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Revising the Classical ‘Habitable Zone’

With my time-out period over (more about this next week), I want to get back into gear with the help of Ramses Ramirez, a specialist on planetary habitability whose work has now taken him to Japan. Born and raised in New York City, Ramses tells me he is much at home in his new position as a research scientist at the Earth-Life Science Institute (ELSI) in Tokyo, where opportunities for scientific collaboration abound and the chance to learn a new language beckons. We’ve looked at Ramses’ papers a number of times in these pages, and I was delighted when he offered this description of his work to our readership. A student of James Kasting, he received his Ph.D. from Penn State in 2014 and went on to postdoc work with Lisa Kaltenegger at Cornell’s Carl Sagan Institute. A fascination with astrobiology and the issues involved in defining habitable zones continues to be a primary focus. Ramses’ new paper ponders whether we are best served by looking for life similar to Earth’s because this is what we know, or whether there is a broader strategy, one that probes all the assumptions in our ideas of the classical habitable zone.

By Ramses Ramirez

I am glad to have the opportunity to formally introduce myself and give a summary of the recent work on planetary habitability and the habitable zone. I define the habitable zone (HZ) as the circular region around a star(s) where standing bodies of liquid water could exist on the surface of a rocky planet [1]. The inclusion of the phrase “standing bodies of water” excludes dry worlds that may exhibit small outpourings of seasonal surface water (e.g. possibly Mars). Defined this way, the HZ is properly focused for detecting worlds that have large surface bodies of water (e.g. seas, big lakes, oceans) that are in direct contact with the atmosphere. If life is present on such a world, potential atmospheric biosignatures could be detected with current technology. However, in the absence of such large water bodies, life would not be detectable even if it were present. Likewise, although life may be possible within the seas of a Europa or Enceladus exoplanetary analogue, the global ice layer covering their oceans would prevent the detection of such subsurface life. Such observational issues keep the HZ within an orbital region that is placed somewhat closer to the star.

When I first started my Ph.D. in 2010 under my mentor Professor James F. Kasting, I did not know the exact topic that I would be working on at first, but with my interest in the search for extraterrestrial life, I knew that I wanted to work on planetary habitability. Fortunately, I got involved as one of the two lead authors on the 2013 HZ paper [2], where we updated the seminal Kasting et al. [3] HZ limits [2,3]. Although I was fascinated by the HZ concept as a navigational tool to find potentially habitable planets, my investigations soon led me to realize that the HZ definition described in these earlier works, what I dub the “classical HZ”, would be insufficient for capturing the diversity of such planets. From that point on, it became my personal mission to turn the HZ into an even more capable navigational tool.

The classical HZ assumes that CO2 and H2O are the key greenhouse gases on potentially habitable planets, following the carbonate-silicate cycle on the Earth, which is thought to regulate CO2 between the atmosphere, surface, and the interior (e.g. [3]). Given that the concept of a universal carbonate-silicate cycle on habitable exoplanets is itself far from proven (e.g., [4]), I always thought that this assumption was needlessly restrictive and geocentric. After all, HZ planets with atmospheres consisting of different gas mixtures can also support standing bodies of liquid water and potentially be habitable. Reduced greenhouse gases, like H2 and CH4, have been considered as major atmospheric constituents on both early Earth and early Mars (e.g., [5,6]). It has even been suggested that planets with primordial hydrogen envelopes may be habitable in some circumstances [7]. If hypothetical planets consisting of dense 10-bar CO2 atmospheres near the outer edge of the classical HZ are potentially habitable (e.g. [2][3]), then why not worlds composed of these other atmospheric constituents (Figure 1)?

Figure 1: The classical HZ extended to A-stars (blue) with CO2-CH4 (green) and CO2-H2 (red) outer edge extensions for stars of stellar effective temperatures between 2,600 and 10,000 K (reproduced from Ramirez [1]).

Moreover, the classical HZ really targets potentially habitable planets orbiting main-sequence stars. However, this approach ignores the importance of the temporal evolution of the HZ, particularly a star’s pre-main-sequence phase. It is during this early stage that many M-stars are bright and luminous enough to completely desiccate any planets that are now thought to be located within the main-sequence HZ (e.g. [8][9][10]), like Proxima Centauri-b and many of the TRAPPIST-1 planets, unless such worlds are able to accrete enough water to offset losses (e.g., [11][12]) (Figure 2).

Figure 2: The pre-main-sequence HZ for a late (M8) star. A planet that forms at ~0.03 AU undergoes a runaway greenhouse state for ~100 Myr before finally entering the HZ, settling near the outer edge after ~1 billion years (reproduced from Ramirez [1]).

In my view, we are currently ill-equipped to infer the atmospheric conditions that are most suitable for extraterrestrial life. All we know is that life did somehow arise on this planet. It is therefore pretentious to take our one poorly-understood example and assume that alien life must follow a similar trajectory. Some might argue that we should focus on finding life similar to Earth’s because it is familiar and would be simpler to find. However, this argument from the principle of mediocrity is not convincing to me because we have no idea how common or rare our particular brand of life is until we are able to find a second instance of life’s occurrence elsewhere.

It is then illogical to rely on any one iteration of the HZ to find potentially habitable planets. Our inadequate understanding of biology, the origin of life, and planetary processes require that all of these working hypotheses, including the assumptions used in the classical HZ, be tested by observations. Ideas that are later found to be unsupported by nature can then be rejected whereas those that are confirmed should be refined. Only then will we begin to truly understand life’s possibilities and make more informed – and possibly more restrictive – design decisions for subsequent missions. But only proper observations (and possibly better theoretical constraints) can tell us this, and not adherence to some ambiguous and untested geocentric philosophy. Finding extraterrestrial life will be one of the hardest endeavors undertaken by our species. To meet the challenge, we need to start with a thorough and openminded search for potentially habitable planets.

Thus, as some Centauri Dreams readers may already know, part of my work (in collaboration with Lisa Kaltenegger) in recent years has focused on improving our understanding of both the spatial [13][14] and temporal evolution of the HZ [8][15]. These papers have already been discussed in previous Centauri Dreams posts. However, in addition to our own work, other researchers and colleagues have also proposed their own revisions and extensions to different aspects of the HZ, further increasing its utility as a tool for finding life that is both similar and dissimilar to Earth’s. This gradual but steady evolution in how we think about the HZ has come to a good point (I believe) for a review paper to come along such as this one.

I hope that your readers will like my new summary of recent advances (linked below) in our understanding of the HZ. I see this work as both a primer for the student and layman as well as a guide for space missions. It includes many recommendations and suggestions for how the classical HZ, in conjunction with newer HZ formulations, can be used to maximize our chances of finding extraterrestrial life. For example, I do not think that a proper assessment of planetary habitability can be made without properly assessing a planet’s pre-main-sequence habitability. A-stars should also be considered as potential hosts for life-bearing planets. Most importantly, we should employ the various HZ formulations and rubrics to rank which planets are most likely to host life. Finally, my paper clarifies many common misconceptions about the HZ concept and explains why the search must necessarily be limited to finding surface liquid water (at least for now).

The review paper is “A more comprehensive habitable zone for finding life on other planets,” published in Geosciences 8(8), 280 (28 July 2018). Full text available here. [PG: Expect a close look at this paper in coming weeks on Centauri Dreams].

References

1) Ramirez, R.M. 2018. “A more comprehensive habitable zone for finding life on other planets.” Geosciences 8(8), 280.

2) Kopparapu, R., Ramirez, R.M. (co-primary author), Kasting, J., et al., 2013. Habitable zones around main-sequence stars: New Estimates. ApJ, 765, 2, 131

3) Kasting, James F., Daniel P. Whitmire, and Ray T. Reynolds. “Habitable zones around main sequence stars.” Icarus 101.1 (1993): 108-128.

4) Bean, Jacob L., Dorian S. Abbot, and Eliza M-R. Kempton. “A statistical comparative planetology approach to the hunt for habitable exoplanets and life beyond the solar system.” The Astrophysical Journal Letters 841.2 (2017): L24.

5) Wordsworth, Robin, and Raymond Pierrehumbert. “Hydrogen-nitrogen greenhouse warming in Earth’s early atmosphere.” Science 339.6115 (2013): 64-67.

6) Ramirez, R.M., Kopparapu, R., Zugger, M., Robinson, T.D.,Freedman, R., Kasting, J.F., 2014. Warming early Mars with CO2 and H2. Nat. Geosc., 7, 59 – 63

7) Pierrehumbert, Raymond, and Eric Gaidos. “Hydrogen greenhouse planets beyond the habitable zone.” The Astrophysical Journal Letters 734.1 (2011): L13.

