Spazio 2050 n. 5 - ENG- The weather of the Sun

Magazine of the Italian Space Agency

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July 2022

The weather of the Sun Space missions and frontier studies to get to know our star and its space weather In partnership with

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SUMMARY

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ISSUE NUMBER 5, JULY 2022

In the cover Solar Orbiter.

Creditis Esa/Atg medialab.

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The Parker’s journey

by Luca Mingotti Landriani

Sun: it’s a matter of physics

by Giuseppe Nucera

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The adventures of a star called Sun

by Marco Cattaneo See the word “Sun”

by Valeria Guarneri

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Living under another star

by Amedeo Balbi

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Open Innovation: the 2022 edition of the #T-TeC Telespazio kicks off

by Marco Brancati

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Solar Italy - infographic

by Manuela Proietti

Eugene Newman Parker, the pioneer of heliophysics

by Giuseppina Pulcrano

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Cses-Limadou hunting for earthquakes from space

by Manuela Proietti

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Light on the dark Universe with Euclid by the ASI’s editorial staff

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Italy reaches the Sun with the Soho mission

by Fulvia Croci

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Touching the Sun with the Solar Orbiter

by Giulia Bonelli

Newspaper of the Italian Space Agency Insert of Global Science Media outlet of the Globalist group Registration at the Court of Roma 11.2017 of 02.02.2017

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Spacearth Technology – Commercial solutions from Science

by Silvia Ciccarelli

Aspis, a new prototype of scientific data centre, targeted at the study of space weather

by Giuseppe Nucera

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Identikit of the space weather

by Mirko Piersanti

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Space weather, under special surveillance

by Mauro Messerotti

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What’s the weather like… in the Solar System?

by Barbara Ranghelli

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Unraveling the dark side of the Sun

by Paolo D'Angelo

Printed by Peristegraf srl Via Giacomo Peroni 130, Roma

Editorial coordination Manuela Proietti, ASI Multimedia Unit

Curated by ASI Multimedia Unit Head of Unit: Giuseppina Pulcrano

Design Paola Gaviraghi

Managing director Gianni Cipriani

Thanks to ASI colleagues Barbara Negri, Cristhina Plainaki, Marco Stangalini and Simona Zoffoli for scientific advice.

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The adventures of a star called Sun

by Marco Cattaneo

If we look up to the sky, in a clear night without Moon, in a place spared by artificial lights, we can count a few thousand stars. A handful, compared to the endless landscape of celestial bodies around us. Thanks to increasingly powerful tools, we are classifying them with accuracy and stubbornness. We may get lost if we navigate the huge map of the Milky Way produced by the observations of the Gaia space mission and published on June 13th by the European Space Agency. Almost two billions of stars which, if we look at them distractedly, have the aspect of more or less identical bright dots, scattered along the cosmos’ black carpet. And think that all those stars are a minimum part of all the celestial bodies which compose it, at least 100 billion.

Among all those stars, there’s a special one, or at least one which is special for us. Because, as a matter of fact, the Sun doesn’t seem to have anything special, in hindsight. In fact, if we observe it with detachment, it’s an anonymous star from the main sequence, located on a peripheral arm of the galaxy’s disk, 28.000 light years away from its center. However, even if it’s just an ordinary star, it has its numbers. First of all, it contains 99.8% of the matter of the whole Solar System, its diameter is over 100 times higher than the Earth and its superficial temperature is about 5.500 degrees, which, however, become 15.000.000 degrees in its core, which is home to the fusion reactions which make it shine. And even if it burns as many as 5 million tons of hydrogen per second, it’s been there for at least 4 billion and a half years and will remain there for almost as many years, before running out of fuel and turning into a huge red star. While its core will shrink, the most external layers will be expelled until the orbit of Mars, will swallow anything they will find along their way, including the Earth, and will produce a planetary nebula. At the end of this spectacle, what will remain is a white dwarf, which will continue to shine, more and more weakly, with residual heat. But let time run its course, and let’s take 4 | SPAZIO 2050

William Herschel, in the end of the XVIII century was pioneer of stellar cartography.

Istoria e dimostrazioni intorno alle macchie solari (History and demonstrations around sunspots) by Galileo Galilei, Rome, 1613.

Florence, National Central Library.

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a step back.

A pioneer of stellar cartography such as William Herschel already knew, at the end of the XVIII century, that we aren’t in a particularly privileged position in the cosmic spectacle. But the Sun is our star: it has formed a planetary system that, up to a few decades ago, was the only one we knew and, with its bustling activity, has allowed the birth of life on this planet, and our birth. We ask ourselves questions, after all the Sun is so close that, according to ancient people, it was located on an orbit a stone throw away from us, between Venus and Mars. And its daily being born and dying has been catching the attention of human beings since the dawn of time.

However, for millenniums our curiosity about what happens inside that fireball hanging over us was frustrated by its blinding light, which prevents us from observing it with the naked eye, except at our risk and peril. And yet we tried, so much so that the ancient Chinese astronomers, at least in the II century BC, had already noted down the presence of spots, one for each decade according to their texts, on that shiny and apparently uniform surface. And even before, Theophrastus of Athens, a pupil of Aristotle, in its De Signis Tempestatum, had put them into relation with the meteorological weather, and had got to use them to formulate weather forecasts which, ça va sans dire, weren’t really accurate.

It’s with the advent of the telescope that we were able to start observing the Sun more closely, although with even more risks. In 1610 Thomas Harriot, a British astronomer and mathematician, thought to observe the Sun at dawn, on a winter’s morning with thick fog – according to the typical British stereotype – when the light, a few degrees above the horizon, would cross a thicker layer. The method developed by Galileo in the same years was definitely more ingenious. In fact, the scientist from Pisa studied the Sun without directly staring into its light. He would let the light come out of the ocular and project it on a piece of paper. By doing that, he didn’t just consistently observe the solar spots, but by following the motion of what he interpreted as flat clouds on the star’s surface, he realized that the Sun had to rotate on its axis and, based on their deformation, he inferred that it was a sphere. Galileo threw into crisis both the conception of the Sun as a perfect celestial body and the immutability of skies and in 1613, with his Istoria e dimostrazioni intorno alle macchie solari e loro accidenti (History and demonstrations around sunspots and their accidents), he exacerbated his endless challenge to the Aristotelians’ theories.

However, for quite a long time the Sun confined us to its

An image of the solar activity.

Credits: Nasa/Sdo.

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surface, where we gradually observed the violent expressions of the turbulences which, with all likelihood, shook its internal part. Among them are the magnetic fields of solar spots, which were discovered by George Ellery Hale at Mount Wilson Observatory. But after Galileo, it took three centuries, or even something more, to understand what lets the Sun and the other stars blaze – let’s leave love apart, so as not to upset the great Dante -. In 1920, Arthur Eddington was the first one to suggest that stars release their energy thanks to the fusion in their cores of hydrogen into helium and heavy elements are formed inside them. And almost twenty years later, in a memorable article published in Physical Review (“Energy production in Stars”), Hans Bethe analyzed the possible fusion reactions happening in stars, and concluded that there were two processes that could be regarded as the most plausible: the proton-proton chain reaction, which is predominant in small-sized stars, and the carbon-nitrogen-oxygen cycle, which is more relevant in the heaviest from the main sequence.

But the golden age of solar studies arrived with the space age, also because satellites can detect solar radiations and particles which do not reach ground level. And it’s precisely 60 years ago, with the launch of the first Orbiting Solar Observatory satellite, that we started to measure the X-rays and gamma rays emitted by solar flares. From then on, the dynamics which regulate the activity of the Sun – including the dangers for our fragile civilization, related to its most violent expressions – have been clarified in more and more detail, even if it still takes a lot of time to disclose all its secrets. «There are three specific mechanisms that we are exploring with the current missions», explains Marco Velli, professor of Space Physics at the University of California, in Los Angeles, and principal investigator of the Parker Solar Probe, the NASA probe launched in 2018 with the task of observing the external solar corona. «The first aspect is understanding why the solar corona exists and why it gives origin to wind». Because the heating of the solar corona, the most external part of the solar atmosphere, looks like a paradox. Whereas a temperature of a few degrees is recorded at the star’s surface, the corona can reach up to 2 million degrees. «Since the heat doesn’t spontaneously flow from a cold body to a warm body, there are some mechanisms with which the magnetic body transfers energy to the corona. And therefore, it’s exactly the magnetic field which generates it and, at the same time, confines it.

By the way, the magnetic field is the engine of the solar wind, the stream of particles which, from our star, permeate the interplanetary space, but then some dynamics are triggered between the magnetic field itself and the wind, which we don’t understand much yet».

The solar wind is also the protagonist of the second aspect that we’re investigating with the Parker probe, but also with the European Space Agency’s Solar Orbiter. «We must understand how the magnetic field gives origin to wind», continues Velli, «what properties of wind are related to the source on the Sun which emits it, and what are the main properties of the different types of solar wind. And by doing this, we must enter into the dynamics of solar flares, magnetic storms, coronal mass ejections (CMEs), which are essential phenomena for the space weather», that is space meteorology, the young science which studies the perturbations of the interplanetary space and how it may end up influencing the functioning of our technological systems, in space and on Earth. «And finally, we’re trying to understand the solar cosmic rays, the origin of the swarms of energy particles emitted by the Sun and why some flares give 6 | SPAZIO 2050

60 years ago, the launch of the first Orbiting Solar Observatory satellite.

The first Nasa’s Orbiting Solar Observatory during the assembly stage.

Credits: Nasa.

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origin to extremely collimated beams, whereas some others fill the heliosphere like a bubble».

All of this seems so far away from our terrestrial daily life, but might have important implications and applications in different fields. «First of all, it may improve our knowledge in terms of space weather – specifies Velli – because we’re still very much behind when it comes to the ability to predict violent events. We’re unable to accurately predict flares or coronal mass ejections, unless we do it just a few hours earlier.

And it still takes a very long time before being able to understand what could be their impact on Earth.

The amount of energy released by a CME is equal to 10 million Tsar Bombas, the most powerful hydrogen bomb ever tested, a 50-megaton bomb. If this energy was collimated enough, towards our planet, the resulting beam of particles may lead to relevant consequences. By restricting the terrestrial magnetic field, it would produce an electric field in the atmosphere, capable of crashing power plants».

Being able to predict, reasonably in advance, such extreme phenomena would at least allow to try and batten down the hatches. But that’s not all of it. The whims of solar activity cause a risk which we are unable to assess for a potential mission on Mars with a human crew aboard. «At the moment, a mission to Mars implies an 8-9 month journey in the interplanetary space. Should one of these solar storms hap-

pen during that time, the crew, without the protection of the terrestrial magnetic field and the atmosphere, would most likely be destined to an atrocious death due to an acute radiation syndrome”.

Finally, there’s another aspect, which may give us a few tips to revolutionize our production of energy.

«What we are investigating on the Sun is frontier physics, which covers different subjects. The studies on the magnetic field confinement of the plasma in the solar corona have drawn the attention of those who, on Earth, are trying to bridle the nuclear fusion to produce energy». And the knowledge of the mechanisms with which the magnetic field interacts with the corona might give us some good tips to be able to finally “bottle”, the fusion processes in a reactor for the production of energy.

The stars of the Milky Way. Map made by the Gaia satellite.

Credits: Esa/Gaia.

According to Velli, one of the future priorities is the exploration of solar dynamics in three or four dimensions. Because, so far, the Sun has allowed us to “touch” just its surface, a bit like it happened with oceans until a few decades ago. Instead, we would need to study its phenomena even in depth. And not only that. We would need to have tools available which can follow the course of events at least for one or two solar cycles, each one lasting 22 years. Only by doing so we can hope to unravel the mechanisms of our star.

