III. Ecosmos: A Revolutionary Fertile, Habitable, Solar-Bioplanet, Incubator Lifescape

H. Stellar Planetary Systems: A Stochastic Profusion of Galaxies, Solar Orrerys, and Habitable Zones

Seager, Sara, organizer, moderator. The Next 40 Years of Exoplanets. http://seagerexoplanets.mit.edu/next40years.htm. Full video talks can be found here from this May 27, 2011 event at MIT where advocates and researchers waxed on this grand vista just opening for our intelligent, technological world. But all is not well in this endeavor. Pioneer finder Geoff Marcy denounced NASA cuts of future search projects, due much to a myopic, pinched bureaucracy. Anyway, speakers such as David Charbonneau, Vikki Meadows “A Futuristic Virtual Planetary Laboratory,” Shawn Murphy, Natalie Batalha, Dimitar Saselov “Life, the Universe, and Everything,” William Bains “New Life and New Civilizations,” and others extoled many promising pathways. The meeting was covered in Science for August 19, 2011 as “A Distant Glimpse of Alien Life?”

Setiawan, Johny, et al. A Giant Planet Around a Metal-Poor Star of Extragalactic Origin. Science. December 17, 2010. A European Space Agency team reports the first sighting of an extrasolar globe that appears to have initially come from beyond our local galaxy. Another significant indicator is registered of our Earth’s epochal discovery of a different kind of cosmos that innately seeds itself with such myriad potentially ovular worlds.

Because HIP 13044 belongs to a group of stars that have been accreted from a disrupted satellite galaxy of the Milky Way, the planet most likely has an extragalactic origin. (1642)

Seyler, Lauren, et al. Metabolomics as an Emerging Tool in the Search for Astrobiologically Relevant Biomarkers. Astrobiology. June, 2020. A seven member team from the Woods Hole Oceanographic Institution, Centro de Astrobiología, Madrid, Blue Marble Space Institute, Seattle, and Cal Tech including James Cleaves scope out how such an expansive –omics approach, properly integrated and applied, can well facilitate this grand new exoplanetary phase as Earthlings begin to search for near and far celestial neighbors.

It is now easy to sequence and recover microbial genomes from environmental samples. If transcriptional and translational functions can be assigned to these genomes, it should be possible to understand the molecular inputs and outputs of a microbial community. However, gene-based tools alone are presently insufficient to describe the full suite of chemical reactions and small molecules that compose a living cell. Metabolomic tools have developed quickly and now enable rapid detection and identification of small molecules within biological and environmental samples. These technologies will soon facilitate the detection of novel enzymatic activities, novel organisms, and potentially extraterrestrial life-forms. (Abstract)

Shahar, Anat, et al, Anat, et al. What Makes a Planet Habitable. Science. 364/434, 2019. Carnegie Institute of Washington geochemists add another requirement for life’s long-term viability. Suitable internal core conditions are a vital factor within the overall conduciveness for living systems to appear and evolve.

The Milky Way Galaxy teems with planetary systems, most of which are unlike our own. It is tempting to assume that life can only originate on a planet that is similar to Earth, but different planets able to sustain Earth-like features could be important for habitability studies. To aud the search for extraterrestrial life, scientists must assess which features of Earth are essential to the development and sustenance of life for billions of years and whether the formation of such planets is common. External effects such as stellar variability and orbital stability affect habitability, but internal processes that sustain a clement surface are also vital. A combination of observations, experiments, and modeling of planetary interiors can guide the search for extraterrestrial life. (Summary)

Shields, Aomawa. The Climates of Other Worlds: A Review of the Emerging Field of Exoplanet Climatology. Astrophysical Journal Supplement Series. 243/2, 2019. A UC Irvine astrophysicist adds another important detectable feature for exoplanet searches across near and far Milky Way environs. Just as here, atmospheric weather patterns are a good indicator of relative habitability.