8) Ramirez, R.M., Kaltenegger, L., 2014. Habitable Zones of Pre-Main-Sequence Stars. The Astrophysical Journal Letters, 797, 2, L25

9) Luger, Rodrigo, and Rory Barnes. “Extreme water loss and abiotic O2 buildup on planets throughout the habitable zones of M dwarfs.” Astrobiology 15.2 (2015): 119-143.

10) Tian, Feng, and Shigeru Ida. “Water contents of Earth-mass planets around M dwarfs.” Nature Geoscience 8.3 (2015): 177.

11) Levi, Amit, Dimitar Sasselov, and Morris Podolak. “The Abundance of Atmospheric CO2 in Ocean Exoplanets: a Novel CO2 Deposition Mechanism.” The Astrophysical Journal 838.1 (2017): 24.

12) Ramirez, R.M. and Levi, A. 2018. The ice cap zone: a unique habitable zone for ocean worlds. The Monthly Notices of the Royal Astronomical Society, 477, 4, 4627- 4640

13) Ramirez, R.M., Kaltenegger, L., 2017. A volcanic hydrogen habitable zone. The Astrophysical Journal Letters, 837, 1

14) Ramirez, R.M., Kaltenegger, L. 2018. A methane extension to the classical habitable zone. The Astrophysical Journal 858, 2

15) Ramirez, R.M., Kaltenegger, L., 2016. Habitable Zones of Post-Main Sequence Stars. The Astrophysical Journal, 823, 6, 14pp

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Time Out

Dave Brubeck’s Time Out album was the first jazz LP I ever bought, just after it came out in 1959, the same year that Miles Davis released Kind of Blue. Watershed moments both. Paul Desmond once said of his alto sax work that he was trying to create the sound of a dry martini, a description I certainly can’t top.

Last night, while listening to Desmond and Brubeck, I realized that the Time Out album would be emblematic for today’s post. For it’s that time of year, and I am indeed taking time out for a much needed break. Centauri Dreams will be back in the first week of August, but until then, my break will include a good bit of jazz, much catch-up reading, a lot of long walks and, perhaps, a few of those martinis Desmond talks about. I’ll keep an eye on the site to handle comment moderation as well. Meanwhile, I hope all of you are having a splendid summer.

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Unusual Companion for a Brown Dwarf Binary

A cluster of stars sharing a common origin, now gravitationally unbound, is referred to as a stellar association. I’ve written before about how useful some of these groupings can be. In the form of so-called moving groups — a stellar association that is still somewhat coherent — they help us identify stars of similar age, an aid as we discover new objects. Now we have word of an object called 2MASS 0249 c, found in the Beta Pictoris moving group, that has striking similarities to the most famous member of that group, Beta Pictoris b.

2MASS 0249 c, like Beta Pictoris b, was found by direct imaging, meaning we’re actually looking at the object under discussion in the image below. The two objects are all but identical in mass, brightness and spectrum. Images from the Canada-France-Hawaii Telescope (CFHT) showed an object moving at a large distance from its host, which turned out to be a pair of closely spaced brown dwarfs.

Follow-up observations with the Keck instrument allowed that determination, while spectroscopy at the NASA Infrared Telescope Facility and the Astrophysical Research Consortium 3.5-meter Telescope at Apache Point Telescope completed the data.

“To date, exoplanets found by direct imaging have basically been individuals, each distinct from the other in their appearance and age. Finding two exoplanets with almost identical appearances and yet having formed so differently opens a new window for understanding these objects,” said Michael Liu, astronomer at the University of Hawai`i Institute for Astronomy, and a collaborator on this work.

Image: Image of the 2MASS 0249 system taken with Canada-France-Hawaii Telescope’s infrared camera WIRCam. 2MASS 0249 c is located 2000 astronomical units from its host brown dwarfs, which are unresolved in this image. The area of sky covered by this image is approximately one thousandth the area of the full moon. Credits: T. Dupuy, M. Liu.

The difference in formation scenarios that Liu talks about is instructive. Here we have two host stars, one of them being a binary system of brown dwarfs, that formed in the same stellar nursery, as per their membership in the moving group. But while Beta Pictoris b, a gas giant of about 13 Jupiter masses, orbits a star 10 times brighter than the Sun, 2MASS 0249 c orbits a brown dwarf pair 2000 times fainter. At a distance of 9 AU, Beta Pictoris b is relatively close to its star, while 2MASS 0249 c is a whopping 2000 AU from its brown dwarf hosts.

These distances imply different formation scenarios. Beta Pictoris b likely formed from the accumulation of dust grains in the circumstellar disk surrounding its star. 2MASS 0249 c could not have done so, given that the two brown dwarfs it orbits would not have had sufficient disk material to produce it. That implies the new planet took form through the gravitational collapse of a gas cloud found in the original stellar birth cluster.

“2MASS 0249 c and beta Pictoris b show us that nature has more than one way to make very similar looking exoplanets,” says Kaitlin Kratter, astronomer at the University of Arizona and a collaborator on this work. “They’re both considered exoplanets, but 2MASS 0249 c illustrates that such a simple classification can obscure a complicated reality.”

Image: The infrared spectra of 2MASS 0249 c (top) and beta Pictoris b (bottom) are similar, as expected for two objects of comparable mass that formed in the same stellar nursery. Unlike 2MASS 0249 c, beta Pictoris b orbits much closer to its massive host star and is embedded in a bright circumstellar disk. Credit: T. Dupuy, ESO/A.-M. Lagrange et al.

What we get out of all this is opportunity. The formation of gas giants is a key phase in the emergence of new planetary systems, and being able to use direct imaging to study such worlds means we can probe their atmospheres directly, examining the composition, surface temperature, chemistry and other physical properties of the exoplanet. Moreover, direct imaging is most effective when working with planets far from their star, as this object is. If we are after insights into gas giant formation, the different formation pathways for Beta Pictoris b and 2MASS 0249 c may provide evidence both orbital and spectral. The paper notes:

As directly imaged objects, β Pic b and 2MASS J0249−0557 c provide a new opportunity to test atmospheric compositions and angular momentum evolution for a close-in planet and a very wide companion that share a common mass and age and that formed from the same material.

And on the issue of spectra:

If different formation mechanisms produced these objects, then their spectra could contain evidence of their divergent pasts. As noted above, we suspect that 2MASS J0249−0557 c arose from a star-formation-like process of global, top-down gravitational collapse in the same way as the freefloating object 2MASS J2208+2921. On the other hand, β Pic b bears architectural resemblance to planetary systems and thus may have formed via core accretion. Core accretion models and observations of solar system gas giants show substantial metal enrichment (e.g., Stevenson 1982; Bolton et al. 2017). Thus, if β Pic b is a scaled-up gas giant (≈13 MJup), then we may expect to see substantial metal enrichment in its atmosphere.

What an interesting find 2MASS 0249c turns out to be. Is it a planet or actually a brown dwarf? One thing is for sure: The discovery puts a spotlight on the boundary between planet and brown dwarf, both in terms of composition and in terms of formation history. Maybe it’s best to fall back on how today’s paper describes the object: a ‘planetary-mass companion.’ Now we can go to work, via direct imaging, on issues like variability, rotation and atmospheric composition. How these data vary across different formation histories should occupy astronomers for some time.

The paper is Dupuy et al., “The Hawaii Infrared Parallax Program. III. 2MASS J0249-0557 c: A Wide Planetary-mass Companion to a Low-mass Binary in the beta Pic Moving Group,” accepted at the Astronomical Journal (preprint).

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An Unusually Interesting Asteroid

We learned late last week that the near-Earth asteroid 2017 YE5, discovered just last December, is what is described as an ‘equal mass’ binary. This would make it the fourth near-Earth asteroid binary ever detected in which the two objects are nearly identical in size, both about 900 meters. The binary’s closest approach to Earth was on June 21, 2017, when it came to within 6 million kilometers, some 16 times the distance between the Earth and the Moon. It won’t be that close again for at least another 170 years.

Image: Artist’s concept of what binary asteroid 2017 YE5 might look like. The two objects show striking differences in radar reflectivity, which could indicate that they have different surface properties. Credit: NASA/JPL-Caltech.

What you have above is an artist’s impression of how 2017 YE5 appears, but have a look at the radar imagery below. This comes from NASA’s Goldstone Solar System Radar (GSSR, observations conducted on June 23, 2018), and shows the presence of two lobes. We don’t yet see a binary, but these radar images were enough for Goldstone scientists to alert astronomers at Arecibo Observatory, who had already inserted 2017 YE5 into their observing list.

Image: Radar images of the binary asteroid 2017 YE5 from NASA’s Goldstone Solar System Radar (GSSR). The observations, conducted on June 23, 2018, show two lobes, but do not yet show two separate objects. Credit: NASA/JPL-Caltech/GSSR.

Working with researchers at the Green Bank Observatory in West Virginia, the Arecibo scientists linked the two observatories in a bi-static radar configuration, meaning that Arecibo transmits the radar signal while Green Bank receives the return signal. It was the combination of data from the two observatories that allowed 2017 YE5 to be confirmed as two separated objects.