And, a bit like Prometheus did when he stole fire from the gods, to treasure its benevolence for our wellbeing and for the planet’s health. Because, in the end, we already owe everything to the Sun. SPAZIO 2050 | 7

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It is characterized by a layer configuration and a wide range of “exotic” and impetuous phenomena which influence space also at a distance of billions of kilometers; furthermore, its “effervescent” activity, which is partly yet to be investigated, is a constant object of study. We are talking about the Sun, the parent star of our planetary system, the protagonist of exploratory missions – such as the ESA Solar Orbiter and the NASA Parker – which are providing precious data to outline an increasingly accurate profile.

See the word “Sun”

by Valeria Guarneri

The material which makes up this celestial body and its magnetic fields is in constant motion and gives origin to a set of physical structures and phenomena, whose typical evolution time scale may vary from a few seconds to a few years, or even hundreds of thousand years if we think of the phenomena which cause the variation of the solar activity on the long run. The variety of these characteristics and the phenomena related to them, as well as the peculiarities of the single layers of the Sun, both the internal ones and those within its atmosphere, is such as to deserve a guide, a kind of “solar encyclopedia”.

Let’s begin with the most internal layers, starting from the core. It’s an actual engine, the “heart” of the Sun; it’s 10 times thicker than lead and its temperature is above 16 million degrees; here, the pressure of the surrounding layers is so high that hydrogen atoms are “squeezed” in helium, releasing light and energy during this process. This reaction, known as nuclear fusion, has been giving “charge” to the Sun for over 4 billion years.

Later on, we have the radiative zone. It’s an area with variable density, which owes its name to the process with which energy is produced by nuclear fusion reactions. In this area of the stellar interior, the energy produced in the core is transferred towards the most external layers through the radiation.

A practical guide to the structure and “particular signs” of our star 8 | SPAZIO 2050

The most external layer of the internal structure of the Sun, the convection zone, makes up about 2/3 of the volume of our star and is a lot less dense than the immediately more internal zone, the radiative one. Here, the main mechanism for the transport of energy is convection. This zone’s warm material goes up towards the Sun’s surface and brings heat with it; as soon as it cools down, emitting light, it sinks downwards, where it collects more heat. The convective motions can be seen on the Sun’s surface in the form of plasma “bubbles”, the so-called granules or supergranules.

It’s the first layer of the solar atmosphere, with a thickness of over 400 kilometers and average temperatures of over 5.000 °C: we’re talking about the photosphere, which emits a white sheen, that can be visible with the naked eye. However, that light looks yellow to

Artistic elaboration of the Sun emitting a CME – coronal mass ejection (Credits: Nasa)

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our eyes, due to the dispersive action of the particles of the terrestrial atmosphere.

Right after, we have the chromosphere, which owes its name to the shiny red color; its temperature can be above tens of thousands degrees °C, with a thickness of over 1600 kilometers. It’s a difficult-to-study layer, due to its changing physical characteristics: in fact, in the low chromosphere, physical phenomena are dominated by the plasma, whereas in the upper

chromosphere they are dominated by magnetic fields.

The subsequent transition region is the area where temperatures (mysteriously) increase up to several billion degrees within a few tens of kilometers.

Then, we reach the Sun’s upper atmosphere, the corona: it’s an area where the motion of the plasma is ruled by magnetic fields that emerge on the star’s surface, permeating the entire atmosphere, and is characterized by temperatures which can reach up to million SPAZIO 2050 | 9

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degrees. The corona gives origin to the acceleration of the solar wind, as well as the flares and coronal mass ejections, that is the violent eruptions on which depend the most intense space weather phenomena.

After exploring both the internal layers and those within the solar atmosphere, let’s move to the “particular signs” of the Sun. Some of them behave in a particularly turbulent manner and make their influence be felt also on Earth.

One of the most famous events is the solar wind: these are gusts of material which constantly flow from our star towards any direction. Such flow, which is less thick but faster compared to the terrestrial wind, is made up of charged particles (ionized electrons and atoms) which interact both with each other and with the solar magnetic field. The wide area where the solar wind spreads creates the heliosphere, the region where the Sun exerts its influence within the interstellar space. This sort of bubble “embraces” all the planets of the Solar System and acts like a protective shield, blocking several high-energy cosmic rays coming from other parts of our galaxy.

Another well-known phenomenon is the coronal mass ejection (CME), a large magnetic plasma cloud that is released in space after a solar eruption. The CMEs, which can also be million kilometers wide, expand in space and can collide and interact with the planets’ magnetic fields. In the case of Earth, they are at the origin of geomagnetic disturbances which give way to polar auroras, but also produce technical problems for the satellites and electric infrastructures which can be found on our planet.

Prominences are also quite lively: these are snake-shaped structures, made up of dense and cool solar material, hanging on the Sun’s surface due to an intense magnetic field. Prominences can occur when the magnetic structure becomes unstable and throw plasma outwards through the above-mentioned CMEs. The experts keep them under control because they may be harbingers of space weather phenomena; they are the so-called filament eruptions. These are stre10 | SPAZIO 2050

Almost simultaneous observations of the corona by the EUI/FSI tool (in yellow) and the Italian Metis coronagraph (black and white) show an extremely filamentous structure of the solar corona.

Credits: Esa and Nasa/Solar Orbiter/EUI team/ Metis team.

amers of solar material, which is cooler and denser than what’s around it; when they become unstable, they may fall onto the Sun or disperse in space, producing a coronal mass ejection.

Among the turbulent events is also the solar flare, an energetic explosion of light and particles which is triggered by the sudden release of magnetic energy on the Sun. Flares are by far the most powerful explosions in the solar system and their particles, which travel nearly at the speed of light, can reach Earth in less than 20 minutes.

They can last from a few days to several months, their width can be above 160.000 kilometers and they are

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Artistic elaboration of the solar wind (Credits: Nasa Goddard’s Conceptual Image Lab/Greg Shirah)

Overview of the Sun by the Esa’s Solar Orbiter (Credits: Esa and Nasa/Solar Orbiter/EUI Team – Data processing: E. Kraaikamp)

connected to the trend of solar cycles: we’re talking about sunspots, cooler regions which appear on our star’s visible surface, and are caused by a concentration of magnetic field lines which emerge, floating from the most internal layers of the star, and represent the most visible effect of the Sun’s large-scale magnetism, internally fueled by a huge dynamo. Scientists use these spots to follow the evolution of solar cycles.

It’s a patch in the Sun’s atmosphere, with a lower level of density: it’s the coronal hole, a region where the magnetic field lines are directly connected to the interplanetary space. From this area, the material is dispersed in a flow of solar wind which blows at high speed, leaving a black hole next to the Sun’s surface.

The coronal rain, instead, is made up of huge plasma globes which ooze out of the Sun’s external atmosphere until its surface. This phenomenon happens in particular conditions: for example, when the configurations of the magnetic field and local heating events in the corona make the plasma globes cooler and denser than the surrounding environment, causing a “rain”.

Flux rope, instead, is the technical name with which solar physicists refer to all the concentrations of magnetic field which emerge on the solar surface and, as a matter of fact, determine the overall magnetism of the solar atmosphere and its large- and small-scale behavior. The magnetic structures which emerge due to dynamo processes in the stellar interior can have sizes ranging from a few tens of kilometers, at the limit of the modern telescopes’ resolution power, to tens of thousands kilometers, as in the case of sunspots, which are the most evident, and historically the most famous, expression of solar magnetism.

Nanojets are thin and bright tendrils of plasma which originate from impulsive release phenomena in the SPAZIO 2050 | 11

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energy accumulated by magnetic fields, like rubber bands which are twisted on themselves by the motion of photospheric plasma. They extend for thousands of kilometers and are generated by nanoflares, tiny explosions produced by a phenomenon known as magnetic reconnection, which happens when the magnetic field lines are “tangled”.

It resembles the trend of the water spread by a rotating irritator: it’s a structure defined as Parker spiral, produced by the solar magnetic field when the Sun rotates and the magnetized solar wind blows outwards.

They present themselves as streamers of material that stretch out from coronal holes on the Sun’s surface: they are the so-called plumes, which appear bright in extreme ultraviolet views and are made up of smaller streamers (plumelets). Plumelets play a key role in creating the high-speed solar wind.

Their code name is Seps (Solar energetic particles): these are highly charged particles – mostly electrons and protons – and accelerated by the activity on the Sun. The acceleration can happen in conjunction with solar flares or in space. Seps, whose motion is guided by magnetic fields, are a dangerous source of radiation for astronauts and make themselves felt also on Earth’s atmosphere, where they can hinder high-frequency radio communications like GPS. Also the Sun has a “seismic-like” activity: sunquakes are phenomena which produce ripples on our star’s surface, similar to those of terrestrial earthquakes.

This phenomenon, whose root cause is not yet known exactly, accompanies some solar flares.

Plasma emissions which present themselves as grasslike tendrils: they are the so-called spicules, plasma streams which leave the solar surface at tens of kilometers per second and, before collapsing, can extend for over 9.000 kilometers, transferring energy and material to the most external layers of the atmosphere.

Our journey to the discovery of the characteristic traits of the Sun ends with the granules and the supergranules, which are networks of cells covering the visible surface. Their size is a thousand kilome12 | SPAZIO 2050

Solar flare observed by the Nasa Sdo mission (Credits: Nasa/Sdo/ Goddard)

Filament eruption observed by the Nasa Sdo mission (Credits: Nasa/ Solar Dynamics Observatory)

ters (granules) or 25.000 kilometers (supergranules) and they are produced by the convection motions of the solar material. They can be seen, respectively, for 8-10 minutes (granules) or up to a few hours or days (supergranules).

Parker and Solar Orbiter have been active, respectively, from 2018 and 2080 and they are working to unravel new details about the Sun and create a few unpublished “portraits”. In May 2022, the Solar Orbiter released the closest images of the Sun ever taken, and with unprecedented detail: this successful result has been obtained also thanks to the Metis coronagraph, funded and managed by the Italian Space Agency.

Such tool has been created, designed and manufactured by a team made up of the National Institute for Astrophysics, the universities of Florence and Padua, the Cnr-Ifn and an Italian industrial consortium made up of Ohb Italia and Thales Alenia Space Italia.

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Living under another star

by Amedeo Balbi

Last March, the number of discovered planets around other stars, the so-called extrasolar planets or exoplanets, passed the 5000 mark. Obviously, there’s nothing special in such figure, but it’s a remarkable goal, particularly if we think that, only thirty years ago, the only worlds we knew were the few which keep company to the Earth in its orbit around the Sun. Since 1995, the year of the discovery of the first planet around a star like ours, the total has been growing at impressive pace. If we project this statistical data to the hundreds of billions of stars which make up our galaxy, the Milky Way, we reach the conclusion that virtually each of them hosts a planetary system.

Among the thousands of known exoplanets, there are quite a few which don’t have a counterpart in the solar system: for example, the so-called “Super-Earth planets”, which represent the middle range between our SPAZIO 2050 | 13

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planet and Neptune, or the “warm Jupiters”, which are big, gaseous and very close to their star. However, these aren’t the only differences with our planetary system. There are planets which orbit around extreme objects such as neutron stars, and even around double stars, like the Tatooine planet does in the Star Wars saga.

