Webinar with Juri Poutanen (University of Turku, Finland)
recorded on September 26, 2024
Electromagnetic radiation observed from various cosmic sources is intrinsically polarized, with its polarization depending on the geometry and, specifically, the asymmetry of the source. Polarimetry offers an independent method for exploring the physics and astrophysics of cosmic objects, complementing traditional techniques such as imaging, spectroscopy, and timing. It enables us to determine the geometry of otherwise unresolved sources—for instance, identifying the orientation of the symmetry axis of a source or the magnetic field in the sky—providing insights that no other technique can offer.
Game Changers Online Seminar with Fabio Crameri (ISSI, Bern, Switzerland)
recorded on September 5, 2024
Online Seminar with Louise Harra
(PMOD/WRC, Davos & ETH Zurich, Switzerland)
The instruments measure the solar wind as it flows past the spacecraft as well as the sources of the wind across the electromagnetic spectrum. A scientific focus has been on understanding the small-scale jets and brightenings that can feed into the solar wind, as well as the larger scale eruptions now that the solar activity cycle is reaching its peak.
Online Seminar with Amy Simon (NASA, GSFC, USA)
In September 2023, NASA’s OSIRIS-REx returned an amazing 121 grams of regolith from near-Earth asteroid (101955) Bennu. To successfully collect the sample, the mission had to carefully navigate the microgravity environment while also collecting important information about Bennu’s surface. These data provided the high-resolution mapping of the surface that enabled autonomous natural feature tracking during sample collection, while also collecting surface composition information.
Online Seminar with Tilman Spohn (DLR, Berlin, Germany)
ISSI’s Game Changers online seminar series was launched during the first Covid-19-related lockdown in summer 2020 to help keep the community together. Up until this 100th webinar, the series has covered a wide range of topics, from climate change on Earth to life in the universe and the Big Bang.
Online Seminar with Roberto Maiolino (Cambridge University, UK)
The James Webb Space Telescope is revolutionising most areas of astrophysics. One of the most exciting and puzzling findings has been the discovery of a large population of massive black holes within the first billion years after the Big Bang.
Digital twin technologies – already established in engineering – are becoming increasingly interesting for applications in Earth sciences. Digital twins offer effective tools for dealing with the dramatic impacts of climate change and extremes on our society. They allow exploring the vast amounts of data produced by numerical models and Earth observations to identify causes and effects of environmental change on water, food, energy and health management, and for finding pathways for a more sustainable future. The enormous computing and data handling challenges for Earth-system twins can only be overcome by substantial investments in super-computing and machine learning. These are addressed by the European Commission flagship activity Destination Earth (DestinE). DestinE was launched in 2021 with a projected lifetime of 7-10 years and is implemented by the European Space Agency (ESA), the European Centre for Medium-Range Weather Forecasts (ECMWF) and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). The project is entering its 2nd phase in mid 2024 and is already delivering first examples of digital-twin technology to selected users.
We are now more than a full year into the era of JWST, NASA’s flagship observatory and successor to the Hubble Space Telescope. Exoplanet characterization has historically been dominated by space-based facilities, and the new infrared capabilities of JWST are uncovering the atmospheres of exoplanets in an unprecedented way. The chemical signatures of planets are being actively probed and detected, with an array of new chemical species now detectable including oxygen, carbon and nitrogen-bering molecules. This opens up spectral constrains to the rich atmospheric chemistry ongoing in a wide range of planetary types, temperatures, and metallicities. In this talk, the speaker will discuss some of the outstanding questions in the exoplanet field and how the atmospheric chemistry can help address these questions. He will also present new transit and phase curve results from ongoing JWST programs, including a Neptune and Jupiter mass planet discussing the implications of the chemistry and atmospheric physics of these planets.
Computer simulations of the universe have been in common use since the 1980s, and are now a vital tool in helping us interpret data from increasingly powerful telescopes. Amongst other things, simulations have helped establish the case for dark matter and dark energy, and have been key to creating a broad consensus around the idea that galaxies start small and grow over time through merging. The speaker reviews in outline how these simulations work, and highlight that a key difficulty in understanding their results is to untangle cause and effect. For example, the observed diversity of different galaxy sizes, shapes and colours can be reproduced in a statistical sense, but there is still considerable uncertainty around which causal processes give rise to this diversity. The speaker explains how exerting careful experimentation with the initial conditions for our simulations, which represent conditions shortly after the ‘big bang’, we can start to address these uncertainties. We call this technique ‘genetic modification’, since it loosely corresponds to controlling the genes of our virtual galaxies, to see how the galaxies mature and develop in response. This in turn helps to build a more complete physical picture of how galaxies mature over time, with carefully quantified uncertainties. The speaker discusses how such efforts are vital to making sense of new observations from cutting-edge and future facilities like Gaia, JWST, ELT, SKA and LISA.