Image: Bi-static radar images of the binary asteroid 2017 YE5 from the Arecibo Observatory and the Green Bank Observatory on June 25. The observations show that the asteroid consists of two separate objects in orbit around each other. Credit: Arecibo/GBO/NSF/NASA/JPL-Caltech.

A surprising number of near-Earth asteroids may be binaries, according to this JPL news release, which tells us that among near-Earth asteroids larger than 200 meters in size, about 15 percent are binaries with one larger object and a much smaller asteroid satellite. While equal-mass binaries are apparently rare, contact binaries (two equally sized objects in contact with each other) make up another 15 percent of the population in this size range.

Thus at 2017 YE5 we have two objects that revolve around each other every 20 to 24 hours, as confirmed through brightness variations at visible light wavelengths at the Center for Solar System Studies in Rancho Cucamonga, California. As to composition, the two components do not reflect as much sunlight as a typical rocky asteroid, making it likely that 2017 YE5 has a surface as dark as charcoal. Differences in reflectivity of the two objects suggest that they have different composition at the surface or perhaps different surface features.

I was startled to learn that more than 50 binary asteroid systems have turned up in radar studies since 2000, with the majority consisting of one large object and a much smaller satellite. The differences in radar reflectivity found at 2017 YE5 have not appeared in this population. That makes this binary a useful system for the study of binary formation. Further study of combined radar and optical observations may allow tighter constraints on the density of the 2017 YE5 objects, which should give us a window into their composition and structure.

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Red dwarfs have a lot of things going for them when it comes to finding possibly habitable planets. A planet of Earth size in the HZ will produce a substantial transit signal because of the small size of the star (‘transit depth’ refers to the amount of the star’s light that is blocked by the planet), and the tight orbit the planet must follow increases the geometric probability of observing a transit. But planets that do not transit are also more readily detected because of the large size of the planet compared to the star, gravitational interactions producing a strong radial velocity signature, which is what we have in the case of Ross 128b.

About 11 light years from Earth, the planet was culled out of more than a decade of radial velocity data in 2017 using the European Southern Observatory’s HARPS spectrograph (High Accuracy Radial velocity Planet Searcher) at the La Silla Observatory in Chile. The location of the planet near the inner edge of its star’s habitable zone excited interest, as did the fact that Ross 128 is much less subject to flares of ultraviolet and X-ray radiation than our nearest neighbor, Proxima Centauri, which also hosts a planet in a potentially habitable orbit.

Image: Artist’s impression of the exoplanet Ross 128b. Credit: ESO.

What we know about Ross 128b is that it orbits 20 times closer to its star than the Earth orbits the Sun, but receives only 1.38 times more irradiation than the Earth, with an equilibrium temperature estimated anywhere between -60 degrees Celsius and 20°C, the host star being small and relatively cool. But bear in mind that what we get from radial velocity is a minimum mass, because we don’t know at what angle this system presents itself in our sky. Now a team led by Diogo Souto (Observatório Nacional, Brazil) is attempting to deduce more about the planet’s composition using an unusual method: Analyzing the composition of the host star.

If we learn the chemical abundances found in the star Ross 128, the thinking goes, we should be able to make reasonable estimates about the composition of any planets that orbit it. Souto and team are presenting new techniques for making these measurements, using data from the Sloan Digital Sky Survey’s APOGEE spectroscope. Measuring the star’s near-infrared light, where Ross 128 shines the brightest, the researchers have been able to derive abundances for carbon, oxygen, magnesium, aluminum, potassium, calcium, titanium and iron.

“The ability of APOGEE to measure near-infrared light, where Ross 128 is brightest, was key for this study,” says co-author Johanna Teske (Carnegie Institution for Science). “It allowed us to address some fundamental questions about Ross 128 b’s `Earth-like-ness.’”

APOGEE is the Apache Point Galactic Evolution Experiment, an investigation using high-resolution spectroscopy to probe the dust that obscures the inner Milky Way. The project surveyed 100,000 red giant stars across the galactic bulge, but also observed M-dwarfs in the neighborhood of the Sun as a secondary study. Tightening up our knowledge of stellar parameters, the paper notes, offers an indirect route to studying exoplanet composition.

The assumption in this work is that the chemistry of a host star influences the contents of the disk from which planets form around it, which in turn affects the interior structure of any planet. Thus we can hope to tell from the amount of magnesium, iron and silicon available something about the exoplanet. This is the first detailed abundance analysis for Ross 128, and it shows that the star has iron levels similar to the Sun. The silicon level could not be measured, but the ratio of iron to magnesium points to a large core for the planet, larger than Earth’s.

Souto and team believe that knowledge of Ross 128b’s minimum mass (from the radial velocity data), coupled with their data on stellar abundances, can provide a broad estimate of the planet’s radius, a key factor because it would allow a calculation of its density. From the paper:

While both mass and radius are not available for Ross 128b, we can estimate its radius given its observed minimum mass and assuming the stellar composition of the host star is a proxy for that of the planet. We calculate the range of radii possible for Ross 128b using the ExoPlex software package (Unterborn et al. 2018) for all masses above the minimum mass of Ross 128b (1.35M; Bonfils et al. 2017). Models were run assuming a two-layer model with a liquid core and silicate mantle (no atmosphere). We increase the input mass until a likely radius of 1.5R was achieved, roughly the point where planets are not expected be gas-rich mini-Neptunes as opposed to rock and iron-dominated super-Earths…

Measurements of the temperature of Ross 128 coupled with the estimated radius of the exoplanet and its inferred composition allow the team to calculate Ross 128b’s albedo, the amount of light reflecting off its surface. These estimates allow the possibility of a temperate climate, taking into account the insolation flux (energy received from the host star) and equilibrium temperature. “Our results,” the authors write, “support the claim of Bonfils et al. (2017) that Ross 128b is a temperate exoplanet in the inner edge of the habitable zone.”

But the paper urges caution in the interpretation:

However, this is not to say that Ross 128b is a “Exo-Earth.” Geologic factors unexplored in Bonfils et al. (2017) such as the planet’s likelihood to produce continental crust, the weathering rates of key nutrients into ocean basins or the presence of a long-term magnetic field could produce a planet decidedly not at all “Earth-like” or habitable due to differences in its composition and thermal history. Furthermore, other aspects of the M-dwarf’s stellar activity and its effect on the retention of any atmosphere and potential habitability should be studied, although we find no evidence of activity in the Ross 128 spectra.

Indeed. The number of variables affecting ‘habitability’ is striking. So let’s say this: We have a planet for which mass-radius modeling based on the composition of its host star indicates a mixture of rock and iron, the relative amounts of each being set by the ratio between iron and magnesium. The derived values for insolation and equilibrium temperature are not inconsistent with previous studies indicating a temperate planet at the inner edge of its star’s habitable zone.

The work hinges on modeling of an exoplanet based on a deeper analysis of its host star than has previously been available for an M-dwarf. Tuning up such modeling will demand further data, in particular applying these methods to the host stars of transiting worlds (think TRAPPIST-1) to test their accuracy and reliability in characterizing planets we cannot see.

The paper is Souto et al., “Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra,” Astrophysical Journal Letters Vol. 860, No. 1 (13 June 2018). Abstract / preprint.

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Pluto Maps Inspire Thoughts of Bradbury

Something happens when we start making maps of hitherto unknown terrain. A sense of familiarity begins to settle in, a pre- and post-visit linearity, even when the landscape is billions of miles away. To put a name on a place and put that name on a map is a focusing that turns a bleary imagined place into a surface of mountains and valleys, a place that from now on will carry a human perspective. It can’t be undone; a kind of wave function has already collapsed.

And what place more remote than Pluto? At the dwarf planet’s Tenzing Montes, we find striking peaks, some of them running up to 6 kilometers in height, and all this on a world that, until 2015, we weren’t sure even had mountains. Certainly we weren’t expecting mountains this tall, or a terrain this rugged. Given how many years may pass before we have another chance to visit Pluto/Charon, these first official validated topographic maps of the dwarf planet and its moon, just released, will carry our science — and our imaginations — for a long time to come.

Image: Perspective view of Pluto’s highest mountains, Tenzing Montes, along the western margins of Sputnik Planitia, which rise 3-6 kilometers above the smooth nitrogen-ice plains in the foreground. The mounded area behind the mountains at upper left is the Wright Mons edifice interpreted to be a volcanic feature composed of ices. Area shown is approximately 500 kilometers across. Image credit: Lunar and Planetary Institute/Paul Schenk.

