Weight-Watching from Space – Tracking Changes in Earth’s Surface Water with GRACE & GRACE-FO with Felix Landerer (JPL, USA)

Earth’s distribution of water – in the form of ice, snow, soil moisture, groundwater, as well as lake and sea levels – is undergoing profound changes as the climate changes over seasons to decades. The original Gravity Recovery and Climate Experiment (GRACE) mission, launched in early 2002, has provided a unique and valuable data record to monitor and study changes in our global water cycle, and allowed precise determination of sea-level rise, polar ice-cap mass loss in Greenland and Antarctica, and large-scale water storage changes over land. By measuring small month-to-month changes in Earth’s gravity field, these observations provide a unique window into Earth’s evolving climate and water stores, and a glimpse into possible future impacts. The twin satellites of the GRACE Follow-On mission, in operation since June 2018, continue and extend the groundbreaking mass change data record from GRACE. In this presentation, I will describe the fascinating technology of contemporary gravity measurements from space, and present break-through science discoveries and every-day applications from the two GRACE missions, such as the variable ice mass loss over Greenland and Antarctica, and the emerging long-term trends of land water storage that impact water availability.

Felix Landerer is the Project Scientist for the joint NASA-GFZ GRACE Follow-On satellite mission at NASA’s Jet Propulsion Laboratory. He earned a degree in Geophysics from the University of Kiel, a doctorate in Physical Oceanography from the Max Planck Institute for Meteorology in Hamburg (Germany), and was a NASA Postdoctoral Fellow at JPL from 2008 to 2010. He explores and studies Earth’s constantly changing hydrosphere by using data from geodetic satellite observations (e.g., from GRACE(-FO) and ocean altimeters), and geodetic ground observations (e.g., GPS, tide gauges) to understand global and regional sea level variations and underlying processes, and to provide relevant data to track water redistribution and availability (e.g., ice mass, aquifer storage) in a changing climate. 

Seminar was recorded on February 25, 2021

 

 

Observing our Magnetic World: When Theory Follows Space Measurements with Mioara Mandea (CNES, France)

Over the last decades, the convergence of novel approaches has led to substantial progress in our understanding of the Earth’s magnetic field characteristics and properties. These advancements have been possible due to the high quality geomagnetic data, which have been obtained either from ground magnetic observatories or from dedicated satellite missions. A radical move took place in 1980, after the launch of the very first satellite carrying a vector magnetometer to measure the full magnetic field, MAGSAT. The state-of-the-art has dramatically changed with measurements obtained from the Oersted, CHAMP, SAC-C satellites, and mostly with the recent ESA Swarm mission, launched in 2013. An overview of these space missions and of our present understanding of the geomagnetic field is given, covering commonly accepted and some of the more controversial aspects. The geomagnetic observations have been crucial in developing new insights and new theories, and a few aspects of the Earth’s deep and shallow processes grasped by the magnetic field are presented, in closest relation with some other geophysical data.

Mioara Mandea is currently the Programme Manager for Solid Earth at the Directorate for Innovation, Applications and Science at Centre National d’Etudes Spatiales in Paris (French Space Agency). Over recent decades, she has been involved in many activities of the International Association of Geomagnetism and Aeronomy (both Secretary General and President), European Geosciences Union (General Secretary and Chair of Outreach Committee), American Geophysical Union (Chair of Education Award Committee), International Space Science Institute (Chair of Science Committee), Commission for the Geological Map of the World (President of the Sub-commission of Geophysical maps), to name the most important. Mioara Mandea has published more than 250 papers, has been involved in organising many workshops and conferences, and has also led several multi-partner research projects or work packages within projects at different national and EU levels. Mioara Mandea is member of the Academy of Romanian Scientists, Academia Europea, Académie Royale de Belgique, Russian Academy of Science. She received the International Award of AGU, the Petrus Peregrinus medal of EGU, and the prestigious French “Ordre National de Mérite” (more information on www.mioara-mandea.eu).

