HD 158259: 6 Planets, Slightly Off-Tune

What an exceptional system the one around HD 158259 is! Here we have six planets, uncovered with the SOPHIE spectrograph at the Haute-Provence Observatory in the south of France, with the innermost world also confirmed through space-based TESS observations. Multiple things jump out about this system. For one thing, all six planets are close to, but not quite in, a 3:2 resonance. That ‘close to’ tells the tale, for researchers believe there are clues to the formation history of the system within their observations of this resonance.

Image: In the planetary system HD 158259, all pairs of subsequent planets are close to the 3:2 resonance : the inner one completes about three orbits as the outer completes two. Credit & Copyright: UNIGE/NASA.

The primary, HD 158259, is itself interesting, in that it’s a G-class star about 88 light years out, an object just a little more massive than our Sun. But tucked well within the distance of Mercury from the Sun we find all six of the thus far discovered planets. In fact, the outermost planet orbits at a distance 2.6 times smaller than Mercury’s, making this a compact arrangement indeed. Five of the planets are considered ‘mini-Neptunes’, while the sixth is a ‘super-Earth.’

The innermost world masses about twice the mass of Earth, while the five outer planets weigh in at about six times Earth’s mass each. The 3:2 resonance detected here runs through the entire set of planets, so that as the planet closest to the star completes three orbits, the next one out completes two, or close to it (remember, this is an ‘almost resonant’ situation). And so on — the second planet completes three orbits while the third completes about two.

Nathan Hara (University of Geneva), who led the study, likens the resonance to music, saying “This is comparable to several musicians beating distinct rhythms, yet who beat at the same time at the beginning of each bar.” The researchers involved (who used, by the way, the same telescope deployed by Michel Mayor and Didier Queloz in their ground-breaking detection of 51 Pegasi b in 1995, though with added help from SOPHIE) believe that the ‘almost resonances’ here suggest that what had been a tight resonance was disrupted by synchronous migration.

In other words, the six planets would have formed further out from the star and then moved inward together. As Hara puts it:

“Here, ‘about’ is important. Besides the ubiquity of the 3:2 period ratio, this constitutes the originality of the system. Furthermore, the current departure of the period ratios from 3:2 contains a wealth of information. With these values on the one hand, and tidal effect models on the other hand, we could constrain the internal structure of the planets in a future study. In summary, the current state of the system gives us a window on its formation.”

And here’s how the paper deals with the issue;

…period ratios so close to 3:2 are very unlikely to stem from pure randomness. It is therefore probable that the planets underwent migration in the protoplanetary disk, during which each consecutive pair of planets was locked in 3:2 MMR [mean-motion orbital resonance]. The observed departure of the ratio of periods of two subsequent planets from exact commensurability might be explained by tidal dissipation, as was already proposed for similar Kepler systems (e.g., Delisle & Laskar 2014). Stellar and planet mass changes have also been suggested as a possible cause of resonance breaking (Matsumoto & Ogihara 2020). The reasons behind the absence of three-body resonances, which are seen in other resembling systems (e.g., Kepler-80, MacDonald et al. 2016), are to be explored.

It’s interesting that while other systems with compact planets in near-resonance conditions have been detected (TRAPPIST-1 is the outstanding example, I suppose, but as we see above, Kepler-80 also fits the bill), this is the first to have been found through radial velocity methods. According to the authors, the method demands a high number of data points and accurate accounting of possible instrumental or stellar noise in the signal. In this work, 290 radial velocity measurements were taken, and supplemented by the TESS transit data on the inner planet.

Compact systems with multiple planets on close orbits do not appear only among M-dwarfs like HD 158259. Kepler-223, for example, is a G-class star with four known planets. Here the orbital periods are 7, 10, 15 and 20 days respectively. The Dispersed Matter Planet Project (DMPP) has turned up data on an F-class star (HD 38677) with four massive planets with orbital periods ranging from 2.9 to 19 days. The ancient Kepler-444 is a K-class star with five evidently rocky worlds orbiting the star in less than ten days.

Rather than the size of the star, at least one recent paper argues that metallicity is a key factor in producing compact systems (Brewer et al., (2018) “Compact multi-planet systems are more common around metal-poor hosts,” Astrophys J 867:L3). Clearly we have much to learn about planet formation and migration in compact systems. Such systems are near or below the current detection limits of radial velocity surveys — this is where the work on HD 158259 truly stands out — but they are good targets for transit studies. It will be instructive to see what TESS comes up with as it continues its work.

The paper is Hara et al., “The SOPHIE search for northern extrasolar planets. XVI. HD 158259: A compact planetary system in a near-3:2 mean motion resonance chain,” Astronomy & Astrophysics Vol. 636, L6 (April 2020). Abstract / preprint.

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On Freeman Dyson

Freeman Dyson’s response to the perplexity of our existence was not purely scientific. A polymath by nature, he responded deeply to art and literature and often framed life’s dilemmas through their lens. Always thinking of himself as a mathematician first, he unified quantum electrodynamics and saw the Nobel Prize go to the three who had formulated, in different ways, its structure, but he would cast himself as the Ben Jonson to Richard Feynman’s Shakespeare, a fact noted by Gregory Benford in his review of Phillip F. Schewe’s recent biography. That would be a typical allusion for a man whose restless intellect chafed at smug over-specialization, something neither he nor Feynman could ever be accused of.

Feynman, Julian Schwinger and Shinichiro Tomonaga each came up with ways to describe how electrons and photons interrelate, but it was Dyson, on one of his long cross-continental bus trips, who worked out the equivalence of their theories, giving us QED. He would publish the unifying paper in Physical Review in 1949. A year later, he met Tomonaga at Princeton, describing him in a June 24, 1950 letter to his parents as “a charming man, like so many of the really good ones. He talked with me for three hours with much humour and common sense… I have the impression that he is an exceptionally unselfish person.”

Which is exactly the impression I had of Dyson in the one interaction (other than email) I had with him, back in 2003 while I was pulling together material for Centauri Dreams and called the Institute for Advanced Study, his scholarly home since 1953, to schedule an interview. It was a spring day and, unfortunately for my purposes, a loud lawn mower was moving up and down outside Dyson’s window. I was having to shout to be heard, a nuisance, and I had trouble hearing him, but we persisted with much repetition and his good humor.

Always associated with Project Orion, the dramatic concept to propel a spacecraft by exploding nuclear charges behind it, Dyson had moved away from the idea, and indeed from nuclear energy entirely. He wanted to talk about microwave and laser propulsion, and expressed an interest in Clifford Singer’s ideas on pellet streams, an idea he liked because of the lack of diffraction. Over a close pass by the outside lawnmower, I heard him clearly: “Nuclear energy doesn’t cut it! Nuclear energy is too small. You’re using less than one percent of the mass with any kind of nuclear reaction so you’re limited to less than a tenth of lightspeed. Nuclear is great inside the Solar System, but not very interesting outside of it.”

If you would know something of this man, of his values and his conception of life, I direct you to the splendid Maker of Patterns: An Autobiography Through Letters, published in 2018. The concept is daring, for by eschewing standard autobiography to present himself largely through letters he wrote at the time, Dyson gives up the opportunity to edit his persona. None of us can point to a lifetime without contradiction, which is just another way of describing growth. Dyson was willing for that growth to be in full view. Thus the Dyson of 1958, writing about the Project Orion work he would later discount:

The basic idea is absurdly simple. One is amazed that nobody thought of it before. But the only man who could think of it was somebody who had been working and thinking for years with bombs, so that he could know exactly what a bomb of a given size will do. It was not an accident that this man happened to be Ted [Taylor]. The problem is to convince oneself that one can sit on top of a bomb without being fried… Ted’s genius led him to question the obvious impossibility. For the last six months Ted has spent his time talking to people in the government and trying to convince them that this idea is not crazy. He has had a hard time. But it seems we have now a lot of influential people on our side… Ted and I will fly to Los Alamos this evening. We travel like Paul and Barnabas.

Nothing would come of these travels, of course, because of the signing of the Limited Nuclear Test Ban Treaty of 1963, though Dyson would later support the treaty amid his deep concern over nuclear destruction. The idea of Orion still tantalizes many interstellar advocates today.

The lack of self-justifying ego — so rare in all too many quarters — that informs Dyson’s writings informs his wide reach into non-scientific markets, where he became the eloquent explainer of concepts he worked with in the course of his long life. I doubt there are many Centauri Dreams readers who do not have at least a few of his titles, books like Disturbing the Universe (1981) and Infinite in All Directions (1988). So many concepts sprang from his insistence on seeing things from a cosmological perspective, including for our interstellar purposes the Dyson sphere and the biological, self-replicating probe called ‘astrochicken’ that was enabled by artificial intelligence.

Image: Around the table clockwise are Dyson, Gregory Benford, Jim Benford and David Brin. Taken Jan. 30, 2019, before a discussion between Greg and Dyson at the Clarke Center (available here on YouTube).

All of these concepts he could relate to the general public through a style that was at once clear and enabling, so that the reader would, like this one, often look up from his or her reading to take in the audacity of ideas that were as logical as they were innovative. The archives of this site are awash with references to Dyson’s contributions, a tribute to his range and his reach. Remarkably, that intellect never deserted him even as his physical strength began to fail. Jim Benford, who has known Dyson since the 1960s, told me on the day of Dyson’s death that he had continued his yearly trips across the country to his La Jolla (CA) residence up until last year. This time around, at 96, he told Jim his doctors had argued against it. He would die a week later, a loss as deep to this field as his contribution was rich.

We shall know what we go to Mars for only after we get there. The study of whatever forms of life exist on Mars is likely to lead to better understanding of life in general. This may well be of more benefit to humanity than irrigating ten Saharas. But that is only one of many reasons for going. The main purpose is a general enlargement of human horizons.

Thus Dyson in a letter from La Jolla in 1958. Really, you must read Maker of Patterns. And from my 2003 interview with him:

Look at how people spread around the Earth. It’s not clear why we want to travel so much, but we do. It seems to be characteristic of humans from the time we left Africa. Why do people leave Africa to spread out to all these desolate places, to Siberia and across the Pacific? We know that people just do this. It’s part of human nature…

I think of him foremost as a deeply sane man, one who saw both the aspirations of the human mind as well as its limitations and took on the challenge of explaining life’s mysteries with a fierce joy. No one who reads, and re-reads, his essays and papers can miss this affirmation of mind at work, always building in new directions, unifying, shaping, questioning. It would be superfluous to try to summarize his many accomplishments in one post, for we will, inevitably, be turning his ideas over in our discussions for the rest of the lifetime of Centauri Dreams.

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Trident: Firming up the Triton Flyby

It’s not a Triton, or even a Neptune orbiter, but Trident is still an exciting mission, a Triton flyby that would take a close look at the active resurfacing going on on this remarkable moon. Trident has recently been selected by NASA’s Discovery Program as one of four science investigations that will lead to one to two missions being chosen at the end of the study for development and launch in the 2020s.

These are nine-month studies, and they include, speaking of young and constantly changing surfaces, the Io Volcanic Observer (IVO). The other two missions are the Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy (VERITAS) mission, and DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus).

Each of these studies will receive $3 million to bring its concepts to fruition, concluding with a Concept Study Report, at which point we’ll get word on the one or two that have made it to further development and flight. The NASA Discovery program has been in place since 1992, dedicated to supporting smaller missions with lower cost and shorter development times than the larger flagship missions. That these missions can have serious clout is obvious from some of the past selections: Kepler, Dawn, Deep Impact, MESSENGER, Stardust and NEAR.

Active missions at the moment include Lunar Reconnaissance Orbiter and InSight, but we leave the inner system with Lucy, a Discovery mission visiting a main belt asteroid as well as six Jupiter trojans, and Psyche, which will explore the unusual metal asteroid 16 Psyche. Discovery missions set a $500 million cost-cap excluding launch vehicle operations, data analysis or partner contributions. The next step up in size is New Frontiers, now with a $1 billion cost-cap — here we can mention New Horizons, OSIRIS-REx and Juno as well as Dragonfly.