While climate models have often used to analyze and predict climate and weather on Earth, a growing community of researchers has begun to apply relative models to extrasolar planets. This work has provided a better understanding of how orbital, surface, and atmospheric properties affect planetary climate and habitability; how these climatic effects might change for different stellar and planetary environments; and how observational signatures of newly discovered planets might be influenced by these climatic factors. This review summarizes the active field of exoplanet climatology thus far, recent work using a hierarchy of computer models to identify planets most capable of supporting life, and offers a glimpse into future directions for exoplanet science. (Abstract excerpt)

Shorttle, Oliver, et al. Why Geosciences and Exoplanetary Sciences Need Each Other. arXiv:2108.08382. In an article to appear in a special Geoscience Beyond the Solar System issue (17/4) of Elements: An International Magazine of Mineralology, Geochemistry and Petrology, Cambridge University and Southwest Research Institute astrogeologists including Cayman Unterborn contribute to this grand project going forward as our fittest global genius begins to explore and quantify near and farther orbital environs. A glossary from Abiogenesis Zone and Albedo to Tidal Lock and White Dwarf suits the wild frontier. See also Compositional Diversity of Rocky Exoplanets at 2108.08383, and The Diversity of Exoplanets: From Interior Dynamics to Surface Expressions st 2198L09385, for this issue. See Blue Marble, Stagnant Lid: Could Dynamic Topography avert a Waterworld? by this group at 2201.05636 for more considerations.

The study of planets outside our solar system may lead to major advances in our understanding of the Earth, and provide insight into the universal set of rules by which planets form and evolve. To achieve these goals requires applying geoscience's wealth of Earth observations to fill in the blanks left by the necessarily minimalist exoplanetary observations. In turn, Earth's many one-offs, e.g., plate tectonics, surface liquid water, a large moon, and life - which have long presented chicken and egg type conundrums for geoscientists - may find resolution in the study of exoplanets possessing only a subset of these phenomena. (Abstract)

Shostak, Seth. Searching for Smart Life around Small Stars. Astronomy. February, 2014. The SETI Institute astronomer and advocate contends that “red dwarfs” ought to be an especially favorable locale for bioworlds with intelligence. Article illustrations go on to depict a Residential Areas around a G type stars (our sun) and this K type, dubbed No Fry Zones or habitable areas. But by displaying both a planetary band and the host star, one is led to wonder if they altogether are “solar incubator” systems, which would be conceivable from a revolutionary conducive spacescape, heavenly hatchery, vista. See How Did Life Begin? by SS in The Search for Alien Life issue from Scientific American (Summer 2022).

A red dwarf is a small and relatively cool star on the main sequence, either late K or M spectral type. Because of their small size, they burn their fuel slowly, which allows them to live a very long time. (Internet)

Sibony, Yves, et al. The Rotation of Planet-Hosting Stars. arXiv:2204.01421. University of Geneva and University of Zurich researchers perform initial analyses that indicate the presence of whole solar system interactivities between physical stellar forces and nascent orbital worlds.

Simpson, Fergus. An Anthropic Prediction for the Prevalence of Waterworlds. arXiv:1607.03095. As myriad orbital objects of every possible kind are being detected, the University of Barcelona, Institute for Cosmic Sciences, researcher notes that in contrast to a default state of wholly wet or dry surfaces, Earth’s mottled mantle of ocean and land is a rare anomaly. By way of a “planetary fecundity,” life has been able to evolve from primitive rudiments to human observers, thus an anthropic explanation. We include longish quotes to catch the gist, which appends another reason why this home Earth is so uniquely precious.

Should we expect most habitable planets to share the Earth's marbled appearance? Terrestrial planets within the habitable zone are thought to display a broad range of water compositions, due to the stochastic nature of water delivery. Such diversity, taken at face value, implies that the surfaces of most habitable planets will be heavily dominated by either water or land. Convergence towards the Earth's equitably partitioned surface may occur if a strong feedback mechanism acts to regulate the exposure of land. It is therefore feasible that the Earth's relatively balanced division of land and sea is highly atypical amongst habitable planets. We construct a simple model for the anthropic selection bias that may arise from an ensemble of surface conditions. Across a broad class of models we consistently find that (a) the Earth's ocean coverage of 71% can be readily accounted for by observational selection effects, and (b) due to our proximity to the waterworld limit, the maximum likelihood model is one where the majority of habitable planets are waterworlds. This 'Dry Earth' scenario is consistent with results from numerical simulations, and could help explain the apparently low-mass transition in the mass-radius relation. (Abstract)