Furthermore, the Earth orbits around a type of star which is not particularly common. The stars which are smaller and fainter than the Sun, known as red dwarfs or, technically, as M-type stars, are much more numerous. In absolute terms, these stars are the most abundant in our galaxy, and are nearly five times more common than Sun-like stars. And not only that: they also live way longer than our star, and their average life is dozens of times higher. So, the most common planets in the universe are most likely those with a reddish sun in their skies.

The planets around the red dwarfs are also relatively easier to discover. In fact, the observation techniques tend to be more effective if the host star is small and 14 | SPAZIO 2050

Artistic representation of the Trappist-1 star’s planetary system Credits: Nasa-JPL/Caltech

An artistic representation of the surface of a planet of Trappist-1 star system.

weak, particularly when we’re searching for Earth-size planets in the so-called “habitable zone”. This zone is simply the region of a planetary system which favors the stable presence of liquid water, one of the requisites which are regarded as essential for life as we know it. In fact, the majority of the potentially habitable exoplanets which were discovered in the last decades is located in orbit, just around M-type stars.

This is the case, for example, of the rocky planets orbiting around the Trappist-1 star, a red dwarf located nearly 40 light years away from the Sun: three out of the seven planets discovered in 2017 in that system fall within the habitable zone. Even the closest potentially habitable extrasolar planet orbits around an M-type star, Proxima Centauri. More in general, as many as 18 out of the 20 terrestrial exoplanets in the habitable zone, which we know as of today, orbit around a red dwarf.

So, we might be tempted to define our planet as a statistical abnormality. However, when we consider the issue with more attention, we realize that things aren’t as simple as they may seem. Are we really sure

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the future observations and theoretical studies will help us to shed some light and understand whether our planetary system is the rule or the exception.

that life is possible around an M-type star? In the past years, several theoretical studies have tried to answer this question.

The first factor to be considered is the distance from the star. Red dwarfs are not very bright, therefore the potentially habitable zone is very close to the star, typically at a smaller distance than that between Mercury and the Sun. This is not good news, unfortunately. In fact, M-type stars are way turbulent than ours, and release frequent rushes of energy: ultraviolet radiation, X-rays and charged particles, which can be extremely harmful for living organisms. Furthermore, in the long run, such violent events may deprive a planet which is too close to the star from a substantial part of its atmosphere, making it even more hostile to life.

Being at short distance from a red dwarf has another consequence: the gravitational interaction with the star leads the planet to synchronize its orbital period with the rotation period. In simple terms, the planet ends up always showing the same side to the star, just like the Moon does with the Earth. Therefore, a hemi-

sphere is constantly enlightened, whereas the other one is always in the dark. Not only the lack of alternation between night and day may be incompatible with life, but the planet’s metal core might not be mobile enough to produce an intense magnetic field. This would make the planet’s surface and its atmosphere even more exposed to the harmful cosmic radiations.

Promotional poster by the Nasa, where the agency imagines a journey to the Trappist-1e planet, the best candidate to host the life of the Trappist-1 star’s system. Credits: Nasa/Jpl

If to all this, we add the fact that the poor luminous intensity may inhibit the photosynthesis and formation of biologically relevant molecules, it would look like red dwarfs, overall, are less suitable to host habitable planets than Sun-like stars. This may explain why we aren’t orbiting around the most common type of star in the galaxy. However, the verdict is not final yet. We have just started to investigate the complicated factors which make a planet habitable: among them, the characteristics of the star itself surely play a not insignificant role, although the latter hasn’t been yet fully understood. The future observations and theoretical studies will help us to shed some light and understand whether our planetary system is the rule or the exception SPAZIO 2050 | 15

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Open InnOvatIOn: the 2022 edition of the #t-teC telespazio kiCks off

by Marco Brancati Telespazio SVP Innovation and Technological Governance

«Any sufficiently advanced technology is indistinguishable from magic». These are the words of Arthur C. Clarke, known to many as the writer and screenwriter of 2001: A Space Odyssey and the father of satellite telecommunications. In 1945, when Clarke’s article was published in the Wireless World magazine, the idea that satellites placed in a geostationary orbit could put in communication every point on the globe looked like pure science fiction. Almost eighty years later, that intuition has completely changed the way we live.

Innovations have this power. They accelerate reality, they shape it, until reaching unexpected goals. All of this is particularly true for the space sector, which has switched from an isolation that was typical of its pioneering stage to a continuous dialogue, not to say permeation, with the digital world and the several specialist niches that make it up.

It doesn’t matter how big a company is, and how much experience it has in the field. Today there’s no company, in the space and non-space sector, that can 16 | SPAZIO 2050

think to have all the internal skills required to keep up with a constantly evolving world.

Telespazio has embodied the concept of Open Innovation for some time, starting from the belief that the dialogue with startup companies, research centres and universities is a key element of the success of a big company. Starting from 2019, and with this belief, Telespazio and Leonardo have created the #T-Tec, the Telespazio Technology Contest, dedicated to students and researches, with the aim of promoting technolo-

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Space; GeoInformation Applications and Platforms for a sustainable Earth, Space Domain Awareness for the Protection of Space and Ground Infrastructures; Secure and Resilient Communications with future technologies; Positioning, Navigation and Timing Infrastructures and Solutions for Earth and other celestial bodies. These are important topics, which will increasingly influence our daily life in the coming years and decades.

Same as the previous editions, the three winning teams will receive checks of different amounts, based on the achieved result. The judging panel, which will be made up also of representatives from the Italian and European Space Agency, will also select a few special mentions and will assess the possibility of funding the most promising ideas by means of research contracts or partnerships.

In particular, starting from this year, Telespazio has decided to turn into an actual incubator for startup companies. If they wish so, the winning team will be able to access an acceleration process for the next stages of the awarded project.

Each company must set itself the goal of giving value to ideas. Contests such as the #T-TeC are valuable opportunities to create connections with innovative realities, exchange opinions and, sometimes, discover talents.

gical innovation in the space sector among the younger generations, promoting their ideas and intuitions and imagining together the technologies that will shape our future.

For the 2022 edition of the #T-TeC, the competing teams will discuss six technological macro-themes which are relevant for the present and the future of the space sector: Space and Extraterrestrial Exploration; In Orbit Servicing towards a Circular Economy in

Leop Control Room at Fucino Space Center.

In the last three years, Telespazio has welcomed two participants in the past editions of the #T-TeC, who currently work on some of the most innovative projects conducted by the company, such as the study for the manufacturing of a lunar communication and positioning system.

Furthermore, a few partnerships with important universities have been facilitated by the participation of their respective teams in the #T-TeC. Also this year, the #T-TeC can boast prestigious sponsorships: “historic” sponsors such as the Italian Space Agency and European Space Agency will be joined, for the 2022 edition, by the Italian Association of Aeronautics and Astronautics (Aidaa) and international sponsors such as the Space Generation Advisory Council in Support of the UN Programme on Space Applications (Sgac) and the Council of European Aerospace Societies - (Ceas). As well as giving further prestige to the initiative, such sponsorships will allow even more to make a way into the academic world and the world of national and international research; in the three past editions, 57 innovative proposals were submitted by 200 participants among students, PhD students and researchers coming from 30 global universities.

Always Clarke thought that the only way to discover the limits of the possible is to go beyond them into the impossible. Ultimately, the #T-TeC, and more in general the Open Innovation, perform this extremely difficult task: to draw a line somewhere just to be able to cross it.

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THE SOLAR ITALY All the missions dedicated to the study of our star, to which Italy contributes by providing scientific tools or support

By Manuela Proietti

Present missions Future missions

SOHO 1995

PARKER SOLAR PROBE 2018 NASA mission. Overall, the closest probe to the Sun so far for the study of the solar corona. Italy provides support to the exploitation of scientific data.

A joint ESA-NASA mission for the study of the Sun and, in particular, the temperature of the solar corona. The spectrometer in the visible channel of the UVCS ultraviolet coronagraph is Italian.

SOLAR ORBITER 2020 An ESA mission dedicated to the study of the internal heliosphere, the solar wind and the polar regions. Italy contributes with the Metis coronagraph, the data processing unit (DPU) of the SWA tool for the data analysis of the solar wind and the image reconstruction software of the Stix tool.

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CSES-1 2018 Chinese-Italian partnership to study the seismic precursors and electromagnetic phenomena related to the space weather. The Italian contribution, named as Limadou, consists of the Hepd-01 particle detector and the participation in the manufacturing of the Chinese E-01 tool.

MUSE 2027 A NASA mission dedicated to the study of the solar dynamics, Sun-Earth connection and space environment.

Italy is in charge of manufacturing the telescope’s mirrors and the multi-layer filters, as well as providing support to the coating and scientific support.

PROBA 3 2023 ESA technological demonstrator for the formation flying of high-accuracy satellites.

Italy is in charge of the positioning system and provides scientific support.

SOLAR-C EUVST

CSES-2

2027

2023

Japanese-led mission to unravel the formation mechanisms of hot plasma and the effects of the solar activity on Earth and the Solar System. Italy manufactures the slit system of the spectrometer and provides scientific support.

In the second mission of the Chinese-Italian partnership, the Italian contribution grows: through the ASI, Italy provides the Hepd-02 particle detector and the Efd-02 electric field detector.

Infographic Infolab

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Touching the Sun with the Solar Orbiter

by Giulia Bonelli

The Esa-Nasa mission to explore our star and Italy’s role in this fascinating journey to discover the Sun

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Since the prehistory, the Sun has been at the same time venerated and feared. In several ancient cultures, our star is the most important divinity, and the Egyptians regarded the Pharaoh as the son of the Sun, whereas in the Greek myth of Icarus the young son of Daedalus ignores his father’s warnings and gets too close to the boiling star: his wings, held together by wax, melt and make him fall down.

The long scientific research related to the Sun is also accompanied by fascination and fear and today is the object of several international space missions. The Solar Orbiter, the Esa-Nasa probe which, astronomically speaking, got a stone’s throw from the Sun, wanders here, in this extreme cosmic environment.

It took two years for the Solar Orbiter, which departed in February 2020 from Cape Canaveral aboard an Atlas V carrier rocket, to make its first close encounter with the Sun. During its journey towards our star, it made spectacular images, such as the Venus – Earth – Mars triplet, which was immortalized in an unprecedented overview, to then reach our star and start to study it with its ten scientific tools.

«The Solar Orbiter – explains Barbara Negri, head of the Asi’s Human Flights and Scientific Experimentation unit – can be regarded as a scientific breakthrough mission, or as a turning point: it’s exploring the solar corona, and will observe our star from a distance never reached before by other probes. We’re talking about a highly prohibitive environment, with temperatures up to 500° C, whereas up to -200° C can be reached in the shady side. Because of this, Thales Alenia Space has manufactured in Turin a really innovative heat shield to protect the Solar Orbiter’s ten scientific tools: six remote-sensing tools, to observe solar phenomena as a whole, and four in-situ tools, which carry out punctual analyses of the corona’s environment”.

There’s a lot more Italy aboard the Solar Orbiter. The Asi’s Metis tool is Italian: it’s a coronagraph which has been manufactured in partnership with the Inaf, the Cnr and the universities of Florence and Padua, and with the contribution of the Max Planck Institute for Solar System Research (Germany) and the Astronomical Institute of the Science Academy (Czech Republic).

Artistic representation of the Solar Orbiter probe.

Credits: Esa/Atg medialab.

«Metis is the first tool of its kind which is able to observe simultaneously the Sun and the most extended solar corona in several bands of the electromagnetic spectrum, in the visible and ultraviolet spectra, and allows to obtain a set of highly innovative analyses.

For example, we’re mapping for the first time the expansion speed of the plasma in the whole corona, and we’re obtaining very high resolution images», explains Marco Stangalini, ASI researcher and Project Scientist of the Metis tool.