I assume that New Horizons’ success at Pluto/Charon helped Trident along, showing how much good science can be collected from a flyby. Triton makes for a target of high interest because of its atmosphere and erupting plumes, along with the potential for an interior ocean. The goal of Trident is to characterize the processes at work while mapping a large swath of Triton and learning whether in fact the putative ocean beneath the surface exists. A mid-2020s launch takes advantage of a rare and efficient gravity assist alignment to make the mission feasible. Louise Prockter, director of the Lunar and Planetary Institute in Houston, is principal investigator.

Image: Dr. Louise Prockter, program director for the Universities Space Research Association, as well as director of the Lunar and Planetary Institute, is now principal investigator for Trident. Credit: USRA.

We can thank Voyager 2 for providing our only close-up images of Triton, which was revealed to be a place where explosive venting blows dark material from beneath the ice into the air, material which falls back onto the surface to create new features. The terrain is varied and notable for the striking ‘cantaloupe’ pattern covering large areas. With its distinctive retrograde rotation, orbiting opposite to Neptune’s rotation, and high inclination orbit, Triton may well be an object captured from the Kuiper Belt, in an orbit where tidal forces likely lead to interior heating that could maintain an ocean. What we learn here could inform our understanding not just of KBOs, but also giant moons like Titan and Europa, and smaller ocean worlds like Enceladus.

This would be a flyby with abundant opportunities for data collection, as this precis from the 2019 Lunar and Planetary Science Conference makes clear:

An active-redundant operational sequence ensures unique observations during an eclipse of Triton – and another of Neptune itself – and includes redundant data collection throughout the flyby… High-resolution imaging and broad-spectrum IR imaging spectroscopy, together with high-capacity onboard storage, allow near-full-body mapping over the course of one Triton orbit… Trident passes through Triton’s thin atmosphere, within 500 km of the surface, sampling its ionosphere with a plasma spectrometer and performing magnetic induction measurements to verify the existence of an extant ocean. Trident’s passage through a total eclipse allows observations through two atmospheric radio occultations for mapping electron and neutral atmospheric density, Neptune-shine illuminated eclipse imaging for change detection since the 1989 Voyager 2 flyby, and high-phase angle atmospheric imaging for mapping haze layers and plumes.

Image: Global color mosaic of Triton, taken in 1989 by Voyager 2 during its flyby of the Neptune system. Color was synthesized by combining high-resolution images taken through orange, violet, and ultraviolet filters; these images were displayed as red, green, and blue images and combined to create this color version. With a radius of 1,350 kilometers (839 mi), about 22% smaller than Earth’s moon, Triton is by far the largest satellite of Neptune. It is one of only three objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn’s giant moon, Titan). Triton has the coldest surface known anywhere in the Solar System (38 K, about -391 degrees Fahrenheit); it is so cold that most of Triton’s nitrogen is condensed as frost, making it the only satellite in the Solar System known to have a surface made mainly of nitrogen ice. The pinkish deposits constitute a vast south polar cap believed to contain methane ice, which would have reacted under sunlight to form pink or red compounds. The dark streaks overlying these pink ices are believed to be an icy and perhaps carbonaceous dust deposited from huge geyser-like plumes, some of which were found to be active during the Voyager 2 flyby. The bluish-green band visible in this image extends all the way around Triton near the equator; it may consist of relatively fresh nitrogen frost deposits. The greenish areas includes what is called the cantaloupe terrain, whose origin is unknown, and a set of “cryovolcanic” landscapes apparently produced by icy-cold liquids (now frozen) erupted from Triton’s interior.
Credit: NASA/JPL/USGS.

If it flies, Trident would launch in 2026 and reach Triton in 2038, using gravity assists at Venus, the Earth and, finally, Jupiter for a final course deflection toward Neptune. The current thinking is to bring the spacecraft, which will weigh about twice New Horizons’ 478 kg, within 500 kilometers of Triton, a close pass indeed compared to New Horizons’ 12,500 kilometer pass by Pluto. This is indeed close enough for the spacecraft to sample Triton’s ionosphere and conduct the needed magnetic induction measurements to confirm or refute the existence of its ocean. As this mission firms up, we’ll be keeping a close eye on its prospects in the outer system. Remember, too, the 2017 workshop in Houston examining a possible Pluto orbiter, still a long way from being anything more than a concept, but interesting enough to make the pulse race.

My friend Ashley Baldwin, who sent along some good references re Trident, also noted that Trident’s trajectory is such that the gravity assist around Jupiter could, at 1.24 Jupiter radii, provide a close flyby of Io. Interesting in terms of the competing Io Volcanic Observer entry.

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A Deep Dive into Tidal Lock

Mention red dwarf habitable zones and tidal lock invariably comes up. If a planet is close enough to a dim red star to maintain temperatures suitable for life, wouldn’t it keep one face turned toward it in perpetuity? But tidal lock, as Ashley Baldwin explains in the essay below, is more complex than we sometimes realize. And while there are ways to produce temperate climate models for such planets, tidal lock itself is a factor in not just M-dwarfs, but K- and even G-class stars like the Sun. Flip a few starting conditions and Earth itself might have been in tidal lock. The indefatigable Dr. Baldwin keeps a close eye on the latest exoplanet research, somehow balancing his astronomical scholarship with a career as consultant psychiatrist at the 5 Boroughs Partnership NHS Trust (Warrington, UK). Read on to learn a great deal about where current thinking stands on a subject critical to the question of red dwarf habitability.

by Ashley Baldwin

“Tidal locking”, “captured rotation” or “spin-orbit locking” etc occurs in most recognised guise when an orbiting astronomical body (be it a moon, planet or even a star) always presents the same face towards the object it is orbiting. In this instance, the orbit of the “satellite” body can be referred to as “synchronous”, whereby the tidally locked body takes as long to rotate around its own axis as to orbit its partner. This occurs due to the primary body’s gravity flexing the orbiting body into an elongated “prolate” shape. This in turn is then exposed to varying gravitational interaction with the central body.

Figure 1: Tidal stresses and tidal locking

As the “orbiter” rotates, its now elongated axis falls out of line with the central mass, which consequently perturbs it as it rotates across its orbit. It thus becomes subject to gravitationally induced torques that can act as a brake — through energy exchange and dissipation, the latter via friction-induced heat loss in the perturbed orbiting body. As M dwarf habitable zones are closer to their central star and their gravitational influence thus greater, it’s easy to see how this dissipated heat can contribute substantially to an exoplanet’s overall energy flux and can even affect its habitability potential – possibly tipping it into a runaway greenhouse scenario. (Kopparapu 2013).

Over millions of years (or more) this process can lead to “orbital synchronisation”. This arises when the orbiting body reaches a state where there is no longer any net exchange of rotation during the course of a completed orbit (Barnes 2010). Leaving a tidal locking state would only be possible with the addition of energy to the system. This might occur should some other massive object (such as a planet, or a star in, say, a binary system) break the equilibrium. If the masses of the two bodies (for instance Pluto & Charon) are similar, they can become tidally locked to each other.

Not all tidal locking involves synchronisation. “Super-synchronisation” occurs where an orbiting body becomes tidally locked to its parent body but rotates at a fixed but quicker rate. A topical example of this is the erstwhile “geosynchronous transfer orbit” (GTO). We see this on launcher specs all the time: “Payload to GTO”. This orbit is external to geosynchronous orbit, where many satellites start their operational lives, but allows for pre-orbital insertion inclination changes — economically expending less propellant prior to final insertion. Alternatively, such orbits can be used as dumping grounds for non-functioning satellites or related debris, so-called “geo-graveyard belts” (Luu 1998). Simulations suggest many exoplanets could exist in variants of such orbital types.

Gravitational interaction with a central star leads to progressive rotational slowing of a smaller planetary body like Mercury via energy exchange and heat dissipation. This is due to subtle but important tidal force variations across the orbiting body (remembering that gravity is inversely proportional to the square of the distance between any two bodies — thus “gravitational gradients” exist across solid bodies, leading to bulges). However, if the initial planetary orbit is significantly eccentric, this effect varies substantially across the orbital period (especially at periapsis — the point of strongest gravitational interaction) and can instead result in a spin-orbit resonance. In Mercury’s case, this is 3:2 (three rotations per two orbits) but other ratios can occur from 2:1 through 5:2 (Mahoney 2013). It’s worth noting that this effect is most pronounced for closer-in planets where the gravitational effects are greatest, so the effect should be even more relevant for the tightly packed exoplanetary architectures (e.g. TRAPPIST-1) that seem to be prevalent.

In extreme cases where the orbiting body’s orbit is nearly circular AND has a minimal or zero axial tilt — such as with the Moon — then the same hemisphere (libration allowing) faces the primary mass.

That said, for simplicity we will now assume that a smaller mass body (exoplanet) is orbiting a very much more massive body (star) — this is the focus of this review, with an unavoidable nod towards habitability.

For reasons of brevity and also pertaining to the exoplanet subject matter of recent posts, we will limit ourselves to the specific case of terrestrial exoplanets and their orbits around smaller main sequence stars.

The time to tidal locking can even be described by the adapted equation :

Tlock ≈ wa6 (0.4 m*R2) / (3 Gmp2 kR5) (Goldreich, Goldreich & Soter 1966); (Peale 1977); (Gladman 1996); (Greenberg 2009)

Where Tlock is “time to tidal locking”, w and k are constants which can be ignored for simplicity, m* is mass of the star, mp is mass of the planet, R is the exoplanet radius and “G” is Newton’s all important gravitational constant.

Tlock is substantially lengthened by “a” — increasing planetary semi-major axis (to the sixth power!). Tidal locking time is also increased by 0.4 X m* in this equation. However it is important to remember the context and just how massive a star, indeed ANY star, is — even an M dwarf star — many times, orders of magnitude even, more massive than a planet. A star thus plays the major role in the tidal locking of its attendant planets.

The gravitational constant G ensures that increasing stellar mass will substantially decrease Tlock. All other things being equal, increasing stellar mass is a major factor in reducing time to tidal locking.

Figure 2: Stellar mass & type versus semi-major axis orange / red graph with superimposed Tsync for 0.1,1 and 10 gigayear times for an Earth mass planet. (Penz 2005)

The concept of synchronisation is relatively new, dating back to Stephen Dole’s seminal Habitable Planets for Man at the beginning of the space age in the early 1960s. The concept was purely theoretical, with somewhat arbitrary parameters at this point, but it implied that tidal lock would be a major impediment to the human-friendly “habitable” exoplanets Dole had in mind for his book. It was here that tidally locked orbits and planets in M-dwarf systems were first linked, in a negative way that to some extent still exists today (before we even get to coronal mass ejections, EUV and stellar flares et al !) Atmospheric collapse due to freezing out on the side of the planet facing away from the star is not the least of these problems.

It was only in 1993 that Kasting et al employed sophisticated 1-D climate modelling as part of describing what constituted habitable planets. Habitable planets essentially now meant planets with conditions that could sustain liquid water on their surfaces. This is a rather lower bar than that set by Dole thirty years earlier, but far more applicable and still a pillar of exoplanet science today. More importantly, Kasting’s team also simulated star/planet gravitational interaction.

They did this by utilising the “Equilibrium Tide” model (ET). Refined variants of this have now become THE staple of all subsequent related studies, as it too has “evolved”. The model essentially assumes that the gravitational force of the tide-raiser (star) produces an elongated shape in the perturbed body (exoplanet) and that its long axis is slightly misaligned with respect to an imaginary line connecting the two centres of mass.

The misalignment is crucial and is due to the dissipating processes within the “deformed” exoplanet, leading to evolution of the orbit and spin angular moments. From this, various equations can be created which map out the orbital and rotational evolutionary history of exoplanets over time (see above). ET was originally derived from the Earth/Moon system by Darwin in 1880 before refinement by Pearle in 1977. Iterations vary in subtle but significant ways and are used as the basis for increasingly sophisticated simulations as computing power increases. Barnes 2017 has carried out a detailed review of synchronising and ET modelling (see below).

Kasting et al showed synchronisation of putative exoplanets orbiting in the habitable zones of M-dwarfs, stars with a mass of up to 0.42 Msun, within 4.5 billion years. They introduced the now familiar term “tidal locking radius”. Though a big step forward, this had the unfortunate consequence of continuing to propagate a pessimistic view of habitable exoplanets orbiting such stars. Importantly, stellar mass was still viewed as the major if not sole cause of synchronisation. The graph below (from Yang et al 2014), though based on sophisticated modelling, still captures this type of thinking. Here various habitable zone model ranges are superimposed on a graph of relative stellar insolation (and star type) versus semi-major axis examples of known exoplanets, adding realistic perspective. You will note also that for a 0.42 Msun star, with a temperature around 3500 K, the 1-D inner habitable range is very close to the value attributed to recently discovered TOI 700d — mid-80s percent.