The lunar surface allows a unique way forward, to go well beyond current limits in astronomy and cosmology. The far side provides a unique radio-quiet environment for probing the dark ages via 21 cm interferometry to seek elusive clues on the building blocks of the galaxies and the nature of inflation. Optical interferometers will eventually provide up to a few microarsecond imaging of the nearest exoplanets. Far-infrared telescopes in cold and dark polar craters will probe the cosmic microwave background radiation back to the first months of the Big Bang.
Satellite gravimetry missions such as the on-going GRACE Follow-On (FO) mission, the planned GRACE-FO continuation mission as well as a Next Generation Gravity Mission (NGGM) that will form together with the GRACE-FO continuation mission the Mass-change and Geosciences International Constellation (MAGIC), are unique observing systems to measure the tiny variations of the Earth’s gravity field. Time-variable gravity derived by satellite gravimetry provides integrative measures of Terrestrial Water Storage (TWS) variations on a regional to global scale. Given the large interest of the scientific community to understand the processes of changes in TWS, comprising all the water storage on the Earth’s continental areas in frozen and liquid state, including ice caps, glaciers, snow cover, soil moisture, groundwater and the storage in surface water bodies and the interaction with ocean mass and sea level, TWS was adopted as a new Essential Climate Variable (ECV) in the implementation plan 2022 of the Global Climate Observing System (GCOS).
As Earth’s energy source and a variable star, the Sun has been credited over the past century with causing climate change that is a significant fraction of industrial-era warming… or so small as to be undetectable. Now, with more than forty years of space-based observations of solar irradiance and multiple geophysical quantities, and extensive advances in modelling solar irradiance and terrestrial variability, we can clarify with greater certainty the extent to which the Sun alters Earth’s environment, especially since 1850. This talk summarizes current observational evidence for the Sun’s role in global climate change and ozone-depletion recovery, and discusses the scientific (and societal) consequences of faulty detection and attribution.
The DART (NASA) and Hera (ESA) missions offer the first fully documented asteroid deflection test based on the kinetic impactor technique, allowing us to check and potentially validate our impact numerical models at the real scale of an asteroids. DART succesfully tackled the challenge to deflect the small moon, called Dimorphos, of the binary asteroid Didymos on September 26th, 2022, causing a decrease of the orbital period of Dimorphos around its primary. But many questions remain that will be answered by the Hera mission. Moreover, images sent by space missions to asteroids reveal that these objects are not simple rocks in space but very complex small geological world, whose response to external actions in their low gravity environment challenges our intuition. What did we learn from past missions, what are the challenges, the surprises and the remaining uncertainties? How will Hera measure the outcome of the DART impact and the properties of the asteroid? This presentation will address these questions that are not only relevant for planetary defense but also for the scientific understanding of those small worlds, which are the remnants of the bricks that formed our planets, and of the impact process, which plays a major role in all phase of our Solar System history.
NASA interest in climate change goes back decades, and the now 50-year long record of remote sensing has provided clear evidence of ongoing change, as well as process-based information that inform the climate models that help us explain what is happening (and what will likely happen in the future). This talk reviews the highlights of NASA’s work in this area across multiple methods as well as some of the ongoing challenges.
In the blockbuster science fiction movie “Interstellar” (Warning: spoiler alert!), a team of intrepid astronauts set out to explore a system of planets orbiting a supermassive black hole named Gargantua, searching for a world that may be conducive to hosting human life. With Kip Thorne as science advisor, the film legitimately boasts a relatively high level of scientific accuracy, yet is still restricted by Hollywood sensitivities and limitations. In this talk, we will discuss a number of additional effects that may be important in determining the (un)inhabitable environment of a planet orbiting close to a giant, accreting black hole like Gargantua. In doing so, we hope to reach a greater understanding of the fascinating physics governing accretion, relativity, astrobiology, dark matter, and yes, even gravitational waves.
Extreme geomagnetic storms can have significant impact on a wide range of technologies and a particular challenge is quantifying their occurrence likelihood since they are rare events. Geomagnetic storm occurrence varies with the solar cycle and each cycle has a unique amplitude and duration. Whilst there are comprehensive high fidelity space weather relevant observations over the last four to five solar cycles, observations that extend over multiple cycles are more limited. Nevertheless, historical ground magnetic observations over the last 150 years can be used to quantify space weather risk. They can be combined with the sunspot record to construct a uniform ‘clock’ for space weather activity which reveals a fast switch-on (and off) between the relatively quiet conditions around solar minima, and more active conditions around solar maxima. The clock provides a framework to predict the switch-on and off times, imperative since some of the most extreme events have occurred just after the switch-on.