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These images show the Sun as we had never seen it before. At the end of March 2002, the Solar Orbiter completed its first close pass and reached up to a distance of less than 50 million kilometers away from our star. Nearly two months later, the Esa published the first photographs: a set of breathtaking pictures of the Sun and, even more importantly, a goldmine of scientific data, several of which have been collected

by Metis, which has allowed to explore extreme phenomena, such as the violent expulsions of coronal mass. One of these eruptions has been immortalized during the last overflight of the Sun: the Solar Orbiter has captured the “journey” of a solar eruption, starting from the superficial layers of the atmosphere until its explosion in space.

«Metis – continues Stangalini – observes the most extended solar corona. But obviously, what we observe in the corona is the result of the energy coming from the most internal layers of the solar atmosphere. These layers are observed by other tools aboard the Solar Orbiter, such as Stix, an X-ray spectrometer-telescope for which Italy has provided the software for images reconstruction. Therefore, by combining all the information obtained by the different tools, we can better study the physical processes happening in the solar atmosphere. We manage to follow the solar energy, which is responsible for the expulsions of coronal mass that can have an impact also on the interplanetary space».

«These phenomena of the solar corona – adds Barbara Negri – are capable of damaging satellites orbiting around the Earth, and also of putting at risk several activities on our planet. Therefore, observing closely the mechanisms which lead to the expulsion of coronal mass and other similar phenomena is a unique opportunity, which will allow us to collect new clues on space weather and study appropriate countermeasures».

In these months, the scientific community is working incessantly on the data collected by the Solar Orbiter. But several precious data have yet to arrive: it’s the data obtained from in-situ tools, which directly collect particles coming from the Sun. Among them is the Swa tool, an acronym for Solar Wind Analyzer, with a significant contribution from Italy.

«Swa is a suite of tools which allow to measure the particles of solar wind. It’s made up of a tool which measures electrons, a tool which measures protons and alpha particles and another one which measures heavy ions. Finally, there’s the Data Processing Unit (Dpu), which is the core of the tool and is under the Italian leadership. Swa allows an in-situ calculation of the characteristics of solar plasma, such as density, speed and temperature, and characterizes the environment in which the probe is immersed. An actual cosmic laboratory experiment», says Denise Perrone, 22 | SPAZIO 2050

Metis explains the origin of fluctuations in the solar wind Thirty years after the first discovery of sudden fluctuations in the magnetic field of the solar wind, by the Nasa-Esa Ulysses mission, the measurements carried out in 2021 by the NASA Parker Solar Probe mission had highlighted a surprisingly high amount of such events. This had led to the formulation of several hypotheses on their origin.

Such fluctuations are actual inversions of the magnetic field which, as if they were under the effect of a whip, propagate in the interplanetary space. Today, just slightly over one year after the Parker’s observations, the Italian Metis coronagraph, aboard the Solar Orbiter, has directly observed for the first time one of these fluctuations, the so-called switchbacks, in the solar corona. The result was obtained thanks to the data acquired immediately after the beginning of the nominal phase of the Esa probe, in March 2022.

The data obtained by Metis, which are currently being published in the Astrophysical Journal Letters, show the propagation of one of these disturbances of the magnetic field in the solar corona and have finally allowed to discriminate among the different possible mechanisms of formation that have been proposed so far and create a relationship between this type of processes and the acceleration of solar wind.

Composite image of the solar disk, observed in ultraviolet light by the Eui tool aboard the Solar Orbiter and the (blue) corona observed simultaneously by Metis. The yellow box identifies the coronal perturbation observed at high resolution by Metis. From Telloni et al. 2022 (in press ApJL).

Solar eruption immortalized by the Solar Orbiter on March 2nd, 2022. Credits: Esa & Nasa/Solar Orbiter/ Eui & Stix Teams.

ASI researcher and Project Scientist of the Swa tool.

Before the launch of the Parker Solar Probe and Solar Orbiter solar missions in the last few years, the last mission dedicated to the in-situ analysis of solar wind in the internal heliosphere dates back to 1975: it’s the pair of Helios probes, launched by the German Dlr in partnership with the Nasa.

«Still today – explains Perrone – we continue to publish the data collected by Helios, but we can’t compare the resolution of such data with what the Solar Orbiter will be able to reach. Swa and the other in-situ tools will allow to obtain information on what we call kinetic effects: very low-scale phenomena which, however, may have a big impact on the overall solar dynamics.

For example, they may help us to explain the issue of

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the abnormal heat of solar wind. Since we’re talking about an expanding gas, we expect solar wind to cool down as it approaches space, but previous data show that such cooling doesn’t happen at the expected speed. This means that there must be a local source of energy which heats the plasma and may be related to kinetic effects. Thanks to the Solar Orbiter, we hope to add new information to find an answer».

We expect many other discoveries from this revolutionary mission a stone’s throw away from the Sun, which combines science and technology with an unprecedented level of innovation to study our star. Another great enigma which may be solved thanks to the Solar Orbiter is the difference of temperature between the corona and the surface of the Sun. The first data

First pictures of the solar corona obtained by the Metis coronagraph aboard the Solar Orbiter on May 15th and June 21st, 2020. Credits: Esa & Nasa/Solar Orbiter/Metis Team.

The Sun seen from the Solar Orbiter at perihelion. Picture taken on March 26th, 2022. Credits: Esa & Nasa/Solar Orbiter/Eui Team.

collected from the probe already lead us to think of a potential role of campfires, tiny eruptions which are ubiquitous on the solar surface. They may be related to a process which is capable of contributing significantly to the heating of the solar corona: such data, if confirmed by the Solar Orbiter, would explain one of the big mysteries of solar physics.

Again, several expectations are linked to the exploration of the Sun’s poles: as of today, this region is completely uncharted, and the Solar Orbiter will be able to observe it when inclining its orbit.

But before that, starting from next October, we expect further and spectacular overflights of the Sun, which will offer us new data and new images, capable of moving also who’s been studying our star for his whole life.

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The Parker’s journey

by Luca Mingotti Landriani

What is the most direct way to study the Sun, except for touching it? Contrarily to what the extremely high temperatures reached in the solar atmosphere may lead us to think, it’s not madness, but the pure reality. The primacy belongs to the Nasa and its Parker Solar Probe, the first space probe in history to cross the Sun’s corona, the most external layer of its atmosphere.

The Parker Solar Probe was launched almost four years ago, on August 12th, 2018, from the Cape Canaveral space center, in Florida, and will end its journey in 2025. Over almost seven years, the probe will orbit around the Sun for a total of 24 hours; each orbit’s perihelion, the point of closest approach to the Sun, will be gradually reduced by taking advantage of Venus’s gravity, in proximity of which the space vehicle will transit seven times overall. The minimum distance from the solar surface that the Parker Solar Probe is expected to reach is 6.1 million kilometers – approximately ten times lower than the average distance between Mercury and the Sun. It may seem a mission impossible, since the solar corona reaches temperatures around one million degrees Kelvin. How can the equipment aboard the probe and the vehicle itself withstand such a hostile environment and, above all, the fusion? As a matter of fact, the solar corona has an extremely low particle density: while crossing it, the Parker Solar Probe runs into such a low number of particles that the amount of heat transferred by them to the vehicle is capable of heating its surface “only” up to a temperature of 1104 K. Most equipment aboard the probe is protected by a thermal shield, which has a thickness of 11.5 centimeters and maintains such equipment approximately at room temperature; the 24 | SPAZIO 2050

outdoor equipment is built with metals whose fusion point is almost 1000 K higher.

The data collected by the tools aboard the Parker Solar Probe are one of a kind. In fact, the Sun is the only star that we can study so closely and that has such an important impact on our planet. Solar activity is declined in an amount of phenomena which involve Earth and the surrounding space and give origin to the conditions which make up the so-called space weather.

The solar wind, the flow of charged particles produced by the incessant expansion of the Sun’s corona, plays the main role. The solar wind interacts with the terrestrial magnetosphere, the magnetic shield which

Image of a coronal streamer observed above the Eastern edge of the Sun, on November 8th 2018 at 6:12 UTC, captured by the Parker Solar Probe’s Wispr tool. The bright object next to the center of the image is Mercury.

Photo: Nasa/ NRL/Parker Solar Probe.

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protects Earth from the dangers of the interplanetary space and sometimes causes alterations of the Earth’s magnetic field, which are reflected in the malfunctioning of electric networks, communication systems and satellites. The extent of such phenomena increases substantially when the Sun ejects a whole portion of material from its corona – a phenomenon known as coronal mass ejection. The acceleration of high-energy charged particles, known as solar energy particles, is linked to this ejection; they represent a serious danger for the safety of astronauts and the correct functioning of the orbiting devices. In addition to the merely scientific goals, the Parker Solar Probe aims at investing the environment where such events have their

The launch of the Parker Solar Probe with a Delta IV Heavy rocket from the Cape Canaveral Air Force Station, in Florida (USA), on August 12th 2018 at 7:31 UTC. Photo: Nasa/Bill Ingalls.

origin, in order to expand the knowledge of a few mechanisms that concern them and haven’t been clarified yet. In this way, it would be possible to improve the current monitoring and protection systems from the corresponding space weather events.

Already a few months after the launch, the Parker Solar Probe has flown over some structures, known as coronal streamers, from which coronal mass ejections are believed to be forming. In 2019, the probe discovered the diffuse existence of zigzag configurations of the solar wind, known as switchbacks, in the proximity of the star. Only two years later, their region of origin was identified: it is located in the proximity of the Sun’s surface. Should we be able to understand the relationship between the onset of these structures and the formation of the fast component of the solar wind, we would finally be able to solve a mystery which has been gripping scientists for a long time: how does the Sun’s corona reach way higher temperatures than the Sun’s surface?

Last June 2nd, the Parker Solar Probe completed her twelfth perihelion. The mission is now at its turning point, but the enthusiasm for the potential, upcoming discoveries is not decreasing because of this.

After all, it’s no coincidence that the probe symbolically bears the name of a pioneer of the Sun’s physics – Eugene Parker, who passed away this year, on March 15th. After the great steps taken by the American astronomer, to whom we owe the first theory capable of explaining the dynamics of the solar wind, the Nasa mission represents a unique opportunity to revolutionize the landscape of the star which guarantees our own life.

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EugEnE nEwman ParkEr, the pioneer of heliophysics

by Giuseppina Pulcrano

Emeritus professor and great revolutionary thanks to his theories about the Sun: he leaves us a mission which bears its name, and an example of the genius of imagination

Eugene Newman Parker, a life spent among innovative theories and irrefutable evidences of his vision on the studies of the Sun. Gene, as he was affectionately called by the Heliophysics Division Director, Nicky Fox, had a sweet and kind face and leaves us an indelible heritage on how challenges should be faced in life, generally speaking, and in particular in the work of a scientist: «If you do something new or innovative, expect trouble. But think critically about it because if you’re wrong, you want to be the first one to know that». A sort of will for young scientists: he left it in the year of the launch of the Parker Solar Probe mission, which he attended at the age of almost 91, when he was already ill, accompanied by three generations of his family and by the Nasa team. He was clear headed, determined and a dreamer and his innovative theories have been the object of criticisms, which were not always respectful, by representatives of the international community. Parker graduated in Physics at the Michigan State University in 1948 and obtained a PhD in Philosophy at the Caltech in 1951.