The maps are the work of New Horizons researchers led by Paul Schenk (Lunar and Planetary Institute). The team examined all the images from New Horizons’ Long Range Reconnaissance Imager (LORRI) and Multispectral Visible Imaging Camera (MVIC) systems as the raw material for their mosaics. They aligned surface images where they overlapped and performed digital analysis of stereo images both cameras acquired, producing topographic maps for each region, then assembling these into integrated topographical charts for both Pluto and Charon.

Pluto’s mountains are likely made of water ice, because ices from volatiles like methane and nitrogen would not be strong enough to support such tall features, and as the images show, the steep peaks along the southwestern edge of Sputnik Planitia, itself a frozen sheet of nitrogen, have slopes pushing 40° or more. The topographical maps put large-scale features into perspective and help us see both Pluto’s and Charon’s surfaces in a broader context.

Sputnik Planitia is a good example. Fully 1000 kilometers wide, it contains an ice sheet that averages 2.5 kilometers below Pluto’s mean elevation, which corresponds to sea level on our own planet. The maps also show us that the outer edges of the sheet are an even deeper 3.5 kilometers below mean elevation. These are the lowest known areas on Pluto, a fact that emerges only through study of the stereo images and subsequent elevation maps they spawned. The deep ridge-and-trough system running north to south near the western edge of Sputnik Planitia is more than 3000 kilometers long, evidence for extensive fracturing, as this LPI news release explains. It is the longest known feature on the dwarf planet.

And then there’s Charon. Who would have dreamed in 1978, when astronomer James Christy discovered it, that we would ever have the kind of detail that shows below?

Image: Perspective view of mountain ridges and volcanic plains on Pluto’s large moon Charon. The ridges reach heights of 4 to 5 kilometers above the local surface and are formed when the icy outer crust of Charon fractured into large blocks. The smoother plains to the right are resurfaced by icy flows, possibly composed of ammonia-hydrate lavas that were extruded onto the surface when the older block sank into the interior. Area shown is approximately 250 kilometers across. Image credit: Lunar and Planetary Institute/Paul Schenk.

Maps and Sea Change

In my first paragraph today, I summoned quantum mechanics for inspiration, saying that producing maps created the collapse of a kind of psychological wave function. Adam Alter made the same point a few years back in an article in The New Yorker, where he talked about our association of linguistic labels with the things they denote. The effects can be subtle. Northerly movement, for example, is associated in psychological testing with going uphill, apparently a remnant of the decision of ancient Greek mapmakers to put the northern hemisphere above the southern one.

Alter goes on to speak of what he calls a ‘linguistic Heisenberg principle,” meaning that as soon as you label a concept, you change how people perceive it, and I would assume this goes for landscapes as well. So we’d better choose the place names we put on our maps with care, given the freight they carry in our imaginations. Ray Bradbury knew this as well. His ‘The Naming of Names’ takes Earth colonists on Mars to strange places indeed as they begin to name the places they see.

For in the world of The Martian Chronicles, Mars is a place with a long, long history, and pretty soon the new place names the colonists have chosen begin to morph back into their ancient forms, as spoken by the original inhabitants of the planet. Before long not just the names but the people themselves are changing, returning to existences ancient, rich and strange:

The nights were full of wind that blew down the empty moonlit sea-meadows past the little white chess cities lying for their twelve-thousandth year in the shallows. In the Earthmen’s settlement, the Bittering house shook with a feeling of change.

Lying abed, Mr.Bittering felt his bones shifted, shaped, melted like gold. His wife, lying beside him, was dark from many sunny afternoons. Dark she was, and golden, burnt almost black by the sun, sleeping, and the children metallic in their beds, and the wind roaring forlorn and changing through the old peach trees, violet grass, shaking out green rose petals.

It’s a great tale, and one worth re-reading any time mapping new landscapes comes to mind.

The papers are Schenk et al., “Basins, fractures and volcanoes: Global cartography and topography of Pluto from New Horizons,” Icarus Vol. 314 (1 November 2018). abstract; and Schenk et al., “Breaking up is hard to do: Global cartography and topography of Pluto’s mid-sized icy Moon Charon from New Horizons,” Icarus Vol. 315 (15 November 2018). Abstract. Adam Alter’s “The Power of Names” appeared in The New Yorker’s May 29, 2013 issue.

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TVIW Symposium on The Power of Synergy

Ever since I started Centauri Dreams in 2004, I’ve been talking about the question of infrastructure within the Solar System. My thinking has always been that while we will doubtless get off interstellar missions beginning with robotics on an ad hoc basis during this century, the prospect of a sustained effort will require a built-out infrastructure that will help us create and test out deep space systems of many kinds, from new propulsion technologies to closed loop life support experiments. One step at a time, but do this right and we may push deep into the Kuiper Belt, then the Oort Cloud and, we can hope, beyond.

That’s a long-term vision and it clashes with what we’ve seen since Apollo, a retreat from lunar exploration by humans that may eventually be reversed as we think about partnerships between commercial aerospace and government space programs. To explore these concepts, an upcoming meeting called the TVIW Symposium on The Power of Synergy is to be held in Oak Ridge, TN from October 23-25, 2018. Participants from NASA, DOE ARPA-E, Oak Ridge National Laboratory, the Y-12 National Security Complex, and several private companies are being tasked with the challenge of evaluating where we stand in just such an infrastructure.

TVIW stands for the Tennessee Valley Interstellar Workshop, which has held symposia for a number of years in Oak Ridge, Huntsville and Chattanooga — I’ve been pleased to attend most of these, and you can find my reports from past meetings in the archives here. The upcoming meeting is a departure, a gathering convened to explore a set of specific technologies in the context of the resources and technologies being readied in these high-tech areas.

Synergy — that unpredictable, frequently rewarding process of getting more out of a partnership than the apparent sum of its parts — is to be the theme throughout. Focusing on how the work of government laboratories can mesh with private industry, the symposium is to look at a set of seven key technologies, the thinking being that many of these are reaching the stage where they can create transformative progress in space within a decade. That’s a bracing thought, but the organizers believe that multi-agency cooperation can accelerate space exploration.

Participants in the symposium will be examining, for example, high-impulse nuclear propulsion, as studied in DARPA’s Timberwind Program. Political issues always swarm around nuclear ideas, but high-performance technologies realized through upper-stage nuclear rockets fired only once they have reached Earth orbit or beyond could allow faster transit times, enough so to make human expeditions to Mars far more practical than currently envisioned. Going nuclear has ramifications as well in space solar power and cislunar operations including manufacturing.

Have a look at the symposium website for more on the ideas to be discussed, which include high-energy lasers of the sort now being considered by Breakthrough Starshot as a way to propel small sailcraft with miniaturized payloads to the Alpha Centauri triple system. Closer to home, power beaming in space can help to build a transportation network in the inner system and incentivize exploratory missions to the outer planets. Likewise transformative are high-temperature superconductors, developed for several decades at Oak Ridge National Laboratory. Magnetically inflated cable (MIC) technologies can help in the construction of large space structures. Large-scale 3D printing, another ORNL specialty, points toward manufacturing capabilities in space that would be a necessary part of a permanent human presence.

Rounding out the list of enabling technologies are self-replicating von Neumann machines, solar power satellites and lightweight large-aperture optics. Can we reach the point where small machines can build larger ones out of abundant space resources found, for example, in nearby asteroids? For that matter, can we consider asteroids themselves, suitably modified by such means, as habitats safe from dangerous radiation from cosmic rays or solar storms?

And on the astronomical front, large-aperture optics offers the prospect of space telescopes that dwarf the scale of today’s efforts, including interferometer arrays for the imaging of exoplanets and advances in our knowledge of cosmology. What the symposium organizers are arguing is that all of these technologies are developing at a pace sufficient to think realistically about fleshing out a near-Earth infrastructure that can swiftly be extended to Mars and beyond.

The speaker list is being fleshed out now, but among those scheduled so far are Michael Raftery (Boeing and Explore Mars, Inc) on the ‘NASA Lunar Gateway Concept;’ Franklin Chang-Diaz (Ad Astra Rocket Company) on ‘Living and Working in Space;’ Phil Lubin (UCSB) on ‘Directed Energy Propulsion – Interplanetary and Interstellar;’ John Mankins (Artemis Innovation Management Solutions) on ‘Space Solar Power Stations;’ Bill Peter (ORNL) on ‘Large 3D Printing;’ Robert Bagdigian (NASA MSFC) on ‘Environmental Control & Life Support;’ and Joel Sercel (Trans Astronautica Corporation) on ‘Capture & Uses of 10 Meter Asteroids.’

The venue in Oak Ridge will be the Y-12 New Hope Visitor Center. Those interested in attending can visit the TVIW Symposium on the Power of Synergy website for more information.

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Listening in on Enceladus

When I was a boy, I used to scan shortwave frequencies with an old Lafayette receiver in search of distant stations. When I learned that Jupiter was a radio source, my passion for radio DXing took a new turn, merging with my interest in astronomy. When I tried to log the planet’s violent outbursts, I learned with a little digging in the library that Jupiter could be detected from about 15 MHz up to 40 MHz, with the best window somewhere between 18 MHz and 28 MHz.

