Enrico C. Lorenzini

University of Padua | UNIPD · Department of Industrial Engineering

Autonomous navigation is becoming an increasing area of interest, especially in the space sector. This is evident in the development of planetary exploration rovers, which rely heavily on terrain traversability capabilities to explore extraterrestrial terrains. This technology assesses the ability of a rover to identify potential obstacles of a giv...

More than half a century after pioneering theoretical works proposed their use in several space applications, about 26 missions with long orbiting conductors have been flown on suborbital and orbital flights. The analysis of this review work organized them based on type of tether (insulated or bare), type of cathode (hollow cathode, expellant-less...

Five electrodynamic tether simulators (BETsMA v2.0, DYNATETHER, EDTSim, FLEX, and TeMPEST) have been cross-verified by running and analysing simulations of increasing complexity. A set of ten simulations without any tether was run to test the orbital propagators and the implementation of the perturbation force due to the non-sphericity of the Earth...

To mitigate the growing problem of space debris, current international guidelines require spacecraft in low Earth orbit (LEO) to implement post-mission disposal strategies to be deorbited within 25 years from the end of their operative life. Electrodynamic tethers (EDTs) are an effective and promising option for deorbiting as they do not require fu...

According to current international guidelines introduced to mitigate the space debris problem, spacecraft in Low Earth Orbit (LEO) shall implement post-mission disposal strategies in order to be deorbited within 25 years from the end of their operative life. Among the proposed deorbiting technologies, electrodynamic tethers are an effective and pro...

In this work, we have analyzed the problem of relative pose initialization between two satellites: a chaser and a non-cooperating target. The analysis has been targeted to two close-range methods based on a monocular camera system: the Sharma-Ventura-D'Amico (SVD) method and the silhouette matching method. Both methods are based on a priori knowled...

The increasing number of man-made objects in near-earth space is becoming a serious problem for future space missions around the Earth. Among the proposed strategies to face this issue, and due to the passive and propellant-less character, electrodynamic tethers appear to be a promising option for spacecraft in low Earth orbits thanks to the limite...

The increasing number of man-made objects in near-earth space is becoming a serious problem for future space missions around the Earth. Among the proposed strategies to face this issue, and due to the passive and propellant-less character, electrodynamic tethers appear to be a promising option for spacecraft in low Earth orbits thanks to the limite...

In Low Earth Orbit, it is possible to use the ambient plasma and the geomagnetic field to exchange momentum with the Earth's magnetosphere without using propellant. A device that allows an efficient momentum exchange is the electrodynamic tether (EDT), a long conductor attached to the satellite. EDT technology has been demonstrated in several past...

The dynamical stability of tethered systems can be strongly affected by deployment strategies and environmental disturbances and consequently energy dissipation strategies are implemented to reduce oscillation amplitudes. Among the possible solutions for passive dissipation, in-line dampers consist in small mechanisms employing viscous-elastic devi...

We propose to locate transponders and atomic clocks in at least three of the Lagrange points of the Sun-Earth pair, with the aim of exploiting the time of flight asymmetry between electromagnetic signals travelling in opposite directions along polygonal loops having the Lagrange points at their vertices. The asymmetry is due to the presence of a gr...

In the last decades, green deorbiting technologies have begun to be investigated and have raised a great interest in the space community. Among the others, electrodynamic tethers appear to be a promising option. By interacting with the surrounding ionosphere, electrodynamic tethers generate a drag Lorentz force to decrease the orbit altitude of the...

Payloads left in space at the end of life create debris. A high number of space debris surround our planet and within a few years, experts argue, it will no longer be possible to send payloads safely into space. Our study strives to demonstrate the ability to bring a payload back to Earth without the use of active propulsion system in close proximi...

Current investigations on space tethers include their application to space debris deorbiting, specifically on the set of manoeuvres performed by a chaser tug to change the orbital parameters of a target body. Targets can be cooperative spacecraft at the end of their life or uncontrolled objects such as defunct satellites without clearly available c...