Seminar was recorded on February 18, 2021 

SMOS, Soil Moisture and Sea Surface Salinity with Yann Kerr (CESBIO, France)

SMOS, a L Band radiometer using aperture synthesis to achieve a good spatial resolution, was successfully launched on November 2, 2009. It was the first instrument to operate operationally at L band – the first instrument thus to deliver direct estimates of surface soil moisture and sea surface salinity – and the first interferometer flown in space. A true game changer! SMOS carries a single payload, an L band 2D interferometric, radiometer in the 1400-1427 MHz protected band. This wavelength penetrates well through the vegetation and the atmosphere is almost transparent enabling to infer both soil moisture and vegetation water content, the so called L-VOD. SMOS achieves an unprecedented spatial resolution of 50 km at L-band maximum (43 km on average) with multi angular-dual polarized (or fully polarized) brightness temperatures over the globe and with a revisit time smaller than 3 days. SMOS has been now acquiring data for almost 12 years. The data quality exceeds what was expected, showing exceptional sensitivity and stability. The data is however impaired by man-made emission in the protected band, leading to degraded measurements in several areas including parts of Europe and China. Many different international teams are now addressing data use in various fields. We have now acquired data over a number of significant “extreme events” such as droughts and floods giving useful information of potential applications and are now working on the coupling with other models and or disaggregation to address soil moisture distribution over watersheds. Furthermore, we are also concentrating efforts on water budget and regional impacts. From all those studies, it is now possible to express the “lessons learned” and derive a possible way forward. This seminar thus gives an opportunity to present the achievements of the SMOS mission, a description of its main elements, and a taste of the results including performances at brightness temperature as well as at geophysical parameters level and how they are being put in good use in many domains.

Yann Kerr’s fields of interest include the theory and techniques for microwave and thermal infra-red remote sensing of the Earth, with emphasis on hydrology, water resources management and vegetation monitoring. He is involved in many space missions from conception to launch, and post-launch validation as well as to derivation of applications including EOS principal investigator of interdisciplinary investigations from 1990-1999 and PI of the precursor of the use of Scatterometer (SCAT – on board of the European Remote Sensing (ERS) satellite) data over land, Co-investigator on Interface Region Imaging Spectrograph (IRIS), Optical Spectrograph and Infra-red Imager System (OSIRIS), and Hydrosphere State (Hydros) Satellite Mission for NASA. Yann Kerr was science advisor for Multifrequency Imaging Microwave Radiometer (MIMR) and Land Surface Temperature Mission (LSTM) and Co-I on Advanced Microwave Scanning Radiometer (AMSR). In 1990, he developed interferometric concepts applied to passive microwave Earth observation and was subsequently the science lead on the Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) project for European Space Agency (ESA) with Matra Marconi Space (MMS) and Observatoire Midi-Pyrénées (OMP). In 1997, he first proposed the development of the SMOS Mission that was eventually selected by CNES and ESA in 1999 and launched in 2009 with the incumbent as the SMOS mission Lead-Investigator and Chair of the Science Advisory Group. Yann Kerr also leads SMOS science activities coordination in France and organised all the first SMOS Science workshops and is a member of the Soil Moisture Active Passive (SMAP) Science team. Yann Kerr was deputy director of LERTS and CESBIO and Director of CESBIO. 