Called ‘decametric noise storms,’ the Jovian bursts sometimes sounded like ocean waves hitting a shore, but there were also short bursts that could be confused with local lightning, and to this day I’m not really sure whether I really heard Jupiter or not. When you’re listening for something that sounds like the ocean in the shortwave bands, it’s all too easy to think you’re hearing it in the background noise, and a little imagination makes you think you’ve found your target.

These days we can listen to just about anything on the Internet, so I’ll point you to the Io B storm of November 27, 2001, on a page that offers charts, links and an anecdotal account of a reception. Jupiter seems to have acquired a fan base among amateur radio astronomers.

But enough of Jupiter. This morning we need to talk about Saturn and the plasma waves Cassini detected moving from the planet to its rings and the moon Enceladus. These produce the distinctive sound you can hear in the YouTube video below. (If you get Centauri Dreams through email, the video isn’t going to show, but go to this link to see it). Here the recording time was compressed from 16 minutes to 28.5 seconds.

Image: New research from the up-close Grand Finale orbits of NASA’s Cassini mission shows a surprisingly powerful interaction of plasma waves moving from Saturn to its moon Enceladus. Researchers converted the recording of plasma waves into a “whooshing” audio file that we can hear — in the same way a radio translates electromagnetic waves into music. Much like air or water, plasma (the fourth state of matter) generates waves to carry energy. The recording was captured by the Radio Plasma Wave Science (RPWS) instrument Sept. 2, 2017, two weeks before Cassini was deliberately plunged into the atmosphere of Saturn. Credit: NASA/JPL-Caltech/University of Iowa.

The plasma wave interactions are the subject of a recent paper from lead author Ali Sulaiman (University of Iowa), who is a member of the Radio Plasma Wave Science team, RPWS being the instrument on Cassini that recorded these waves traveling on magnetic field lines.

“Enceladus is this little generator going around Saturn, and we know it is a continuous source of energy,” says Sulaiman. “Now we find that Saturn responds by launching signals in the form of plasma waves, through the circuit of magnetic field lines connecting it to Enceladus hundreds of thousands of miles away.”

Image: NASA’s Cassini spacecraft’s Grand Finale orbits found a powerful interaction of plasma waves moving from Saturn to its rings and its moon Enceladus. Credit: NASA/JPL-Caltech.

Enveloped by Saturn’s magnetic field, Enceladus is a geologically active place, emitting the famous geysers we’ve so often examined in Cassini imagery. The plumes of water vapor from what appears to be an inner ocean become ionized, accounting for the strong interaction between Enceladus and the planet; similar interactions occur between Saturn and its rings.

We get this information thanks to Cassini’s high-inclination Grand Finale orbits, which brought the spacecraft both to its closest approach to the cloud tops and to the inner edge of the D ring. The recording itself was captured on September 2, 2017, just two weeks before Cassini’s final plunge. Measurements of the top of the ionosphere as well as the environment around the rings showed the plasma wave interactions and underline the dynamic nature of the Saturn system.

The paper is Sulaiman et al., “Enceladus auroral hiss emissions during Cassini’s Grand Finale,” published online by Geophysical Research Letters 7 June 2018 (abstract).

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Kelvin Long is a familiar face on Centauri Dreams, the author of several previous articles here and many publications in the field of interstellar studies. The creator of Project Icarus, the re-design of the Project Daedalus starship of the 1970s, Long was a co-founder of Icarus Interstellar and went on to head the Initiative for Interstellar Studies. He also served as editor of the Journal of the British Interplanetary Society during a critical period in the journal’s history, and authored Deep Space Propulsion: A Roadmap to Interstellar Flight (Springer, 2011). Today he turns his thoughts to catastrophe, and the question of what would happen to human civilization if it were reduced to a small remnant. Could we preserve the most significant treasures of our science, our culture, in the face of a devastated Earth? Exploring these ideas takes us deep into the past before turning toward what Kelvin sees as a possible solution.

by Kelvin F Long

The year is 2050. Earth is a thriving metropolis with a population exceeding 9 billion. Progress has been made in harmonising social-cultural tensions around the world and nation state war is now an infrequent event. A young child of the future steps out into the bright sunshine of a gorgeous new morning. Her day is still ahead of her as she out stretches her arms and smiles at the mellifluous call of the singing birds. But then looking up, she notices something in the distance, a long streak across the sky that is moving rapidly, and seems to be descending towards the ground. It disappears behind the horizon, and shortly later a blinding flash engulfs the world. The girl looks on stunned, eyes struggling against the light, to see the gradual build-up of a mushroom cloud that starts to reach high into the atmosphere. The impact event was hundreds of miles away, yet soon it engulfs the world in a global climate change and sends Tsunamis sweeping over coastal cities destroying all in the path. In response to oceanic earthquakes, the water becomes so big, that it pushes across the flat land masses; unrelenting mega white horses to a trampled poppy field below. One day, this will form into wedge shaped chevron deposits hundreds of feet high, composed of ocean floor micro-fossils. Within days of the event the girl will learn that billions of people are wiped out as the human civilization draws to a rapid stagnation. All infrastructure and governments are gone, and only small pockets of communities around the world survive, numbering thousands at best. She was one of the lucky ones, her small community of one hundred people survived just barely on their high mountain top position. This is fortunate for a girl named Hope.

Introduction

The future is uncertain. Whilst it is important to emphasise the positive reasons for the exploration of Earth and space, it is also important not to be in denial about the risks that really face us; for they are not insignificant. They are many and varied in type. From the potential for nation state warfare, to disease pandemics, to global climate change, to risks from above such as impact events by asteroids or comets or even the possibility alien invasion. The sure way to guarantee our survival is to follow the lead of Elon Musk and to make the human race an interplanetary species; and indeed to go further with an interstellar species. But until we have reached this point we are vulnerable. The proposal made in his article is not an alternative to the current plans for the colonization of space and the continued building up of infrastructure, but it is a complimentary pathway to increase the probability of human survival into the coming centuries. In particular, it should be taken on board that the assumptions of this project is that a possible future exists where rocket technology no longer even exists as a worst case survival scenario.

The Apkallu initiative is a proposed project to help reboot human civilization, on the assumption that some small pockets of human communities survive around the world during a global cataclysm, but all the remnants of our industrialised and developed civilization are destroyed. This includes our cities, our farms, our libraries, our infrastructure, and our transport networks; in essence the human race is thrown back to being a hunter-gatherer species and must begin again. It is named after the Sumerian sages who are said to have helped humankind establish civilization and culture and giving us the gifts of a moral code, mathematics, architecture, agriculture and all ways necessary to teach us how to become civilized. The Sumerian civilization is one of the first to appear in recorded history, which included the invention of its own writing form called Cuneiform. Before we discuss what the Apkallu initiative actually is, it is worth reminding ourselves of some essential context.

Impact Threats and Other Risks to Human Survival

We know that objects have impacted the Earth throughout its history and continue to do so today. Approximately 66 million years ago, it is believed that an impact event resulted in the Cretaceous-Tertiary (K-T) extinction. This led to devastation in the global environment and a prolonged winter which affected the photosynthesis of plants and plankton life. It also resulted in the destruction of a plethora of terrestrial organisms, including mammals, birds, insects and most famously the dinosaurs. The object, an asteroid or comet, was 10-15 km in diameter with a likely impact velocity of around 20 km/s and an associated kinetic energy of impact of around 30,000 – 1000,000 Gtons TNT equivalent, depending on the assumptions. It left an impact crater in the Yucatan Peninsula in Mexico, and likely created 300 feet high Tsunami’s over an impact zone of around 3,000 miles.

Another example is the Arizona Meteor crater, which was the result of a Nickel-Iron object around 50 m in size impacting the Earth 50,000 years ago. With impact velocities ranging from 2.8 – 20 km/s this would have impacted with an associated kinetic energy of 10.7 – 26.2 Mtons TNT equivalent. Today, a crater remains of the impact event, 1.2 km in diameter and over 550 feet deep.

In 1908 a comet is believed to have impacted eastern Siberia, causing a flattening of a forest 2,000 square km in size. Since no impact crater was found, it is believed that the object disintegrated at an altitude of 5 – 10 km above the ground. The estimated energy of the air burst explosion was 10 – 15 Mtons TNT equivalent; depending on the assumptions one makes.

In July 1994 a comet split into 21 fragments ranging in size up to 2 km, and impacted the upper atmosphere of Jupiter with an impact velocity of around 60 km/s. The total energy of these impacts was around 6,000 Gtons TNT equivalent creating dark red spots with some being 12,000 km in size. Had this comet impacted the Earth, it would have posed a major threat to human existence.