Figure 3: Temperature of star versus stellar flux graph with superimposed coloured star classes and dashed gray “tidal locking radius” line.

The effects of other factors — such as starting orbital eccentricity (already encountered above with Mercury), baseline rotation rate, the presence of companion bodies (Greenberg, Corriea 2013) thermal tides arising from atmospheres (Leconte et al 2015), and stellar and planetary interiors (Driscoll & Barnes 2015), orbital tilt (Barnes 2017) — were not considered. As can be seen, it has only been over the last five years or so that these things have been added to simulations. Indeed, the results of these studies very much alter the whole tidal locking paradigm with particular relevance to habitable zones, which despite refinement (Kopparapu 2013, Selsis 2007) have only changed slightly, a big compliment to Kasting’s work in 1993.

Taken altogether, habitable zone planets of M,K and G stars all have the potential to become tidally locked. Not just M dwarfs — though their potential remains very much the greatest and especially for < 0.1 Msun stars such as TRAPPIST-1. Even the Earth, had its starting rotation been greater than just three days, according to Barnes 2017, might have become synchronous.

For the sake of brevity, this review has largely focused on stellar mass as a major driver in exoplanetary synchronisation. As can be seen above, as knowledge in this area progresses, other processes come into account. It is also becoming increasingly difficult to tease these out from drivers of exoplanetary habitability. So to this end we must look in more detail at some of the factors named above.

The planet Venus is unusual in many ways, but one in particular stands out: its retrograde and slow rotation rate that is longer than its orbital period. Why? What makes Venus different? One factor is that it is a rocky planet with a substantial atmosphere (92 bar at its surface). We all know about the infamous runaway greenhouse effect this drives, making Venus the hottest planet in the Solar System despite being further from the Sun than (spin/orbit resonant) Mercury. However, does this atmosphere have any other effects?

On Earth, the day/night cycle leads to variations in heat distribution in the atmosphere. It is known that the hottest time of day on Earth does not occur when the Sun is at its zenith and thus nearest to the Earth, but rather several hours later. This is because of thermal inertia. There is a delay between solar heating and thermal response, leading to mass redistribution. As the atmosphere and the Earth’s surface are generally well linked via friction, this will give rise to non-negligible thermal torques.

These torques are akin to the torques arising from the Sun’s uneven gravitational interaction with the Earth described above, though not as potent. On the Earth with its extended 1 AU orbit, they are largely inconsequential, but for 0.3 AU nearer Venus, they become significant. Depending on their direction, they can either slow up OR speed up planetary rotation, but either way they help to resist synchronisation. Over time, torques arising in Venus have acted to slow down its rotation, so much so that it has reversed to the retrograde pattern we see today.

So if this is true of Venus, how about exoplanets? Can these atmospheric torques resist or at least delay synchronisation and tidal locking in vulnerable areas around a star? This has been extensively modelled by Leconte et al 2015 and the answer was a resounding yes, especially for smaller, less luminous stars with close-in habitable zones, and not just for exoplanets with 90 bar atmospheres, either. Even 1 bar Earth-like atmospheres could help resist synchronisation for the habitable zones in stars of 0.5 Mearth – 0.7 Mearth.

Ten bar atmospheres were simulated and shown to resist synchronisation even for habitable zone planets orbiting 0.3 Mearth stars (mid-M dwarfs). These are the high bar “maximum greenhouse” CO2 atmospheres that are postulated to occur in the outer regions of stellar habitable zones. But there are limits. Venus’ 92 bar atmosphere is ironically so thick that most of the incident sunlight that isn’t reflected back into space is either absorbed or scattered before it can reach the planetary surface and exert the driving effect of thermal torques (Leconte et al 2015).

Figure 4: Red arrow synchronous rotation / blue arrow asynchronous rotation graph (Leconte 2015).

Orbital synchronisation and exoplanet habitability remains a contentious theoretical field that is subject to continual debate and constant change. Modern Global Climate Modelling (GCM) has become a sophisticated sub-science. Using an earlier iteration of GCM, Yang et al showed in 2013 that synchronised M-dwarf habitable zone planets would form thick cloud banks above their sub-stellar point. This would then reflect much of the incident stellar flux, thus reducing the energy reaching the surface. In turn, this would reduce the overall energy reaching the planet and so reduce global temperatures. The net effect in theory is to extend the stellar habitable zone inwards. However, the same author collaborated with Wolf and Kopparapu in 2016 to apply an updated 3-D model to the same problem. This showed that a sub-stellar cloud bank could not form, or would form and then move, a result effectively rebutting the 2013 findings and moving the habitable zone back to its original pre 2013 starting point. Expect more of this !

So, all things considered, just how easy is it for an exoplanet to become tidally locked and just how easy can habitable zone planets become tidally locked ? Barnes 2017 attempted to address just this question for exoplanets in circular orbits. He applied two well recognised refined variants (CPL left, CTL right in the graphic below) of the ET to two model populations of exoplanets orbiting differing stellar masses, and ran thousands of giga-year simulations for each (think of the computing power and time!) One population had a starting orbital period of 8 hours and an orbital tilt of 60°. The other had a starting period of ten days and a tilt of 0°. This produced the four outcomes illustrated below. The superimposed grey shading represents the latest habitable zones (Kopparapu 2013) iteration, with the dark grey representing the “conservative” and the light the “optimistic”.

Figure 5: “Four in one” black and white stellar mass vs semi-major axis / superimposed greyscale habzone graphs.

These results are indicative and significantly different from the status quo, which is that tidal locking is only something that applies to exoplanets orbiting in close to M dwarf and smaller K dwarf stars. For one thing, even this older paradigm implies that at least some “Goldilocks” stars are not quite as homely as expected (more Kasting than Dole). The Barnes work hints at potential overlap of the habitable zone for potentially a large fraction of K-class and even many G-class stars, driven by factors beyond simple stellar mass. Clearly planets with a slow initial rotation rate and low orbital tilt are at greater risk, as may prove the case. Opposed to this are non-synchronising factors such as, inter alia, higher baseline orbital eccentricities and the close proximity of other orbiting bodies (moons, planets …thinking TRAPPIST-1 and binary stars/brown dwarfs, as with the recently described Gliese 229Ac system).

What this also shows is the inextricable link between orbital features and planet habitability. No more so demonstrated than by Kepler, and likely even more so with its greater number of short orbital period planets, with any potential habitable zone planetary candidates lying within just tenths or less of an AU from their parent star. This is very much in the “red arrow” synchronous zone in the Leconte graphic above.

There are now over 4000 known exoplanets. The current focus is on their “characterisation” and this is largely about atmospheres and biosignatures. However, it is obvious that we need to know far more about their evolving and historical orbital properties. This is a part of a process of determining habitable planets/zones, which are about so much more than stellar mass.

Most of the exoplanets discovered already by Kepler et al orbit close in to their stars, including those few in the potential tidal lock habitable zone. Ongoing Doppler photometry and TESS will identify thousands more such exoplanets, many of which will be even closer to their latest star given TESS’ shorter 27 day observation runs. TOI 700d and Gliese 229Ac are just for starters. Hopefully the search for habitability will expand to encompass the unavoidable connexion with planetary orbital features.

Know the star to know the planet, but know the orbit to know them both.

Figure 6: Stellar effects/planetary properties/planetary systems (Meadows and Barnes 2018)

References

Barnes,R. Formation and evolution of exoplanets. John Wiley & Sons, p248, 2010

Barnes, R. Tidal locking of habitable exoplanets. Celestial mechanics and dynamical astronomy Vol 129, Issue 4, pp 509-536, Dec 2017

Darwin, G H. On the secular changes in the elements of the orbit of a satellite revolving about a tidally distorted planet. Royal Society of London Philosophical Transactions, Series I, 171:713-891 ; 1880.

Dole, S H. Habitable Planets for Man. 1964

Goldreich, P. Final spin rates of planets and satellites. Astronomical Journal, 71, 1966

Goldreich, P., Soter, A., Q in the solar system. Icarus 5, 375-389, 1966

Gladman, B et al. Synchronous locking of tidally evolving satellites. Icarus 133 (1) 166-192, 1996

Greenberg, R. Frequency dependence of tidal Q, The Astrophysical Journal, 698, L42-45, 2009

Kasting, J. F. Habitable zones around main sequence stars. Icarus,101 d 108-128 Jan 1993

Kopparapu, R K et al. Habitable zones around main sequence stars: New Estimates. The Astrophysical Journal, 765;131, March 2013

Kopparapu R K, Wolf E, Yang et al. The inner edge of the habitable zone for synchronously rotating planets around low-mass stars using general circulation models. The Astrophysical Journal Volume 819, Number 1, March 2016

Luu, K. Effects of perturbations on space debris in super-synchronous storage orbits. Air Force Research Laboratory Technical Reports, 1998

Mahoney,T J. Mercury. Springer Science & Business Media, 2013

Meadows V S, Barnes R K. Factors affecting exoplanet habitability. In Handbook of Exoplanets P57, 2018

Peale, S J. Rotation histories of natural satellites. Burns, J A, Editor, IAU Colloquium 28; Planetary Satellites, p 87-111, 1977

Penz,T et al. Constraints for the evolution of habitable planets: Implications for the search of life in the Universe: Evolution of Habitable planets, 2005

Yang, J et al. Stabilising cloud feedback dramatically expands the habitable zone of tidally locked planets. The Astrophysical Journal Letters: 771:L45, July 2013

Yang, J et al. Strong dependence of the inner edge of the habitable zone on planetary rotation rate. The Astrophysical Journal Letters: 787:1, April 2014

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Bound in Shallows: Space Exploration and Institutional Drift

If those of us from the Apollo era sometimes look back with regret at the failure of our society to follow through on early lunar exploration, we can still acknowledge that the issue is far from settled. As Nick Nielsen points out in the essay below, we’re in an interesting period, one in which commercial interests are changing how we look at future space missions, and indeed, changing our view of what may be considered the central project of our civilization. With historical sweep that takes in the death of Socrates, paleolithic art and Arthurian mythology, Nick sees as the great monuments of civilization not just the Pyramids, the Parthenon and the Taj Mahal, but also the Large Hadron Collider and the International Space Station. Here’s a richly textured probe, then, into the mythologies that make us who we are and who we will be, and the forces that shape what a civilization chooses to do.

by J. N. Nielsen

There is a Tide in the affayres of men,
Which taken at the Flood, leades on to Fortune:
Omitted, all the voyage of their life,
Is bound in Shallowes, and in Miseries.

Shakespeare, Julius Caesar, Act IV, scene iii, lines 2217-2220
Brutus to Cassius, before the battle at Philippi

1. Ankle Deep in the Shallows
2. Periodization of the US Space Program
3. Scenarios for Spacefaring Breakout
4. A Stagnant Space Age
5. A Digression on Periodization
6. Institutions and Their Central Projects
7. Institutional Drift in Private Enterprise
8. The Consolation Prize for Institutional Drift
9. How the Space Industry Got Its Groove Back
10. Finding a Compromise That Works
11. Human Purposes in Deep Time
12. Sufficient Conditions for Spacefaring Civilization
13. The Weston Principle
14. The Beginning of the Inquiry

1. Ankle Deep in the Shallows

Carl Sagan opened his Cosmos, both the television series and the book, with this reflection:

“The surface of the Earth is the shore of the cosmic ocean. From it we have learned most of what we know. Recently, we have waded a little out to sea, enough to dampen our toes or, at most, wet our ankles. The water seems inviting. The ocean calls. Some part of our being knows this is from where we came. We long to return.” [1]

For Sagan the water seemed inviting, but to continue the metaphor with which Sagan began, if the ocean had called to humanity, we could have continued wading further into the tide, into deeper waters, until eventually we lost our firm footing and, in order to continue, we would have had to swim forward, out into the deeper, darker waters. Instead, we waded out ankle deep with Apollo, but then retreated and now are only keeping our toes damp.

