The paper describes the architecture for a data repository and distribution system to be used in the case of a SETI detection event. This system is conceptually modelled after the Deep Space Network, although the hardware and infrastructure involved are different and substantially less expensive to operate. The system is designed to accommodate a large number of users from a variety of fields who wish to contribute to the analysis and comprehension effort that would follow the detection of an information-bearing signal.

Some stochastic model of rumours asserts that even an advanced communication network does not guarantee every agent hears certain news because they predict that rumour spreaders convert to stifflers when contacted with an informed agent. In this study, we adapted two rumour spread models to interstellar communication by developing an agent-based model (ABM) for exploring the issue more rigorously. We enhanced the spread models by adding two additional parameters called conversion probability and stop-criterion, which represent the eagerness and persistency of civilizations to establish new contacts. Results of the ABM under several settings suggest that limited SETI searches lead to undiscovered civilizations. Earth may be one of these undiscovered civilizations although an advanced communication network might already be set up. Hence, we speculate that rumour spread models can propose another solution to Fermi's Paradox.

First contact with another civilization, or simply another intelligence of some kind, will likely be quite different depending on whether that intelligence is more or less advanced than ourselves. If we assume that the lifetime distribution of intelligences follows an approximately exponential distribution, one might naively assume that the pile-up of short-lived entities dominates any detection or contact scenario. However, it is argued here that the probability of contact is proportional to the age of said intelligence (or possibly stronger), which introduces a selection effect. We demonstrate that detected intelligences will have a mean age twice that of the underlying (detected + undetected) population, using the exponential model. We find that our first contact will most likely be with an older intelligence, provided that the maximum allowed mean lifetime of the intelligence population, τmax, is ≥ e times larger than our own. Older intelligences may be rare but they disproportionately contribute to first contacts, introducing what we call a ‘contact inequality’, analogous to wealth inequality. This reasoning formalizes intuitional arguments and highlights that first contact would likely be one-sided, with ramifications for how we approach SETI.

Zagami is a basaltic shergottite well characterized among Martian meteorites. For this reason, it is used as a reference sample to verify the feasibility of the vibrational spectroscopy techniques. In general, these techniques seeking extract spectral signatures from individual mineral present in the meteorite samples. Among some FTIR results were detected organic compounds in the Zagami meteorite and recorded in some articles. Based on these results, an analysis of a Zagami meteorite sample was performed using FTIR and Raman spectrometry. Examining the fragment of Zagami meteorite using the FTIR technique, it was possible to identify the same band of 2920 and 2850 cm−1 described by other references, which were interpreted as organic components and were recorded such as aliphatic hydrocarbon. Another unusual result in Martian meteorite was the detection of the 1300 cm−1 band using Raman. The main reason for this peculiarity is that band is characterized in meteorites as a D band. Generally, this band is attributed to structural defects and the disordering of carbon. However, care should be taken when interpreting Raman spectra around 1300 cm−1 and FTIR spectra 2950–2840 cm−1 of the sample from oxidizing environments such as Mars. Misconceptions can occur during the interpretations of the bands, and this can lead to incorrect identification. Thus, an analysis of the mentioned peaks, such as chemical and mineralogical assignments, will be provided and suggested in order to compare the results that mentioned the presence of organic compounds in the Zagami meteorite.

In SETI, when searching for ‘beacons’ – transmissions intended for us and meant to get our attention – one must guess the appropriate frequency to search by considering what frequencies would be universally obvious to other species. This is a well-known concept in game theory, where such solutions to a non-communicative cooperative game (such as a mutual search) are called ‘Schelling points’. It is noteworthy, therefore, that when developing his eponymous units, Planck called them ‘natural’ because they ‘remain meaningful for all times and also for extraterrestrial and non-human cultures’. Here, I apply Planck's suggestion in the context of Schelling points in SETI with a ‘Planck Frequency Comb’, constructed by multiplying the Planck energy by integer powers of the fine structure constant. This comb includes a small number of frequencies in regions of the electromagnetic spectrum where laser and radio SETI typically operates. Searches might proceed and individual teeth in the comb, or at many teeth at once, across the electromagnetic spectrum. Indeed, the latter strategy can be additionally justified by the transmitter's desire to signal at many frequencies at once, to improve the chances that the receiver will guess one of them correctly. There are many arbitrary and anthropocentric choices in this comb's construction, and indeed one can construct several different frequency combs with only minor and arbitrary modifications. This suggests that it may be fruitful to search for signals arriving in frequency combs of arbitrary spacing. And even though the frequencies suggested here are only debatably ‘better’ than others proposed, the addition of the Planck Frequency Comb to the list of ‘magic frequencies’ can only help searches for extraterrestrial beacons.