The Earth Space Elevator is an ingenious concept aimed at providing easy access to space, eliminating the need for rockets and potentially reducing drastically the launch costs. Technical advancements that could make the Space Elevator possible, among others, would be the availability of long carbon nanotubes or other super-strong and light materia...

This paper presents results of a study conducted for the project IPERDRONE that aims at the design and development of a small re-entry system, able to perform in-orbit operations near the International Space Station (ISS), to reenter the atmosphere, and to land safely on Earth bringing back scientific payloads/experiments intact from the ISS. The r...

This works presents a system level analysis of a Deorbit Kit (DK) based on electrodynamic tether technology. The analysis is focused on two relevant scenarios for deorbiting space debris: (i) Earth Observation (EO) satellites with mass in the range of 700 kg -1000 kg and initial orbital altitude of 800 km and 98° inclination, and (ii) Mega Constell...

The Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit (E.T.PACK) is a project aimed at the development of a deorbit kit based on low-work-function Tether (LWT) technology, i.e., a fully passive and electrically floating system made of a long conductive tape coated with a low-work-function material. The LWT interacts passively...

The Earth Space Elevator is an ingenious concept aimed at providing easy access to space, eliminating the need for rockets and potentially reducing drastically the launch costs. Technical advancements that could make the Space Elevator possible, among others, would be the availability of long carbon nanotubes or other super-strong and light materia...

This works presents a system level analysis of a Deorbit Kit (DK) based on electrodynamic tether technology. The analysis is focused on two relevant scenarios for deorbiting space debris: (i) Earth Observation (EO) satellites with mass in the range of 700kg -1000kg and initial orbital altitude of 800km and 98º inclination, and (ii) Mega Constellati...

A deployed electrodynamic tether, provided with a tip-mass, can be used to deorbit a spacecraft at the end of its operative life. During the deployment of the tether from the spacecraft, the distance measurement between the spacecraft and the tip-mass may be useful to control the whole system. In the present work, three vision-based approaches to m...

This paper presents the concept of a dual cubesat mission designed for Moon exploration that enables scientific measurements that are not accessible by high orbital or landed missions thanks to the use of a long passive tether for orbital insertion. Due to the intrinsic characteristic of the Moon environment, low altitude orbiting spacecrafts are i...

An improved approach for the measurement of the relative pose between a target and a chaser spacecraft is presented. The selected method is based on a single camera, which can be mounted on the chaser, and a plurality of fiducial markers, which can be mounted on the external surface of the target. The measurement procedure comprises of a closed-for...

Presently, no competitive or commercial technologies are available to perform autonomous rendezvous and docking between small-satellites, even though the considerable international interest. One possible solution is represented by relative magnetic navigation, where the chaser relative position and attitude can be controlled thanks to magnetic inte...

We propose in this paper to use a polygon whose vertices are Galileo or GPS satellites in the same orbital plane as a closed space loop along which circulate electromagnetic signals. The expected right/left asymmetry in the times of flight would be related to the motion of the satellites and to the angular momentum of the earth, which is the source...

The unexpected mission termination of ENVISAT in 2012 created a novel hazard in the already critical LEO debris environment: the significant mass (more than 7 tons) and the long natural decaying time (more than 150 years) makes ENVISAT up to now one of the largest and most dangerous debris in LEO. Different solutions have been proposed to remove su...

Presently, no competitive or commercial solution is available to perform autonomous rendezvous and docking between small-satellites. Therefore, in the last years there has been an increasing interest in developing different technologies, addressing the main issues of fuel consumption and the strong impact of close range navigation subsystems on sat...

The use of tethers in space has been proposed to carry out several different tasks, including, for instance, electrodynamic drag devices, spacecraft tugging, novel docking systems. Tether deployers developed and flown so far demonstrated lack of engineering knowledge during tether operations; in particular, a tether retrieval has never been perform...