 

Seminar was recorded on February 11, 2021

CryoSat – A Decade of Polar Altimetry with Andrew Shepherd (University of Leeds, UK)

CryoSat-2 is ESA’s first satellite mission dedicated to measuring changes in the cryosphere and its measurements have transformed our capacity to study the polar regions. Thanks to CryoSat-2, we now have an altogether new appreciation of how Earth’s ice sheets, ice shelves, sea ice, glaciers, and polar oceans are evolving. As global temperatures have risen, so to have rates of snowfall, ice melting, and sea level rise, and each of these changes impacts upon the neighbouring land, marine, and atmospheric environments. CryoSat-2 measurements are now central to our awareness and understanding of Arctic and Antarctic environmental change; a case in point is the marine ice sheet instability that is underway in West Antarctica, widely understood to be among the greatest contemporary imbalances in the climate system, whose evolution has been charted in satellite altimeter data since its onset. In this presentation, Andrew Shepherd will introduce the CryoSat-2 mission concept, describe the technical advances that have improved our capability to monitor land ice, sea ice, and the polar oceans, and review a series of flagship studies that have allowed both long-standing and unanticipated scientific problems in cryospheric research to be solved.

Andy Shepherd is Professor of Earth Observation at the University of Leeds, Director of the NERC Centre for Polar Observation and Modelling, Principal Scientific Advisor to the European Space Agency CryoSat satellite mission, and co-leader of the ESA-NASA Ice Sheet Mass Balance Inter-comparison Exercise. He uses satellites to study the physical processes of Earth’s climate, and his main contributions to science have involved developing remote observations of the cryosphere, with particular emphasis on radar interferometry and radar altimetry. He has also led field campaigns in Europe, Africa, Greenland and Antarctica, to calibrate and validate satellite missions. Andrew was educated in the Department of Physics and Astronomy at the University of Leicester, and prior to working at Leeds he has held academic posts at University College London, at the University of Cambridge, and at the University of Edinburgh. He has co-authored over journal 100 papers that are often reported in the media, and he regularly contributes to broadcast documentaries such as the BBC’s Blue Planet 2 and Climate Change: the Facts. Andrew was awarded a Philip Leverhulme Prize in 2008 and a Royal Society Wolfson Research Merit Award in 2014.

 

Seminar was recorded on February 4, 2021. 

From Satellite Observations and Atmospheric Modeling to Air Quality Forecasts with Guy Brasseur (Max Planck Institute for Meteorology, Hamburg, Germany)

According to the World Health Organization, poor outdoor air quality is responsible for the premature death of about 4 million people each year. From a health point off view, air pollution is currently the worse environmental problem facing humanity, particularly in low- and medium income countries. In the last decades, remote sensing observations from space have provided unique information on the abundance, annual variations and long-term trends of chemical species including ozone in the stratosphere. Today, a grand and difficult challenge is to probe the troposphere at high spatial and temporal resolution to monitor air quality at the regional and even local scales. The TROPOMI instrument on Sentinel 5p, for example, provides unique information on nitric oxide, a major pollutant emitted by traffic, industrial operations, energy generation, etc. while several forthcoming geostationary satellites including the Korean GEMS mission, just launched, will measure chemical species at a  spatial resolution than higher than most model resolutions.

Space observations and in situ monitoring of chemical species in the atmosphere together with information about surface emissions and atmospheric chemical and physical processes provide the basis for the development of air quality forecast systems. An important concern from policymakers is the attribution of the sources responsible for our pollution episodes. The seminar will present an integrated view on these questions.

Guy Brasseur is a Senior Scientist and former Director at the Max Planck Institute for Meteorology in Hamburg, Germany. He is also a Distinguished Scholar and a former Associate Director at the National Center for Atmospheric Research (NCAR) in Boulder, CO, USA. He is a Visiting Professor at the Polytechnic University of Hong Kong. Brasseur was the Chair of the International Geosphere Biosphere Program and more recently of the World Climate Research Program. His interests include atmospheric chemistry and climate change. His early focus was first on stratospheric ozone and chemistry of the upper atmosphere. He has contributed to the development of global atmospheric chemistry models and climate models.