During late 2017 we observed the close flyby pass of an asteroid of interstellar origins named ‘Oumuamua. Much of the nature of this objects remains uncharacterised, but some sensible estimates of the maximum potential impact energy suggest 4.2 – 46.9 Gtons TNT equivalent, had it impacted the Earth.

Then in April this year that an object named Asteroid 2018 GE3 passed closed to Earth and was spotted 119,500 miles away, which is closer than the Moon, which orbits at an average distance of 238,900 miles. The object was first observed by the NASA funded Catalina Sky Survey project based at the University of Arizona Lunar and Planetary Laboratory. It was first observed a mere 21 hours before the closest approach to the Earth. The object was estimated to be at least 150 – 360 ft in diameter.

How many more are out there waiting for us? No doubt some will argue that the impact risks are statistically small and we should not be concerned about them. We know there are many asteroids in our own Solar System, varying in size from 1 m up to 1,000 km. Approximately 16,000 objects have been found near Earth, but this is a small fraction of the estimated total that is out there, which varies between 1 – 2 million. Statistically, this presents a threat to human existence and life as we know it. Indeed, it is the belief of this author that impact events which can lead to global devastation of the human population may be as frequent as 1/1,000 – 1/10,000 years.

In addition to impact risks there are many other threats to human existence. This may include the implications of magnetic field reversal. Such an event occurred 41,400 years ago during the last ice age, called the Laschamp event. It caused a magnetic field reversal leading to a drop in its strength. This resulted in more cosmic rays reaching the Earth and an increased production of the isotopes Beryllium 10 and Carbon 14.

There are also the risk of enhanced solar activity such as through large scale solar flares, or the possibility of the Sun entering unstable periods in its evolution for which are current models of stellar-structure are not aware. This could be due to the passage of our Sun through the spiral density arms of the galaxy. There are the risks of nation state war or even global thermonuclear war that could drive us towards extinction, either through direct destruction or through altering the climate. There are the risks of human disease pandemic, which surely must become more probable in an increasing global population. There are the risks of human destruction of elements of the biosphere, such as pollutions of the oceans, soils, deforestation or polluting of the atmosphere. There are the risks that microbes could be introduced into our biosphere from an alien planet that is infectious to our biodiversity.

Then there is the actual risk of alien invasion, from a species set on conquering other lower species or seeking resource acquisition no matter the costs. It may be assessed that some of these are low probability. However, the fact that there are so many risks to the future survival of humankind should be a concern, and it is vital that we take a proactive approach to adaptability and survival, instead of a reactive one when such events occur.

Assumptions of a hypothetical Near-Human Extinction

Imagine a situation where human kind is nearly wiped out by some global cataclysm. This could be an impact event or one of the other risks highlighted earlier. In a worst case scenario, but one where some humans survive, we might make the following assumptions:

  • 1. All infrastructure is destroyed, to include buildings, power utilities, city plumbing, dams, transport networks, agriculture and farming, huge portions of the plant and animal kingdom.
  • 2. All information sources are destroyed, to include all the world libraries, computers and electronic memory. It is possible that some books will be discovered over time as communities explore the rubble remaining from the metropolis. Books would become precious beyond their current value.
  • 3. The global climate is in turmoil and hostile, but with isolated regions of stability such that with determination survival is possible.
  • 4. The geological, climatic, oceanic activity and effects of the cataclysm event, within weeks, months or years will gradually return towards some level of stable Earth.
  • 5. Small pockets of humans survive around the Earth, perhaps 10s to 100s each but with the total not exceeding thousands.

Given this scenario, we can note that the surviving generation will remember the world as it was before. They will use this knowledge to teach their children. At this point knowledge is based upon direct memory. Those children will then grow up, with their parents dying off, and they will remember what their parents taught them and some of those children may even have some memories of the world before. But for the most part we are dealing here with recent history and part mythology. The grandchildren will also be born and grow up, but they will have no direct memory of the world the way it was before. At this point we are dealing with history and mythology. Within the third or fourth generation there is a risk that all knowledge will be lost, and especially if that knowledge is not captured and written down. All received knowledge then becomes both mythology and fantasy.

There are solutions to this practiced by the Native North Americans for example, which is to communicate stories verbally and also use this to impart wisdom, and those stories are accompanied by rituals. However, one cannot believe that such a method of communication does not contain significant information error propagation with each successive generation, compared to the original version.

The History of Humans on Planet Earth

In the event of a global cataclysm, assuming small pockets of human communities survive, but the majority of human civilization and associated technological infrastructure is destroyed, how can we ensure a chance at rebooting human knowledge? Indeed, is it possible that this has in fact occurred in the recent past and this is a part reason for the many Megalithic structures on Earth?

Until recently, Sumer was the earliest known civilization in the historical Mesopotamia, and is located in modern Iraq. It dates back to 3,000 B.C and was likely settled around 4,000-5,500 B.C by proto-Euphrateans or Ubaidians. The people from this era are credited for many great inventions and discoveries which led to the advance of their society. This includes in mathematics, geometry, agriculture, architecture, economics and law to name a few. One of the most famous objects discovered from this period is the Code of Hammurabi, a 2.25 m tall stone wall consisting of 282 laws, such as “an eye for an eye” and is the first legal system from the Old Babylonian period.

The Code of Hammurabi, created 1750 B.C, currently housed at the Louvre, Paris (image credit: K. F. Long)

It is important to note that in the Babylonian creation mythologies, which were written in Cuneiform, there are around a thousand lines of text on seven clay tables. The focus of this text is the creation of humankind for the service of the gods. These texts are called the Enûma Eliš, and arguably they have a clear lineage to the Judeo-Christian Bible. The Cuneiform script was scribed, using a wedge-shaped marker onto a wet clay tablet and also cylinder seals. These are small round objects typically an inch in length engraved with information. Once dried the inscription was permanent. The information preserved on tablets and seals was Cuneiform text but also contained figurative scenes or descriptions of events or objects. Such objects are breathtaking in their clarity, gorgeous in their artistic nature, and contain a wealth of information about the society, its rituals, values, business, science and technology.

Photographs of Sumerian Cylinder Seals from the Private Collection of the Author (image credit: K. F. Long)

The Holy Bible records a flood story that engulfed all of planet Earth. This is recorded in Genesis chapters 6 – 9, and the flood seems to last for around one hundred and fifty days. Other cultures have recorded similar stories. For example the Sumerian tale of Ziusudra and the Atra-Hasis also describes a global flood story that is similar to that told in Genesis. In the Sumerian story the flood lasts for seven days. An account is also told in the Epic of Gilgamesh, which is more similar to the Biblical story. Also, the Hindu mythology tells of a great flood in the Satapatha Brahmana. It is very easy to dismiss the possibility of a global flood as pure mythology, but the occurrence of a similar story in so many cultures around the world is at least suggestive that it may be a memory of an actual event which many today are regarding as mythology. Indeed, science may be catching up with the past.

Geologists and climatologists study a period in Earth’s history called the Younger Dryas, which occurred 12,900 to 11,700 years ago and saw a return to glacial conditions which temporarily reversed the gradual climatic warming after the last glacial maximum which began receding around 20,000 years ago. It led to many catastrophic effects including the decline of the Clovis culture in North America and the extinction of many megafauna which included the Mammoths; the last of which survived into the Holocene around 4,500 years ago in Africa, Europe, Asia and North America.

Illustration of the Younger Dryas period

In recent years, evidence is emerging that the Younger Dryas period may have been caused by a cometary impact event on the North American ice sheet, around 12,900 years ago. The evidence for his includes the discovery of a 10 million ton deposit of impact spherules across four continents, and the discovery of a Nano-diamond rich layer. In addition, analysis of underground soils indicates massive wildfire and abrupt ecosystem disruption on California’s Northern Channel Islands. Scientists have also discovered very high temperature impact melt products as evidence for an air burst explosion. All of this is dated to around 12,900 years ago, at the onset of the Younger Dryas. If this is proven to be correct, then a global cataclysm may indeed have occurred in our recent past. Speculating, if any advanced civilizations existed on Earth prior to this date, they may have been wiped out by this cataclysm forcing civilization to start from the beginning again.

At some point in our past we moved from a hunter-gatherer species to an agricultural-farming one, where we embraced the domestication of animals and crops. This is marked by a period called the Neolithic, and occurred around 10,200 years ago. It is considered to be the last period of the stone age and commenced the beginning of the Neolithic revolution. It ended with the emergence of the Copper and Bronze and Iron ages and our new abilities to use metals. It is remarkable that we have apparently exploded technologically and social-culturally over the last 10,000 years or so to the state where we have computers, cars, aeroplanes and communication satellites. What was it that propelled us forward over such a short space of time? Why had we not achieved this level of maturity previously? Was it the formation of a critical population density? Was it global climatic conditions? What is our tribal nature and inability to get organized? What it some other threats to our existence?