He spent four years at the University of Utah, before joining the University of Chicago in 1955, where he spent the rest of his career. After obtaining this prestigious teaching post, in the mid 1950-s, Parker developed the theory of the supersonic solar wind and predicted the Parker spiral shape of the solar magnetic field in the outer Solar System. His theoretical modelling wasn’t immediately accepted by the astronomical community. When he submitted the results to The Astrophysical Journal, two reviewers recommended its rejection. The editor of the journal, Subrahmanyan Chandrasekhar, couldn’t find a fault in Parker’s mathematics and overruled the reviewers. Chandrasekhar, a future Nobel Prize, courageously decided to publish the paper anyway. Parker’s theoretical predi-

ctions were confirmed by satellite observations a few years later, especially by the Mariner 2 mission, a Nasa space probe launched on August 27th, 1962, towards Venus. During its path, the probe measured the solar wind and confirmed the measurements conducted by the Luna 1 probe in 1959.

It also measured the interplanetary dust, which turned out to be less than expected, and detected high-energy charged particles coming from the Sun, including a few brief solar flares, and also a few cosmic rays coming from the outer Solar System. His theories and mathematical models talked about conditions which generated the supersonic flow of particles from the Sun’s surface. “Well I would suggest that Parker go to the library and read up on the subject before he tries to write a paper about it, because this is utter nonsense”: this is what Parker recalled in an interview for the UChicago News in 2018, quoting one of the harsh comments coming from the scientific world about his advanced theories. He was elected to the National Academy of Sciences in 1967, and was a member of the American Physical Society and Legacy Fellow of the American Astronomical Society; during his long career, he was the author of important publications.

The testimony of Nicky Fox, director at the Nasa, on Parker’s genius is particularly impressive: «Known as the father of heliophysics, Gene’s discoveries are foundational to what we know about space weather and how stars behave. His level of brilliance is rare. He described the discovery of the solar wind as “simple.”

It was derived from just four lines of algebra». Gene passed away last March 15th, after having his revenge with the Nasa Parker Solar Probe mission, which was launched in 2018 to observe the Sun’s outer corona and bears his name. It’s the first Nasa space vehicle named after a living person.

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Cses-Limadou hunting for earthquakes from space

by Manuela Proietti

Is there a correlation between earthquakes and geomagnetic storms? Do seismic events have an impact also on the space environment? Is it possible to monitor an earthquake from space?

These are some of the investigation fields of the Chinese Space Agency’s Cses (China Seismo-Electromagnetic Satellites) satellites, whose goal is to identify electromagnetic, ionospheric and magnetospheric seismic precursors and study possible space-time correlations with the arrival of high intensity earthquakes.

In fact, several studies have highlighted the possible existence of cause-effect relationships between electromagnetic emissions, related to Earth’s seismic activity on the one hand and the occurrence of perturbations in the iono-magnetospheric plasma on the other hand.

Cses-01, launched on February 2nd, 2018, aboard a Chinese carrier rocket, has already started to provide the first answers, in particular thanks to the Hepd-1 high-energy particle detector, one of the Italian contributions to the Chinese mission.

«From a scientific standpoint, the evaluation of the first four years of flight of the Cses satellite – says Mirko Piersanti, scientific director of the Li.M.I.C., Lithosphere – Magnetosphere – Ionosphere Coupling research group – is extremely positive. The Hepd, along with the other payloads, has transmitted a huge 28 | SPAZIO 2050

amount of data, whose analysis has led to a better understanding of the magnetosphere-ionosphere coupling mechanisms during periods of high solar activity.

An artistic representation of the interaction between the Sun and the terrestrial magnetosphere Credits: Nasa’s Goddard Space Flight Center/Mary Pat Hrybyk-Keith

In particular, the data obtained by the Cses on the magnetic field and energy particles were added to two global multi-tool analyses on geomagnetic storms in August 2018 and May 2021, showing the huge capacity of the Cses, in the field of space weather, to understand the dynamics of Van Allen radiation belts in connection with solar forcing. Furthermore, the Hepd has measured for the first time in the ionosphere, at 500 km altitude, the flow of low-energy cosmic protons with great accuracy, providing a key contribution to the understanding of the interplanetary magnetic field. Lastly – adds Piersanti -, thanks to the extreme sampling frequency of the electric field detector (Efd), we have been able to identify, for the first time, the small spatial-scale fluctuations of the electric field when entering the auroral oval, where charged particles interact with the terrestrial ionosphere».

The Cses-01 satellite has nine scientific tools aboard, designed to measure the magnetic field, the pro-

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perties of the ionospheric plasma and the flow and spectrum of high-energy particles: for the first time, all the main sensors required to study the ionosphere, magnetosphere and their possible coupling are aboard a single satellite.

The orbit of the satellite is Sun-synchronous and is located at approximately 500 km altitude. The Italian contribution for the Cses-01, which is governed by an agreement between the Asi and the Chinese Space Agency, is called Limadou in honor of the Italian Jesuit missionary Matteo Ricci – whose Chinese name was, in fact, Li Madou – consists in manufacturing of a payload, the High Energetic Particle Detector (Hepd1), and supporting the manufacturing the Electric Field Detector (Efd), as well as conducting the plasma chamber tests for the Efd and other tools manufactured by the Chinese partner.

The in-orbit operations are carried out from the Chinese ground stations, whereas the scientific data are stored and distributed by the Asi Ssdc data centre.

The Infn – with its branches of Bologna, Napoli, Perugia, Roma Tor Vergata, the Tifpa-Trento centre and the National Laboratories in Frascati – is the Asi’s

main partner in its cooperation with the Cnsa. The Inaf-Iaps of Rome, the universities of Bologna, Perugia, Roma Tor Vergata, Trento, the International Telematic University UniNettuno, the Ifac/Cnr and the National Institute of Geophysics and Volcanology are also involved in this cooperation, with their own scientific expertise as regards data analysis and development of geophysical models.

Cses-02 will create the first core of a satellite constellation, which will be in charge of a new type of remote sensing.

A second satellite, the so-called Cses-02, will be launched in 2023, and a higher contribution is expected.

«The excellent results reached in the first mission and the strong expertise of our scientific community – explains Simona Zoffoli, Program Manager for Limadou at the Asi – have allowed the Asi to strengthen its participation in the Cses-02, the second mission which, along with the Cses-01, will create the first core of a satellite constellation, which will be in charge of a new type of remote sensing. In this second mission, the Italian cooperation will not only provide an updated version of the particle detector, the Hepd-02, but also the tool to measure the electric field, the Efd-02, which in the first satellite had been manufactured by the Chinese partner».

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Light on the dark universe with eucLid by the ASI’s editorial staff

the integration of the satellite, which will explore dark energy and delve into the mysteries of dark matter, is now completed

Euclid is a European Space Agency (Esa) mission for astronomy and astrophysics, aimed at investigating the nature of dark matter and dark energy with the important contribution of the Italian Space Agency (Asi) and the French Space Agency (Cnes). Thales Alenia Space (a joint venture between Thales (67%) and Leonardo (33%)) is the prime contractor for the manufacturing of the satellite, leads an industrial consortium made up of the largest European space companies and takes advantage of the scientific contributions from universities and specialized research centres. Euclid will analyze how the universe has evolved in the last 10 billion years to better understand the dynamics of its expansion and why it is accelerating. Euclid’s launch is scheduled for 2023; the mission will last 6 years around the L2 Lagrange point, located 1.5 million kilometers away from Earth. As of today, all the satellite integration activities have been completed at the Thales Alenia Space factory in Turin, whereas the environmental tests before the launch campaign will be conducted at the Thales Alenia Space factory in Cannes. Following the individual integration and testing of the on-board sub-systems and the Vis (Visible Instrument) and Nisp (Near Infrared Spectrometer and Photometer) scientific tools, now the telescope, which had previously been integrated at the Airbus factory in Toulouse, has been installed in the service module and the solar panel and antenna have also been integrated. The next stage will be the final acceptance tests of the satellite and, in particular, the functional tests in the thermal vacuum chamber, the acoustic and sinusoidal mechanical tests and the electromagnetic compatibility tests. The next review and decisive moment will be the Flight Accep30 | SPAZIO 2050

Euclid will study how the Universe has evolved over the last 10 billion years.

tance Review, which will be followed by the transfer of the satellite to Kourou, in French Guyana, to start the launch campaign. Thanks to the cold gas microthrusters manufactured by Leonardo, the Esa will be able to control the probe’s orientation in space with infinitesimal corrections of the observation direction. The information on the telescope’s line of sight will also come from a Leonardo sensor: the Fine Guidance Sensor (Fgs). Finally, Leonardo provides the photovoltaic panels, which will provide power for all the probe’s systems. «I would like to emphasize the excellent work carried out over the last few years by both the project team and the entire industrial consortium for the Esa Euclid mission – said Walter Cugno, Vice-President of Exploration and Science at Thales Alenia Space -, a very synergic and punctual work that confirms Thales Alenia Space’s ability to lead the development of highly challenging scientific missions, such as this one.

A special thanks goes to the team which, with the contributions from Spain, Belgium and France, enabled Thales Alenia Space to reach this important program milestone, which will be now followed by the environmental tests carried out in Cannes and the beginning of the launch campaign».

SPACE FOR LIFE WE BELIEVE IN SPACE AS HUMANKIND’S NEW HORIZON TO BUILD A BETTER, SUSTAINABLE LIFE ON EARTH

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Italy reaches the sun wIth the soho mIssIon

by Fulvia Croci @asi_spazio

The scientific and technological contribution of our country in the esa/nasa soho mission If today Italy is aboard one of the main Sun observation missions, the Solar Orbiter, it definitely owes it to the expertise developed thanks to the participation in the Esa/Nasa Soho mission.

The Solar and Heliospheric Observatory was launched in 1995, at 1.5 million kilometers from Earth. From this point of observation, Soho constantly observes the Sun, returning spectacular images and data of the storms that rage on its surface. Soho’s studies range from the Sun’s interior, through its visible surface and atmosphere, to distant and difficult-to-observe regions, where the solar wind clashes with the atoms and the elements coming from the other stars.

Italy has contributed significantly to the mission, by designing and manufacturing the Uvcs spectrometer in the visible channel of the ultraviolet coronagraph (Uv Coronagraph Spectrometer), which measures the density and temperature of the corona. The tool, financed by the Nasa and the Italian Space Agency, is a flagship of our country’s scientific excellence and has been manufactured thanks to the partnership between the National Institute for Astrophysics (Insf), 32 | SPAZIO 2050

the universities of Florence, Padua and Turin and the Harvard-Smithsonian Center for Astrophysics.

In more detail, the spectrometer has allowed to know more specifically some physical parameters of the solar wind: expansion speed, kinetic temperatures, speed distribution of minor protons and ions and chemical composition.

The Uvcs has allowed to analyze in more detail the ultraviolet solar corona until its most external layers, unraveling the regions where the solar wind is accelerated. The tool has also detected the most likely energy deposition processes which guide the wind, differentiating it between fast wind (800 kilometers per second) and slow wind (400 kilometers per second). In particular, the Uvcs has led to the discovery of different kinetic temperatures for different ions, whose values, unexpectedly, are hundreds of million degrees higher than electrons and hydrogen in the corona. This has been suggestive of heating and acceleration mechanisms of the solar wind, related with the resonance interaction between magnetic field waves and plasma.

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hydrogen atoms. This spectral line, the most intense line of the external corona, is extremely important because it allows to use the diagnostic techniques developed by the Uvcs team to measure the speed of the solar wind.

Besides the Uvcs, Soho includes 11 complementary tools, developed and provided by 12 international consortia which involve 29 institutes from 15 countries, including Italy. Nine consortia are guided by European scientists, the remaining three by U.S. scientists. More than 1500 scientists from countries all over the world are directly involved in the tools of the mission and have used data in their research programs.