What has happened to space exploration? Why has it faltered from its ambitious and hopeful beginnings to become what it is today? Who is responsible for the contemporary state of space exploration? What can be done about the state of space exploration? Are we to expect more of the same, such as we have seen for the past fifty years, or will there be a revival of space exploration no less ambitious than its initial efflorescence?

Here I am going to attempt to discuss many matters that I have also discussed earlier and elsewhere, but hopefully to bring together some disparate threads so as to see them whole in their social context. While the lens of my discussion will be the US space program and its institutional drift since the Space Race, what I have to say about the US space program applies, mutatis mutandis, to other institutions and their programs. Specifically, what I have to say about the institutional drift of the US space program applies to the institutional drift of other institutions, both larger and smaller than the space program. It applies to larger institutions, such as the largest of all human institutions — civilization (one of my eight definitions of civilization is that civilization is an institution of institutions)—as well as to smaller institutions—say, individual businesses, or particular scientific research programs—both of which, large and small, falter, founder, and fail when purpose is lacking.

2. Periodization of the US Space Program

Considered historically, the US space program may be roughly divided into three periods:

1. Prehistory: aviation and aeronautical development leading up to the Sputnik Crisis
2. Founding Era: from the Sputnik Crisis to the Apollo Program
3. Stagnant Era: from the Apollo Program to the present day

The prehistory of the space program can be traced all the way back to the first use of tools by human beings. For any technological development we might identify as the authentic beginning of the aviation and aeronautics, there is another technological development prior to this that could be identified as a prerequisite for the later technological development, so that the identification of any one technological threshold is merely conventional. We can identify conventional historical thresholds if we like—for example, we could identify an immediate predecessor era to the Founding Era that could begin with Robert Godard’s liquid-fueled rocket of 1926, or, before that, with Hermann Oberth’s 1923 book The Rocket into Planetary Space (Die Rakete zu den Planetenräumen), or, before that, with Konstantin Tsiolkovsky’s 1903 book Exploration of Outer Space by Means of Rocket Devices (???????????? ??????? ??????????? ??????????? ?????????)—in order to give an earlier bound to a immediate predecessor period. The many possible thresholds for a more narrowly defined prehistory to aerospace technology (narrower, that is, than simply taking the whole of technological prehistory) points to the problem of identifying an authentic origin. There is nothing at all illegitimate about an inquiry into origins, or in formulating a periodization based on such an inquiry, but it is not a problem with which I will concern myself here.

The Founding Era [2] speaks for itself. It begins with an accomplishment, the first artificial satellite, but this accomplishment was not the end of a great effort; rather, Sputnik was the beginning of a great effort, and was immediately followed by further accomplishments building upon the Sputnik success, ultimately culminating in the Apollo moon landings. The Russian space program did not ultimately send cosmonauts beyond low Earth orbit, but the trajectory of the Soviet program could be given a similar periodization to that I have given for the US space program, as during the Space Race the Soviet space program was rapidly advancing in technology and the pace of operations in order to match the US space program, and, given time, might have launched its enormous N1-L3 rocket, rival to the Saturn V, and made its own attempt at a moon landing.

The Stagnant Era, the present era of space exploration, is that period since the end of the Apollo program which has been characterized by a lack of clear purpose, both public and private institutional drift, and a failure to aggressively develop the technologies of space exploration, that is to say, a failure to push the envelope of technological development. (I have earlier discussed the stagnancy and institutional drift of the US space program in A Strategic Pause in the Development of Spacefaring Civilization.) In section 4, below, we will go into much greater detail on the Stagnant Era.

We can postulate a nascent fourth period now underway (a post-Stagnancy Era) during which private space industries may fulfill and expand upon the promise of the Founding Era, though at the present time it is not yet clear if we have emerged from fifty years of space exploration stagnation, or whether the apparent momentum of the present is illusory and will either come to an end in the near future, or it will enter into its own comfortable plateau of stagnation once it passes beyond infancy. I have a theoretical and analytical interest in history, but I am not a prophet, so I will not attempt to predict which fork in the road our civilization will take over the next few decades. (However, my theoretical perspective does not mean that I am without any agenda, and I will make no secret of my preferred outcome.)

One of the remarkable features of the Stagnant Era is that there has been, at least since the 1930s (judging by the science fiction of the period), a clear awareness of the possibility of how space exploration and space industry could transform human life on Earth and lead to a human civilization encompassing and transcending Earth, but, despite the awareness of the vision, that vision alone was insufficient to drive a spacefaring breakout. An active space program, both in terms of crewed missions and space science robotic missions, also has been insufficient to drive a spacefaring breakout. Given that being a space-capable civilization is a necessary condition of spacefaring breakout, this begs the question as to what exactly would constitute a sufficient condition for a spacefaring breakout.

3. Scenarios for Spacefaring Breakout

What do I mean by “spacefaring breakout”? In The Spacefaring Inflection Point I distinguished three scenarios for what I call spacefaring breakout, which is when some heretofore exclusively planetary civilization becomes a spacefaring civilization:

Early Inflection Point: when spacefaring is pursued with exponential scope and scale immediately upon the technology being available.
Mediocre Inflection Point: when spacefaring is pursued with exponential scope and scale only after it has been available for a substantial period of time, but in the same longue durée period within which the technology became available.
Late Inflection Point: when spacefaring is pursued with exponential scope and scale only after the technology has been available throughout a longue durée period of history, so that the realization of spacefaring appears in a subsequent longue durée period of history. [3]

To return to our opening metaphor of the cosmic ocean borrowed from Carl Sagan, spacefaring breakout is the moment when we no longer feel the sand beneath our feet, and we must begin to swim if we wish to continue to move forward, rather than to retreat; the transition from wading to swimming is the inflection point. Once you’re swimming in the cosmic ocean, even if you are still in sight of the shore, you are no longer reliant upon this proximity, and the whole of the cosmos is open to the strongest swimmers.

The same transition from planetary to spacefaring civilization can be formulated as the distinction between space-capable civilizations and spacefaring civilizations, a distinction due to Dr. Jim Pass and elaborated in his paper “An Astrosociological Perspective on Space-Capable vs. Spacefaring Societies” Employing Pass’s terminology, spacefaring breakout is the transition from space-capable to spacefaring civilization, and the above schematic trichotomy distinguishes three formulations of this transition as an historical process. A spacefaring breakout is not yet part of human history, but it can be thought of in historical terms, i.e., as an historical process, albeit an historical process that, if it occurs, will occur in the future. However, the process is no less historical for being set in the future.

Making this tripartite distinction in spacefaring breakout makes the question of the previous section—What exactly would constitute a sufficient condition of a spacefaring breakout?—three distinct questions:

• What could constitute a sufficient condition of an early spacefaring inflection point?
• What could constitute a sufficient condition of a mediocre spacefaring inflection point?
• What could constitute a sufficient condition of a late spacefaring inflection point?

In each of the above questions, the necessary condition of a spacefaring breakout, whether early, mediocre, or late, is the same: being a space-capable civilization. For a sufficient condition, there may be a single response that answers all three questions, or there may be a distinct answer for each distinct historical process representing spacefaring breakout, accordingly as the distinct stage of development at which a civilization finds itself as it faces the question of launching a new Age of Discovery in space—or not.

4. A Stagnant Space Age

During the Founding Era it seemed as though the space exploration vision was about to be realized, and it was in fact partially realized, but after fifteen exciting years of the Space Race, the initial efflorescence of the space program faded, and subsequent space exploration confined itself within less ambitious horizons. If the Founding Era had been the historical point of origin for spacefaring breakout, human civilization would have experienced an early spacefaring inflection point. [4]

The Space Race was a superpower competition by proxy, and was not about achieving a spacefaring inflection point, although the two seemed to coincide for a time. Instead of (or, perhaps I should say, in addition to) fighting each other on proxy battlefields of the Cold War, the US and the USSR fought for supremacy in space: “The US and USSR utilized the space fight and planetary exploration programs as an assertion of superiority. What made this conflict extraordinary was the fact that it was a nonviolent war.” [5] While prominent intellectuals like Bertrand Russell expressed their contempt for the superpower competition aspect of space exploration [6], there is an important sense in which the Space Race represented the best of humanity, when our destructive drive for warfare was sublimated into achievements in science, technology, and engineering. [7]

The Stagnant Era began when superpower competition reverted to less imaginative, more conventional forms of proxy warfare, but a counterfactual in which the Space Race form of superpower competition continued is far from inconceivable. Indeed, space artist Mac Rebisz, in Space That Never Was, illustrates just such a counterfactual. Rebisz writes of his artistic vision, “Imagine a world where Space Race has not ended. Where space agencies were funded a lot better than military. Where private space companies emerged and accelerated development of space industry. Where people never stopped dreaming big and aiming high.”

After fifty years of the Stagnant Era, a spacefaring breakout even in the near future would constitute a mediocre spacefaring inflection point (which would exemplify the principle of mediocrity and thus would seem more intrinsically plausible than an early inflection point). If no spacefaring breakout occurs for some time, the best that can be hoped for is a late spacefaring inflection point (if any breakout is to occur at all), though we can’t say, apart from other contingent historical circumstances not known to us, how long the present stage of development can be extended before it spills over into a new period of history.

In his Civilisation: A Personal View, Kenneth Clarke noted that, “Great movements in the arts, like revolutions, don’t last for more than about fifteen years.” [8] In so saying, he might well have been speaking of the Founding Era of space exploration, a revolution through which he had just lived as he spoke these lines. [9] Clark also noted in the same book, “People sometimes wonder why the Renaissance Italians, with their intelligent curiosity, didn’t make more of a contribution to the history of thought. The reason is that the most profound thought of the time was not expressed in words, but in visual imagery.” (p. 126) In the same spirit, it would be reasonable to say that the most advanced thought of our time is expressed in science, technology, and engineering, and that great movements in science, or in technology, or in engineering, don’t last for more than fifteen years. Perhaps no one should have expected anything more than this initial efflorescence of the dawning Space Age.

In identifying the period since the end of the Apollo Program as the Stagnant Era, I do not mean to say that nothing of significance has been done by the space program. I have many times pointed out that the space science missions NASA has mounted since the end of the Apollo program have transformed our knowledge of cosmology, and have done so at a relatively low cost in comparison to much “big science.” [10] Judged by the magnitude of the knowledge acquired, these space science missions may have been the best money human beings have ever spent. But expanding our knowledge of the cosmos, while admirable and scientifically exciting, is not going to transform our terrestrial civilization into a spacefaring civilization.

A mature planetary civilization needs to extend itself a little beyond its planetary surface, as homeworld observation is and will be a crucial part of managing a planetary biosphere over the longue durée, but such a civilization could limit itself to operations in a low orbit and still achieve the necessary observational evidence gathered by satellites—much as we have maintained a de facto limitation on human space exploration within low Earth orbit throughout the Stagnant Era. In other words, a mature, long-lived civilization is consistent with a space-capable civilization that never experiences a spacefaring breakout.

I have repeatedly encountered a number of arguments intended to explain, excuse, rationalize, or otherwise justify the stagnation of the Stagnant Era, and I understand why these arguments are made. There are expressions of the inevitability of robotic space exploration (it’s not inevitable and it’s not the same as human space exploration); that human exploration isn’t necessary because machines can do it better (the argument for space exploration isn’t from its necessity) and it would be dangerous for human beings anyway (not everyone is risk averse; some individuals seek out risk) [11]; that Apollo and similar programs were too expensive (there is no economic study that demonstrates that expenditures on the Apollo Program adversely impacted the US economy), and so on and so forth. While each individual rationale for the failure of human space exploration can be argued in its own right and on its own merits, the fact of multiple rationales for this stagnation, such that as soon as we have dismissed one, another is offered in its place, is also significant. I have called this serial excuse-making The Waiting Gambit: if we will just wait, things will be better. There will be a right time for space exploration, but that time is not now.

For those who have never lost sight of the space exploration vision, it is painful to fully accept and to internalize the fact that we have possessed the economic and technological and scientific resources necessary to a spacefaring civilization, but have simply failed as a species to pursue this opportunity. [12] One way to reconcile oneself to this painful state of affairs is to make excuses to justify this failure, but I find it both more interesting and more instructive to face the failure head-on and to try to understand it for what it is. That is what I am trying to do here.