Homo sapiens in our modern form may be several hundred thousand years old. Paleolithic cave art certainly goes back to 40,000 years but may be 60,000 years if we include what is currently being claimed to be art from Neanderthal man. Evidence from the out of Africa hypothesis puts homo sapiens at around 130,000 – 180,000 years old. But there are alternative versions which claim populations emerging out of Africa as early as 350,000 years ago. Evidence for older findings includes discoveries of anatomically modern human skull fossils at Jebel Irhour in Morocco (315,000 years) and Middle Awash in Ethiopia (160,000 years). The history of human evolution is far from settled and ‘thinking man’ may be much older than we realised.

Ancient Megaliths

A story from ancient Sumeria is that of an amphibious being called Oannes (also known as Adapa) who apparently taught humankind wisdom. The story was told by Berossus in 290B.C, a Chaldean Priest in Babylon. Berossus described Oannes as having the body of a fish but underneath the figure of a man. He is said to dwell in the Persian Gulf, rising out of the waters in day time and furnishing humankind in the instruction of writing, arts and other subjects. Here are the words of Berossus:

“At first they led a somewhat wretched existence and lived without rule after the manner of beasts. But, in the first year appeared an animal endowed with human reason, named Oannes, who rose from out of the Erythian Sea, at the point where it borders Babylonia. He had the whole body of a fish, but above his fish’s head he had another head which was that of a man, and human feet emerged from beneath his fish’s tail. He had a human voice, and an image of him is preserved unto this day. He passed the day in the midst of men without taking food; he taught them the use of letters, sciences and arts of all kinds. He taught them to construct cities, to found temples, to compile laws, and explained to them the principles of geometrical knowledge. He made them distinguish the seeds of the earth, and showed them how to collect the fruits; in short he instructed them in everything which could tend to soften human manners and humanize their laws. From that time nothing material has been added by way of improvement to his instructions. And when the sun set, this being Oannes, retired again into the sea, for he was amphibious. After this there appeared other animals like Oannes.“

Whether this is pure fiction or has any resemblance to historical events does not matter, but it is this story that has given rise to the idea of building what this author is calling a ‘minilithic artefact’ under the Apkallu Initiative as will be discussed further below. As an aside it is worth noting that in his book Intelligent Life in the Universe, written with L. S. Shklovskii (Pan Books, 1977), the astronomer Carl Sagan opened a discussion on the Sumerian civilization with “I came upon a legend which more nearly fulfils some of our criteria for a genuine contact myth”.

On planet Earth we know that species rise up and fall and suffer extinction. The fossil record has shown this for many a species. There are also arguments that Homo Sapiens are not the only occurrence of intelligence on Planet Earth (see for example the recent book Other Minds by Peter Godfrey-Smith’ on the Octopus, William Collins, 2016). Why then is it not possible, in the last million years, that an earlier species of man, or other life form on Earth, could have evolved to similar levels of intelligence to that which we possess today, to include a technological level similar in extent? Such a people would predate modern recorded history, and it is at least plausible that some memory of them could be preserved in the creation mythologies of our various ancient cultures.

Many ancient Megalithic structures have been found by archaeologists around the world. This includes for example the Great Pyramid and the Great Sphinx in Giza (4,500 years old), Tiwanaku and Pumapunku in West Bolivia (3,500 years old), Stonehenge in England (5,000 years old), Machu Picchu in Peru (550 years old) to name a few. However, recently our linear understanding of human evolution from a hunter-gatherer species to an agricultural-farming one has been placed under scrutiny, by the discovery in 1996 of Gӧbekli Tepe, a site in the South eastern Anatolia region of Turkey, which may date back to 12,000 years old. The site demonstrates a superior knowledge of construction techniques, geometry and other disciplines and to enable its construction would have required a food surplus to exist – before the arrival of the Neolithic revolution. In addition, it is arguable that to get to a point where you can construct something like Gӧbekli Tepe would take thousands of years of advancement of knowledge in itself. This might suggest that the builders were 15,000 – 20,000 years old.

A potentially even older site has also been found in West Java, called Gunung Padang, which was discovered in 1914. It may be the largest megalithic site in South Eastern Asia. Radiocarbon dating puts the site at several different eras spanning 6,500 – 20,000 years ago, although the dating claims are controversial among archaeologist in Indonesia. A large structure has also been discovered beneath the surface some 15 m down and includes large chambers. This discovery, and that of Gӧbekli Tepe, is telling us that our linear understanding of history is in need of revision.

Interglacial Periods in Earth’s History

Given the existence of Gӧbekli Tepe and Gunung Padang, the idea that an earlier intelligent and advanced civilization existing on Earth is not so implausible. However, were there opportunities in Earth’s history for this to occur? An examination of climatic conditions would seem to suggest so.

During the history of Earth there have been five major ice ages, and we are currently in the Quaternary Ice Age at this time, which spans from 2.59 million years ago. Within the ice ages are sub-periods known as glacial and interglacial periods.

Recent measurements of the relative Oxygen isotope ratio in Antarctica and Greenland show the periods of glacial and interglacial periods throughout history over the last few hundred thousand years. This is a measurement of the ratio of the abundance of Oxygen with atomic mass 18 to the abundance of Oxygen with atomic mass 16 present in ice core samples, 18O/16O, where 16O is the most abundant of the naturally occurring isotopes. Ocean water is mostly comprised of H216O, in addition to smaller amounts of HD16O and H218O. The Oxygen isotope ratio is a measure of the degree to which precipitation due to water vapour condensation during warm to cold air transition, removes H218O to leave more H216O rich water vapour. This distillation process leads to any precipitation having a lower 18O/16O ratio during temperature drops. This therefore provides a reliable record of ancient water temperature changes in glacial ice cores, where temperatures much cooler than present corresponds to a period of glaciation and where temperatures much warmer than today represents an interglacial period. The Oxygen isotope ratios are therefore used as a proxy for temperature changes by climate scientists.

The Vienna Standard Mean Ocean Water (SSMOW) has a ratio of 18O/16O = 2005.2×10-6, so any changes in ice core samples will be relative to this number. The quantity that is being measured, δ18O, is a relative ratio calculated as in the units of % parts per thousand or per mil. The change in the oxygen ratio is then attributed to changes in temperature alone, assuming that the effects of salinity and ice volume are negligible. An increase of around 0.22% is then defined to be equivalent to a cooing of 1˚C.

There are differences in the value of δ between the different ocean temperatures where any moisture had evaporated at the final place of precipitation. As a result the value has to be calibrated such that there are differences between say Greenland and Antarctica. This does result in some differences in the proxy temperature data based on ice core analysis, and Greenland seems to stand out, such as indicating a more dramatic Younger Dryas period (11,600 – 12,900) than other data.

An analysis of this data shows that the climate has varied cyclically throughout its history and is manifest of natural climate change. In particular what emerges out of the data are some interesting lessons about the recent history of planet Earth. Data shows the rapid oscillations of the climate temperature from the average temperature of today, indicative of glacial and interglacial periods. In particular, the data shows that during the Holocene period, beginning approximately 11,700 years before present, the temperature varied between 2-4 ˚C.

It is reasonable to assume that human civilizations under development will do better when the climate is kinder. This means that the warmer it is the better civilisations will do, and the colder it is, the harder the struggles. In particular we can expect that during the conditions of a colder climate that agricultural farming will suffer, and so there will be less food to go around, which will affect both lifespan and population expansion. To support this it is worth noting that the current epoch, the last 10,000 years has been one of the longest interglacial period for at least the last quarter of a million years and it is reasonable to therefore assume that this is one of the factors which has allowed human development from the emergence of the Neolithic period coming out of the last ice age.

The data also shows that there was a large global warming period known as the Eemian around 115,000 – 130,000 years ago. The average global temperatures were around 22 – 24 ˚C, compared to today where the average is around 14 ˚C. Forests grew as far north as the Arctic circle at 71˚ latitude and North Cape in Norway Oulu in Finland. For comparison North Cape today is now a tundra, where the physical growth of plants is limited to the low temperatures and small growing seasons. Given that homo sapiens may have been here since around 300,000 years ago, this seems like a major opportunity for the development of human society from a people of hunter gatherers to one of agricultural developers and the development of a civil society.

There have been other interglacial periods that have resulted in global temperatures being either equivalent or above the average today, and the data shows temperature spikes of periods at around 200,000 years, 220,000 years, 240,000 years, 330,000 years and 410,000 years. Each of these interglacial periods will typically last at least 10,000 years.