For six decades, SETI has attempted to prove the existence of technologically advanced intelligence by detecting artificially generated electromagnetic signals. While such signals could certainly exist and – given the right circumstances – might be measurable here on Earth, contemporary searches are all compromised by limited sensitivity and a reliance on persistent transmissions. The energy required for any putative transmitters, the possible wish of the senders to be cryptic, and a likely ignorance about Homo sapiens’ existence all lead to the reasonable conclusion that greater attention to artefact searches could hasten the discovery of alien intelligence. We consider both the motivation, the advantages and the disadvantages of this approach. We also enumerate some of the specific artefact strategies that have been proposed and pursued.

Among the several steps involved in molecular evolution, molecular preconcentration is the first and most important. If the molecules are not preconcentrated the other steps of molecular evolution cannot occur. There are several ways to preconcentrate molecules: sorption, wetting/drying cycles, freezing/sublimation and sorption/precipitation with minerals. In the present work, the effect of NH4SCN and artificial seawater 4.0 Gy on the synthesis of ferrihydrite was studied. It should be noted that thiocyanate could play the same role as that of CN− in the Strecker reaction. Unlike today's seawater that has high Na+ and Cl− concentrations, the seawater used in this work has high Mg2+, Ca2+ and SO42− concentrations. Two results stand out, first SCN− and NH4+ were preconcentrated by sorption/precipitation in some syntheses and second, in some experiments, a mixture of goethite, hematite and magnetite was obtained. The sorption/precipitation of SCN− is always associated with the synthesis of goethite. This could be an indication that SCN− interacts with Fe3+ through the sulphur group of SCN−. In addition, the synthesis of magnetite could be an indication that the SCN− ion oxidized, forming thiocyanogen-(SCN)2 or trithiocyanate ion-(SCN)−3 and that Fe3+ reduced to Fe2+. Besides the sorption/precipitation of SCN− and NH4+, Fourier-transform infrared spectroscopy also showed that sorption/precipitation of SO42− and CO32− occurred. Ferrihydrite synthesized with artificial seawater presented the highest surface area and pore size. The pHpzc values of the samples were in the range of pHpzc described in the literature. The X-ray photoelectron spectroscopy (XPS) measurements performed show proportions of iron present in different oxidation states, however, the electronic similarities observed in the mixtures of iron oxides and oxy-hydroxides make it difficult to quantify them. Direct comparison between XPS spectra of the Fe2p and O 1s core-levels reveal no significant differences from the effect of artificial seawater 4.0 Gy on the synthesis of ferrihydrite.

According to the Kardashev scale, possible Type-II and above civilizations could use energy sources of the universe in different ways. Self-replicator von Neumann probes believed to invade any galaxies in various studies could also have uses for gaining energy, in which Dyson swarm structures are likely to consist of probes that could emit energy from any luminous celestial object is to be considered first. On addressing some possible dynamical properties of probes, the study has examined in which size and populations they could enfold a star and how they could have observational evidences according to relevant star's energy output. On the basis of our solar system, it has also been shown using a weighted-directed network structure what kind of population and route they could have in case of spreading to the nearest-neighbouring stars.