In the last few years machine learning techniques have proven capable of forecasting space weather events with a much higher accuracy with respect to long-used traditional empirical and physics-based models. Even though very few operational models are currently empowered by machine learning, it appears to be unavoidable that the community will embrace in the near future such powerful techniques. Indeed, it is hard to imagine the future of space weather without machine learning. Presently, we are moving one step further from the initial ‘early-adopter’ stage, where proof-of-principles models were elaborated and tested, and more consideration is being given to the issues of reliability, uncertainty, and trustworthiness of machine learning models, finding the right balance between physics priors and data-driven discovery. In this talk the speaker presents the state-of-the-art of machine learning applications for space weather problems and discusses a few challenges and opportunities that this field presents to us.
Propagation parameters of electromagnetic waves such as amplitude, phase and polarization are impacted when traveling within the ionospheric plasma of the Earth. Related effects can be used on one hand to monitor and study the ionosphere by analysing the changes of measured propagation parameters. On the other hand, space weather impact on the ionosphere may cause unwanted distortions of signal detection in modern ground and space-based radio systems applied in telecommunication, positioning, navigation and remote sensing. After clarifying the main terms, the talk focuses on the discussion of space weather induced changes of the ionospheric plasma and associated impact on radio wave propagation used in diverse applications. Besides ionizing solar radiation and ionospheric plasma dynamics also solar radio bursts may seriously impact the functionality of radio systems via interference.
In the recent years, thanks to Solar System exploration, our knowledge on the interactions between a planetary body and its local space environment, where perturbations of solar or non-solar origin may occur, has been dramatically increased. Our understanding of the so called planetary space weather science is of paramount importance also for getting clues on similar –in their nature– phenomena that evolve in the circum-terrestrial environment, nevertheless, at different temporal and spatial scales. Moreover, determining the properties of radiation environments inside planetary magnetospheres is one of the key challenges of magnetospheric physics research. At the same time, it allows the design and manufacturing of satellites and payloads that are resistant to hazardous environments. In this talk, the speaker will discuss some examples of space weather science approaches, especially in the context of the Outer Solar System exploration. Moreover, the speaker will try to evidence the role of theoretical and/or data-driven modeling during preparation for upcoming exploration missions and discuss some future perspectives.
Satellites in low Earth orbit travel through the uppermost layer of the neutral atmosphere, where their movement is affected by variations in the density and wind. These variations affect the amount of fuel required by active satellites to fulfil their mission, as well as the duration that debris objects remain in space. The number of objects in low Earth orbit has been rapidly increasing. With it, concerns over the long-term sustainability of the use of this region of space have been on the rise as well. The trend in the number of objects is due to the ever increasing relevance of satellite missions to our society, combined with technological developments such as miniaturisation and the rise of mega-constellations. But also in-orbit breakups of rocket stages and satellites have been major contributors. In this talk, the speaker will provide an overview of the physics and technology related to this topic, as well as the ways in which international collaboration will be essential to provide solutions.
The aurora borealis (to the north, and australis to the south of the Earth) are the most spectacular phenomena of a chain that connects the planet’s upper atmosphere to the solar activity. In this lecture, the speaker addresses the questions they raise: What solar origin ? What interaction between the solar wind and the space environment ? How are they formed? What are they witnessing? Do they exist elsewhere than on Earth? What research is still being done on auroras?
Giant planets and brown dwarfs at an orbital separation great than 5 AU are important puzzle pieces needed for constraining the uncertainties that exist in giant planet formation and evolutionary models that are plagued by a lack of observational constraints. In order to observationally probe this mass-separation parameter space, direct imaging is necessary but faces the difficulty of low detection efficiency. To utilize the power of direct imaging, pre-selecting companion candidates with long-period radial velocities, coupled with astrometry from Hipparcos and Gaia, provide a powerful tool to hunt for the most promising candidates for direct imaging. Not only does this increase the detection efficiency, but this wealth of information removes the degeneracy of unknown orbital parameters, leading to derived dynamical masses which can serve as benchmark objects to test models of formation and evolution. With the recently launched JWST, as well as upcoming facilities like the ELT and the Nancy Grace Roman Space Telescope, observing time is valuable and the strategy of direct imaging needs to be re-defined to pre-select targets and characterize the companions that we do discover.
