Stefan Frey

• Doctor of Philosophy
• PhD Student at Politecnico di Milano

This paper presents a framework for integrating Low-Earth Orbit (LEO) platforms with Non-Terrestrial Networks (NTNs) in the emerging 6G communication landscape. Our work applies the Mega-Constellation Services in Space (MCSS) paradigm, leveraging LEO mega-constellations’ expansive coverage and capacity, designed initially for terrestrial devices, t...

Satellite missions demand ever greater connectivity, especially in the LEO regime. In this paper, we introduce the new mega-constellation services in space paradigm: we show that mega-constellations, deployed to offer innovative services to Earth’s users, can provide excellent connectivity to LEO spacecrafts, too. First, we characterise the communi...

In the context of space sustainability and space traffic coordination and management, it is important to define an internationally recognised and accepted approach to measure the Space capacity, defined as the quantity and type of missions/objects that the Space environment can sustain. In parallel to the study on how the capacity can be measured,...

Mega-constellations are being deployed to offer innovative services to Earth's users. Our work shows how they can provide seamless connectivity to LEO spacecrafts too, and transform them into highly responsive nodes of a space-to-space network characterized by high throughput, low latency, and low cost. For realizing the new mega-constellation serv...

Mega-constellations are being deployed to offer innovative services to Earth's users. Our work shows how they can provide seamless connectivity to LEO spacecrafts too, and transform them into highly responsive nodes of a space-to-space network characterized by high throughput, low latency, and low cost. For realizing the new mega-constellation serv...

Mega-constellations are being deployed to offer innovative services to Earth’s users. Our work shows how they can provide seamless connectivity to LEO spacecrafts, too, and transform them into highly responsive space network nodes, thus enabling a myriad of innovative applications. For realizing the new mega-constellation services in space paradigm...

It is estimated that almost one million debris greater than 1 cm currently orbit the Earth, posing hazard to operational satellites. Therefore, the traditional piece-by-piece approach, to monitor the evolution of such small space debris, is computationally prohibitive. This problem is here addressed through an analogy with fluid dynamics, consideri...

Space, like any other ecosystem, has a finite capacity. The continuous growth of space activities is contributing to overload this delicate ecosystem. In this paper, the THEMIS software tool will be presented, conceived to assess the impact of a space mission on the space environment and its contribution to the overall Space capacity. THEMIS is dev...

Everyday thousands of meteoroids enter the Earth's atmosphere. The vast majority burn up harmlessly during the descent, but the larger objects survive, occasionally experiencing intense fragmentation events, and reach the ground. These events can pose a threat for a village or a small city; therefore, models of asteroid fragmentation, along with ac...

Everyday thousands of meteoroids enter the Earth's atmosphere. The vast majority burn up harmlessly during the descent, but the larger objects survive, occasionally experiencing intense fragmentation events, and reach the ground. These events can pose a non-negligible threat for a village or a small city; therefore, models of asteroid fragmentation...

In this paper we will present the design of a software to assess the impact of a space mission on the space environment and its contribution to the space overall capacity developed within an ESA-funded study by Politecnico di Milano and Deimos Space. The aim of this project is to create an open software platform for the evaluation of the impact of...

Fragmentation clouds from explosions or collision of payloads and rocket bodies in space pose a threat to objects in Earth orbit. Most of the fragments are too small to be tracked and can only be accounted for statistically. Here, a framework for the fully statistical treatment of a fragmentation cloud, its evolution and ramifications, without the...

The study of the fragmentation of meteorites entering the Earth's atmosphere allow to predict the consequences such events can have on the ground. Existing models for meteoroid fragmentation follow either a pancake approach, where the cloud of fragments resulting from the meteorite explosion expands together in the shape of a disk, or a discrete fr...

The Starling suite estimates the non-linear evolution of densities in orbit. These densities can be probability density functions describing uncertainties about states or distributions of particle clouds modeled as continua. In this work, the Starling suite is applied to satellite fragmentations in a circular as well as highly eccentric orbit aroun...

Numerical integration of orbit trajectories for a large number of initial conditions and for long time spans is computationally expensive. Semi-analytical methods were developed to reduce the computational burden. An elegant and widely used method of semi-analytically integrating trajectories of objects subject to atmospheric drag was proposed by K...

Numerical integration of orbit trajectories for a large number of initial conditions and for long time spans is computationally expensive. Semi-analytical methods were developed to reduce the computational burden. An elegant and widely used method of semi-analytically integrating trajectories of objects subject to atmospheric drag was proposed by K...

To calculate the effects of on-orbit fragmentations on current or future space missions , accurate estimates of the fragment density and its time evolution are required. Current operational tools estimate the risks involved through representative objects. Such tools, however, cannot accurately estimate the fragment density at any point in space and...

A considerable number of fragments orbit around the Earth in Highly Eccentric Orbits (HEOs), mainly in the geostationary transfer orbit. These are believed to have originated in part from the 100 plus fragmen-tations of parent objects in the same orbit. Many of these objects are characterised by a high area-to-mass ratio, and, as such, especially s...

Many historical on-orbit satellite fragmentations occurred in Highly Eccentric Orbits (HEOs) such as the Geostationary Transfer Orbit (GTO). Such fragmentations produce fragment clouds that interfere with the Low Earth Orbit (LEO) environment and pose a threat to operational satellites. Objects in HEO undergo complex dynamics due to the influence o...

The Inter-Agency Space Debris Coordination Committee (IADC) Space Debris Mitigation Guidelines, issued in 2002 and revised in 2007, address the post mission disposal of objects in orbit. After their mission, objects crossing the Low Earth Orbit (LEO) should have a remaining lifetime in orbit not exceeding 25 years. Objects near the Geostationary Or...

To counter an ever increasing number of man-made objects orbiting Earth which are endangering current and future space missions, the Space Debris Mitigation (SDM) guidelines, issued by the Inter-Agency Space Debris Coordination Committee (IADC), were first published in 2002. These guidelines were a model for various international and national stand...