The KAVLI-IAU Symposium (IAUS 387), held on April 15-19, 2024 at University of Durham, UK, brought together specialists from a range of complementary fields to discuss the probability of extraterrestrial life, methods of detection and the ramifications of its detection for humanity, The Symposium underscored the need for strong cooperation between scientists, ethicists, theologians, and journalists. Critical outcomes included the exploration of detection protocols to elevate the credibility of the Search for Extraterrestrial Intelligence (SETI), and the need to increase outreach activities on the possibility of life detection (or non-detection). The Symposium’s Discussion panels focussed on the importance of defining life, extending the concept of habitability, and exploring the Great Filter. The Symposium concluded with a strong advocacy for integrating these perspectives into global sustainability policies, highlighting the benefits of astrobiology for understanding both the cosmos and Earth.

We propose the implementation of an AstroLab project in Africa, dedicated to Astronomy and Planetary Science Education. Our goal is to contribute significantly to the development of digital education in astronomy across universities and schools on the African continent. The AstroLab project seeks to inspire and engage students from diverse cultural backgrounds by providing them with a unique opportunity to conduct astronomical research and education through remotely accessed telescopes. This initiative is particularly crucial in regions where the lack of astronomy infrastructure impedes students from hands-on experience in this field. In addition, we will implement this program in three distinct languages to ensure accessibility and inclusivity for the diverse communities of the continent.

The Search for Extraterrestrial Intelligence (SETI) is, at its core, a grand endeavour in communication. While we hope to detect signals from intelligent civilisations beyond our solar system, searching for cosmic company has profound implications for our species’ curiosity, technological capabilities, and innate need to connect socially. It gives pause for thought that while we focus the search and post-detection, we undervalue what evolutionary psychologists assert, neuroscientists have demonstrated, science communicators know works in connecting science with society, and journalists employ: We are hardwired for storytelling by evolution, remaining our most effective form of communication. What if the most important message is not from the stars but what the search tells about wanting to know what is in the last chapter of one of the most profound stories ever told? Should the experiment succeed, the stories of survival of intelligence from a distant civilisation may be of most interest.

Astrobiologists are moving purposefully towards the detection of extraterrestrial intelligence (ETI) through the radio and optical methods of SETI. Meanwhile, members of the public have formed their own opinions, only partially informed by science. In the United States, two thirds of all adults believe there is intelligent life beyond Earth, and a substantial minority believe we have already made contact. Opinions about the existence and nature of aliens are part of a complex landscape of beliefs that includes pseudoscience and superstition and extends to conspiracy theories. The widespread belief that unidentified flying objects (UFOs) represent visits by ETI is at the center of this landscape. Beliefs about ETI are also shaped by films, TV shows, and popular culture. This chapter summarizes what the public believes about ETI and presents possible explanations for these beliefs. Some international comparisons are presented. The author has surveyed the opinions and beliefs of tens of thousands of students on topics relating to life beyond Earth and the data gives insights into the modes of thinking of the college-age population. People are not “blank canvasses” when it comes to their beliefs and expectations about ETI, and this should be considered by the scientists who are preparing for eventual, actual contact.

On 24 May 2023, a simulated extraterrestrial message was transmitted towards Earth by the Trace Gas Orbiter, a spacecraft of the European Space Agency. The radio signal containing the message was received by several terrestrial radio antennas, as part of the interdisciplinary project “A Sign in Space”. I conceived the project in 2019, and developed it in collaboration with the SETI Institute, the Green Bank Observatory, the Italian Institute for Astrophysics and the European Space Agency. The message designed for the project required one year to be decoded by citizen scientists. The public reaction to the project provides preliminary insights into the unfolding of a concrete First-Contact scenario.

In recent years, the protection of dark and quiet skies (D&QS) has become an increasingly urgent concern, driven by the proliferation of artificial light at night (ALAN) and the deployment of mega-constellation satellites in low-earth orbit (LEO). This paper presents preliminary research findings from the IAU CPS Policy Hub National Analysis Team, focusing on the national policy and legal approaches to safeguarding D&QS for astronomical observations worldwide. It synthesises the key interim results with a primary focus on light pollution mitigation, outlining measures to combat light pollution and emerging regulatory trends. The study also identifies obstacles to mitigating light pollution and offers examples of national approaches for D&QS protection, along with future research prospects.