On p. 10 of the 2018 National Academies Exoplanet Science Strategy document (NASEM 2018), ‘Expect the unexpected’ is described as a general principle of the exoplanet field. But for the next 150 pages, this principle is apparently forgotten, as strategy decisions are repeatedly put forward based on our expectations. This paper explores what exactly it might mean to ‘expect the unexpected’, and how this could possibly be achieved by the space science community. An analogy with financial investment strategies is considered, where a balanced portfolio of low/medium/high-risk investments is recommended. Whilst this kind of strategy would certainly be advisable in many scientific contexts (past and present), in certain contexts – especially exploratory science – a significant disanalogy needs to be factored in: financial investors cannot choose low-risk high-reward investments, but sometimes scientists can. The existence of low-risk high-impact projects in cutting-edge space science significantly reduces the warrant for investing in high-risk projects, at least in the short term. However, high-risk proposals need to be fairly judged alongside medium- and low-risk proposals, factoring in both the degree of possible reward and the expected cost of the project. Attitudes towards high-risk high-impact projects within NASA since 2009 are critically analysed.

Can multicellular life be distinguished from single cellular life on an exoplanet? We hypothesize that abundant upright photosynthetic multicellular life (trees) will cast shadows at high sun angles that will distinguish them from single cellular life and test this using Earth as an exoplanet. We first test the concept using unmanned aerial vehicles at a replica moon-landing site near Flagstaff, Arizona and show trees have both a distinctive reflectance signature (red edge) and geometric signature (shadows at high sun angles) that can distinguish them from replica moon craters. Next, we calculate reflectance signatures for Earth at several phase angles with POLDER (Polarization and Directionality of Earth's reflectance) satellite directional reflectance measurements and then reduce Earth to a single pixel. We compare Earth to other planetary bodies (Mars, the Moon, Venus and Uranus) and hypothesize that Earth's directional reflectance will be between strongly backscattering rocky bodies with no weathering (like Mars and the Moon) and cloudy bodies with more isotropic scattering (like Venus and Uranus). Our modelling results put Earth in line with strongly backscattering Mars, while our empirical results put Earth in line with more isotropic scattering Venus. We identify potential weaknesses in both the modelled and empirical results and suggest additional steps to determine whether this technique could distinguish upright multicellular life on exoplanets.

It is shown that W UMa-type and SX Phe-type stellar populations are both perfectly and uniquely suited for maintaining hyper-effective biopolymer chain reactions (BCR) on their planets once the planet is in the stellar habitable zone. W UMa-type stars are known to be contact binaries, and SX Phe-type stars are presumably post-binaries, i.e., products of stellar mergers. In case of the contact binaries, the eclipse-driven periodic heating/cooling of planetary surfaces has period-amplitude parameters that perfectly satisfy stringent conditions for maintaining BCR-like reactions. In case of the post-binaries, the stars pulsate with periods and amplitudes also perfectly suited for maintaining the reactions. Therefore, the ‘W UMa – SX Phe’ metamorphosis (from a contact binary to a post-binary, via the merger) seems to provide a potential biosystem reboot on planets in these systems.

In Mars-analogous hyperarid soils of the Atacama Desert, phospholipid fatty acids (PLFAs) as the main component of biomembrane play a role in reliably determining viable microbes. PLFA analyses illustrated a rise of the microbial abundance (from 5.0 × 106 to 4.2 × 107 cells g−1) and biodiversity (from 7 to 15 different individual PLFAs) from the north hyperarid core of the Atacama Desert to the southern arid region. Abundant cyclopropyl PLFAs (47.2 ± 4.6%) suggested the resistance to oligotrophic and hypersaline environments by Atacama microbial communities. The southernmost arid site had the highest proportion (8.7%) of eukaryotic and fungal lipid biomarkers. Different precipitations (ranging from 0.7 to 2 mm year−1) in the hyperarid core exerted different effects on microbial biomass, PLFA diversity, bacteria and microeukaryotes. By principal component analysis (cumulative 74.6% of variance), the dominance of PLFA hydroxylation was associated with the microbial viability; bacteria rich in C16:0, C18:0 and C16:1ω9 favoured higher soil conductivity and nitrate; and other PLFAs contributed more to the organic content. Additionally by comparing the ratios of PLFAs to well-preserved organics (e.g., mineral-bound organic carbon and microbial phosphorus), I found that the degradation of PLFAs decreased to a minimum when the mean annual precipitation is lower than 2 mm. These findings may further specify identifiable biomarkers on Mars, if potentially extant Martian microbes possess comparable phospholipid membrane structure.