion?
One aspect of Kuznicki’s paper which was not touched upon were the underlying motives for the Jesuits being in North America and attempting to convert the natives there: The French wanted to secure the New World for themselves from the competing British and Spanish powers. Having the Native Americans as allies would certainly help their cause, either through assimilation or coercion. Should an ETI contact us via interstellar transmissions or arrive in person at our world, this is one aspect of such an encounter that requires the study of historical precedents from our species. The scientists would assume the alien visitors are just explorers, but the historian might think otherwise. Even an ETI that came here with the purpose of doing what it thinks is good for us might have unexpected consequences for humanity.
The Question of Artificial Intelligence
Civilizations Beyond Earth does have its limitations. The focus is mainly on biological entities, which makes sense considering the authors. However, to not offer at least a few papers by some computer experts on artificial intellects, or Artilects as coined by Hugo de Garis, is hardly advancing our knowledge base of all scientific aspects of ETI. In this respect it is no better than focusing on radio as a means of interstellar detection and communication while ignoring Optical SETI and searching for Dyson Shells and alien probes in our Sol system.
Granted, there is a paper by William Sims Bainbridge titled “Direct Contact with Extraterrestrials via Computer Emulation”, which proposes the idea that a person could have themselves downloaded into a computer simulation as an avatar, or at least a psychological reproduction of themselves. Bainbridge envisions the avatars being beamed into space via radio waves to do the exploring and contacting with ETI.
Presumably this would have to be an enhanced version of the humans who choose to go this route, otherwise we encounter the limits of understanding an alien mind that would be little different than if we tried to comprehend an ETI with our own selves. Other chapters do deal with the complexities and difficulties in trying to communicate even basic concepts to an alien species, especially if we have few frames of reference. Would an Artilect with its faster computing speeds and much larger data storage do this better? Would sentience be required for this task or just a highly sophisticated simulation resembling awareness? Perhaps a revised edition of this book will add papers devoted to these questions concerning Artilects.
As Seth Shostak says in his article “Are We Alone?” regarding the Drake Equation, but which could also mirror what is missing and incomplete from this book:
“In other respects, [the Drake] equation might be too cautious. It assumes that all transmitting cultures are still located in the solar system of their birth. This ignores the possibility of colonization of other star systems (difficult, but not forbidden by physics), or the possible deployment of transmitting facilities far from home. In addition, it does not deal with the development of synthetic intelligence – thinking machines that would not be constrained to watery worlds orbiting long-lasting stars. In short, it makes the assumption that “they” are much like “us.”
For those who might argue that we may be unable to deduce the thought processes and motives of artificial minds far larger and faster than our own, the same could be said for any kind of biological alien species: Such beings could take on many forms and be just as inscrutable as an Artilect, yet that has not stopped many humans of all stripes on this planet from offering their views on organic ETI. One advantage with Artilects is that we can work towards actually creating or simulating them and thus have direct access to another intelligent mind.
Unfortunately, many people fear that Artilects could use their superior intellects to dominate or destroy humanity, just as they also expect advanced ETI to arrive in starships with similar goals. Whether that may ultimately happen or not, this general fear combined with a limited education on and cultural ridicule about the subjects relevant to SETI/METI have made their “contributions” to the reality that over half a century after the first serious SETI program, traditional searches continue in a largely sporadic fashion with limited funds, seldom expand beyond the radio and optical realms, and remain dominated by astronomers and engineers.
Human Expansion into the Galaxy
These views and paradigms also extrapolate to interstellar efforts such as Worldships, self-contained vessels carrying thousands of people on multigenerational journeys to other star systems. The goal of these Worldships is to colonize suitable planets and moons in the target system or at least collect resources from them before moving on to other galactic destinations.
How those who will remain onboard for perhaps many centuries will survive and adapt has been studied far more in the pages of science fiction than anywhere else, for obvious reasons. Will those who arrive at their intended worlds be radically different from their ancestors back on Earth? Will their interaction with any ETI they encounter diverge from the initial intentions of those who sent them off into the galaxy? As said earlier regarding Artilects, perhaps a revised edition of this work or a new book altogether devoted to very long term exploration and its consequences on those who make the voyage both aboard the Worldship and upon the places they settle will make inroads to answering these questions.
There is a strong desire or perhaps even a natural reaction to colonize any Earthlike exoworlds as part of some cosmic manifest destiny. Unless we terraform some barren rock, a planet similar to our own will be so not only in terms of size and environment, but also due to having life upon it. Even if none of the organisms on this alien world are sentient (and how exactly will we define that?), do we have the right to introduce terrestrial species there? If the situation was reversed and an ETI arrived at Earth to set up a new home, even if they desired a peaceful coexistence, imagine the reaction from humanity.
Even a robotic mission could cause unforeseen issues in the future. Already at this early stage in our expansion into space we have five probes and most of their final rocket stages heading beyond the boundaries of the Sol system into the wider Milky Way galaxy. Although none of them will be functioning by the time they could ever reach another star system, their very existence drifting and tumbling uncontrolled and aimless through deep space might one day become a problem for beings of which we are completely unaware at present.
We can declare that the galaxy is much too vast and these probes far too small to ever gain notice by any intelligences out there. We can say that any beings who could find these emissaries from Earth would have to be quite sophisticated and savvy with the ways of the interstellar realm and thus capable of dealing with a comparatively primitive, ancient, and inactive derelict from a species such as us.
In the end, however, the truth is that we do not yet know who or what is occupying the galaxy with humanity. We cannot say with certainty how an alien species might react and respond to an unexpected visitor from another world – though we can make some pretty good guesses as to how our civilization would behave in a similar scenario.
As we have already discussed with regards to SETI and METI, again the astronomical scientists and space engineering and technical fields often differ in their views on these matters compared to the anthropologists, sociologists, biologists, and historians. At least some of the gaps between the disciplines were bridged by the incorporation of messages and information packages on the Pioneer, Voyager, and New Horizons space probes. Whether these “gifts” will be recognized and understood by the recipients is yet another unknown factor, but they are a step in the right direction.
The issue of our physical intrusion into the Milky Way will become even more prominent and serious as we develop and launch probes – operated by Artilects most likely – designed to reach and explore other solar systems. In this case, humanity may receive responses from other intelligent beings in a matter of years or decades as opposed to millennia. What may happen and how our descendants might handle an ETI reaction will depend on how far our culture has come in terms of being more wide ranging and inclusive in our understanding of the Cosmos.
Civilizations Beyond Earth may be a slim book, but it is a good introduction to fields that need to be vital parts of any serious discussion of the scientific activities regarding extraterrestrial intelligences. If SETI and METI remain lopsided in their thinking, methods, and executions, the stars will likely continue to remain silent for the human species for a long time to come.
Not to know if we are either alone or one of many living beings in the Universe when we finally have the awareness and ability to answer this very important question would be a tragic shame, an affront to the very reason we have science and a civilized society in the first place. Let us not answer the L portion of the Drake Equation too soon from a lack of wonder, education, and funds.
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