The vast observational survey project aimed to search and study of variable stars in different regions of the Galaxy is presented. This project is undertaking within the frame of international research collaboration between Indian and Uzbekistan astronomers. The main targets were the open star clusters and stellar associations but we also considered a multitude of known variable stars of various types with prominent activity. The observations were carried out at Maidanak astrophysical observatory (Uzbekistan) and ARIES observatories at Devasthal and Manora Peak as well as Hanle observatory (India). The main results of the projects are presented briefly. The prospects of the project especially in a point of view to support the possible programs and projects using the James Webb Space Telescope are discussed.

In this work, we compared the chemistry and emission spectra of nitrogen-dominated Ultra-Short-Period (USP) super-Earth atmospheres at various surface pressures (0.1 to 10 bar) in and out of chemical equilibrium. We used the VULCAN chemical kinetic code, which includes thermochemical kinetics, vertical transport, and photochemistry, linked with the petitRADTRANS radiative transfer model to predict emission spectra. Radiative-convective temperature-pressure profiles were computed with the HELIOS code. Using PandExo noise simulations, we explored the observability of disequilibrium effects with JWST. Our results showed that surface pressure significantly impacted temperature profiles, atmospheric abundances, and emission spectra. Disequilibrium signatures in cooler planets were detectable by targeting HCN, C2H4, and CO, while warmer planets showed CH4 and HCN features using JWST’s NIRSpec and MIRI instruments. These species also provided insights into the presence of surfaces in nitrogen-dominated atmospheres, revealing details about atmospheric thickness.

Planetary Protection is an effort to prevent inadvertent biological or organic contamination in solar system exploration. That effort cannot be perfect in actual exploration missions, but the price of not attempting it can be seen in numerous actual contamination events on Earth (e.g., kudzu and starlings in the US, Australia-released rabbits) and the more fanciful, but possibly valid, works of fiction (The War of the Worlds, The Andromeda Strain). Extraterrestrial contamination spread by Earth missions is known as forward contamination, while backward, or back contamination refers to contamination brought to Earth. Both robotic and human missions may be affected by planetary protection practices, which strive to apply the most current science to those efforts, but it is clear that those same missions may discover new information (the hope of most missions) that could argue for new and potentially altered requirements on the next mission, or on the ongoing missions themselves.

Astrobiology and SETI search for life-not-as-we-know-it (yet). Researchers aspire to an understanding not yet found. With that in mind, knowledge about three types of context can inform and improve the search. Observational context: knowing our location as humans (anthropism) can mitigate biases introduced by our desire to over-value humanity (anthropocentrism). Historical context: knowing the history of the search, not just the last 10–30 years, can clarify concepts and significance. Disciplinary context: understanding the rules by which different disciplines operate can reveal the limitations of a single perspective (astronomy, biology, ecology, sociology, law, medicine, philosophy, theology…). Astrobiology and SETI tell epic stories about the place of life in the cosmos. They locate humans morally as well as physically. We should ask why we tell them and how our context shapes the telling, because the stories shape human interactions with the world.

The motion of planetesimals was studied in the Proxima Centauri and TRAPPIST 1 exoplanetary systems. The size of the feeding zone of planet Proxima Centauri c is discussed. It was noted that after hundreds of Myrs, some planetesimals could still move in elliptical resonant orbits inside the feeding zone of this planet that had been mainly cleared from planetesimals. The probability of a collision of a planetesimal initially located in the feeding zone of planet c with inner planet b was obtained to be about 0.0002 and 0.001 at initial eccentricity of orbits of planetesimals equal to 0.02 or 0.15, respectively. A lot of icy material and volatiles could be delivered from the icy zone near the orbit of planet c to inner planets b and d. The inclinations of orbits of 80% of the planetesimals that moved between 500 or 1200 AU from the star did not exceed 10°. It was obtained that several planets in the TRAPPIST-1 system accumulated planetesimals initially located at the same distance. Outer layers of neighbouring TRAPPIST-1 planets can include similar material.

We present perspectives from six panellists on “Life as a cosmic phenomenon facing human culture”, contrasting our experience and knowledge of life as found on Earth with the vastness of the Universe and the fact that Earth-centric and/or anthropocentric views have repeatedly proven untenable. How does an outwards view of projecting Earth-based experience into the cosmos combine with the inwards view of the potential detection of life beyond Earth telling us who we are?