Seminar was recorded on January 21, 2021

Reshaping Earth: How the TOPEX and Jason Satellites Revolutionized Oceanography and Redefined Climate Science with Josh Willis (JPL, USA)

Humans are reshaping the Earth. Not just the climate of Earth, but the planet itself.  As the Earth warms due to human interference with the climate, the oceans rise. And covering more than two thirds of the planet’s surface it means the rising oceans are literally changing the shape of the planet we call home. And since the early 1990s, a single series satellites has captured this change with unbelievable accuracy. Built to measure changes in ocean currents, our sea level satellites have revolutionized our understanding of the oceans and now provide one of the most important records of how fast our climate is changing. The unprecedented success of these missions has led to the development of the Jason-CS Mission, which includes the recently launched Sentinel-6 Michael Freilich satellite. This US-European collaboration includes two satellites, launched 5 years apart, and will guarantee another full decade of sea level observations. In addition, the upcoming SWOT mission will improve the resolution of sea level measurements, allowing oceanographers to explore new ocean physics.  SWOT will also provide unprecedented coverage of lake and river observations, likely touching off a similar revolution in the field of hydrology.

Josh Willis is the lead NASA scientist for the US and European Jason satellite missions that measure sea level, and the recently launched Sentinel-6 Michael Freilich satellite that will help carry this legacy through the rest of the coming decade.  Willis is an expert in sea level rise and its causes.  He is also the lead scientist for NASA’s airborne mission Oceans Melting Greenland (OMG for short!).  He enjoys using comedy to communicate about climate change has has been known to tell the occasional or sing a song to help people understand why the climate is changing.

“You take a bunch of weather and you average it together and you’re doing the Climate Rock!” Climate Elvis meets a curious 11-year old and answers her question about climate with a song.

Climate Rock” Josh Willis (aka Climate Elvis) Music by Kevin Stafford Lyrics by Josh Willis Produced and Mixed by Mike Wojtkiewicz Backup Vocals by Denah Angel, Shayla Tharp, Jhanna Nocon, and Lizze Gordon Portuguese Captions by Américo Ambrózio and Rui Ponte. Script by Lizze Gordon and Josh Willis, Directed by Lizze Gordon.  Animation: Joe Homokay.

Seminar was recorded January 14, 2021

Herschel – A Cool Mission Unveiling the Cold Universe with Göran Pilbratt (European Space Agency, Noordwijk, The Netherlands)

 

The ESA Herschel Space Observatory – generally known as Herschel – was the first space observatory dedicated to performing observations in the poorly explored far-infrared and submillimetre part of the spectrum. It operated as an observatory open to the entire community for almost four years in 2009-2013. This talk will introduce Herschel and provide a – by necessity – subjective overview of Herschel science achievements.

Herschel was until 2000 known as the Far Infra-Red and submillimetre Space Observatory (FIRST), it was one of the four Cornerstone missions incorporated into the ESA Horizon 2000 long term plan from its inception in 1984. Herschel covered the wavelength range 55-670 um, which corresponds to a blackbody temperature range of 5-55 K, hence it targeted the ‘cold dark’ universe, although to Herschel it was certainly anything but ‘dark’.

Herschel carried a 3.5 m diameter Cassegrain telescope, produced using new silicon carbide (SiC) technology. The telescope, which was passively cooled and had a very low emissivity, fed three focal plane instruments, called HIFI, PACS, and SPIRE. These instruments were very different in their designs and use of technology, but together were a complementary whole from a science perspective. The focal plane units were sitting on an optical bench inside a superfluid liquid helium cryostat, the cryogen supply constraining the mission lifetime.

Herschel was flawlessly launched on 14 May 2009 (together with Planck) and operated successfully for almost 4 years, its cryogen was exhausted on the 1447th operational day on 29 April 2013. In this period it successfully conducted a total of 23,400 hours of science observations approved by the Herschel Observing Time Allocation Committee, and in addition 2600 hours of science calibration, a total number of ~37,000 and ~6600 observations, respectively. All data are available at different levels of data processing through the Herschel Science Archive. By May 2020 close to 2700 papers had been published based on Herschel.