Space weather has affected aviation in many ways; effects include short-wave radio disturbance, single-event effects leading to upsets in electronics, Satellite Navigation systems disturbance via scintillation, solar radio burst effects on secondary surveillance radar, increased radiation dose at flight altitudes. In November 2018, a long process involving experts from many countries of the world came to a conclusion when the ICAO Air Navigation Commission and the Council of ICAO, the International Civil Aviation Organization, approved and published provisions in ICAO Annex 3 and guidance material on Space Weather in ICAO Document 10100. The advisories intend to provide the most up to date information on space weather impacts on aviation. The introduction of space weather in the ICAO framework has been a great achievement. What is still outstanding is the development of procedures that are globally standardized on the application of the advisories, as well as the provision of adequate space weather knowledge to pilots, controllers and other aviation personnel. Recent events are used to illustrate this. The talk will be about space weather for aviation: what´s been achieved – and what needs more work.
Human activities have become a dominant force of terrestrial transformations, inducing a clearly observable change of the climate, ubiquitous pollutions of air, soil and water, and an unprecedented decrease of the living. Faced with this situation, the assessment of the environmental footprint of human activities becomes a key instrument to inform sustainability action plans and roadmaps. In this webinar the speaker summarises the current knowledge on the environmental footprint of Space Sciences, explaining its origins and impacts. A particular focus will be placed on the carbon footprint of astronomical research, for which detailed estimates are becoming available. Forecasts for the evolution of the field will be discussed and confronted with the imperative to drastically reduce green house gas emissions over the coming decades. The speaker demonstrates that profound changes are required for making Space Sciences environmentally sustainable.
There is life on Earth thanks to the energy we get from the Sun. But how exactly does the Sun and our space environment result in a habitable climate? Some of the energy we get directly as radiation, some as charged particles from the solar wind and Earth’s magnetosphere. In this seminar, we learn how these two distinct sources influence our atmosphere and what the implications to Earth’s climate are. We particularly focus on the influence of charged particles of solar and magnetospheric origin, a pathway recently included for the first time in the climate simulations informing the Intergovernmental Panel on Climate Change (IPCC).
Solar energetic eruptive processes, such as flares and coronal mass ejections, are relatively well-studied during the past decades of direct observations. Although their maximum strength/energy is not constrained by direct data because of a too-short period of observations, we know that extreme events do occur rarely on the Sun over the last millennia, thanks to cosmogenic-proxy data, and also on sun-like stars, thanks to high-precision stellar photometry. Not only we can estimate their occurrence probability but even reconstruct energy spectra and assess the dramatic terrestrial and societal impacts. However, the nature of such events remains unclear – are they ‘normal’ but just extremely strong solar flares (Black Swans) or do they represent an unknown type of solar events (Dragon Kings)? A summary of the existing pieces of knowledge will be presented along with a try to make a distinction between the Black-swan and Dragon-king scenarios of the extreme events.
In this last year, the Pantheon+ and SH0ES teams released likely our last measurements of the expansion history of the universe. On one hand, constraints from Pantheon+ show a universe consistent with the Lambda-CDM model, where dark energy can be described by a cosmological constant. On the other hand, constraints combining Pantheon+SHOES data find a high value of the Hubble constant, now 5sigma away from the value inferred using Lambda-CDM from measurements of the Cosmic Microwave Background. How can both these statements be true? In this talk, the speaker goes over these separate but overlapping measurements, and discussess how we can have tensions with some parts of the cosmological model but not others. The speaker discusses possible explanations to the Hubble tension, and goes over how other tensions have arisen in cosmology. Finally, the speaker talks about how new telescopes, like the James Webb Space Telescope, can help resolve these controversies.
Studies have shown that stars contain very little baryonic matter and that the majority of the baryons in the universe likely exist in gaseous form. Cool baryons are more easily observed, but what have been seen cannot account for the expected number of baryons produced in the early universe. The lack of understanding of the origin and distribution of “missing baryons” is impeding the progress in completing the picture of baryon cycling in galaxy ecosystems. The bulk of the “missing baryons” may be exist in the form of hot, extended halos around galaxies and/or filamentary structures in the cosmic web; recent observations seem to support such scenarios. However, due to the lack of a sensitive probe, the physical and chemical properties of such hot baryons are poorly measured with existing facilities, but carry critical information on the feedback processes that are deemed critical to galaxy evolution. Theory is far ahead of observation in this area; data are severely lacking. The speaker describes the missing baryon puzzle and provide a personal perspective on how to solve it.
Dark matter is believed to comprise five-sixths of the matter in the universe, and is one of the strongest pieces of evidence for new fundamental physics. But dark matter does not interact directly with light, making it very difficult to detect except by its gravity. It’s described how various properties of dark matter could lead to observable signals, and how we can attempt to identify those signals from telescope observations. The speaker gives examples of cases where possible signals have been seen, but their origin is not yet fully understood. Furthermore, the speaker discusses how solving the puzzle of those observations will advance our understanding of our Galaxy and cosmos, either by revealing properties of dark matter or providing new insights into astrophysics.
