THE six mysterious objects are a few steps away from us, protected in a sterile room, and we observe them through a glass. They are made up of three small overlapping cubes of 10×10 centimetres and they weigh just over 5 kilos each. Seeing them, you wouldn’t think they could fly 500 kilometers above our headsand recover data important to the basic physics of the universe. Yet it is precisely this the objective of the Hermes project (High Energy Rapid Modular Ensemble of Satellites), a space mission developed in collaboration between Inaf (National Institute of Astrophysics) and Polytechnic of Milanfinanced by the European Commission and the ASI (Italian Space Agency).
For the scientific part, under the responsibility of the Trieste Observatory, the centers of Rome and Bologna are involved together with the University of Cagliari. The Milanese university deserves credit for having developed small satellites completely in-house for the first time, both for the hardware and software parts.
Scientific responsible for the technological part, and therefore for this important result, is Michèle Lavagna, 57 years old, professor of Flight Mechanics and professor of Design of missions and space systems. Pupil, or rather heir, of Amalia Ercoli Finzi, always passionate about flight, Professor Lavagna welcomes us in her bright studio at the Polytechnic of Milan, to lead us on a fascinating virtual journey into deep space, that is, beyond the atmosphere, thanks to these satellites as big as one and a half liter soda bottles.
Hermes, new scenarios on the study of the universe
What is Hermes for?
The project was born from a group of astrophysicists who study the universe and its high-energy radiation, i.e. X-rays and gamma rays, the shortest wavelengths of the electromagnetic spectrum. When there is a collision of stars in deep space, beyond the atmosphere, energies are released which we can capture thanks to the waves that are generated. From there we can trace what caused them and study the basic physics of the universe linked to the theory of relativity, and therefore the space-time relationship. But other scenarios also open up on the study of the universe and its formation: Why do cosmic explosions happen? What do these clashes produce? From the technological point of view that most closely concerns us at the Polytechnic of Milan, measurement is not new, it is already done. The news is something else.
Michèle Lavagna, 57 years old, professor at the Polytechnic of Milan, with the six small satellites created by her team. Photo by Giovanni Hänninen
The Polytechnic University of Milan would like to reach a constellation of 15 satellites
Which?
The fact that not just one satellite is launched into orbit but six, three plus three: we don’t just pick up the signal but we localize the position of the event on the celestial vault, through triangulation. A bit like the GNSS-Galileo and GPS satellite navigation system but in reverse, because in that case the signal is sent towards the ground, while we look at the sky. Our constellation can communicate the coordinates of the event to Earth telescopes or other more powerful satellites, which can quickly orient themselves towards the point where the explosion occurred before it fades. This communication is not easy, because the satellite must be able to see the Earth antenna below and, due to the Earth’s rotation and the movement of the satellite in its orbit, there must be perfect synchrony. Since cosmic explosions are not predictable, satellites must be able to observe the entire celestial vault and at the same time always be in contact with a communication channel. From when the signal arrives, the data must pass to the other instruments in 15-20 minutes .
How many satellites does Hermes have?
Multiples of three are needed. Today there are six, we at the Polytechnic of Milan would like to reach a constellation of at least 15. The first three were built thanks to a tender from the European Commission. The other three thanks to a contribution from ASI, through a project of the Ministry of University and Research.
Were there already satellites this small?
Not so performing. Each is made up of three 10 cm cubes which contain the electronic boards, the scientific instrument and the control systems. For outdoor pointing, two fins house the solar cells. In the dark, operation is guaranteed by batteries as large as radio batteries. They fly 500 km from Earth.
Why are you launching them from California?
We will launch them from Space Force Base Vandenberg via Space X’s Falcon 9 rocket, because the frequency of launch availability and costs are not comparable with the current offering on the European market. The launch is expected in March, in one fell swoop. We are very excited.
Michèle Lavagna: «The credit goes to the guys on my Astra team»
How many people work on the project?
For the Polytechnic part, 25-30. If we managed to build these latest generation satellites at home it is thanks to the guys in my Astra work group, who made it possible day, night and weekends, with competence, passion, desire to learn and the right stubbornness. . This work requires collaboration. Now, with the skills gained, the doors are opened to other projects.
For example?
Making water from the sand on the Moon. We have already succeeded, thanks to a prototype and sand that simulates that of the lunar surface.
To return to the satellites: there aren’t too many of them, and what happens to them when they turn off?
It is true that the brightness of some satellites has influenced the activities of Earth telescopes. But, for example, the second generation of Starlink has reduced the problem by using less reflective materials. The issue is delicate, but we citizens are the first to complain when the internet is down, especially for useful services such as localization, telemedicine or teaching at a distance. Today there are rules: you cannot launch a satellite into space without certifying that you are able to remove it within five years of shutting down: either it will have to move into deep space, or it will be destroyed by friction with the atmosphere. There is a line of research on the sustainability of space, on decommissionable or recyclable materials and the development of garbage robots to move dead satellites into landfill areas or make them operational again.
The charm of the celestial vault
Elon Musk says the first manned trips to Mars will be in four years. Realistic?
It seems risky to me. The problem is radiation, when we leave the Earth’s magnetosphere the effects on organic material – aging, genetic mutation – are accelerated and devastating. The technology to defend oneself exists in theory but the problem is not solved. The alternative is to travel very fast. But the Earth-Mars transfer can last up to six months, and you can only return every two years, because certain Earth-Mars alignment conditions are necessary. A more effective propulsion would be needed, but we are at the prototype stage. But if there is anyone who can accelerate technological development, it is Musk.
When did you fall in love with space?
I am a sailor and I have always been fascinated by the vault of heaven and observing the sky. I also come from a family of pilots, at 16 I got my pilot’s license for tourist planes. After classical high school I was undecided, I chose Engineering to apply the knowledge to real life. I started with Electronics, then moved to Aeronautics. At the time at the Polytechnic of Milan there was no degree course in Aerospace Engineering but only a course in Aerospace Mechanics held by Professor Amalia Ercoli Finzi. That was my turning point; I did my thesis and doctorate with her, a friendship was born. From there it was easy to take flight beyond the atmosphere.
She is considered the heir of Amalia Ercoli Finzi.
Amalia is Amalia, she certainly has a much greater caliber than mine. You created the first “spatial” course at the Polytechnic, which, again thanks to you, later became a master’s degree course.
Do you still go boating?
Certain! I sail in the Mediterranean but when I retire I will cross the Atlantic. I also go to the mountains with my partner, who is an enthusiast. As kids we went climbing and ski mountaineering, now we walk. I need to be in nature, respect it. Nature teaches us to be humble, we must know the boundaries not to be crossed. © ALL RIGHTS RESERVED
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