Herschel observations are very wide ranging, in terms of lookback time of its targets they cover 17 orders of magnitude, from a near Earth object to the current record of redshift z=6.95, well within the first billion years after the Big Bang.

The main science areas include star formation and cosmic star formation history. Herschel studied star formation in detail in nearby galactic molecular clouds, a main area was the study of ‘filaments’ and their role in connection with the physics of star formation. The cosmic history of star formation was studied through large (in time and sky coverage) extragalactic surveys of dust enshrouded submillimetre galaxies. A third ‘signature’ science area was water in the universe, also in terms of the ‘water trail’ and the origin of water on Earth. But there was much more.

Finally this talk will attempt to deal with the question of whether, why, and how Herschel can be considered a Game Changer. Spoiler alert – it can.

Göran Pilbratt obtained his PhD in 1986 from the Onsala Space Observatory at Chalmers University of Technology in Göteborg, Sweden. Moving to ESA/ESTEC, Noordwijk, The Netherlands, initially for a research fellowship, he was appointed Study Scientist for Herschel (then FIRST) in 1991, in 1995 becoming the Project Scientist, a post he held until the end of 2019.

Seminar was recorded on December 17, 2020

“XXM-Newton – New Visions of the X-Ray Universe” with Arvind Parmar (European Space Agency, Noordwijk, The Netherlands)

The XMM-Newton mission – ESA’s X-ray observatory – which was launched in 1999 and continues to provide the worldwide astronomical community with an unprecedented combination of imaging and spectroscopic X-ray capabilities, together with simultaneous optical and ultra-violet images, using the European Photon Imaging Camera (EPIC), the Reflection Grating Spectrometer (RGS), and the Optical Monitor (OM) will be introduced. The EPIC consists of three CCD detectors; two of these are MOS (Metal Oxide Semi-conductor) CCD arrays. They are installed behind the X-ray telescopes that are equipped with the gratings of the Reflection Grating Spectrometers (RGS). The gratings divert about half of the telescope incident flux towards the RGS detectors such that about 44% of the original incoming flux reaches the MOS cameras. The third X-ray telescope has an unobstructed beam and uses pn CCDs. The EPIC cameras offer the possibility to perform extremely sensitive imaging observations over the telescope’s field of view of 30 arcmin and in the energy range from 0.15 to 15 keV with moderate spectral (E/Delta E ~ 20-50) and angular resolution (15 arcsec HEW, point spread function). The peak effective are of all three cameras combined is around 2500 cm2 at around 1.5 keV. All the EPIC CCDs operate in photon counting mode with a fixed, mode dependent frame read-out frequency, producing event lists, i.e. tables with one entry line per received event. Each of the two RGS instruments consists of an array of reflection gratings, which diffract X-rays onto an array of dedicated CCD detectors. The RGS instruments achieve high resolving power (150 to 800) over a range from 5 to 35 Å (0.33 to 2.5 keV) (in the first spectral order). The effective area peaks around 15 Å (0.83 keV) (first order) at about 150 cm2 for the two spectrometers. The OM uses a 30 cm diameter Ritchey-Chretien telescope to provide coverage between 170 nm and 650 nm of the central 17 arc minute square region of the X-ray field of view, permitting routine multiwavelength observations of XMM targets simultaneously in the X-ray and ultraviolet/optical bands.

XMM-Newton was originally approved for 2.25 years of operations with a design lifetime of 10 years. Operations have been extended via a series of rolling extensions until 31 December 2022, with further extensions possible. The design of the spacecraft and its instruments requires continuous real-time supervision at the Mission Operations Centre at ESOC and at the Science Operations Centre (SOC) at ESAC. The SOC is responsible for running the annual “Call for Observing Proposals”. These typically result in an oversubscription of the available time by a factor >5 and involve more than 1500 astronomers, worldwide. ESAC also hosts the XMM-Newton Scientific Archive, which contains a treasure trove of undiscovered surprises. The ground segment also includes the Survey Science Consortium, a multi-national consortium which together with the instruments’ Principal Investigator teams continue to provide valuable expertise and support. 