The tool that has produced the most spectacular results is definitely the Extreme Ultraviolet Imaging Telescope (Eit). The telescope is capable of recording detailed images of the whole solar surface in the ultraviolet light: in this way, it’s possible to detect solar flares, violent material eruptions which influence the solar atmosphere.

The vast legacy of expertise and knowledge developed in the manufacturing of the Uvcs is at the core of the design of Metis, the first multi-band space coronagraph mounted aboard the Esa Solar Orbiter mission.

Metis is capable of obtaining simultaneous coronal images, both in the visible and in the ultraviolet light, and particularly in the Lyman-α line, emitted by the

Photo credits: Esa-Nasa.

The Large Angle and Spectrometric Coronagraph (Lasco), instead, is mainly dedicated to the study of the solar corona and the solar wind. This tool is in charge of taking some spectacular images which depict two comets that crashed on the Sun in 1997. Soho has also helped to develop a completely new science, helioseismology, which, like terrestrial seismology, offers an indirect method to obtain information on our star’s internal structure and dynamics.

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A showcase for small and medium-sized enterprises and national start-up companies, whose goal is highlighting unique growth paths, evolving business models and adaptation and anticipation strategies of the most advanced New Space trends, so that the whole sector can draw inspiration from them.

ZOOM ON SMALL AND ZOOM MEDIUM SULLE SIZED PMI ENTERPRISES

Spacearth technology – CommerCial solutions from sCienCe

by Silvia Ciccarelli

SpacEarth Technology was born in 2014 as a spin-off company of the National Institute of Geophysics and Vulcanology (Ingv), the largest European scientific institute in the sector of geophysics, located in Rome.

Today, it’s an innovative small and medium-sized enterprise, capable of turning sophisticated scientific analyses into high added value commercial products.

In its 8 years of life, it followed a path aimed at detecting and patenting innovative solutions, capable of generating a high impact on markets such as precision agriculture, air and sea navigation, over-the-horizon (Oth) telecommunications, control of the stability of structures and mitigation of natural risks, including those deriving from the solar activity. SpacEarth operates in two main fields: monitoring of infrastructures and space weather. The latter is the discipline which deals with monitoring and predicting the changes in the interplanetary space caused by the solar variability. Such phenomena may lead to operational abnormalities, decreased performance, disturbances for ground-based applications based on the use of space-derived data or even damages to the in-orbit equipment.

In particular, the degradation of the satellite positioning services based on the signals emitted by the Global Navigation Satellite System (Gnss) and the disturbances to the HF-band radio communication 34 | SPAZIO 2050

(3-30 MHz) induced by the presence of the terrestrial ionosphere have turned out to be critical in different fields which are more and more frequently applied.

Therefore, the ability to monitor and predict the ionospheric adverse events becomes extremely important to develop adequate countermeasures.

The algorithm developed and patented by SpacEarth is capable of predicting a few minutes early the occurrence of the so-called ionospheric scintillations, that is the stochastic fluctuations induced by the presence of the irregularities of ionospheric plasma on the Gnss signals received at ground level, and allows to maintain a level of centimetric accuracy also in such conditions.

Still on the topic of ionospheric monitoring, SpacEarth manufactures and develops the Ais (Advanced Ionospheric Sounder), a radar operating in the HF-band which is capable of measuring the main ionospheric parameters (such as the height of the different layers and their respective densities) and, through its own specific “Autoscala” software, automatically derives the local electronic density profile in real time.

Therefore, an interdisciplinary team made up of researchers, engineers, physicists, geologists and commercial profiles is working to mitigate the effects of such phenomena and develop customized solutions for different ground-based markets, by turning a highly scientific activity into a commercial product. A key role has been played by building a wide network of industrial relationships, not only on a national scale, by a privileged relationship with the world of science and, last but not least, by the essential support received from institutions, including the Asi. All this has allowed to conduct the necessary activities to enhance the degree of technological maturity of products, a key step to increase their commercial potential.

The products made by SpacEarth have a strong international projection; in fact, there’s an ongoing relationship with the Asian markets, including Vietnam, and Latin American countries, also because the impacts of solar variability are higher for specific latitudes. Exactly how ground-based weather forecasts have become common use services, due to the increasingly higher pervasiveness in the use of space-derived data in the field of terrestrial Spacearth economy, space weather will be destined to technology become a strategic domain also for the future ROME commercial developments.

Follow Spacearth technology’s page in the Italian Space Industry Online Catalogue, with updated contents and a link to the company’s official channels.

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Sun: it’s a matter of physics

by Giuseppe Nucera

The Italian contribution to the next solar physics mission Earth travels in the solar plasma, which, to all effects, is the most tenuous and external layer of the Sun’s atmosphere. Fed by the solar wind, its flow of particles can trigger dangerous geomagnetic storms, with important impacts on our planet, satellites and communication systems. Particles are ejected by the corona, the most external part of the solar atmosphere.

Understanding this region’s physical processes will be the goal of two future solar physics missions: the first one is the Nasa Multi-slit Solar Explorer (Muse); the second one is the Jaxa Solar-C (Euvst).

For both missions, Italy has proposed itself with an

important scientific and technological contribution.

In fact, the Italian skills play a key role on different fronts of such missions’ innovation, from the approach to the equipment.

One of the Sun’s biggest enigmas is the problem of coronal heating. The solar corona, made up of low-density plasma, has a temperature of one million degrees Celsius; the lowest layer, the photosphere, has a temperature of about 5600 °C, whereas the chromosphere, the middle layer, has a temperature of about 10000 °C. It’s a counterintuitive phenomenon, according to which the temperature increases the further away we get SPAZIO 2050 | 35

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from the solar surface. «In the first 500 kilometers, we observe a decrease in temperatures, but then we immediately observe a sudden increase – says Marco Stangalini, researcher in Solar Physics and program manager of the Solar-C and Solar Orbiter mission at the Asi -; in a few hundred kilometers, the plasma switches from a few thousand to over one million degrees Celsius. We suspect that significant plasma energization processes happen in this thin transition region».

It looks like the energy that heats the gas is coming from the Sun’s magnetic field, made up of different lines which act as rubber bands. In the photosphere, the gas of the plasma wraps such rubber bands, charging them with energy. When a line of the field breaks due to the excessive accumulation, it releases energy in the plasma: therefore, the solar atmosphere becomes unstable.

An interweave between circumscribed events, the release of energy, and large-scale phenomena in the magnetic fields and solar plasma, with a mutual influence.

The Sun’s magnetic field, made up of different lines which act as rubber bands.

«The magnetic structures can take up several thousand kilometers, whereas the release of energy happens on small scale. This is why we simultaneously need a large scale-sight and a detailed look», says Stangalini.

Muse and Solar-C will have to observe with very high timings. In fact, these releases happen in a matter of few seconds in the most external layers of the atmosphere. However, the energy is stored by the magnetic field across the whole atmospheric depth. From here comes the need for a 3D mapping of all the altitudes of the solar atmosphere.

«It is not enough to observe where the release of energy happens: in order to predict whether there are any areas of the field which will start a release, we must understand the energy storage process by following it over time and across all the spatial scales of interest», says Stangalini.

Therefore, in order to study the physical processes underlying the Sun’s dynamism, we move towards missions with a mix of performance: a high-resolution investigation for details; a high space coverage to observe large-scale areas; a broad-spectrum coverage to investigate in more wavelengths; finally, a high timing for observations, in a matter of few seconds.

A complex recipe, implemented by technology underlying Muse and Solar-C, the slit-grating spectrograph: a scanner capable of combining a broad visual field with a fine space sampling, by providing simultaneous information across a wide spectral range.

A small opening allows to investigate a section of the Sun’s atmosphere in different wavelengths. However, 36 | SPAZIO 2050

This image of the Sun’s magnetic field, taken thanks to computer models by the scientists of the Nasa Solar Dynamic Observatory (SDO), clearly shows the concentration of lines which make up the Sun’s magnetic field, whose activities influence the Sun’s dynamism.

Credits: Nasa/ GSFC/Solar Dynamics Observatory

by doing so we must move the opening each time during the investigation stage, to cover broader areas. It takes some time to complete this movement, and there is the risk to miss a few moments of the observed phenomenon. The solution adopted by Muse is a grid of 37 slits, which simultaneously scan 37 sections of the solar surface and are subsequently stitched together, like a puzzle. Each slit will provide information on the different levels of the observed region, like a scanner which is capable of analyzing the ink, quality of paper and type of tabletop for each sheet of solar atmosphere.

«This technique allows us to obtain a spectral bidimensional information, but with smaller timescales than those of the Sun’s intrinsic dynamism: this means that we’re able to freeze the solar atmosphere’s evolution processes and have a very high spectral resolution, but across large fields of view», says Stangalini.

An alternative technique is the spectral imaging, used by the Esa/Nasa Solar Orbiter mission. In this case, we use filters that are set only on a small portion of the bright spectrum: the 3D photograph of the solar at-

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fic community, thanks to its multidisciplinary skills.

«The smaller the wavelength is, the more light is suffering from the asperities and roughness of the optics.

Like a small wheel on a rough road, which, unlike the wheel of a tractor, perceives every perturbation.», says Stangalini.

Furthermore, the interweave of skills has enabled the national scientific community to propose innovative technological solutions for Muse, such as the special types of filters, mirrors or coatings, that is the levels deposited on optics to increase their performance.

«These solutions are the result of the skills acquired

by Italy in several fields of the astrophysics. As well as requiring very extreme realization capacities, they can positively affect the performance of the whole tool», says Stangalini.

Following the investigation stage, we need the contribution of modeling. In fact, after detecting each wavelength, the latter must be associated to its original atmospheric altitude; to do so, and to interpret what we observe in images, we must use complex realistic models of the solar atmosphere.

Also in this field, the Italian scientific community participates with an important contribution to the Muse and Solar-C missions.

mosphere is obtained by overlapping several images, each of them obtained in just a wavelength. In the case of Solar-C, the slit is provided by the contribution of the Italian scientific community, thanks to which the Japanese mission will be able to simultaneously investigate the Sun’s atmosphere at different altitudes.

«Each wavelength of the solar radiation is formed at different altitudes of the solar atmosphere. Therefore, to explore different spectral ranges means to move to different solar altitudes: by observing simultaneously in the infrared and in the ultraviolet, we are investigating a phenomenon along the different atmospheric altitudes. This is why we tend to increase the spectral coverage of solar physics missions», says Stangalini.

A depth capacity which implies the availability of mirrors and their respective filters, characterized by a perfect sanding, with a very small intrinsic roughness.

This is to limit the perturbations that any superficial asperities may cause in the observation of light with such small spectral lines. Also in this case, the solution to Muse and Solar-C is provided by the Italian scienti-

The Esa Proba-3 demonstrative mission.

Expected to start in 2023, it will field-test a technology to increase the corona and magnetic field’s investigation region.

The Italian expertise in the field of solar physics will be also aboard the Esa Proba-3 demonstrative mission. Expected to start in 2023, it will field-test a technology to increase the corona and magnetic field’s investigation region. Italy will provide four sensors and, along with the Asi, is the third contributor to the mission. Proba-3 is based on the formation flight of two satellites: the Aspiics coronagraph and its occulting disk, which is 150 meters away. Compared to the traditional coronagraphs, whose disk is one meter away, Proba-3 will reduce the occulted region from 3 to approximately 1 solar rays. The four sensors manufactured by the INAF, the Shadow Position Sensors, will assess whether the front disk is in a correct position, by monitoring its shadow on the coronagraph or whether lighting is unbalanced. An essential Italian technology for tandem flights in future solar missions.