5. A Digression on Periodization

There is a term for the duration that usually characterizes great movements and revolutions (which is what the Founding Era was), as Clark humanistically described them, and that is Fernand Braudel’s term conjuncture. Braudel distinguished three kinds of history:

“…time may be divided into different time-scales and thus made more manageable. One can look at the long or the very long-term; the various rates of medium-term change (which will be known in this book as the conjuncture); and the rapid movement of very short-term developments—the shortest usually being the easiest to detect.” [13]

Braudel also touched on these terms in the Glossary to his The Identity of France:

longue durée, la: literally ‘the long term,’ an expression drawing attention to long-term structures and realities in history, as distinct from medium term factors or trends (la conjuncture) and short-term events (l’évènement) [14]

Richard Mayne, in his Translator’s Introduction to Braudel’s A History of Civilizations, argued that Braudel had arrived at his tripartite levels of periodization as a response to the problem posed by the relationship between, and the concurrent exhibition of, the immediacy and drama of history as it transpires before our eyes, and the silent background to these events which changes little but constitutes the context that makes the passing spectacle meaningful and comprehensible. Mayne described Braudel’s three nested periodizations intended to address this problem in the following terms:

“…the quasi-immobile time of structures and traditions (la longue durée); the intermediate scale of ‘conjunctures,’ rarely longer than a few generations; and the rapid time-scale of events.” [15]

Braudel deemphasizes the history of the event, and Braudel’s revaluation (and indeed devaluation) of the event is the occasion of a quote from Braudel that is poignantly instructive for his conception of history:

“Events are the ephemera of history; they pass across its stage like fireflies, hardly glimpsed before they settle back into darkness and as often as not into oblivion.” [16]

Intuitive and naïve historiography—if there is such a thing, which we might also call folk historiography — privileges the event, much as it privileges narrative. A narrative usually takes the form of a succession of events, often succeeding one another at a rapid pace:

“All historical work is concerned with breaking down time past, choosing among its chronological realities according to more or less conscious preferences and exclusions. Traditional history, with its concern for the short time span, for the individual and the event, has long accustomed us to the headlong, dramatic, breathless rush of its narrative.” [17]

Both the Founding Era and the Stagnant Era can be considered historical conjunctures in Braudel’s sense, and both conjunctures fall within the longue durée of industrialized civilization, which is less than three hundred years old. A space exploration mission like the Voyager Program, which has endured for decades, constitutes its own conjuncture. In the popular media, however, it is the event that is noted and celebrated, torn from the context of its conjuncture and its longue durée. Voyager 2 was in the news a year ago (cf. NASA’s Voyager 2 Probe Enters Interstellar Space, 10 December 2018) because it had passed out of the Solar System, as Voyager 1 had earlier, in 2012. This was an event, and, as Braudel said, it has passed across the stage like a firefly, hardly glimpsed before its settles back into darkness and eventually into oblivion. For space exploration to be more than an ephemeral sequence of events, to be something more than a headlong, dramatic, breathless rush of narrative, it needs to be more than an event; it needs to be recognized as an age in which we find ourselves — the Space Age, a space exploration conjuncture, or the longue durée of industrialized civilization converging upon and transforming itself into a spacefaring civilization.

One way to do this is to begin thinking about space exploration in terms of the longue durée, and, following Braudel, placing less emphasis upon the event. I have already invoked the longue durée in defining spacefaring inflection points; this use of Braudelian periodizations can be made more thorough, as in the following:

Early Inflection Point: when spacefaring is pursued with exponential scope and scale as a continuous sequence of events, so that the immediate prehistory conjuncture to space exploration is followed by the Founding Era conjuncture, and the Founding Era conjuncture is followed by a further conjuncture that builds upon the Founding Era. This sequence of conjunctures, in turn, begins to define a spacefaring longue durée.
Mediocre Inflection Point: when spacefaring is pursued with exponential scope and scale only after the Founding Era conjuncture is followed by several further conjunctures, some of them tightly-coupled with the Founding Era and some only loosely-coupled with the Founding Era, but the sequence of conjunctures eventually leads to a spacefaring breakout conjuncture within the same longue durée period within which the technology became available.
Late Inflection Point: when spacefaring is pursued with exponential scope and scale only after the technology has been available throughout a longue durée period of history, so that a spacefaring breakout appears in a subsequent longue durée period of history. In this way, the Founding Era is the culminating conjuncture for space technologies within a given longue durée, and after lapsing for a time, the next spacefaring conjuncture occurs in the next longue durée. It is possible that this historical rhythm might be iterated several times over before a spacefaring breakout occurs as a result of one of these spacefaring conjunctures.

The justification for thinking historically about spacefaring civilization is to employ the conceptual resources of historiography to analyze and thus to clarify our relationship to historical time, even if this historical time constitutes a period we have not yet completed, or not yet even entered. Arguably, we are not yet a spacefaring civilization, even if we are space-capable civilization, but we can think historically about potential developments, regardless of whether they come to pass.

6. Institutions and their Central Projects

The Stagnant Era, although a conjuncture of space exploration by a space-capable civilization, has been, and continues to be, characterized by the institutional drift of the space program, which latter drift has been the result of a lack of purpose. I have taken to calling the purpose of an institution its central project, having adapted this from Frank White’s The Overview Effect, in which he wrote:

“Since beginning the Overview Project, I have come to see space exploration as part of a long tradition of central projects… These projects, although involving visible material artifacts, were actually vehicles for more abstract social and psychological aims.” [18]

Human beings have created and participated in institutions large and small, and of a bewildering variety, and one of the lenses we can employ in an analysis of these institutions that have governed human social life is that of the central projects of these institutions. Despite the eponymous centrality of central institutions, it is not always easy to identify the central project of an institution, and sometimes it is downright difficult to do so. In Plato’s Republic, Socrates suggests discussing justice in relation to the state rather than justice in relation to the individual because it should be easier, he says, to see justice writ large as embodied in a just state, but this Socratic conceit does not seem to apply to the study of central projects, as the largest institution that human beings have created is civilization, and correctly identifying the central project of a civilization is often difficult, despite (or perhaps because of) the scope and scale of civilizations and their central projects.

Human communities, whether small and temporary or large and long-lasting, have coalesced around common purposes; purposes are the focus of a social group, the force that binds individuals together, and the seed from which civilizations grow into the largest common purposes that have yet emerged among human beings. These purposes begin as something small, parochial, mute, and inarticulate, but over historical time grow and adapt to become something great, cosmopolitan, eloquent, and meticulously, carefully, and explicitly articulated in the creeds and founding documents of a social tradition.

But even as great purposes grow into civilizations that unify the efforts of millions of individuals, there continue to be smaller institutions with smaller purposes, and the space programs of the various space-capable nation-states exemplify these smaller purposes. The US space program after the Sputnik Crisis [19] had a clearly articulated and easily understood goal: beat the Russians in the Space Race, which efforts were given a concrete direction by President Kennedy in 1961:

“I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish.” [20]

The goal was further elaborated in a speech at Rice Stadium in 1962 (the “Moon Speech”):

“We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too. It is for these reasons that I regard the decision last year to shift our efforts in space from low to high gear as among the most important decisions that will be made during my incumbency in the office of the Presidency.” [21]

Despite the ultimate success of the Apollo program and the clear purpose that it represented, or perhaps because of the success of the Apollo program and the purpose it represented, once that limited purpose was fulfilled, the space program of the Space Race vanished once the race had been won. For reasons related to this, John M. Logdson called Apollo a dead-end:

“Apollo turned out to be a dead-end undertaking in terms of human travel beyond the immediate vicinity of this planet; no human has left Earth orbit since the last Apollo mission in December 1972. Most of the Apollo hardware and associated capabilities, particularly the magnificent but very expensive Saturn V launcher, quickly became museum exhibits to remind us, soon after the fact, of what once had been done.” [22]

However, a few sentences further along Logsdon adds:

“In 1969 and 1970, even as the initial lunar landing missions were taking place, the White House canceled the final three planned trips to the Moon. President Richard Nixon had no stomach for what NASA proposed: a major post-Apollo program aimed at building a large space station in preparation for eventual (in the 1980s!) human missions to Mars.”

Apollo was a dead-end in so far as it was not followed by additional missions of a similar scale, but this was due to lack of political leadership and unwillingness to fund the vision, not due to any lack of a space exploration vision. The purposes for an ongoing space program were clearly articulated, but these purposes did not enjoy the spontaneous acclaim of the social body. If the additional flights to the moon had gone forward—obviously, the technology and infrastructure was all in place to do this—we would have continued to learn about conducting a space program at the scale of Apollo, and these lessons would have been applied forward to any plan that was funded to continue the momentum established by Apollo. This would have been the time to ride the flood tide to spacefaring fortune; instead, we omitted the flood tide are now bound in shallows and in misery.

For anyone with even a passing familiarity with plans for space exploration, the big picture context for the Apollo Program was the Wernher von Braun mission architecture so memorably laid out in Collier’s magazine (and thus sometimes called the “Collier’s Space Program”) from 1952 to 1954 (years before Sputnik). [23] The Space Shuttle, which was built, was a small fragment of this program, the Integrated Program Plan (IPP) [24]—it was a spacecraft without a mission, because the other parts of the IPP, which would have functioned integrally with the Space Shuttle, were not built. In this sense, the Space Shuttle was a poignant reminder of a lost opportunity (no less than Saturn V launchers, already transformed into museum exhibits, as Logsdon observed), rather than the triumph it was presented as being at the time.

We see, then, that there was a clear vision for the continuation of the US Space Program that would have involved ongoing achievements in space exploration, and moreover that this vision was given an explicit formulation by NASA with its IPP, and before that by Wernher von Braun and other space exploration visionaries. In short, if someone tries to tell you that no one knew what to do next after Apollo, that there were no purposes for the space program once the Space Race had been won, they are simply gaslighting you; there is ample evidence to the contrary.

Within just a few years of the end of the Apollo Program, Gerard K. O’Neill saw the failure to continue to fund the US Space Program at levels commensurate with the Apollo Program as the key problem, and in response to the funding crisis outlined an ambitious space program that would fund itself through solar power satellites (SPS) beaming energy back to Earth. The SPS space program was, if anything, even larger than the von Braun IPP, and involved even greater spaceflight infrastructure, but while O’Neill’s vision was consistent with space exploration, the raison d’être of the O’Neill SPS program was not space exploration per se, but space industrialization. There is a difference of tone, and a difference in rationale, between a space exploration program and a space industrialization program, though a space industrialization program would eventually be exapted for space exploration. Thus while O’Neill’s was a distinct vision of a spacefaring future, and a different purpose for the space program, it was explicitly articulated and constitutes evidence of a multiplicity of space program goals, any one of which would have meant a post-Founding Era distinct from the Stagnant Era.

Even a series of “flags and footprints” missions throughout the solar system, however narrowly conceived, but always leaving flag and footprints at some further remove from Earth, would have both contributed to experience in human spacefaring (meaning experience in the optimal use of available technologies and practical feedback on these technologies that could lead to their incremental improvement) and would have involved the development of a spacefaring infrastructure beyond that which we possess today. [25]

For example, the von Braun space program was focused on a mission to Mars, but that mission to Mars would have entailed all of the elements of the IPP—space shuttle, cislunar shuttle, space tug, nuclear shuttle, low Earth orbit space station, geosynchronous orbit space station, Lunar orbit station, Lunar surface base, and Mars base, with many of these elements assembled in Earth orbit and so providing experience in space-based construction—thus a considerable spacefaring infrastructure. It is at least arguable that, to accomplish a Mars “flags and footprints” mission with the technology known to von Braun, all of this infrastructure would be necessary, whereas the “Mars Direct” mission architecture of Zubrin has been made possible by technologies developed later.

7. Institutional Drift in Private Enterprise

The national space program began to drift when it was essentially defunded by the Nixon administration, and NASA lacked the money to carry out the plans that it had on the drawing board, but the institutional drift of the US space program went beyond government institutions. The largest aerospace contractors that made the US space program possible also began to drift after the Apollo Program, but their drift was, paradoxically, not due to a lack of money, but rather due to a superfluity of money that was made available to them through government programs that had gone adrift: here it seems that institutional drift at the national scale flowed downstream to contractors.

