“Subsurface Life on Earth and on Other Planets in the Solar System” with Barbara Sherwood Lollar (Department of Earth Sciences, University of Toronto, Canada)

The search for extraterrestrial life is a main motivator for the exploration of other planets and moons in the solar system and for the search for extrasolar planets. In the solar system, Mars, Europa and Enceladus – the latter two satellites of Jupiter and Saturn, respectively – are often cited as possibly harboring extraterrestrial life. The surface environments of these, however, are not conducive to life either because of low temperatures or harmful radiations or both. Instead, life may have originated and evolved in the underground, in oceans covered by kilometer thick ice layers for Europa and Enceladus and in the Martian soil. We know from Earth that extremophiles (life forms that tolerate extreme environmental conditions) can be found at depths of at least up to three kilometers. The recent National Academies Report – the 2018 Astrobiology Science Strategy for the Search for Life in the Universe emphasized the need for an expanded focus on investigation of subsurface environments and subsurface processes for our understanding of planetary evolution, habitability and the search for life. Our research program at Toronto focuses on Earth analog systems – in particular, deep fracture waters preserved on geologically long time scales in the Precambrian cratons of Canada, Fennoscandia, and South Africa. Science has long relied on fluid inclusions – microscopic time capsules of fluid and gas encased in host rocks and fracture minerals – to access preserved samples of ore-forming fluids, metamorphic fluids, and remnants of the ancient atmosphere and hydrosphere. Until recently, groundwaters were thought to reflect only much younger periods of water-rock interaction and Earth history, due to dilution with large volumes of younger fluids recharging from surface hydrosphere. In the last 10-20 years, global investigations in the world’s oldest rocks have revealed groundwaters flowing at rates > L/min from fractures at km depth in Precambrian cratons. With mean residence times ranging from Ma to Ga at some sites, and in the latter case, geochemical signatures of Archean provenance, not only do these groundwaters provide unprecedented samples for investigation of the Earth’s ancient hydrosphere and atmosphere, they are opening up new lines of exploration of the history and biodiversity of extant life in the Earth’s subsurface. Beyond Earth, these findings have relevance to understanding the role of chemical water-rock reactions in defining the potential habitability of the subsurface of Mars, as well as that of ocean worlds and icy bodies such as Europa and Enceladus.

Barbara Sherwood Lollar CC FRS NAE FRSC – University Professor in Earth Sciences, University of Toronto is a Fellow of the American Geophysical Union (2015), the Geochemical Society (2019) and European Association of Geochemistry (2019). She is Co-Director of the Canadian Institute for Advanced Studies (CIFAR) program Earth 4D – Subsurface Science and Exploration and co-leads an ISSI working group on “Extant subsurface Life on Mars? Science, Tools & Missions Together”. She is currently a member of the Eni Prize Commission (2013-2021), the American Geophysical Union Honors and Recognition Committee, the United States National Academy of Sciences Space Studies Board, the U.S. National Academy Decadal Survey Steering Committee for Planetary Sciences and Astrobiology, the Fellows Selection Committee for the Royal Society London UK, among others. Recent awards include the 2020 Killam Prize for Natural Sciences, 2019 NSERC Gerhard Herzberg Gold Medal, 2019 C.C. Patterson Medal for Environmental Geochemistry, 2016 NSERC John Polanyi Award, 2014 International Helmholtz Fellowship, and 2012 Eni Award for Protection of the Environment.