We illustrate the proposal, nicknamed LAGRANGE, to use spacecraft, located at the Sun–Earth Lagrange points, as a physical reference frame. Performing time of flight measurements of electromagnetic signals traveling on closed paths between the points, we show that it would be possible: (a) to refine gravitational time delay knowledge due both to th...

At present, both Space Agencies and industries are investigating the use of space tethers for various applications, such as new docking system concepts for On-Orbit Servicing, electrodynamic drag devices, tethered space tug, for which a reliable tether deployer is a key subsystem. This paper presents the development of the Space Tether Automatic Re...

An analytical comparison of four technologies for deorbiting spacecraft from Low-Earth-Orbit at end of mission is presented. Basic formulas based on simple physical models of key figures of merit for each device are found. Active devices - rockets and electrical thrusters - and passive technologies - drag augmentation devices and electrodynamic tet...

A dedicated mission in low Earth orbit is proposed to test predictions of gravitational interaction theories and to directly measure the atmospheric density in a relevant altitude range, as well as to provide a metrological platform able to tie different space geodesy techniques. The concept foresees a small spacecraft to be placed in a dawn-dusk e...

In this paper design, implementation, laboratory and microgravity tests of a space tether length and length rate measurer are discussed. The instrument presented was part of an experimental setup consisting in a new concept of space tether deployer with retrieval capability, which was designed and built in the framework of the Drop Your Thesis! 201...

Bare electrodynamic tethers are proposed in the recent literature as a potential solution for deorbiting large dual-payload adapters, such as Sylda onboard Ariane 5. Deorbit measures are required to mitigate the increase of debris population, and consequent collision risk, in space. The system proposed hereby is made of two bare electrodynamic teth...

New technologies in the fields of relative navigation and control strategies are required and ground-based testbeds can be successfully used to develop and validate these required advancements both in hardware and software. Several design aspects have to be taken into account when reproducing on the ground a reduced-gravity environment typical of s...

In-space proximity manoeuvres between small satellites would enable a wide number of operations, among all docking and assembly of large modular structures. Electromagnetic interactions are the simplest solution employed for proximity operations with respect to fuel-based solutions that strongly influence spacecraft operational life. Preliminary st...

The application of a recent concept, a thermionic bare tether (that is, a long conductor coated with a thermionic material), to a practical engineering problem (deorbit space debris from geostationary transfer orbit) is presented. Lorentz drag on a thermionic bare tether, during each pass through an arc close to the perigee, lowers the apogee progr...

Electrodynamic tethers represent one of the possible means to de-orbit defunct satellites from Low-Earth-Orbit at end of life. However, tethers survivability to orbital debris impacts is still debated because of the large area they expose to the space environment. Recently, increasing consideration has been given to thin-tape tether geometries, who...

The dynamics of a space tether system composed of one active spacecraft, an uncontrolled large debris (e.g., a defunct satellite), and a visco-elastic tether connecting the two bodies are investigated in this paper. The active spacecraft is assumed to be equipped with a propulsive system for carrying out a tug maneuver that forces the orbital decay...

A software model has been developed to simulate the on-orbit dynamics of a dual-mass tethered system where one or both of the tethered spacecraft are able to produce propulsive thrust. The software simulates translations and rotations of both spacecraft, with the visco-elastic tether being simulated as a lumped-mass model. Thanks to this last featu...

A software model has been developed to simulate the on-orbit dynamics of a dual-mass tethered system where one or both of the tethered spacecraft are able to produce propulsive thrust. The software simulates translations and rotations of both spacecraft, with the visco-elastic tether being simulated as a lumped-mass model. Thanks to this last featu...

The dynamics of a space tether system composed of one active spacecraft, an uncontrolled large debris (e.g., a defunct satellite), and a visco-elastic tether connecting the two bodies is investigated in this paper. The active spacecraft is assumed to be equipped with a propulsive system for carrying out a tug maneuver that forces the orbital decay...