Therefore, Italy is a protagonist of the evolution of solar physics, with a strong contribution from the INAF, CNR and some Italian universities, such as Padua and Palermo. Lastly, the coordination role played by the Italian Space Agency is essential to connect the different wealth of knowledge.

«Each community has different background and expertise and the Asi has the task of putting these transversal skills together, to create innovation and open a new way of solar physics», concludes Stangalini.

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Aspis, A new prototype of scientific dAtA centre, tArgeted At the study of spAce weAther

by Giuseppe Nucera

The Italian scientific community has been very active for several years to study space weather, that is the influence of the Sun’s activity on our planet and the other celestial bodies of the Solar System, and the respective implications on the protection of our space assets.

Along with the monitoring of debris and Near Earth Objects, space weather is one of the three pillars of safety in the space environment, of the activities conducted over there and of what depends on those activities on Earth, from navigation to telecommunications.

The science of space weather is characterized by a strong interdisciplinarity, where several scientific sectors and subjects share their skills. In fact, the interdisciplinary approach is essential to understand the nature of the phenomena which guide the Sun-Earth interaction and effectively face the issue of space weather prediction and the definition of any countermeasures.

In such context, of diversification and opportunities at the same time, the partnership between the Asi and the Inaf led in 2021 to the Aspis (Asi Space Weather Infrastructure) tender, aimed at developing the prototype of a national data collection and processing centre for space weather. In Greek, Aspis means “shield” (ασπίς); in fact, it’s the analysis and modelling of data which provide the necessary solid foundation to develop dedicated systems for the protection from 38 | SPAZIO 2050

technological and biological impacts of space weather. The name of the winning proposal is Caesar, a project started in 2022 which involves over 80 scientists from 11 universities and research bodies of all Italy. The two-year objective will be to populate the prototype of the single database, named Aspis, which will collect data provided by tools with the participation of Italy, as well as software and models developed

by Italian researchers.

«The nature itself of the researches targeted at space weather presents a degree of scientific interdisciplinarity and a mutual enhancement between operational and scientific aspects which can hardly be observed elsewhere», says Christina Plainaki, researcher in Solar System Sciences at the Asi and project scientist for Aspis. «What will be implemented within Aspis will range from heliophysics, to the physics of plasmas, planetary sciences, stellar astrophysics and terrestrial aeronomy. It will offer a landscape which will really be capable of providing stimuli to several different communities. Over the years, we’ve been focusing – through Aspis – on such scientific aspects», continues Plainaki.

«Today, researchers spend most of their time to reduce data, that is to treat such data based on the technology that has produced them, before being able to compare them with other data», explains Giuseppe Sindoni from the Asi, a project manager for Aspis.

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have a multilevel look at solar phenomena, switching from chromosphere to the highly energetic events beyond the solar corona, until reaching the interaction with celestial bodies like Earth.

«Each event has a cause which generates it, but it is not certain that cause and effect can be observed with the same tool or at the same time. Aspis will use several data and models to describe different stages of the same phenomenon», says Sindoni.

«We want to facilitate this stage of analysis, so that we can provide data which can be immediately used, interpreted and compared, and maximize their scientific return», adds Sindoni.

The main goal of Aspis will be to ensure a simple and effective access to multidisciplinary data on space weather and, at the same time, provide different kinds of information, such as images, spectra and flows, for different research topics. Therefore, we’ll be able to

Solar eruption (Credits: Nasa/ Sdo).

«We believe that new and important partnership opportunities between the Asi, research bodies and universities will arise from the principle of the spread of skills and the meeting of different expertise within Aspis», adds Plainaki. «Aspis represents an important systematic effort to analyze the obtained data and the modelling related to space weather».

Aspis wants to be a first step towards the next prediction tools which, in the future, can make an early estimate of the entity and evolution of solar particles flows, thanks to the monitoring of a few precursory signs. A frontier which will allow to develop adequate protections for satellite technologies and radioprotection for human exploration of space.

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Identikit of the space weather

by Mirko Piersanti Researcher of the Department of Physics, University of L’Aquila «For now, it’s enough to have shown that spots are neither stars nor consistent materials, and aren’t located far from the Sun but are produced around it, with a material which is not unlike that of clouds or other haziness around Earth». So reads Galileo Galilei’s first letter to Mark Welser, duumvir of Augsburg and member of the Academy of the Lynxes, written in 1612. Galilei was the first one to observe how our star, the Sun, wasn’t a perfect and homogeneous sphere, but was covered with dark spots, which were later named solar spots. Today, we know that solar spots are the Sun’s magnetically active regions, and represent the main risk source of what are commonly named solar storms. Based on the theory which, still today, is the most accepted one, solar spots are generated by very intense magnetic fluxes, which get out of the solar surface once the fluxes themselves twist on top of each other due to the differential rotation of the Sun’s magnetic field. In fact, the Sun has an extremely weak magnetic field with an unstable axis, which migrates from the poles to the equator, and then to the poles again, with an opposite orientation, in a period of approximately 22 years.

Solar activity is measured based on the number of solar spots which can be found on the photosphere. The average number of solar spots is not steady, but varies between periods of maximum and minimum. The solar cycle is the period, lasting 11 years on average, between a period of minimum – or maximum – of solar activity and the following one.

In general, the Sun constantly emits a fully ionized, highly conductive and globally neutral flow of gas, known as plasma, which is essentially made up of protons and electrons and is called solar wind (Sw). The dynamics of the solar wind are described by Parker’s theory, formulated in 1957, according to which the coronal plasma is so warm that can escape solar gravity. In its motion, the solar wind drags behind the Sun’s magnetic field and originates the interplanetary magnetic field (Imf). Since the solar wind is emitted in all directions, its path, due to the solar rotation, is spiral-shaped and is known as Parker spiral. The phenomenon is similar to what happens to the irrigator of a garden, which sprays water by rotating on itself and let water follow a spiral-shaped path.

As well as the Sw, the Sun can impulsively emit from its active regions huge amounts of energy, both electromagnetic, such as solar flares, and particle energy, such as the coronal mass ejections, known as Cmes in the 40 | SPAZIO 2050

The Sun constantly emits a fully ionized, highly conductive and globally neutral flow of gas, known as plasma, which is essentially made up of protons and electrons and is called solar wind (Sw).

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jargon. When one of such emissions hits Earth, it may lead, in particular conditions, to a geomagnetic storm.

Earth owns an internal magnetic field, the so-called geomagnetic field, which on a first approximation can be regarded as dipolar. As a matter of fact, the interaction with the solar wind changes its topology; by compressing field lines in the solar direction and extending them, it creates an actual tail in the anti-solar direction. This new configuration is called terrestrial magnetosphere.

In general, the magnetosphere doesn’t allow the access to the particles carried by the solar wind. In fact, by behaving as a stone in a river, the magnetosphere acts as an obstacle against the solar wind which flows around its external surface, rather than reaching our planet’s atmosphere or surface. This allows to have a stable planetary atmosphere over time, laying the foundations for the creation of complex biological life.

However, during a Cme, the magnetospheric field can be weakened, and can allow solar particles to reach the most external part of the terrestrial atmosphere, the ionosphere. The interaction between the latter and the particles carried by the Sw originates one of the most romantic and wonderful phenomena on Earth: polar lights. These conditions develop when the magnetic field carried by the solar wind has the same intensity and direction, but goes in the opposite way compared to the terrestrial one.

Then, the two magnetic fields neutralize each other and cause the geomagnetic field to decrease, generating the so-called geomagnetic storm.

The timescales of a geomagnetic storm may range from a few hours to whole days, depending on the spatial scales of the solar perturbation. In general, what is observed on Earth is an initial depression of the geomagnetic field due to the increase in loop current, known as the main stage, and a subsequent and slow return to the pre-storm situation, known as the recovery stage, where the solar plasma is slowly ejected from the geomagnetic tail. During the main stage, as well as the decrease of the field, we can also observe at a high latitude the wonderful phenomena known as polar lights. They are caused by the reconnected magnetic flux in the sub-solar region, which is carried towards the geomagnetic tail by the plasma which flows in the magnetosphere’s polar regions, intensifying the field of the geomagnetic tail. The latter discharges its energy through the system of currents aligned with the field, introduces plasma in the ionosphere, the auroral oval, and originates polar lights. During this process, very intense electric currents, known as auroral electrojet, are generated in the ionosphere. In general, the geographical position of the auroral oval is confined in the polar regions. However, the occurrence of a geomagnetic storm can cause the oval auroral to go down to lower latitudes, until reaching, in extreme cases, a latitude of 40°.

The impact that these events may have on our society is mostly of technological nature, even if we can’t overlook some biological effects for the crews of flights with polar routes and for the astronauts on the International Space Station. In fact, the very intense ionospheric currents created during a geomagnetic storm induce, in turn, very intense currents in the subsoil, the so-called Gics. Gics can interact with the national electric networks, causing blackouts which may also last a few hours. Furthermore, all satellite navigation and telecommunication services may suffer inconveniences, whose duration would range from several minutes to several house; this may cause delays/cancellations of flights and issues related with both road and sea transport. Finally, we can’t exclude the possibility of several orbiting satellites suffering transient anomalies or being permanently damaged.

Lastly, the biological risk is strictly related to solar flares. These solar rays are numerous and energetic enough to cross the 2-3 millimeters of SPAZIO 2050 | 41

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wall from the shuttle. Because of this, in case of a solar flare, the astronauts on the Iss take shelter in an area where an artificial magnetic field is used to shield its effect.

These are the reasons why the science of the space weather, that is the science of space weather forecasts, was born in the last 30 years. It deals with trying to predict the arrival on Earth and the potential effects of a solar flare. At the moment, the best results in terms of lead-time range from 1 to 2 hours before, despite the fact that the solar event can be observed at least 2 days in advance.

The science of space weather forecasts try to predict the arrival on Earth and the potential effects of a solar flare.

Overall, the socioeconomic damage of a single extreme space weather event was estimated at up to 15 billion euros, only in Europe, in 2016, in the study contracted by the Esa. This means that accurate and timely space weather services are very important to mitigate impacts and reduce the related socioeconomic costs. Because of this, the Esa will launch this year, along with the European Commission, a new study to analyze by 2024 the potential impact of space weather events on the European economy and infrastructures and estimate the related socioeconomic costs.

The Asi is also moving in this direction. On the one hand, it has created the Aspis (Asi Space Weather InfraStructure), which aims at developing a scientific data centre which will host all the Italian models and databases related to the space weather. This is the first Italian step towards future implementations of forecast models and services for space weather conditions. On the other hand, the Asi is an integral part of the Cses (China Seismo-Electromagnetic Satellite) satellite mission. The Cses constellation – the first satellite has been flying since February 2018 and the second one is expected by mid-2023 – is in charge of monitoring the dynamics of the electromagnetic field, the plasma and the energetic particles in the ionosphere. The Asi is responsible for two of the nine payloads aboard the satellites: the high-energy particle detector, in partnership with the Infn, and the electric field detector, in partnership with the Inaf-Iaps.