Webinar was recorded on December 16, 2021

Forecasting Problem Geomagnetic Storms: Are Stealth CMEs a New Space Weather Extreme? with Tamitha Skov (the Aerospace Corporation, Los Angeles, USA)

The paradigm shift that space weather is real, relevant, and knowable to a general audience is not as impossible as once imagined. Although it remains an extremely difficult topic to convey, new modes of communicating space weather to a very eager public are becoming available. In return, the appetite for more timely and accurate space weather information by the public is driving more robust observation and prediction methodologies in forecasting space weather events. One such example is in the raised awareness of “stealth” Coronal Mass Ejections (CMEs), which are CMEs that are often observed in coronagraph data but not in coronal images. These events often cause problem geomagnetic storms because they go unnoticed until they hit Earth. Largely identified during the deep minimum of cycle 23/24, stealth CMEs appear to be on the rise. Since solar cycle 25 brings with it the possibility of yet another low activity cycle, it is very likely that the number of stealth CMEs will remain a significant fraction of ejecta, which presents additional challenges for the forecasting community. We investigate the properties of stealth CMEs, paying special attention to their proximity to coronal holes. We note the existence of mismatched polarity reversals in the magnetic field and electron strahl measured in situ within ICMEs associated with stealth CMEs and discuss the plausibility of interaction with solar wind emanating from coronal holes as a key element of stealth CME eruption. Finally, we discuss how these near-invisible events have defined a new form of “extreme” when it comes to space weather forecasting, which demands new observational techniques be employed to more routinely detect these events, and we illustrate the kinds of public beneficiaries of these improvements in forecasting, demonstrating the intersection of heliospheric science, meteorology, and public use of space weather information. 

Tamitha Skov holds B.S. degrees in physics and physical chemistry, as well as M.S. and Ph.D. degrees in geophysics and planetary physics from the University of California at Los Angeles (UCLA). In 2004 she joined The Aerospace Corporation in Los Angeles where currently she is a Research Scientist in the Physical Sciences Laboratory. In 2019 she joined Millersville University as an adjunct professor, teaching a graduate curriculum in space environment and policy. Tamitha works primarily in the fields of solar and space physics research and in the testing of spacecraft materials in realistic space radiation environments. She has been an instructor at The Aerospace Institute and has served as an audio forensics analyst and instructor for the National Law Enforcement and Corrections Technology Center (NLECTC), funded by the Department of Justice. Her forecasting work as the “Space Weather Woman” is widely known on social media such as You Tube, Twitter, and Facebook. Tamitha has been featured in Popular Science Magazine, MIT Technology Review, and on television shows for The Weather Channel and The History Channel. She makes regular appearances on TMRO.TV for Space News and TwiT TV for Ham Nation, doing space weather forecasts under her amateur radio callsign WX6SWW. Tamitha Skov is also Co-Leader together with N. V. Nitta of the ISSI Team#415 workin on Understanding the Origins of Problem Geomagnetic Storms.

Webinar was recorded on December 9, 2021

“Tipping Positive Change to Avoid Climate Tipping Points” with Tim Lenton (University of Exeter, UK)

Tipping points exist in social, ecological and climate systems and those systems are increasingly causally intertwined in the Anthropocene. Climate change and biosphere degradation have advanced to the point where we are already triggering damaging environmental tipping points, and to avoid worse ones ahead will require finding and triggering positive tipping points towards sustainability in coupled social, ecological and technological systems. To help with that the speaker outlines how tipping points can occur in continuous dynamical systems and in networks, the causal interactions that can occur between tipping events across different types and scales of system – including the conditions required to trigger tipping cascades, the potential for early warning signals of tipping points, and how they could inform deliberate tipping of positive change. In particular, the same methods that can provide early warning of damaging environmental tipping points can be used to detect when a socio-technical or socio-ecological system is most sensitive to being deliberately tipped in a desirable direction. The speaker provides some example targets for such deliberate tipping of positive change. 

