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.

Using multi-viewpoint observations from STEREO and SOHO during three solar cycles from 23 to 25, we study the magnetic flux rope (MFR) structures of coronal mass ejections (CMEs) near the Sun and magnetic clouds (MCs) at 1au. The study aims to investigate two phenomena: 1) the occurrence rate of CMEs near Hale sector boundaries (HBs) and 2) solar-cycle variation of MFR axial orientations in CMEs and MCs. Our preliminary results include: 1) the axes of MFRs in cycle 25 present a systematic northward orientation, which is the same as in cycle 23 but opposite to cycle 24; 2) the majority of the MFRs occurred near HBs (within 30 degrees) and some exceptional events occurred at non-HBs; 3) the axial fields in MCs present a similar north-south orientation, which changes from cycle to cycle. We discuss the implication of solar cycle variations of MFR axial orientations for space weather forecasts.

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.

Charged particle acceleration and heating in the heliosphere requires detailed observa-tions of the velocity distribution functions (VDFs) of these particles across a range of mass and charge states. Such particle energization is often observed concurrent with transient phenom-ena. Proper characterization of such energization processes and their impact on charged particles requires careful consideration of instrument observation timing and the timing at which a tran-sient phenomenon is observed. Solar Orbiter’s Heavy Ion Sensor (HIS) observes the composition of the solar wind along with suprathermal and pickup ions. As such, it provides the observations necessary to resolve the mass and charge states appropriate for properly characterizing charged particle energization. In this work, we describe the current status of data aggregation at vari-able time intervals and how that enables proper characterization of charged particle energization concurrent with transient phenomena.

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).

Coronal mass ejections (CMEs) play a significant role in space weather. In order to evaluate space weather effects, it is important to understand the origin of CMEs in the solar atmosphere. Among various proxies for CMEs in the low corona, the coronal dimming observed as intensity deficit in extreme ultraviolet (EUV) or soft X-ray wavelengths is thought to be the most reliable observable. We examine dimmings detected automatically by Solar Demon in images taken by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO), and associate strong dimmings with CMEs, flares and EUV waves. The association rate of dimmings with either CMEs or flares is about 75%, and that with EUV waves is about 35%. We also discuss the complementary use of EUV irradiance data, for example, from the Extreme Ultraviolet Experiment on board SDO to isolate dimmings. This may have implications in detecting CMEs from stars.

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.

We report on a study of the kinematics of coronal mass ejections (CMEs) and their shocks depending on the type of solar source: active region flares and filament eruptions. Kinematics of the two group of events near the Sun and their evolution in the corona and inner heliosphere are studied. We compiled a list of CMEs with interplanetary counterparts that originated from close to the disk center. The study includes 45 disk center events of solar cycle 24 (2009–2019). Out of those, 30 events are flare-associated and 15 are filament-associated. Among the 30 flare-associated events, 8 are also associated with a shock. Among the 15 filament-associated events only one event is associated with a shock. We measure the CME flux rope (FR) speed along with the shock speed and the associated reconnection flux (RC). We found that the CME speed and the RC flux are about 30% more for shock-associated events compared without a shock. Similarly, the CME speed and the RC flux are about 50% more for flare-associated events compared to the filament-associated events.

In this contribution to the panel discussion of the IAU Symposium Nº 388 “Solar and Stellar Coronal Mass Ejections”, I concentrate on white-light observations of solar coronal mass ejections (CMEs) from space and specifically address the following aspects: i) history of observations, ii) available catalogs of CMEs, iii) achievements of space observations of CMEs, iv) future of CME observation, and v) challenges and future directions.

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.

A long-standing issue in astrobiology is whether planets orbiting the most abundant type of stars, M-dwarfs, can support liquid water and eventually life. Often previous studies have raised doubts for the habitability of planets orbting M-stars, due to the intense stellar activity during the early evolution. Those include solar-wind-like eruptions of the host star that could erode the planetary atmosphere, as well as the intense XUV radiation from the host. A new study shows that subglacial liquid water that accumulates on the night-side of tidally locked planets may provide an answer, significantly extending the habitability region, in particular around M-dwarf stars, which are also the most promising for biosignature detection with the present and near-future technology.

The impact of stellar energetic particles (StEPs) and galactic cosmic rays (GCRs) on exoplanetary atmospheres, and with that on transmission spectra and biosignatures like methane and ozone, recently became one of the foci of exoplanetary habitability studies. Deriving the exoplanetary radiation field, however, is an interdisciplinary task starting with astrospheric modeling. Although multi-wavelength observations of the Hubble Space Telescope, Kepler, and TESS helped to study the characteristics of planet-hosting cool stars. However, features like stellar wind speeds and mass-loss rates mandatory for astrospheric modeling can only be indirectly derived. Here, a brief review of the astrospheric modeling efforts of three M stars and the transport of cosmic rays within is presented. Using a unique suite of numerical models, the astrospheric plasma environment is modeled magnetohydrodynamically (3D), and the particle transport is modeled using an ab initio GCR modulation code. A recent model effort deriving flare-induced StEP intensities is also discussed.

This paper presents some results from a survey carried out by the UK’s Federation of Astronomical Societies to determine the effect of satellite constellations on (principally) amateur astronomers’ observations, their mitigation methods and the effectiveness of those methods.