Temperature Proxy Data Showing Opportunities for the Rise of Advanced Civilization in Recent Prehistory

The Apkallu Initiative

It is fully admitted that much of the above contains speculation, but until we have a firmer grasp of history it would be unwise to rule such possibilities out. We turn our attention then to the future and solving the problem of how to preserve human knowledge in the event of a global cataclysm such that humankind can restart again so that within centuries we mature back to similar levels of today’s technological advancement. Ultimately this is a statistical problem, in that by reducing the time of each cycle for maturing to technological capability, one improves the probability of survival. It is sensible to think of this concept as a civilization accelerator.

The Apkallu Initiative is therefore a proposal to construct a minilithic artefact (analogous to Megalithic artefacts) that can survive for a time duration exceeding 100,000 years. This duration is chosen for three principal reasons:

  • 1. The recent ice core records suggest that within that time period there may be several opportunities (~4) where the climatic conditions are sufficiently supportive for human existence to facilitate growth beyond basic survival.
  • 2. It approximately corresponds to four processional cycles of the Earth around the equinoxes, which typically last 25,920 years. We note that many of the ancient Megaliths seem to have been preoccupied with the measurement of the equinoxes; which may relate to lost memory of previous cataclysms.
  • 3. It is difficult to design for an artefact that can survive longer than this, although desirable.

The artefact would be a form of archaeological-architectural device from the standpoint of future humans who uncover it. The device would be replicated perhaps 1,000 times and distributed around the seven continents of the Earth. Ideally, some could also be placed in space, on the Moon or Mars. The idea is that any future human surviving a global cataclysm that finds this artefact and studies it sufficiently, it will give them the knowledge they need to rapidly advance human civilization at an accelerated rate.

Painting illustrating future man finding the archaeological artefact (credit: K. F. Long)

The artefact would be a form of long distance communication. We have of course attempted message plaques in the past such as the Voyager Golden Record and the Pioneer Plaque. Indeed, the Code of Hammurabi from the Sumerian civilization is a form of minilithic artefact, but just specific to moral and legal codes. Another example would have been the tablets for the Biblical Ten Commandments.

There is a question of what materials to construct the artefact from. Plastics and metals will likely degrade over thousands of years. Electronic memory is not useful if it is subject to flip switching and also requires a computer interface to read it. It therefore seems sensible to construct the artefact out of stone; perhaps in a similar manner to the Sumerian Cuneiform on wet clay tablets. One of the options may be Diorite. It would perhaps be useful to depict both logograms, with syllabic and alphabetic elements, as well as phonetics and even determinatives to create appropriate semantic descriptions.

There is a question of what information should the artefact contain. It should contain the foundation knowledge of human civilization. This is a subjective decision. One example we might take lessons from for example was the Trivium (logic, grammar, rhetoric) and the Quadrivium (arithmetic, geometry, music, astronomy) of the classical world. Both were considered preparation work before delving into the study of philosophy and theology. In addition to these, the artefact might contain many other disciplines of thought, such as human biology, medicine, architecture, chemistry, physics, law, history, music, language, agriculture, botany, ethics and other subjects. Experts in appropriate disciplines would need to be consulted to derive the say 12 base foundation knowledge or tenets that govern a field from which in principle all else can be derived given time.

The goal of the information content imprinted onto the artefact would be as follows:

  • Goal 1: The continued survival of the human species at peace.
  • Goal 2: The accelerated technological, social-cultural growth of human civilization from an assumed stagnated level.
  • Goal 3: The preservation of moral and ethical philosophy

There is also a question of what language. One approach would be to take lessons from historical artefacts which contained several languages to ensure future interpretation. This includes the Rosetta Stone (2,200 years old) which contains ancient Egyptian hieroglyphics, demotic and ancient Greek. Another example is the Fuente Magna of the Americas (5,000 years old), found in Bolivia but contains both ancient Pukara and a proto-Sumerian alphabet. Another example is the Behistun inscription (2,500 years old) found in Iran, which contains three different cuneiform script languages, that of Old Persian, Elamite and Babylonian.

There is also the question of the size and shape of the artefact, and although you want it big enough to find, you also want to manage the construction cost of the project. Something around 6 – 12 inches would seem a good optimum size. The exact shape would have multiple surface areas to facilitate different disciplines of knowledge. One idea is a Dodecahedron, which has 12 faces.

The proposal of the Apkallu Initiative is to form a team which then designs and leads the construction of such an artefact. This can then be reproduced and distributed to different locations around the world. Some would eventually be displayed in art galleries or museums and some will be lost to the land and sea, but the hope is that in the event of the cataclysmic scenario described above that future human will stumble across such an artefact, and after studying it, teach their community everything they need to become a civilized and socially-technologically advanced society. Currently no team has been formed, but this article is an initial invitation of interest and anyone interested can contact the web site: https://www.apkalluinitiative.com/

Our ability to become an interstellar capable species depends in the near term on our ability to survive here on Earth or in near-space. The preservation of the deep knowledge and learning of the human experience is critical to this future, if we are to continue to progress, avoid stagnation and decay or even complete extinction or avoid repeating mistakes of the past.

Finally, such a project has the potential to inspire long-term thinking among differing human societies, and so in itself may be a self-perpetuating mechanism toward social-cultural harmonization and increased global awareness of our fragility in the great Cosmos. In addition, because of its interdisciplinary nature, it has the potential to involve all of humanity on its journey, as we jointly work toward a back-up plan to ensure that humanity can survive in the millennia ahead.

The author dedicates this article to the efforts of Graham Hancock and Randall Carlson, whose significant research inspired this initiative. It was written to garner scrutiny of the idea, before deciding whether to proceed or not. Feedback is invited.

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Occator Crater Up Close

It’s startling to think that the Dawn spacecraft, now orbiting Ceres at its lowest altitude ever, may have fired its ion engine for the last time. The event occurred by way of positioning the spacecraft for the best possible track near Cerealia Facula, which is a prominent deposit of sodium carbonate in the center of the crater called Occator. Data from the spacecraft’s visible and infrared imaging spectrometer had been used to identify the bright areas called faculae as calcium carbonate deposits earlier in the mission. Vinalia Faculae is in the same area.

“Acquiring these spectacular pictures has been one of the greatest challenges in Dawn’s extraordinary extraterrestrial expedition, and the results are better than we had ever hoped,” said Dawn’s chief engineer and project manager, Marc Rayman, of NASA’s Jet Propulsion Laboratory, Pasadena, California. “Dawn is like a master artist, adding rich details to the otherworldly beauty in its intimate portrait of Ceres.”

Image: A prominent mound located on the western side of Cerealia Facula, in an image obtained by NASA’s Dawn spacecraft on June 22, 2018 from an altitude of about 34 kilometers. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

You’ll recall the intriguing bright material that began showing up during Dawn’s approach to Ceres, the investigation of which has been a major theme for mission controllers. Imagine if we had a Pluto orbiter to rival what Dawn is doing at Ceres, with the opportunity to map the entire surface, and to delve deeply into the unusual geology on display there. In the case of Ceres, we can now say that the mound above, located at about 19.5 degrees north latitude and 239.2 degrees east longitude, is similar, in JPL’s words, to ‘a mesa or large butte with a flat top.’

Image: In this image of the northern rim of Occator crater landslides can be seen. The image was obtained by NASA’s Dawn spacecraft on 16 June, 2018 from a distance of approximately 33 kilometers. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

Researchers have concluded that the dome at the center of Occator is the source of saline solutions that evaporated, leaving the bright deposits identified early in the mission (for further background, see this MPS news release). Here and elsewhere in the crater, we are probably seeing vents that allow a mixture of water and salt to rise from a deeper brine reservoir. The new imagery gives us the best differentiation yet between the bright sodium carbonate and the dark background material, allowing us to probe still further the origin of the faculae.

“The data exceed all our expectations,” says framing camera lead investigator Andreas Nathues (Max Planck Institute for Solar System Research, Germany). “We now hope to understand how the bright deposits outside the crater center came about – and what they tell us about Ceres’ interior.”

Bear in mind as well that new gravity measurements may likewise provide details about the subsurface of the dwarf planet. As with New Horizons, analysis of the data trove will take years as the imagery continues to pour in. The faculae of Ceres are the largest deposit of carbonates ever found outside Earth and possibly Mars, leading to the question of how this material was exposed. This JPL news release notes as major possibilities a shallow, subsurface reservoir of mineral-rich water, or a deeper source of brines percolating upward through fractures.

Image: This close-up image of the Vinalia Faculae in Occator Crater was obtained by NASA’s Dawn spacecraft on June 14, 2018 from an altitude of about 39 kilometers. This image reveals the intricate pattern between bright and dark material across this flow feature. The complex structure of the dark background is reminiscent of lava flows observed on Earth. However, in the case of Ceres, the flow material likely involved a lot of ice. The bright material is mostly composed of sodium carbonate, a salt whose exposure onto the crater floor involved a liquid source. The center of this picture is located at about 21.0 degrees north latitude and 241.3 degrees east longitude. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

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