Tim Lenton is founding Director of the Global Systems Institute and Chair in Climate Change and Earth System Science at the University of Exeter. He has >25 years research experience, focused on modelling life’s coupling to the Earth system, biogeochemical cycling, climate dynamics, and associated tipping points. His books ‘Revolutions that made the Earth’ (with Andrew Watson) and ‘Earth System Science: A Very Short Introduction’ have popularised a new scientific view of our planetary home. Tim co-authored the ‘Planetary Boundaries’ framework and is renowned for his work identifying climate tipping points, which won the Times Higher Education Award for Research Project of the Year 2008. He has also received a Philip Leverhulme Prize 2004, European Geosciences Union Outstanding Young Scientist Award 2006, Geological Society of London William Smith Fund 2008, and Royal Society Wolfson Research Merit Award 2013. Tim is a member of the Earth Commission, an ISI Highly Cited Researcher, and in the top 100 of the Reuters ‘Hot List’ of the world’s top climate scientists. 

Webinar was recorded December 2, 2021 

“Energy Imbalance Observed with Space Geodesy” with Benoit Meyssignac (LEGOS and CNES, Toulouse, France)

Over the past decades, the scientific community and space agencies have continuously developed new geodetic missions with the general purpose of monitoring the Earth shape and gravity field. Two techniques appeared particularly efficient for this objective: radar satellite altimetry to monitor the Earth shape and space gravimetry to monitor the Earth gravity field. Both techniques showed constant progress and soon, in the 1990’s, they enabled to monitor the subtle changes in the Earth shape and gravity field due to climate change. It has been a revolution for climate science because suddenly many consequences of climate change were visible from space with a global coverage and a high repetitiveness including sea level variations, land water changes and polar ice sheet mass loss. After 20 years, this observing system has reached a level of maturity and an unprecedented accuracy.

Such an accurate observing system opens today a new research pathway. Indeed, by combining precisely space gravimetry data with radar altimetry data, it is now possible to derive estimates of the ocean storage of anthropogenic heat and the associated Earth energy imbalance (i.e. the radiative imbalance at the top of the atmosphere known as EEI). It provides an independent estimate of the EEI that anchors the historical top of the atmosphere radiation measurements (ERBE, ScaRaB, CERES) and constraints the global water-energy budgets that are responsible for climate change. This use of the geodetic observing system is a change of paradigm because the system was optimized to monitor the impact of climate change and now it is used to understand the causes of climate change. With this change of paradigm come new scientific opportunities related to climate change. In the same time these new scientific objectives bring new requirements on the accuracy of the geodetic observing system.    

In this talk the speaker will show how the geodetic observing system has progressed and how it can be used now to estimate the Earth energy imbalance. He will also show how, now, the geodetic observing system enables (along with other flux measurements) to constraint the global water-energy budgets leading to new insights on the earth radiative response and the climate sensitivity.


Benoit Meyssignac is a young scientist at the Laboratoire d’Etudes en Géophysique et Océanographie Spatiale (LEGOS) and at the Centre National d’Etudes Spatiales (CNES) in Toulouse, France. He earned a degree in Physics from the Ecole Polytechnique, a degree in astrodynamics from the école nationale surperieure d’aéronautique and a PhD from the university Paul Sabatier in Toulouse (France). His research aims at understanding the variations of the global Earth energy-water cycle at regional and global scales through satellite observations and modelling approaches. His efforts have ranged from the development of global sea level products and global mass redistribution products with associated uncertainties tailored for robust comparisons with climate models to the detection and attribution of anthropogenic forcing and natural forcing in the Earth energy-water cycle variations. His research on high precision geodetic measurements of the Earth energy-water reservoirs leads to new insights on the response of the energy-water cycle to climate change and guide the improvement of climate models. He was a lead author of the last IPCC report. He was awarded in 2017 the Christian Le Provost prize from the French national science academy and in 2021 the EGU/ESA Earth observation excellence award for his work on geodetic observations to better constraint the Earth water energy budgets.