XMM-Newton is contributing to almost all aspects of modern astronomy. The scientific impact is truly impressive with more than 6500 refereed papers so far.  These cover topics ranging from the solar system, exoplanets, stars of all kinds, supernovae, galactic black holes, AGN, clusters of galaxies, the Warm Hot Intergalactic Medium (WHIM) to cosmology and most things in between. A main focus of XMM-Newton exoplanet research is the determination of the X-ray/UV environments of exoplanets and the study of their impact on exoplanets atmospheres. XMM-Newton has continued to shed new light on various aspects of Ultra Luminous X-ray sources (ULXs) and their physical mechanisms through detailed observations, often together with other observatories. XMM-Newton discovered quasi-periodic oscillations from the AGN GSN 069 which became 50 times stronger in X-rays for about one hour every nine hours. No AGN has ever behaved so predictably. Another major breakthrough was the direct measure of a BH spin and mass through X-ray reverberation mapping of the AGN IRAS 13224‐3809 which revealed a dynamic view of the inner accretion region and allowed the breaking of inherent degeneracies. The uncertainty on the blackhole mass is comparable to the leading optical reverberation method. An important result is the clear detection of absorption features associated with the WHIM. A deep XMM-Newton observing campaign of a quasar provided the required RGS spectrum. This result helps to finally resolve the “missing baryons” problem, i.e. the observed number of baryons in the local universe falls far short of the total number of baryons predicted by Big-Bang Nucleosynthesis.

Indeed, XMM-Newton has contributed to such a broad a range of topics that it is difficult to review the science highlights in one presentation! Instead, some selected and my own favourites topics are presented with a view of demonstrating the breadth of science and capabilities of the mission. The metrics, which can be used to examine the scientific productivity of the mission will also be presented. Whilst these provide quantitative assessments of the scientific productivity, which can be useful in comparing with other missions, they provide little guidance as to what attributes, or characteristics, contribute to XMM-Newton’s success. It will be proposed what these factors may be and examine the implications for the successor mission to XMM-Newton – Athena, which is set to be launched in the early 2030s.

Arvind Parmar obtained his PhD in X-ray astronomy from MSSL/UCL in 1981 and joined ESA moving to ESOC to work on EXOSAT in 1982. He then moved to ESTEC to lead the team developing the Low Energy Concentrator Spectrometer instrument for the Italian/Dutch Beppo SAX mission. Following time spent as the study scientist for a number of X-ray missions and working on INTEGRAL, he became the XMM-Newton Mission Manager before moving to ESAC in 2009 to lead the division responsible for the science operations of the operating missions. In 2012 he returned to ESTEC to lead the team of study and project scientists and as the Executive Secretary of the Astronomy Working Group. His scientific interests are focused on X-ray binaries, particularly X-ray dipping sources which are binaries observed close to the orbital plane allowing the location, structure, ionization state and velocity of the absorbing and emitting material to be studied. More recently, he has become interested in how we monitor the scientific performance of Europe’s scientific missions and insights that this can provide to help optimise operations. He is currently on the Board of Trustees of the Royal Astronomical Society.

Seminar was recorded on December 10, 2020

“CoRoT – The First Transiting Exoplanets from Space” with Magali Deleuil (Aix-Marseille Université & Laboratoire Astrophysique de Marseille, France)

The CoRoT satellite, launched in December 2006, was the first mission designed for the search of exoplanets from space. Well adapted to explore the close-in planet population, it has opened the domain of the super-Earth planets, a population that had not been predicted by planet formation models but was later demonstrated by Kepler to be numerous. CoRoT – the name is an acronym for ‚Convection, Rotation and planetary Transits’ – has also shown the existence of close-in brown dwarfs, resurfacing the question of what distinguishes massive planets from low-mass brown dwarfs and bringing the first observational constraints to models. For giant planets, the contribution of CoRoT has been extremely valuable. Massive planets have been found around host stars that are at odds with the regular solar-type stars on which radial velocity surveys concentrated: fast rotators, active stars and even a case of a planetary system whose host star exhibits pulsations.