On a purely statistical basis, one naıvely expects to find a highly asymmetric division of land and ocean surface areas. A natural explanation for the Earth’s equitably partitioned surface is an anthropic selection process. We have highlighted two mechanisms which could be responsible for driving this selection effect. First of all, planets with highly asymmetric surfaces (desert worlds or waterworlds) are likely to produce intelligent species at a much lower frequency. Secondly, planets with larger habitable areas are capable of sustaining larger populations. Both of these factors imply that our host planet has a greater habitable area than most life-bearing worlds. (7) It has been argued that the apparently unique and special properties of the Earth is indicative of the sparsity of life in the Universe - the so-called ‘Rare Earth hypothesis’. However this interpretation fails to account for one of the factors which controls the fecundity: the number of observers produced by each planet. This amplifies the already considerable observational selection effects associated with the emergence of life. The parameters of an observer’s host planet are heavily skewed in favour of those conditions which maximize the abundance of life, not just the probability of its emergence. The apparent fine-tuning of the Earth’s parameters need not reflect the sparsity of life in the cosmos, but on the contrary, it may be driven precisely because we are a small piece within a vast ensemble. (8)

Simpson, Fergus. The Longevity of Habitable Planets and the Development of Intelligent Life. International Journal of Astrobiology. 16/3, 2017. The University of Barcelona cosmologist adds one more qualification for organisms to evolve, develop, proceed so as to reach a stage of global, knowledgeable sentience. It is not so much a “difficult” process as a necessarily “slow” pathway that seems to requires some billion years from microbes to cities to play out.

Why did the emergence of our species require a timescale similar to the entire habitable period of our planet? Our late appearance has previously been interpreted by Carter (2008) as evidence that observers typically require a very long development time, implying that intelligent life is a rare occurrence. Here we present an alternative explanation, which simply asserts that many planets possess brief periods of habitability. We also propose that the rate-limiting step for the formation of observers is the enlargement of species from an initially microbial state. In this scenario, the development of intelligent life is a slow but almost inevitable process, greatly enhancing the prospects of future search for extra-terrestrial intelligence (SETI) experiments such as the Breakthrough Listen project. (Abstract)

Sramek, Ondrej, et al. Thermal Evolution and Differentiation of Planetesimals and Planetary Embryos. Icarus. 217/339, 2012. Czech, American, and French astrogeologists contribute to Great Earth’s discovery of myriad worlds such as our own across galactic and cosmic celestial ages, could one muse as if a uterine universe. And it is always intriguing in such studies how often gestational imageries are employed.

Stevenson, David and Sean Large. Evolutionary Exobiology: Towards the Qualitative Assessment of Biological Potential on Exoplanets. International Journal of Astrobiology. Online October, 2017. A Carlton le Williams Academy, Nottinghamshire, UK (search DS and the school) biologist and a University of Exeter physics consider this READ nascent exploratory phase of Earthkind’s cosmic census of potential near and far neighbors. A novel parameter of the relative “information density” of planetary life is added, along with tidal-locking from a good moon. See also Evolutionary Exobiology II by D. Stevenson in this journal (July 2018), and his 2017 Springer book The Nature of Life and Its Potential to Survive, which develops this informational essence.

A planet may be defined as habitable if it has an atmosphere and is warm enough to support the existence of liquid water. These are a basic set of conditions that allow it to develop life similar to ours, which is carbon-based and has water as its universal solvent. While this definition can allow a broad range of possibilities, it does not address whether any life forms will become complex or intelligent. In this paper, we seek a qualitative definition of which subset of these ‘habitable worlds’ might develop complex and interesting life forms. We identify two key principles in determining the capacity of life to breach certain transitions on route to developing intelligence. The first is the number of potential niches a planet provides. Secondly, the complexity of life will reflect the information density of its environment, which in turn is influenced by available niches. We use these criteria to place the evolution of terrestrial life in a mathematical framework based on environmental information content. Our model links the development of complex life to the physical properties of the planet, something currently lacking in all evolutionary theory. (Abstract edits)

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