Webinar was recorded on November 18, 2021

“Human Spaceflight – Where Are We Going?” with Claude Nicollier (Space Innovation, EPFL Lausanne, Switzerland)

Human spaceflight has been conducted for more than six decades with a multiplicity of objectives. In the early days the goal was essentially political, with the idea to demonstrate superiority in technical and operational capabilities. With the Apollo program and the early space stations operated by the US (Skylab) and the Soviet Union, there was a definite shift towards the use of human space missions for the conduct of scientific research. This shift was clearly continued with the Space Shuttle, and consolidated with the International Space Station. Today we see new components in human spaceflight, with the involvement of private companies, essentially in the US, space tourism (suborbital and orbital), and plans for inhabited space missions to the Moon in a few years, and later to Mars.

Whatever the main objective of any human space mission is, there is always a strong adrenalin flow during the ascent to space end the reentry phases, and also during critical action on orbit, like rendezvous and docking, or spacewalks. Human spaceflight is always an adventure, and a definite source of inspiration!

This talk will not be scientific or technical, but will present the different components, the current status, and future plans of human space missions. The personal experience of the speaker in space, and in particular work performed on the Hubble Space Telescope in Low Earth Orbit, will also be presented. 

Claude Nicollier was born in Vevey, Switzerland, in 1944. He became an astrophysicist after studies in physics in Lausanne and astrophysics in Geneva. He also trained as a Swiss Air Force pilot and as an airline pilot. He is a graduate of the Empire Test Pilot’s School, Boscombe Down, United Kingdom, class of 1988.

He was selected in 1978 in the first group of astronauts of the European Space Agency (ESA), then was detached to the NASA Johnson Space Center (JSC) in Houston, Texas, for full training as Mission Specialist on the US Space Shuttle, following an agreement between ESA and NASA. He served as a crewmember on four Shuttle missions between 1992 and 1999, including two on-orbit interventions on the Hubble Space Telescope. He spent a total of more than 1000 hours in space during these four missions.

He is currently a member of “Space Innovation”, Switzerland, and honorary Professor at the Swiss Federal Institute of Technology EPFL.

He is also a member of the Federal Commission for Space Affairs, which advises the Federal Council on matters related to the space policy of the Swiss Confederation.  Occasionally, he serves as scientific and technical advisor for Masters or Doctoral students working on space related subjects at EPFL.

Webinar was recorded on November 4, 2021


“Of Bubbles, Filaments, Echoes and Eruptions: First Results from eROSITA” with Andrea Merloni (Max Planck Institute for extraterrestrial Physics, Garching, Germany)

The next generation of wide-area, sensitive X-ray surveys designed to map the hot and energetic Universe has arrived, thanks to eROSITA (extended ROentgen Survey with an Imaging Telescope Array), the core instrument on the Russian-German Spectrum-Roentgen-Gamma (SRG) mission. eROSITA high sensitivity, large field of view, high spatial resolution and survey efficiency is bound to revolutionise X-ray astronomy and deliver large legacy samples for many classes of astronomical objects in the energy range 0.2-8 keV. Over this energy range, telescopes are sensitive to the emission of millions of degrees hot gas, revealing, among others, the most massive collapsed structures of the Universe (clusters and groups of galaxies), the hot ISM of the Milky Way and the Supernova remnants that energise it, the atmospheres of neutron stars, the magnetic coronae of accretion discs around black holes. The speaker will present an overview of the instrument capabilities, the current status of the mission, and a few selected early science results and the expectations for the survey program, which has completed last June the third of its eight planned charts of the whole sky. In particular, he will report on the discovery of hot gas in emission from the filaments connecting two clusters of galaxies, of large X-ray bubbles in the Milky Way halo, and of two new pulsating supermassive black holes.

Andrea Merloni (M), Ph.D 2002 from University of Cambridge, UK, is senior staff member of the Max Planck Institute for extraterrestrial Physics, in Garching, Germany. His research develops at the boundary between theory and observations, and focuses, among others, on black hole astrophysics, the theory of accretion, active galactic nuclei and X-ray binaries, cosmological evolution of massive black holes, and multi-wavelength extragalactic surveys. His most influential work from 2003, reporting the discovery of a “Fundamental plane of black holes activity” linking the observable properties of black holes across the known range of masses, has received more than 900 citations alone. Since 2020 he is Principal Investigator of eROSITA, after having served as Project Scientist for 9 years. He is also heavily involved in the development and planning of new wide spectroscopic surveys (SDSS-V, ESO/4MOST), which will help unveil the large scale distribution of the energetic sources discovered by eROSITA.