In the talk the major scientific achievements of the CoRoT mission in planetary science will be reviewed. It will also be explained how the international collaboration on the Exoplanet program of CoRoT worked and how the mission played the role of a benchmark for the European exoplanet community. It has triggered a new generation of young scientists that became familiar with ultra-high precision photometry and have acquired expertise in it. Searching for – and finding – rocky planets outside our Solar System, CoRoT was a very important stepping stone in the European effort to find habitable, Earth-like planets around other stars.

CoRoT used its telescope to monitor closely the changes in a star’s brightness that comes from a planet crossing in front of it. While it was looking at a star, CoRoT was able to also detect ‘starquakes’, acoustical waves generated deep inside a star that send ripples across a star’s surface, altering its brightness. The exact nature of the ripples allows astronomers to calculate the star’s precise mass, age and chemical composition. This technique is known as asteroseismology and ESA’s Solar and Heliospheric Observatory (SOHO) has been taking similar observations of the Sun for years. The CoRoT data is therefore essential to compare the Sun with other stars.

The payload of the CoRoT satellite consisted of a 27 cm off-axis telescope, the associated camera, and the mechanical structures and electronics. To accommodate the two prime scientific objectives (exoplanet search and asteroseimology of stars) the adopted approach consisted in splitting the focal plane in two parts, each dedicated to one of the mission goal. The CoRoT satellite was sent into a circular polar orbit with an altitude of 896 km and remained operative there until November 2, 2012, when a computer error terminated the mission. Its orbit allowed for continuous observations of two large and opposite regions in the sky for half a year each. Within each region there were many stellar fields that were monitored in turn. The reason for the oppositely sited regions was that – because of the Earth’s movement around the sun – the sun’s rays started to interfere with the observations after 150 days. CoRoT then rotated by 180 degrees and started observing the other region. The mission had a nominal lifetime of 2.5 years, after two mission extensions and six years of science operations the instrument stopped working in November 2012. The mission was led by the French space agency, CNES, in association with French laboratories and with a significant international participation. Austria, Belgium, Germany and ESA (Science Programme and RSSD/ESTEC) contributed to the payload whereas Spain and Brazil contributed to the ground segment.

Magali Deleuil is a senior scientist at the Laboratoire Astrophysique de Marseille (LAM) and a Professor at Aix-Marseille University. She has been head of the Exoplanet team at LAM then co-head of the Planetary System Group team at LAM. After a thesis on spectroscopic analyses of subdwarves, she moved to the field of circumstellar disks. She carried out various studies aimed at determining the physical properties of circumstellar disks around young stars and debris disks, such as the Beta Pictoris one. In 1996, she enlarged her scientific interests to detection and characterization of exoplanets by the transit and radial velocity methods. Magali Deleuil was and is involved in the preparation and exploitation of various space-based exoplanet missions: She has lead the international CoRoT/Exoplanet collaboration and is the coordinator of the French participation to PLATO. In the latter, she is a member of the Science Working Team appointed by ESA and of the Board with the responsibility of some high level workpackages in both the PLATO Data Processing Center and the PLATO Scientific Preparation. Magali Deleuil is also very engaged in teaching, covering topics ranging from mathematics, computer science, physics, to astronomy and astrophysics. She also developed a MOOC (Massive Open Online Course).