In its time, Boeing did a lot of visionary work, as in the 1968 Integrated Manned Interplanetary Spacecraft Concept Definition, Final Report (in six volumes — Vol. I, Vol. II, Vol. III part 1, Vol. III part 2, Vol. IV, Vol. V, Vol. VI), which is a model for a clearly and explicitly articulated vision, i.e., a very “nuts and bolts” vision in which engineering detail predominates over everything else. But at some point in the subsequent decades, Boeing lost its way. The widely discussed article in The New Republic, Crash Course: How Boeing’s Managerial Revolution Created the 737 MAX Disaster by Maureen Tkacik, demonstrates in a wider context how Boeing lost its way by focusing on its stock price rather than on its products. This is another way of saying that Boeing’s central project, once clearly defined by the engineering challenges of aerospace innovation, drifted away from this focus and was captured by financial interests, which is the common fate of institutions in a condition of drift: when they cease to aspire to an ideal, they tend to the lowest common denominator.

In any large institution—whether an aerospace contractor or a government or an educational system, etc.—there will always be a variety of human types employed. There will, of course, be those who are true believers in the mission of the institution, but this isn’t necessarily the largest part of the staff. Large enterprises mean that many people are brought into a project who have only a peripheral interest in the central project. There will be some within the institution who are mere time-servers, waiting until retirement so that they can collect a comfortable pension. There will be some managers and administrators who are only involved in order to further their careers. There will be those who will get by with as little work as possible. And there will be those who see their duty as being that of making their institution the most successful institution that it can be, but, since they don’t understand or appreciate the central project, their understanding of institutional success is in terms of conventional measures of profit, career advancement, and market share.

This is not to throw shade on the employees of large aerospace contractors and their motivation and commitment; the problems with large institutions are systemic, and not the fault of individuals. I have no doubt that in the Mongol’s Golden Horde there were probably a good number of mediocre horsemen who were not made of the same stuff as those horsemen who achieved decisive victories against the Hungarians at the Battle of Mohi and against the Seljuks at the Battle of Köse Da?. [26]

It is entirely possible for a given business enterprise to be wildly successful in conventional metrics while failing to fulfill the central project that was its raison d’être when the business was founded. It is also entirely possible that a given business enterprise is founded with the intention of making a profit and advancing the careers of its employees, and only becomes attached to some central project for contingent historical reasons that have no intrinsic relationship to the business enterprise in question. This, again, is a function of size. A very large project like the Apollo Program involved numerous contractors, and it would be unrealistic to expect that all of these contractors were as committed to the mission as those who conceived the vision. That doesn’t mean that these contractors weren’t committed to the mission, only that doing great work on the mission was a means to an end, and not an end in itself.

8. The Consolation Prize for Institutional Drift

I am not unaware that, in an age of technology-driven warfare, a nation-state must spend liberally on its aerospace industry in order to ensure that it possesses the technology and expertise to compete as a peer in the contest for air superiority, and that such liberal spending on defense-related industries will inevitably result in a certain amount of waste and corruption, but the waste is often the price of keeping these industries afloat. However, subsidizing industries crucial to national defense is in no sense inconsistent with a strong sense of purpose, and indeed I would argue that an aerospace industry subsidized by space exploration missions that further the central project of a space program would be more effective subsidies and, more, would lead to greater innovation and capability than the kind of lazy subsidy we see with rewarding contractors cost overruns on unimaginative projects that fulfill the letter, but not the spirit, of the tender.

The uncomfortable scenario that we must consider is that, once the space program was gutted by Nixon administration budget cuts, the blow to morale, both at NASA and among its contractors, led to individuals shifting their focus from the central project of the space program to personal and private pursuits that would not be derailed by government decisions. Careerism can, for some, fill the void created when a larger purpose fails. And so it was that the money continued to flow to the space program, which funds were insufficient to mount a space exploration program at scale, but more than sufficient to pay salaries and bonuses. (Boeing CEO Dennis Muilenburg declined his bonuses for 2019 due to the 737 MAX debacle, but in 2018 pocketed $23.4 million in bonuses and equity awards.) The purpose evaporated but careers continued for the lucky few.

The loss of purpose and consequent institutional drift is not merely a loss of meaning and value, but also a financial loss. A spacefaring breakout at an earlier inflection point would have made Boeing one of the largest companies in the world, with an assured future for as long as it participated in this effort. (Boeing is the largest aerospace and defense contractor in the world, but it is not in the top fifty of the largest companies in the world by revenue.) The rewards of following through on the IPP would have been far greater than Boeing receiving an additional 287 million on the CST-100 Starliner fixed price contract (cf. Boeing seems upset with NASA’s inspector general by Eric Berger). I am reminded of when, in the film Casablanca, Rick Blaine insists that he was well paid for running guns to Ethiopia and fighting for the Loyalists in Spain, police captain Louis Renault says to Rick, “The winning side would have paid you much more.” So too, in economics at the scale of the nation-state, or even at a planetary scale, being on the winning side of history pays much greater dividends than being on the losing side, however successful one is at losing. And, unfortunately, receiving government largesse on the CST-100 Starliner (tested, not entirely successfully, for the first time on Friday 20 December 2019) is just an elaborate way of losing.

9. How the Space Industry Got Its Groove Back

The comfortable and profitable relationship that major aerospace contractors have with government institutions could have continued for decades (as it had been going on for decades), or even for centuries, with enormous quantities of taxpayer money spent, and progress in the programs so incremental as to be indistinguishable from stagnation, had it not been for the disruptive entry of private space companies into the aerospace industry and the work of private industry on reusable rockets. [27] NASA, of course, pursued reusable spacecraft with the Space Shuttle, but this well-intentioned exercise took place within an institutional context that virtually guaranteed that few costs savings would be realized from reusability at this scale. There will come a time when reusable spacecraft at the scale of the Space Shuttle will be built and used again, but the economics of large reusable spacecraft will be very different from the economics of the space shuttle; reusability looks different now than it looked when the Space Shuttle was being designed.

The development of reusable rockets by private companies is a game changer not only because of the technology, which may deliver lower costs for access to space, but also because the private companies involved appear to be interested in space exploration as an end in itself, and not merely as a way to profit from government contracts. [28] This is disruptive of the status quo, which had continued to do space business, but had ceased to believe in the mission, for all practical purposes. The fact that this lack of purpose was rarely discussed in explicit terms, but was rather accepted as the background to business as usual, is further evidence of the stagnation of the aerospace industry.

The problem with transcending the status quo and allowing (or even facilitating) a great disruption to shift the direction of history (as would have been the case with an early inflection point for spacefaring civilization), is that no one really knows who will be in power, and who will get the rewards, after the shift has been accomplished. Those who are now in power, and who now receive those rewards that can be conveyed by historical business-as-usual, have a vested interest in not allowing a revolution to occur that would displace them from their position of preeminence.

During the Space Race, the explicitly stated purposes of the competing parties, the US and the USSR, provided a larger framework within which the uncertainties of the great disruption of a spacefaring breakout were moderated. To compete in the Space Race was to be in the vanguard of history, and to win meant that the social system of the winning party to the race would be iterated beyond Earth. Thus the participants in the Space Race—nation-states, national space programs, their contractors, and the contractor’s employees—knew that the revolutionary disruption they were effecting by engaging in the Space Race would benefit their side, which would either directly or indirectly mean a benefit for themselves

It could be argued that the rise of global capital and transnational industry had to rise to a level comparable to superpower competition before a similar degree of certainty would obtain that those in positions of power would continue to hang on to their positions of power despite any disruptive change on a civilizational scale. This is not the only interpretation that can be given to the emergence of private space industries that have disrupted business-as-usual among national space programs, but it is, I think, a plausible interpretation. (Let me know if you have a better interpretation.) Commercial disruption of business-as-usual becomes an acceptable option when the captains of industry are confident that they will be winners in any likely outcome.

10. Finding a Compromise That Works

The institutional drift of the Stagnant Era has been the cumulative result of the sheer size of the institutions involved and the inevitable weakening of the intensity of the space exploration vision. The space exploration vision itself has passed on from its “gee-whiz” Golden Age of Science Fiction origins and entered into popular culture, which means that an originally heroic and inspiring idea came to be lampooned, ridiculed, mocked, and exposed to every kind of jibe and jeer.

There are some interesting parallels to this in history. Socrates was one of the most respected men in Greece, an inspiring figure to many, but that didn’t save him when the Athenians turned against him. There is a fascinatingly well-expressed passage in the ancient historian Eunapius that describes how Aristophanes’ play The Clouds prepared the Athenians for the trial and execution of Socrates:

“. . . no one of all the Athenians, even though they were a democracy, would have ventured on that accusation and indictment of one whom all the Athenians regarded as a walking image of wisdom, had it not been that in the drunkenness, insanity, and license of the Dionysia and the night festival, when light laughter and careless and dangerous emotions are discovered among men, Aristophanes first introduced ridicule into their corrupted minds, and by setting dances upon the stage won over the audience to his views . . .” [29]

Eunapius was willing to go even farther in his condemnation of the Athenians:

“. . . and so the death of one man brought misfortune on the whole state. For if one reckons from the date of Socrates’ violent death, we may conclude that after it nothing brilliant was ever again achieved by the Athenians, but the city gradually decayed and because of her decay the whole of Greece was ruined along with her.” (op. cit., p. 383)

For reasons related to this, traditional cultures have always carefully erected a veil of sacredness [30] around the mythological central projects that have been the core of all civilizations: by shielding their mythological central project from the ordinary business of life, by separating it and treating it as something fundamentally distinct, to be shown deference regardless of context, and by ensuring that a high price is paid for the violation of this taboo, the mythological central project never enters into predictable trajectory of popular culture, hence never becomes the fashion, hence never goes out of fashion, and never experiences the ups and downs of the wheel of fortune (or, if it does experience them, it experiences this variability of fortune to a greatly attenuated extent).

Socrates was admired and perhaps loved, but he (and his philosophical project) was not sufficiently embedded within the Athenian central project that the veil of sacredness protected him from the light laughter and careless and dangerous emotions that led the Athenians to sentence him to death for impiety. Indeed, the veil of sacredness shrouded the piety against which Socrates was said to have offended. For all that the Greeks achieved in philosophy, philosophy was not the central project of ancient Greek civilization. As I have observed above, it can be surprisingly difficult to discern the central project of a civilization; what appears on the surface to be important may in fact be peripheral, while that which appears peripheral may be the true center.

If a mythology of a central project is to endure for the longue durée, it must be inviolate by convention and consensus, or nearly so. To remain inviolate by convention and consensus is as much as to say that the implicit social contract recognizes limits upon the ordinary business of life, exempting the central project from the kind of rough handling that would call into question the foundation of the community that has this central project as its raison d’être.

It probably is no longer possible for the central projects of civilizations since the Enlightenment to maintain the kind of aura that surrounded the religious central projects of traditional civilizations, but that doesn’t mean that industrialized civilizations are necessarily and inevitably subject to drift. [31] It may be possible that an historical narrative could be constructed in such a way as to justify the raison d’être of a community, and sufficiently held apart from other aspects of life so as to be retained more-or-less intact over historical time. That is to say, actual historical events (like the Founding Era) could be mythologized for a social purpose.

We have seen something like this with the foundation of the US, which is an artifact of the Enlightenment—a nation-state explicitly constituted on Enlightenment principles—such that the Declaration of the Independence, the Constitution, and the Founding Fathers have been sufficiently reverenced to retain the cohesion, continuity, and coherency of the Enlightenment project that is the US. We do not yet know how long this compromise can be sustained, nor whether it will ultimately be successful, but it is the most successful project to emerge to date from the Enlightenment. If the Founding Era were to be mythologized in this way, that is to say, in a way consistent with the Enlightenment (and one could easily argue that this is already underway), the cohesion, continuity, and coherence of the Space Age might be similarly retained over historical time. [32]

11. Human Purposes in Deep Time

We have seen that there have been several explicitly articulated space exploration visions that preceded (Collier’s), coincided with (IPP), or followed immediately after (O’Neill SPS) the Founding Era. However, none of these visions were realized except in the most fragmentary form. I have paid particular attention to these explicitly articulated visions simply to forestall claims that there were no such visions to serve as a purpose for an ongoing space program to fulfill, but the explicitly articulated visions are rarely as powerful as those which remain implicit and which are spontaneously expressed within a given social group.