Astronomers are now able to peer into the atmospheres of distant planets and search for signs of life. With the large diversity in exoplanets being found, confidently identifying remote signs of life is a complex process. E.g. while the high level of oxygen in Earth’s atmosphere is the product of life, different planetary scenarios can produce oxygen rich atmospheres without any life-processes. Therefore we will need multiple lines of evidence to confidently declare a planet inhabited. Earth has been dramatically shaped by life for over 4 billion years and life plays a key role in regulating Earth’s surface chemistry and climate, providing multiple detectable signals a remote observer would be able to detect from afar. The biosphere-Earth co-evolving system is known as ‘Gaia’. Understanding the likelihood of Gaian-systems emerging on inhabited planets will inform us on the probability of confidently identifying an inhabited planet.

Numerous programmes have been conducted to search for techno-signatures using optical wavelengths. PANOSETI provides the opportunity for a link and follow up to new infrared laser optical ground stations (OGS) in the event of first contact for ETI communications within our local neighborhood of the Solar System. The OGS has a transceiver communications system that can provide the opportunity for post-contact protocols to be initiated with a potential ETI.

The U.S. military has recently begun deploying large constellations of small satellites in low Earth orbit (LEO) for communications and missile warning. This paper describes what such systems may entail, and discusses the impacts that they may have on astronomical and environmental interests. While the deployment of such constellations is being motivated by national security interests, the growth of the satellite population in LEO can also pose threats to national security. This includes not only concerns related to orbital congestion and orbital debris, but also issues that are closely related to the preservation of dark and quiet skies. This paper will highlight the overlapping threats posed by the growth of satellite constellations to both astronomical and national security interests, and describe a potential path forward for dark and quiet skies advocacy that leverages and collaborates with national security interests to establish norms against light and spectrum pollution.

Geodetic VLBI is an application of the radio astronomy observation technique to study planet Earth. It is one of the geodetic space techniques which provides information about Earth in space and its rotational behaviour, hence it is fundamental for the global geodetic reference frame (GGRF). In particular with this technique ICRF can be determined at radio wavelengths, further it contributes with other space techniques to ITRF materialisation. Daily geodetic VLBI measurements are vital for determining and predicting the time-varying alignment of the Terrestrial Reference Frame with respect to the celestial reference frame (Earth Orientation Parameters). The routine work is coordinated by the IVS as a service for IAG and IAU and carried out by different institutions such as mapping authorities, space agencies, universities and research centres. In 2015 a UN Resolution emphasised the importance of the GGRF for sustainable development and asked member countries to extend these activities. At the same time the telecommunication networks are expanded on ground and in space increasing the number of transmitters. Large satellite constellations can have an impact on Geodetic VLBI products since they almost all broadcast downlink high power signals in the K band, and uplink signals (e.g. 14.0-14.5 GHz for Starlink). Owing to the increasing number of large constellations, an aggregate effect should also be considered, since they use different frequencies, usually in the K band. Furthermore their unwanted electromagnetic noise degrades the VLBI observations of faint cosmic noise. The signal strength of radar systems can even be destructive to the high-sensitive receivers at VLBI radio telescopes. The strategy is to answer the question of how to protect the global geodetic network infrastructure (locations of VLBI telescopes) in the corresponding study group at ITU-R and to seek for protection of the observed bands (32 channelised frequencies) in geodetic VLBI (which exceed the bandwidths of those bands already allocated to RAS).

The discussion on the second day of the symposium centred on the Great Filter, a concept proposed by Robin Hanson as a way to reframe the analysis of the Fermi Paradox. It asserts that there must be a least one Great Filter – an evolutionary step that is extremely improbable – somewhere along a chain which starts from a lifeless Earth-like planet, followed by the sequential development of simple, complex, intelligent/technological life, and culminating in an explosive phase of readily-detectable galactic colonization. Some 25 years on from Hanson’s proposal, we examine the Great Filter’s continuing usefulness as a concept and current thinking on whether any such filter lies in our past (Early Great Filter), or is waiting in our future (Late Great Filter), and what this means for us and our search for life in the Universe.

It is generally believed that it is unlikely that our civilization is alone in this galaxy. This belief is central to the premise of the Search for Extraterrestrial Intelligence (SETI), which has focused mainly on searching for radio signals originating from extraterrestrial communications, since it is believed that extraterrestrial craft visiting Earth would be an extremely unlikely event. However, the fact that we ourselves are currently working on developing probes to send to the Alpha Centauri system by 2069, strongly suggests that other civilizations may make similar, or more ambitious, efforts. Therefore, it is reasonable to inform our expectations by considering what characteristics and capabilities would be required for an interstellar civilization to find and visit Earth. In this paper, a physics-based analytic model of expanding interstellar civilizations is developed. A million civilizations that encounter Earth are simulated and their statistics are studied to determine their characteristics.