Seminar was recorded on December 3, 2020

“Planck – From the Early Universe to Our Local Environment” with Jan Tauber (European Space Agency, Noordwijk, The Netherlands)

Planck was a space-based experiment to measure the fluctuations in temperature and polarisation of the Cosmic Microwave Background. This talk will present an overview of the most recent Planck data and results and their impact on cosmology and astrophysics. In particular the “game-changing” aspects will be discussed, such as how Planck has shaped our understanding of the Lambda-CDM cosmological model, and how it has revealed new facets of the galactic interstellar medium.

Planck was ESA’s/Europe’s first mission to study the Cosmic Microwave Background, the relic radiation from the Big Bang, which occurred about 14 billion years ago. As the early universe expanded, it cooled, and at a time called ‘recombination’, it had cooled sufficiently for electrons and nuclei to combine and form atoms. At this time the light that had been bouncing about within the plasma became free to travel through space – as if the universe had switched from being opaque to transparent. This freed light was initially energetic, but with the continued expansion of the universe, what was once a searing fireball of radiation has since cooled to become a background sea of microwaves. Planck measured the temperature variations across this microwave background with much better sensitivity, angular resolution and frequency range than any previous satellite, giving astronomers an unprecedented view of our Universe when it was extremely young, just 300 000 years old.

Planck had been selected in 1995 as the third Medium-Sized Mission (M3) of ESA’s Horizon 2000 Scientific Programme, and later became part of its Cosmic Vision Programme. It was designed to image the temperature and polarisation anisotropies of the Cosmic Background Radiation Field over the whole sky, with unprecedented sensitivity and angular resolution. Planck is testing theories of the early universe and the origin of cosmic structure and providing a major source of information relevant to many cosmological and astrophysical aspects. Planck was formerly called COBRAS/SAMBA. After the mission had been selected and approved (in late 1996), it was renamed in honour of the German scientist Max Planck (1858-1947), Nobel Prize for Physics in 1918.

Planck was 4.2 m high and had a maximum diameter of 4.2 m; the launch mass was approximately 1900 kg. The spacecraft was lofted into space in a double launch, together with ESA’s Herschel space telescope, on board an Ariane 5 EC launcher on 14 May 2009. The minimum requirement for success was for the spacecraft to complete two whole surveys of the sky. In the end, Planck operated for about four years, and carried out up to eight full-sky surveys.

The Planck telescope was an off-axis tilted Gregorian design with a primary mirror measuring 1.9 m × 1.5 m and with a projected aperture of 1.5 m diameter. The 1.1 m × 1.0 m secondary mirror focused the collected light onto the two scientific instruments, the LFI (Low Frequency Instrument) – an array of radio receivers using high electron mobility transistor mixers – and the HFI (High Frequency Instrument) – an array of microwave detectors using spider bolometers equipped with neutron transmutation doped germanium thermistors. Able to work at slightly higher temperatures than HFI, the Low Frequency Instrument (LFI) continued to survey the sky for a large part of 2013, providing even more data to improve the Planck final results. After completing seven sky surveys, and upon exhaustion of its helium coolant, Planck was switched off on 23 October 2013. The high-quality data the mission has produced will continue to be scientifically explored in the years to come.

Jan Tauber is ESA Planck Project Scientist. Initially Tauber studied electrical engineering and worked in industry for a couple of years, before starting a PhD in radio astronomy at the University of Massachusetts, which he completed in 1989 with work on submillimetre-wave instrumentation and models of the structure of the interstellar medium. Until 1992, Tauber was a Postdoctoral Research Fellow at the University of California at Berkeley (USA), where he worked mainly in astronomical millimetre-wave interferometry. Tauber joined ESA as a scientist in October 1992 initially working with balloon-borne experiments. He was assigned Study Scientist for Planck in 1993 (the mission was called COBRAS/SAMBA back then). He has been the Project Scientist for Planck since its selection in 1996. Since 2017, he is Study Scientist for SPICA, a mid- and far-infrared observatory which was a candidate to become an ESA medium-sized mission. 

Seminar was recorded on November 26, 2020