Space weaTher, under Special Surveillance

by Mauro Messerotti Senior advisor for Space Weather, Inaf Scientific Directorate Professor of Space Weather and Climatology, Department of Physics, University of Trieste

Safety in space for technological systems and human beings requires a continuous activity to monitor and predict the phenomena which may endanger their integrity during space storms. The main source in our solar system is a star, the Sun. Solar activity is determined by the presence of sunspots in the Sun’s photosphere, which are unstable sources of concentrated magnetic energy, impulsively released in solar 42 | SPAZIO 2050

flares. Space is then irradiated by intense flashes of electromagnetic radiation (gamma, X-ray, extreme ultraviolet, radio) and is crossed by flows of accelerated, high-energy flows of electrons and protons, the so-called Seps (Solar Energetic Particles), and huge bobbles of high temperature magnetized gas, the so-called Coronal Mass Ejections (Cmes). Such emissions involve Earth and all the other planets of the So-

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lar System, and cause malfunctioning of space vehicles and the absorption of dangerous doses of ionizing radiations for astronauts but also for the cross-polar airline traffic on Earth, interfering in the propagation of radio waves in the terrestrial ionosphere and leading to interruptions of the distribution of electric energy.

In order to mitigate the harmful effects of space storms, it is therefore required to arrange a complex system, based on the combined action of three complementary activities in the field of space weather. The first one is the continuous, real-time monitoring of sources and phenomena both from Earth and from space, since the terrestrial atmosphere blocks radiations at different wavelengths. The second one is scientific research, which provides the scientific models of such phenomena; finally, we have prediction operations, based on scientific models which are validated as operational – it can take several years of work for this process, represented by the close Research-Operations-Research connection, known in the jargon as R2o2R – and are used by final users, be it the general public or satellite operators).

It is evident how the manufacturing of a system of this kind requires an infrastructure of observational assets from Earth and space, a seamless collaboration in the field of scientific research and an infrastructure centre for space weather, which uses in a coordinated manner all the available operational resources to conduct the short- (space weather) and medium-term (space climate) monitoring and prediction of pheno-

mena. This kind of system is necessarily distributed among the different academic, industrial and military research contexts of a country.

The European Space Agency has created a Space Situational Awareness (Ssa) system for space weather, to which several European countries, including Italy, contribute with specific services. In the United States, the Noaa (National Oceanic and Atmospheric Administration) manages the Space Weather Prediction Center in partnership with the Nasa and the Air Force (Usaf).

Italy has started to develop a national space weather service, both for civil and military use. The kick-off has been given by the Italian Space Agency, which coordinated the different Italian stakeholders, such as the Inaf, Ingv, Cnr, Infn, universities and industries, in a working table. The Inaf is currently working on the first step of a scientific data archive for space weather at the Asi, named Aspis and known as Caesar (Comprehensive space wEather Studies for the ASPIS prototype Realization).

The Sun-Earth system and the monitored space weather domains (Credits: Nasa, M. Messerotti)

Therefore, a cooperation agreement has been signed between the Italian Air Force, the Inaf and the Ingv, and will be extended to the Asi, for the implementation of the national monitoring and prediction system. The Inaf owns a network of ground-based assets for the solar and heliospheric weather, the Ingv is a reality of excellence for ionosphere weather, the Italian Air Force offers a space weather service for military purposes.

The Asi will significantly expand such skills thanks to its infrastructures and the experience acquired in the Ssa/Sst (Space Surveillance and Tracking) field.

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The Sun is a source of life. A necessary, but also dangerous presence. An expression of nature, which implies the logic of a balance compensating for the strength of creation and destruction.

The space weather, this complex and relatively young subject, studies the influence of the solar activity on the whole Solar System, as well as dealing with the Sun – Earth relationships to prevent any inconveniences on our planet. The interstellar plasma, which can be found in the Milky Way and beyond, complicates the conditions of space weather, which is not determined only by our star.

What’s the Weather like… in the Solar SyStem?

by Barbara Ranghelli

Polar light at Saturn’s North Pole – Cassini – Credits: Esa/Nasa Uranus’ rings and polar lights, filmed by Voyager 2 and Hubble – Credits: Nasa/Esa Hubble Jupiter’s polar lights – Chandra – Credits: Nasa

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The charged particles, magnetic fields and electromagnetic radiations emitted by the Sun occupy an area which includes all the planets orbiting around it, in a sort of bubble called heliosphere. We don’t know exactly how far it extends and what is its shape, but there are a few models generated by the work of space probes such as the Voyager 1 and 2, which have been travelling for 45 years: what is certain is the fact that, in turn, the heliosphere protects us from cosmic us. In fact, some phenomena with a very high energy level are generated in our galaxy, but also in external galaxies. Just think of the supernova emissions, the gamma-ray flashes or the powerful magnetic fields of the quasars.

So, how do celestial bodies defend themselves within the heliosphere? The protective shields par excellence are the magnetic field, the atmosphere and, sometimes, it’s the planet’s mass itself which shelters its satellites from the solar wind; the latter hits the surface of each planet, satellite, asteroid or comet, which reacts differently based on its composition and distance from the Sun. For example, we encounter polar lights, the most fascinating expression produced by the solar wind, on almost all planets, even though with different manifestations.

Let’s start with Mercury, the closest object to the Sun. It doesn’t have an atmosphere, but has a magnetic field: the solar particles, which are canalized through it, hit its surface, extracting gas from the subsoil and creating auroras without lights and sound, in the polar areas. During the coronal mass ejections, instead, the magnetic field is not effective, because its proximity to the Sun has eroded its outer crust over time, and the loss of volatiles substances will reduce it until it disappears. But because of this proximity, who better than Mercury can provide us with information on the influence of our star? After the Nasa Mariner 10 and Messenger missions, now the European Space Agency (Esa) and Japanese Space Agency (Jaxa) Bepi Colombo probe is investigating the evolution of the planet. It was launched in 2018, it completed its second fly-by a few days ago and will enter Mercury’s orbit in 2025. Over a third of the tools of one of the two satellites aboard the shuttle are Italian: Serena (Search for Exosphere Refilling and Emitted Neutral Abundances), Isa (Italian Spring Accelerometer), Simbio-Sys (spectrometers and image recorders) and More (Mercury Orbiter Radio science Experiment).

Then there is Venus, which doesn’t have a magnetic field, but has a very dense atmosphere which protects the surface from solar particles and, subsequently, from erosion, but doesn’t protect it from overheating. The interaction between the solar wind and the atmosphere creates very complex dynamics, which are object of study.

Earth, instead, has an intense magnetic field, which can’t be outdone by coronal mass ejections either; the geometrical configuration of the magnetosphere allows the solar field to collide with the atmosphere and release energy in the form of visible light; this phenomenon gives rise to polar lights with different frequencies, which create extraordinary lights and, sometimes, also sounds. Therefore, Earth would be capable of mitigating the effects of the solar activity, since it has been able to find a kind of balance with our star. This balance has been threatened by man, who-

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Heliosphere and Solar System.

Mercury as observed by Bepi Colombo – Second flyby – Credits: Esa/Jaxa.

se activities have triggered a critical increase in the global average temperature on the planet’s surface.

Mars, the fourth closest planet to the Sun, is helpless.

It looks like it has lost its magnetic field over time, and the Sun will gradually consume its atmosphere, which is already rarefied. The solar wind will continue to take away material from the planet, advancing its erosion process.

Beyond the asteroid belt, and subsequently on the outer planets, the gaseous ones, the interaction with the solar wind is more complex. As well as the dense atmospheres, also satellites come into play; along with the Sun, they participate in the dynamics of their

earth would be capable of mitigating the effects of the solar activity, since it has been able to find a kind of balance with our star.

mother planet, and vice versa. For example, the Italian Jiram (Jovian Infrared Auroral Mapper) spectrometer, mounted on the Nasa Juno probe, has discovered that Jupiter’s polar lights aren’t originated by the solar plasma, but by the particles ejected by the volcanic activity of Io, one of the four largest moons of the planet, visible from Earth.

We know less about Saturn, Uranus and Neptune due to their distance. However, the Nasa, Esa and Asi Voyager and Cassini-Huygens probes, and sometimes also the Hubble telescope, have detected on these far planets the presence of polar lights, each of them with peculiar characteristics, following the impact of a swarm of solar wind particles.

We’ve observed how the space weather transforms the celestial bodies of the Solar System; each of them reacts based on its status, because of this it’s important to understand the origin of phenomena, such as mitigating their consequences or preventing them.

Last February, the Esa announced the name of a future mission which is entirely devoted to space weather forecasts: Vigil. These are two shuttles, whose launch isn’t expected before 2025, which will be placed in the Lagrange 1 and 5 gravitational balance points. Meanwhile, to make news about Mercury, the “messenger of gods”, more usable, Bepit has been set up. It’s the pseudonym chosen by a group of researchers, which is in charge of the scientific dissemination of the Italian tools aboard the Bepi Colombo mission.

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The book Unraveling the dark side of the sUn

by Paolo D’Angelo

The fact that our life depends on the Sun is old news.

Without our star, there wouldn’t be any form of life on the whole Earth planet. However, the Sun wasn’t a key point for space exploration, at least not at the beginning of the space adventure. Just a few probes, mainly from the U.S., studied its physics and dynamics between 1959 and 1968. Scientists were curious also back then, but their curiosity clashed with the technical difficulty of developing missions which could get closer and closer to the Sun to collect further data.

Compared to then, things have definitely improved today, particularly from a technological standpoint.

In fact, for slightly over 30 years, our star has been placed at the centre of the scientific interest of every space agency in the world. Paolo Ferri, a graduate in Theoretical Physics at the University of Pavia, who’s been working for as many as 37 years at the control centre of the European Space Agency in Darmstadt, Germany, tells us the story of how we explored and how we are exploring the Sun. Since the beginning, Ferri took part in the huge scientific and technological effort to send increasingly sophisticated space probes for increasingly ambitious missions. Starting from Ulysses, released in 1990 from the Space Shuttle, Soho, launched in 1995, and Cluster, a constellation of 4 satellites launched in 2000, and then daring to get closer and closer to the Sun, with Venus Express, launched in 2005 towards Venus, first, then with BepiColombo, aimed at studying the planet Mercury, where it will arrive in 2025, and lastly with the Solar Orbiter, the most ambitious mission ever conceived to closely study our star. From 2006 to 2013, he was in charge of the mission operations of solar and planetary probes, whereas from 2013 to 2020 he was responsible for all the Esa robotic space missions.

All these adventures, that he lived as a protagonist, are mentioned in the book, but what transpires is a strong humility in narrating them. This is a book that could have only been written by him, where Ferri nar46 | SPAZIO 2050

how we explored and how we are exploring the most important star for our survival

title: Il lato oscuro del Sole – L’esplorazione spaziale della nostra stella author: Paolo Ferri Publishing house: Editori Laterza Year of edition: 2022 Price: 20 euros

rates, as well as his career, how he faced the technological and human challenges and the thousand difficulties he encountered. A couple of them stand over the other: giving a trajectory to the Ulysses probe to take it to Jupiter first, and then, using a gravitational assist, catapulting it towards the Sun’s poles. A notbad-at-all pool game. Likewise curious is the story of his disappointment when he saw the European Ariane 5 carrier rocket exploding during its opening flight in 1996, with the four Cluster probes, designed to study the Sun, aboard. A strong disappointment, but also a lot of determination to make the program revive, with the initial manufacturing of just a new probe due to economic issues, and then the joy to see the willingness by several scientists and politicians to manufacture three more probes, in order to redesign the project as it had originally been conceived. Such probes were then successfully launched in June 2000 from Baikonur, with a Russian Soyuz carrier rocket. A very good book, conceived for a wide audience, which however lacks the index of names: we would have liked the individual projects or persons mentioned throughout the volume to be listed in alphabetical order in the final pages. Anyway, this is definitely a venial sin, given the type of work.