A purpose does not need to be clearly articulated; it need not even be formulated in language. The most effective purposes are those that are tacitly shared by every member of a society, so that agreement on purpose is spontaneous and unquestioned. In small bands of hunter-gathers (i.e., during the bulk of human history, which was also our environment of evolutionary adaptedness), shared purpose is nothing less than and nothing more than survival and reproduction. In other words, the earliest human purposes were the imperatives of natural selection, which functions by differential survival and differential reproduction. As human groups became larger and better organized, growing in scope and scale, purposes became more complex and more abstract, evolving and adapting as the growing society evolves and adapts to its available niche.

When language emerges, and when human beings are sufficiently long-lived that grandparents can pass down the lore of the tribe to grandchildren, while their parents are out hunting and gathering, a tradition and a culture emerges, and later when written language is invented, this culture can be preserved in a nearly pristine state from the inevitable variations that enter into the oral transmission of culture.

This process has been playing out for hundreds of thousands of years, and for millions of years if we extend the scope of our inquiry to include human ancestors prior to Homo sapiens. We have had cities and settled agriculture for ten thousand years (written language appeared approximately half way through this ten thousand year development of settled human societies), while industrialized civilization is less than three hundred years old—in other words, the human world that we know is very recent, even shallow, though human history is much longer than we usually recognize. Because of this deep human history, later developments unusually include survivals from earlier stages of development that have been sedimented into contemporary institutions. [33]

The deepest layer of sedimentation is evolutionary psychology, shaped by our environment of evolutionary adaptedness, and that is why I touched on these deep sources of mythology in my Spacefaring Mythologies post. After the layers of evolutionary psychology come the layers of past human cultures and societies, built upon the earlier evolutionary psychology, and providing the foundation for later cultures and societies long after the earlier iterations have been forgotten, often entirely effaced from the historical record. As social evolution is more rapid than biological evolution, our hundred thousand years or more of social evolution has left us with a deep history of which we are scarcely aware—layers upon layers of sedimented traditions—though I should point out that social evolution can be pushed much further back into prehistory than the human condition extends; we inherit social instincts with our neurological structures that go back in time at least a half billion years. [34]

The most successful mythologies, even the mythologies of sophisticated civilizations, are at least consistent with this deep evolutionary past of the human mind. Mythology is a kind of recapitulation in which the contributions of ages past—whether biological, psychological, social, or cultural—are each given their due, and these antecedents serve as a springboard to something authentically novel, something unprecedented that facilitates human beings to transcend their past and to accomplish something unprecedented. And this is precisely what will be required of a spacefaring mythology: while maintaining some connection to past traditions, something essentially novel must be superadded in order to provide an adequate framework for the novel activities of spacefaring.

If a human civilization beyond Earth ever comes into being, this will be unprecedented in any historical context we might care to invoke—unprecedented in recorded history, unprecedented in human history, unprecedented in terrestrial history, and so on. There have been many human civilizations, but all of these civilizations have arisen and developed on the surface of Earth, so that a civilization that arises or develops away from the surface of Earth would be unprecedented and in this sense absolutely novel even if the institutional structure of a spacefaring civilization were the same as the institutional structure of every civilization that has existed on Earth. For this civilizational novelty, some human novelty is a prerequisite, and this human novelty will be expressed in the mythology that motivates and sustains a spacefaring civilization.

12. Sufficient Conditions for Spacefaring Civilization

A spacefaring civilization (or what I have called a properly spacefaring civilization, i.e., a civilization that takes spacefaring as its central project) requires a spacefaring mythology, and while a spacefaring mythology would be an unprecedented development in human history, it cannot appear de novo. Any mythology, in order to be viable, must draw from the same human materials as all previous mythologies, which is to say, a viable mythology must draw from the deep past of sedimented traditions that we carry both within ourselves and in our cultures.

The necessity of a spacefaring mythology for a spacefaring civilization offers a key to a problem posed earlier. In section 3 we asked three questions, based on the assumption that the necessary condition for a spacefaring breakout was the existence of a space-capable civilization:

• What could constitute a sufficient condition of an early spacefaring inflection point?
• What could constitute a sufficient condition of a mediocre spacefaring inflection point?
• What could constitute a sufficient condition of a late spacefaring inflection point?

Perhaps the sufficient condition of a spacefaring breakout is an adequate mythology that can inspire, contain, and direct the unprecedented changes that would fall to the human condition in the event of a spacefaring breakout and the transition to a spacefaring civilization. The industrial revolution transformed our way of life, and gave us powers that no one from earlier eras of human history would ever have believed would come to be held by human beings. A spacefaring breakout would be similarly disruptive—different in every detail, but ultimately no less transformative of social institutions and the context of the ordinary business of life.

Mythology takes shape over the longue durée, or over historical time periods longer than the longue durée, and the materials it draws upon are far older. If this is an adequate way to understand the human condition, i.e., historically, over evolutionary time, and if it is also true that mythology takes shape only over the longue durée, then it would appear to be the case that only a late spacefaring inflection point would allow a mythology to come into being that would be adequate as a central project for a spacefaring civilization (assuming that such a mythology is not already in existence, or something close enough to being such a mythology, but waiting in the wings to be exapted for spacefaring).

We could posit, as a counterfactual to our own civilization, another civilization in which the mythologies available during the historical period in which space exploration technologies first become available are suited for a spacefaring breakout, and this serves as the sufficient condition above and beyond the necessary condition of being space-capable. In this scenario, an early spacefaring breakout obtains, and this answers the first of our three questions, though given these assumptions the sufficient condition must subsist in the space-capable civilization.

At one remove from this scenario would be a civilization in which the mythic materials are available in the wider culture, and they merely await some individual or institution to tie together the technologies and the mythic materials into a whole. In this scenario, several conjunctures follow upon the equivalent of a Founding Era in which the mythic material is rapidly adapted to space exploration, and a mediocre spacefaring breakout obtains, which answers our second question.

Where there remains an unbridgeable gulf between the introduction of space exploration technologies and a mythology adequate to their exploitation, such a mythology must develop over a formative period measured over a longue durée, as nothing less would be sufficient for the codification of a mythology on such a scale where none existed previously. This appears to be a chicken-and-egg problem, as we cannot build human experience in space without being in space, and we can’t be in space without the human experience of space exploration. This chicken-and-egg scenario leaves open the window for a very gradual adaptation to spacefaring—so incremental that its effects cannot be discerned over ordinary historical scales of time, but which, looking back over a longue durée, might be obvious in hindsight. The slowness of this incremental process is also the reason for the period of time required for such a mythology to come into being.

13. The Weston Principle

Mythologies come into being over scales of time that are nearly incomprehensible to the individual human being, and because of this we have often—more often than not—misunderstood the mythologies by which we live. We do not know the histories of our mythologies, because these histories are lost in the mists of time, and it is only in relatively recent scholarship that a sustained effort has been made to uncover the origins of stories so close to the human heart that we cannot see them objectively without the greatest effort.

Jessie L. Weston published From Ritual To Romance a hundred years ago in 1920. Weston’s book traced elements of the Arthurian mythology and the Grail legend to pre-Christian sources. Arthurian mythology constitutes a significant corpus of medieval literature, deeply Christian in its symbols and motifs, but the wealth of detail on display in the Arthurian tradition cannot be exhausted by distinctively Christian ideas. Weston’s research supplied the origins of the non-Christian remainder of the Arthurian tradition from earlier and older mythology. In its time Weston’s thesis was controversial much as Frazer’s The Golden Bough, a major influence on Weston, had been controversial. We are no longer shocked by such scholarship.

The principle by which Weston worked can be generalized beyond the specific circumstances of Arthurian mythology supervening upon the mythology of early agricultural societies such as described in Frazer’s The Golden Bough. The mythology of such societies as described by Frazer would have, in turn, been indebted to the earlier mythologies of their predecessor societies, perhaps dominated by intensive gathering and transhumance, and the mythology of these societies would in their own turn have been indebted to yet earlier mythologies of hunter-gatherers, such as we possess a mute record in cave paintings and prehistoric sculpture. And just as past mythologies owed part of their substance to previous mythologies, any future mythology will owe part of its substance to mythologies represented in the present and earlier. I call this the Weston Principle.

Our records of past mythology are significant only up to five thousand years ago, when written language appeared, and before that our evidence is only indirect, if it exists at all. From Çatalhöyük (during the Holocene, from about 9,500 to 7,700 years before present) we have many intriguing paintings and sculptures exhibiting a thematic unity—bulls, aurochs, and corpulent Venus figurines—but, lacking written records, any reconstruction of the belief system of which they are the material expression, can only be speculative. Further excavation may reveal additional evidence, but we have no reason to expect finding the Anatolian equivalent to The Epic of Gilgamesh, as there is no evidence at all for written language during the time of Çatalhöyük.

Before Çatalhöyük we have the remarkable cave art of the Paleolithic, itself a period of prehistory extending over more than three million years and consisting of a succession of cultures, each of which may have had their own mythology, received from a processor and passed down to a successor culture, with descent with modification at each stage of transmission. Over this long succession of hunter-gatherer Paleolithic cultures one suspects that the mythology remained relatively simple as long as social organization remained relatively simple, but that development accelerated with the advent of cities, complex social organization, and eventually written language. We arrive at length at the depth and complexity of something like the Arthurian tradition by the accumulated mythological development of successive human societies extending back in deep time.

Record-keeping technologies introduce an asymmetry into history. First language, then written language, then printed books, and so and so forth. Should human history extend as far into the deep future as it now extends into the deep past, the documentary evidence of past beliefs will be a daunting archive, but in an archive so vast there would be a superfluity of resources to trace the development of human mythologies in a way that we cannot now trace them in our past. We are today creating that archive by inventing the technologies that allow us to preserve an ever-greater proportion of our activities in a way that can be transmitted to our posterity.

The Weston Principle connects these mythologies through time based on an evolutionary sequence in which each stage of development is indebted to the stage that preceded it, and no stage of development begins as a blank slate.

14. The Beginning of the Inquiry

We are, as human beings, adrift without an adequate mythology—where there is no vision, the people perish. The institutions of human life—what Braudel called the structures of everyday life — are no less subject to institutional drift than industries, scientific research programs, and civilizations, though in the absence of more sophisticated social organization, the institutions of human life are ultimately reducible to subsistence. Indeed, a reduction to subsistence is what awaits us if we allow our institutions to drift downward to their lowest common denominator.

Assuming that we wish to avoid a reduction to subsistence, which is social collapse, it is in our interest to cultivate some mythology that will allow us to retain some of the gains that we have made upon mere subsistence, and, if possible, perhaps also to better these gains and to transcend our present condition in favor of a stage of social development as far removed from the present as the present is removed from bare subsistence. But mythology cannot be fabricated on demand; a mythology is organic to the life of a people, or it is not a mythology (perhaps this is the proper demarcation between mythology and ideology).

A spacefaring mythology would be organic to the life of a spacefaring people. Mythologization, including spacefaring mythologization, is a process that occurs over the longue durée (section 12), incorporates material from the deep past of humanity (section 11), and must shape itself to the most recent cultural forms that are its immediate predecessors (section 10). These general principles are some of our clues that point us in the direction of some future spacefaring mythology.

We cannot yet say what a spacefaring mythology would be, but we can make a systematic inquiry into the forms of human experience that will eventually be represented within a spacefaring mythology—the full range of human experiences become lived experience in outer space, and, from that lived experience in outer space, become the raw material to be shaped into mythic forms. This, then, is not the end of the inquiry, but the beginning.

Notes

[1] Carl Sagan, Cosmos, New York: Random House, 1980, Chapter 1, p. 5.

[2] What I am here calling the “Founding Era” Michael J. Neufeld has called the “Heroic Era” in the book he edited, Spacefarers: Images of Astronauts and Cosmonauts in the Heroic Era of Spaceflight (Washington, D.C.: Smithsonian Institution Scholarly Press, 2013): “The missions of the first astronauts and cosmonauts opened a period I call ‘the heroic era’ of human spaceflight—both for the media representation of their image and the actual danger of their occupation.” Neufeld reckons the Heroic Era from Gagarin’s 1961 flight to the 1986 Challenger disaster, so his Heroic Era is a little offset from, and a little longer than, the Founding Era as I define it.