Webinar was recorded on October 28, 2021

“Planetary Magnetic Fields” with Sabine Stanley (Johns Hopkins University, Baltimore, USA) 

Magnetic fields are intrinsic properties of planets. They are – in general – detected by the force they exert on magnetic materials and electrical charges. This principle is used in magnetometers onboard spacecraft with which magnetic fields around planets are detected and measured.  Intrinsic magnetic fields are generated deep inside planets by dynamo action. Because this requires regions of electrically conducting material and energy sources to maintain the dynamo, we can learn about the deep interiors of planets by investigating their magnetic fields. In this talk, we’ll explore some of the interesting questions and possible answers about planetary interiors that have come from studies of planetary magnetism. 

Sabine Stanley is the Morton K. Blaustein Chair and Bloomberg Distinguished Professor in the Department of Earth & Planetary Sciences at the Johns Hopkins University in Baltimore, Md. Dr. Stanley’s research aims to understand planetary interior processes and planetary evolution.   Her focus is on modeling – using numerical methods – to simulate how planetary magnetic fields are created as a means of studying the deep interior of planets.  Sabine covers dynamo theory of the terrestrial planets but also of the giant planets of the outer solar system. In addition, she studies small bodies and extends her research to extra- solar objects. She is involved in planetary missions such as InSight and uses her models to explain their observations.  

This webinar was recorded on October 21, 2021

“Discovery Frontiers in the New Era of Observations with Gravitational Waves and Light” with Raffaella Margutti (University of California Berkeley, USA)

Astronomical transients are signposts of catastrophic events in space, including the most extreme stellar deaths, stellar tidal disruptions by supermassive black holes, and mergers of compact objects. Thanks to new and improved observational facilities we can now sample the night sky with unprecedented temporal cadence and sensitivity across the electromagnetic spectrum and beyond. This effort has led to the discovery of new types of astronomical transients, revolutionized our understanding of phenomena that we thought we already knew, and enabled the first insights into the physics of neutron star mergers with gravitational waves and light. In this talk the speaker will review some very recent developments that resulted from our capability to acquire a truly panchromatic view of transient astrophysical phenomena.

Raffaella Margutti is a Professor in Astrophysics at the University of California at Berkeley, USA.  She completed her undergraduate education at the University of Milano Bicocca, Italy. Afterwards, she was a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics and a James Arthur Research Associate at the New York University. Before moving to UC Berkley, she was assistant and afterwards associate professor at the Northwestern University. Raffaella Margutti received numerous awards, among them the New Horizons in Physics Prize (2022). Time Domain and Multi-Messenger Astrophysics. Supernovae, tidal disruption events, transient large astronomical surveys, gravitational wave sources and neutron star mergers, gamma-ray bursts. Her overarching goal is to acquire truly panchromatic observations of transients across the electromagnetic spectrum and advance our understanding of: (i) the nature of  the compact object remnants; (ii) particle acceleration at newtonian and transrelativistic shocks; (iii) mass-loss events in the decades before stellar demise.