Electrodynamic tethers (EDT) represent one of the possible means to de-orbit defunct satellites from Low-Earth-Orbit at end-of-life. However, considering the large area exposed to the space environment and the consequent high number of debris impacts per unit time, a high tether survivability to orbital debris is of primary importance. This paper p...

An experimental comparison among visual odometry systems using lenses with three different focal lengths (an ultra wide angle, a medium wide angle and a telephoto lens) is presented. For each focal length, several translational and rotational tests are performed, taking into account and analyzing different positions of the system inside the laborat...

Todays single satellites are limited by both the launchers capacity to deliver the whole satellite mass into a proper orbit (2 - 7 tons for European launchers), and the available volume of the launcher fairings (4 m in diameter and 5 - 7.5 m in height). This constrains the capabilities of telescopes, interferometers, coronagraphs, etc., since their...

In this paper a concept demonstration mission employing a 2U CubeSat is proposed, aiming to prove the feasibility and the effectiveness of tethered capture procedure making use of magnetic forces. Until today, no space demonstration of grabbing technologies for CubeSats has been performed, due to a lack of viable solutions in alternative to the cla...

Seven spatial elements and a time element are proposed as the state variables of a new special perturbation method for the two-body problem. The new elements hold for zero eccentricity and inclination and for negative values of the total energy. They are developed by combining a spatial transformation into projective coordinates (as in the Burdet–F...

This paper addresses issues relevant to the deployment operations of a multikilometer tape-shaped tether from an orbiting spacecraft with the aid of an inline low-thrust propulsion system located inside the tip mass to be deployed. The study is part of a technology development project of an end-of-life deorbiting device for debris mitigation that u...

A vision based instrument able to measure the position and orientation of a spacecraft is described and calibrated from a metrological point of view. The instrument comprises a simple camera which observes the external surface of the satellite provided with fiducial markers and a software procedure which employs a closed-form and direct solution of...

Ground-based testbeds have been used since the beginning of space exploration for both hardware and software validation. In this paper we describe the innovative aspects of the attitude module of a cooperating spacecraft testbed under development at the University of Padova. We also present and discuss experimental results of specific attitude cont...

We present here the concept for a new experimental test of the Weak Equivalence Principle (WEP) carried out in the gravity field of the Sun. In this experiment, two test masses of different materials are the central elements of a differential accelerometer with zero baseline. The differential accelerometer is placed on a pendulum, in such a way as...

Ground-based testbed have been used since the beginning of space exploration for the development and verification of both hardware and software. In this paper, we present the calibration and the validation of an optical flow sensor based navigation system for our ground-based spacecraft testbed. This contactless and low cost system is designed to e...

Present guidelines indicate the need to deorbit new satellites launched into low Earth orbit (LEO) within 25 years from their end of life. Our research task is to develop a new technology suitable to deorbit a satellite at the end of life with as small an impact as possible on the mass budget of the mission. An alternative to the traditional chemic...

A new technology for cooperative docking manoeuvres is under study, aiming to reduce the proximity navigation and guidance requirements between chaser and target spacecraft. It involves the use of a tethered probe that is launched from the chaser and employs magnetic forces for automatic self-alignment and soft docking with the receiving interface...

Fundamental Physics, Accelerometer,

Satellite Formation Flying (SFF) is a key technology for several future missions, since, with respect to a single spacecraft, it allows better performances, new capabilities, more flexibility and robustness to failure and cost reduction. Despite these benefits, however, the SFF concept poses several significant design challenges and requires new te...

A cryogenic differential accelerometer has been developed to test the weak equivalence principle to a few parts in 10(15) within the framework of the general relativity accuracy test in an Einstein elevator experiment. The prototype sensor was designed to identify, address, and solve the major issues associated with various aspects of the experimen...

Guidelines for space debris mitigation call for a 25-year limit on the permanence in low Earth orbits for satellites of any mass size. The aim of this paper is to analyze bare electrodynamic tapes/tethers as deorbiting devices for small satellites. The analysis focuses on the deorbiting performances of electrodynamic tether systems from LEO high ra...