[3] I have slightly revised the wording of these inflection points since I introduced them in The Spacefaring Inflection Point.

[4] If human civilization had transitioned into an early spacefaring breakout, with no lapse in the continuity of spacefaring developments, we would by now be more than sixty (60) years into this historical process of becoming a spacefaring civilization. For an historical parallel, if we take the origin of the industrial revolution to be James Watt’s steam engine (commercially introduced in 1776), the continuity of development of the industrial revolution meant that sixty years later we come to a time when railroads were being built and the telegraph was being invented. If the industrial revolution had entered into a period of stagnancy after fifteen years, there would have been no railroads in the 1830s.

[5] Eleni Panagiotarakou, “Agonal Conflict and Space Exploration,” chapter 47 in The Ethics of Space Exploration, edited by James S.J. Schwartz and Tony Milligan, London: Springer International Publishing, 2016.

[6] “I am afraid that it is from baser motives that Governments are willing to spend the enormous sums involved in making space-travel possible.” Quoted in Earth to Russell by Chad Trainer. While Russell never withheld his disdain for the Space Race, in other contexts he was more willing to consider a spacefaring far future for humanity; cf. Bertrand Russell and Olaf Stapledon.

[7] In psychodynamic psychology, the idea of sublimation is that otherwise destructive energies are channeled into some other part of life, often expressed constructively in art or science or invention. Sublimation on a trans-personal level, the sublimation of the worst instincts of the crowd, can also channel otherwise destructive energies into creative projects, and it is this that accounts for the great monuments of civilization such as the pyramids, the Parthenon, the Taj Mahal, the LHC, ITER, and the ISS.

[8] Clark, Kenneth, Civilisation, Chapter 5, “The Hero as Artist,” p. 120. Later in the same book Clark wrote, as if to hammer home his earlier point, “The dazzling summit of human achievement represented by Michelangelo, Raphael, and Leonardo da Vinci lasted for less than twenty years.” (p. 139) And again, regarding the impressionists: “…it is surprising how short a time the movement, as a movement, lasted. The periods in which men can work together happily inspired by a single aim last only a short time—it’s one of the tragedies of civilisation.” (p. 290) It would be instructive to compare computer technology to spacefaring technology, as computer technology seems to have experienced nearly continuous development over several decades—still perhaps within a charitable interpretation of Clark’s window of achievement, but four times as long as the Founding Era. Also instructive is a comparison with nuclear technologies, though in the case of nuclear technologies we know that their stagnation was the result of both proliferation concerns and public discomfort with nuclear power.

[9] Clark’s Civilisation television series, like the book of the same title, was first broadcast in 1969—the same year in which the Apollo Program succeeded in landing human beings on the moon and returning them safely to Earth. Since Clark focused on art and society rather than science and technology, his examples are mostly drawn from traditional humanistic studies of civilization rather than technical studies of civilization, but Clark’s point could be argued either way.

[10] For one superficial example, the total cost of the Voyager Program from 1972 to 1989 was 865 million dollars (51 million dollars per year, on average); the cost to operate the LHC is about a billion dollars per year. This is not a criticism of large particle accelerators, only a comparison of costs. Also, the Voyager costs have not been adjusted for inflation, which one would need to factor in for an apples-to-apples comparison.

[11] The arguments that highlight a simple-minded and ultimately self-defeating distinction between human space exploration and robotic space exploration have led to an artificial debate about whether space exploration funds should be spent on human missions or robotic missions. The debate is artificial because, if our space program had not entered into a state of institutional drift, and if a vigorous space program had tumbled forward into an early inflection point for spacefaring civilization, then the scientific instruments we would have been able to build in space would have far exceeded capacities of the scientific instruments we have sent out with robotic space exploration missions, and cosmology would have become “big science,” so integrated with the central project of spacefaring civilization that it would be virtually indistinguishable from that civilization itself.

[12] In this connection I am reminded of the famous claim that the British acquired their overseas empire in a fit of absence of mind (“We seem, as it were, to have conquered and peopled half the world in a fit of absence of mind.” John Robert Seeley, The Expansion of England, 1883); one might contrariwise claim that we have failed to converge upon a spacefaring civilization in a fit of absence of mind. No one, single decision led us to our present condition, and no conscious choice was made not to pursue the space exploration vision. In the present context I am choosing to employ a strong formulation of our failure to attain spacefaring civilization, largely in order to avoid any ambiguity on the topic. A full discussion of this point would constitute the matter for another essay.

[13] Fernand Braudel, The Perspective of the World (Civilization and Capitalism, Vol. III), p. 17. Both Hegel and Nietzsche, incidentally, also distinguished three kinds of history, but these were not distinct time-scales of history, as in Braudel, but, rather, they were kinds of historiography. I have previously discussed Braudel in my Centauri Dreams post Synchrony in Outer Space. I hope to discuss Hegel and Nietzsche in relation to the historiography of spacefaring civilizations in a future essay.

[14] Fernand Braudel, The Identity of France, Vol. I, New York: Harper & Row, 1988, p. 408.

[15] Fernand Braudel, A History of Civilizations, Penguin Books, 1993, p. xxiv.

[16] Fernand Braudel, The Mediterranean and the Mediterranean World in the Age of Philip II, Volume 2, Part Three: Event, Politics and People, p. 901.

[17] Fernand Braudel, On History, “History and the Social Sciences,” University of Chicago Press, 1980, p. 27.

[18] White, Frank, The Overview Effect: Space Exploration and Human Evolution, third edition, Reston, VA: AIAA, 2014, p. 3. My use of “central project” differs somewhat from White’s use as I have sought to develop the idea in relation to the institutional structure of civilization. However, it was in White’s book that I first encountered the idea, so my use of it is related to White’s use by descent with modification. Some of my posts about the central projects of civilizations include Civilizations and Central Projects, An Anecdote about the Unifying Role of Central Projects, Central Projects and Axialization, Some Desultory Theses on the Central Project of Contemporary Civilization, and The Central Project of Properly Scientific Civilizations, inter alia. What I have not yet done is to write an explicit and systematic exposition of central projects, or to generalize the idea of a central project to other institutions beyond the institution of civilization.

[19] John M. Logsdon argued that there was no Sputnik Crisis: “It was a ‘Gagarin moment’ rather than a ‘Sputnik moment’ that precipitated massive government support for the technological innovations needed for success in space.” (Logsdon, John M., “John F. Kennedy’s Space Legacy and Its Lessons for Today,” Issues in Science and Technology, Vol. 27, No. 3, Spring 2011, pp. 29.) We will have occasion to further consider Logsdon’s paper in what follows.

[20] Excerpt from the ‘Special Message to the Congress on Urgent National Needs’ President John F. Kennedy, Delivered in person before a joint session of Congress May 25, 1961.

[21] John F. Kennedy Moon Speech – Rice Stadium, September 12, 1962. Both speeches are well worth reading in their entirety.

[22] Logsdon, John M., “John F. Kennedy’s Space Legacy and Its Lessons for Today,” Issues in Science and Technology, Vol. 27, No. 3 (Spring 2011), pp. 29-34.

[23] I don’t want to make it sound like the pursuit of von Braun’s vision would have been a cake walk. A mission as complex as von Braun’s Mars mission would have almost certainly resulted in some failures and fatalities, though if the will had been present to carry out a plan this ambitious, the mission would have continued despite fatalities, as indeed the Apollo Program continued despite the fatalities of Apollo 1, and even fulfilled Kennedy’s Lunar landing timetable despite the setback to the program. When space shuttle Challenger exploded shortly after launch, killing all aboard, the Space Shuttle program was suspended for almost three years.

[24] David S. F. Portree’s blog Spaceflight History: a history of spaceflight told through missions & programs that didn’t happen has an excellent treatment of the IPP: Think Big: A 1970 Flight Schedule for NASA’s 1969 Integrated Program Plan.

[25] One of the many arguments put forward against space exploration (other arguments are briefly discussed in section 4) is that we don’t yet possess the requisite technology for the human exploration of deep space. Given that technology is a means to an end, there is a certain fungibility and flexibility where specific technologies are concerned. If a spacefaring breakout had occurred prior to the computer revolution (which would have been the case given an early inflection point), the sciences would have been pursued the old-fashioned way, with human researchers and large physical models, less simulation, and more actual trials. For example, rather than theorize about conditions on Mars for decades prior to going to Mars, we would have gone to Mars and conducted experiments on Mars that would be far more informative and definitive than any experiments conducted with simulated Martian regolith.

[26] Armies recognize the difference in the fighting quality of various troops by positioning the most gung-ho elements as the “tip of the spear.” For example, the Achaemenid Empire had a heavily-armed corps of 10,000 men known as “The Immortals,” and Achilles’ Myrmidons were among the fiercest fighters of the Trojan War. The Immortals were maintained at their number by immediately replacing any soldier who became ill, infirm, or otherwise unable to fight at full capacity, so that The Immortals were “immortal” in the sense that the unit was always maintained at full strength. Achilles’ Myrmidons were personally motivated by their loyalty to Achilles. Both embody familiar models of leadership; Max Weber would have called the management of The Immortals “legal-rational” authority and the management of the Myrmidons “charismatic” authority. Cf. Weber’s essay “The Three Types of Legitimate Rule” (Die drei reinen Typen der legitimen Herrschaft).

[27] Before I am accused of Muskolatry, I should say that it is indifferent to me what private space company proves to be successful, if, in fact, any does prove to be successful. SpaceX is in the lead now, but we know that, over time, one company and then another will take the lead as technologies change and business models flourish or fail.

[28] It is particularly revealing that the popular press presents the authentic beliefs in a spacefaring future held by both Elon Musk and Jeff Bezos as a bizarre and scarcely credible curiosity, rather than as the motivating drive behind these efforts that contributes to their success; a typical article in this vein is The true reason Musk, Bezos, and Branson are obsessed with space by C.W. Headley; I attach no particular importance to this article, and link to it only as an exhibit.

[29] Philostratus and Eunapius, Lives of the Sophists, Cambridge and London: Harvard, 1921, p. 381.

[30] Peter L. Berger called this the “sacred canopy” in his influential book The Sacred Canopy: Elements of the Sociological Theory of Religion.

[31] However, this argument could be made. Science is essential to an industrialized economy, and an industrialized economy is the necessary condition of a space-capable civilization. The pursuit of science inevitably comes into conflict with traditionalism, and science practiced at the scale of civilization may mean that every tradition upon which that civilization is founded eventually comes under attack. If this is true, then it could be formulated as a response to the Fermi paradox, and you could call this the traditionalism hypothesis: no civilization can long persist once science opens Pandora’s Box. On the other hand, civilizations that remain traditional could endure for as long as their homeworld remained consistent with their survival; under this response to the Fermi paradox, the universe could be filled with traditional civilizations that have never experienced a scientific revolution or an industrial revolution. We could not communicate over interstellar distances with traditional civilizations because they never develop electromagnetic technologies.

[32] I have already touched upon this in an earlier Centauri Dreams post, Spacefaring Mythologies, in which I discussed several distinct scenarios by which the Founding Era might be mythologized.

[33] Edmund Husserl used “sedimented” in this sense in his essay, “The Origins of Geometry” (in Husserl: Shorter Works, Notre Dame: Harvester Press, 1981, pp. 255-270; this essay also appears as an appendix in most editions of Husserl’s The Crisis of European Sciences and Transcendental Phenomenology)

[34] Some interesting finds have been made of soft tissue fossils of early central nervous systems; cf. “Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda,” by Jie Yang, Javier Ortega-Hernández, Nicholas J. Butterfield, Yu Liu, George S. Boyan, Jin-bo Hou, Tian Lan, and Xi-guang Zhang, and “Brain and eyes of Kerygmachela reveal protocerebral ancestry of the panarthropod head” by Tae-Yoon S. Park, Ji-Hoon Kihm, Jusun Woo, Changkun Park, Won Young Lee, M. Paul Smith, David A. T. Harper, Fletcher Young, Arne T. Nielsen and Jakob Vinther. Also cf. my blog posts on these papers, How early a mind? and A Counterfactual on Central Nervous System Development.

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