This webinar was recorded on October 14, 2021

“Seeing the Unseeable – Imaging Black Holes with the Event Horizon Telescope” with Angelo Ricarte (Institute for Theory and Computation (ITC) Fellow Center for Astrophysics Harvard & Smithsonian, USA)

Most massive galaxies are believed to host supermassive black holes at their centers, where they play important roles in heating gas and suppressing star formation. Using a large network of radio telescopes around the world, the Event Horizon Telescope (EHT) collaboration produced the first resolved image of a supermassive black hole, located in the elliptical galaxy Messier 87. The EHT combines distant telescopes using the very-long-baseline interferometry (VLBI) technique, achieving equivalent angular resolution to a telescope the size of the Earth. Earlier this year, this image was upgraded to include linear polarization, the oscillation direction of incoming electric fields, which has provided new and substantial information for constraining models of the black hole and its accretion flow. All models that pass both total intensity and linear polarization constraints feature dynamically important magnetic fields. These first EHT images usher in a new era of gravity, accretion, feedback, and plasma physics studies in the direct vicinity of a black hole. Continued development of the EHT will enable novel studies of the image as a function of time as well as observing wavelength.

Angelo Ricarte is a Filipino-American astrophysicist from California. He completed his undergraduate education at the University of California at Berkeley. Afterwards, he completed his Ph.D in the Yale astronomy department with Priya Natarajan. Angelo is currently a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics as well as the Black Hole Initiative, working with Ramesh Narayan. He is a theoretical astrophysicist working on understanding the formation and evolution of supermassive black holes using computer simulations, both on event horizon and cosmological scales. On cosmological scales, he studies the co-evolution of supermassive black holes and their host galaxies. On event horizon scales, he focuses on the theoretical interpretation of polarized black hole images, especially the recent polarized image of the black hole in elliptical galaxy Messier 87. He works actively on the Event Horizon Telescope, the world-wide interferometer which has provided the first image of a supermassive black hole!

Webinar was recorded on October 7, 2021

“Venus: The Next Target of Planetary Exploration” with Richard Ghail (Royal Holloway, University of London, UK)

Three new missions recently selected for implementation by NASA (DaVinci and Veritas) and ESA (EnVision) are opening a new era of space exploration, this time focusing on Earth’s neighbour and sibling, Venus. Few missions have been sent to Venus since the time of the early Venera missions by the then Soviet Union. An important reason lies with the substantial challenges that exploration of Venus faces because of its extreme surface conditions (450°C, 90 atmospheres pressure, and corrosive chemistry). The longest-lived Venera lander, for instance, survived for only two hours. A second factor is that the permanent cloud cover means that the only way to image the surface at high resolution is with an expensive, power-hungry and data-intensive imaging radar system.

But Venus is of interest even beyond planetary science because of its similarity in size to the Earth and because its atmosphere may have experienced a runaway-greenhouse, perhaps as recently as a billion years ago, turning a possibly habitable planet into an almost hellish place. How is it that two planets so similar in size, composition and distance from the Sun, can be so different? The three recently selected missions seek to address different and complementary aspects of these questions: DaVinci will provide a very detailed geochemical ‘snapshot’ through the atmosphere; Veritas will make a global geophysical survey; while EnVision will undertake a set of complementary targeted observations of the atmosphere, surface and interior. Its goals are to locate and characterise geological activity on the surface and to track how that activity drives atmospheric chemistry, especially in the clouds, and to infer how both evolved through time and, in particular, what evidence there may be for past oceans. To do so, EnVision carries an imaging radar (VenSAR), a sounding radar (SRS), a spectrometer suite (VenSpec-U and -H) and mapper (VenSpec-M) and will additionally conduct radio science experiments (RSE).

Richard Ghail is a Professor in the Department of Earth Sciences of the Royal Holloway University of London. Richard specializes in intra-plate tectonics on Earth and Venus uses radar interferometry (InSAR) to measure fault movements on exceedingly small scales of millimetres per year. He applies the technology to monitoring the surface effects of engineering in the ground and to understanding impact of intra-plate deformation on civil engineering infrastructure, particularly tunnels. He founded the Engineering Scale Geology Research Group to develop these ground investigation techniques and advance their study. Richard proposed Envision and led the ESA science study up to its selection. The mission will apply many of the InSAR technologies and techniques developed for ground engineering to characterise and measure geological activity on Venus.

Webinar was recorded on September 30, 2021