fabrizio piergentili | Università degli Studi "La Sapienza" di Roma (original) (raw)
Papers by fabrizio piergentili
The increasing population of space debris and NEO objects is becoming a severe threat for all the... more The increasing population of space debris and NEO objects is becoming a severe threat for all the on-ground and in-space infrastructure, because of the risk of potential collisions that may seriously damage these active systems. It is therefore of paramount importance to maintain updated catalogues containing estimates of the orbital parameters of objects belonging to the whole trackable population. Space Surveillance activities, such as in-orbit collision avoidance and re-entry campaigns, are typical based on publicly available orbital parameters (TLE), accessible only for catalogued and unclassified space objects. Unfortunately, TLEs are generally characterized by a few days or even faster degradation, which makes the information provided not completely reliable: object positions may be affected by errors of the order of several kilometers, mainly in the in-track direction, making the orbital prediction unreliable both at short (few hours in the specific case of objects at the end...
Aerospace
In recent years, the increase in space activities has brought the space debris issue to the top o... more In recent years, the increase in space activities has brought the space debris issue to the top of the list of all space agencies. The fact of there being uncontrolled objects is a problem both for the operational satellites in orbit (avoiding collisions) and for the safety of people on the ground (re-entry objects). Optical systems provide valuable assistance in identifying and monitoring such objects. The Sapienza Space System and Space Surveillance (S5Lab) has been working in this field for years, being able to take advantage of a network of telescopes spread over different continents. This article is focused on the re-entry phase of the object; indeed, the knowledge of the state of the object, in terms of position, velocity, and attitude during the descent, is crucial in order to predict as accurately as possible the impact point on the ground. A procedure to retrieve the light curves of orbiting objects by means of optical data will be shown and a method to obtain the attitude ...
Acta Astronautica, 2014
ABSTRACT The space debris is a challenging problem for the human activity in the space. Observati... more ABSTRACT The space debris is a challenging problem for the human activity in the space. Observation campaigns are conducted around the globe to detect and track uncontrolled space objects. One of the main problems in optical observation is obtaining useful information about the debris dynamical state by the images collected. For orbit determination, the most relevant information embedded in optical observation is the precise angular position, which can be evaluated by astrometry procedures, comparing the stars inside the image with star catalogs. This is typically a time consuming process, if done by a human operator, which makes this task impractical when dealing with large amounts of data, in the order of thousands images per night, generated by routinely conducted observations. An automated procedure is investigated in this paper that is capable to recognize the debris track inside a picture, calculate the celestial coordinates of the image׳s center and use these information to compute the debris angular position in the sky. This procedure has been implemented in a software code, that does not require human interaction and works without any supplemental information besides the image itself, detecting space objects and solving for their angular position without a priori information. The algorithm for object detection was developed inside the research team. For the star field computation, the software code astrometry.net was used and released under GPL v2 license. The complete procedure was validated by an extensive testing, using the images obtained in the observation campaign performed in a joint project between the Italian Space Agency (ASI) and the University of Bologna at the Broglio Space center, Kenya.
Remote Sensing
This paper presents the HORUS mission, aimed at multispectral and multiangle (nadir and off-nadir... more This paper presents the HORUS mission, aimed at multispectral and multiangle (nadir and off-nadir) planetary optical observation, using Commercial Off-The-Shelf (COTS) instruments on-board a 6-Unit CubeSat. The collected data are characterized by a sub-kilometer resolution, useful for different applications for environmental monitoring, atmospheric characterization, and ocean studies. Latest advancements in electro-optical instrumentation permit to consider an optimized instrument able to fit in a small volume, in principle without significant reduction in the achievable performances with respect to typical large-spacecraft implementations. CubeSat-based platforms ensure high flexibility, with fast and simple components’ integration, and may be used as stand-alone system or in synergy with larger missions, for example to improve revisit time. The mission rationale, its main objectives and scientific background, including the combination of off-nadir potential continuous multiangle c...
Journal of Spacecraft and Rockets, 2007
IEEE Transactions on Aerospace and Electronic Systems, 2011
SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di I... more SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di Ingegneria Aerospaziale dell'Università di Roma "La Sapienza", dal gruppo di ricerca GAUSS (Gruppo di Astrodinamica dell' Università degli Studi "la Sapienza"). Lo scopo fondamentale del programma è impartire agli studenti un'educazione di tipo pratico, completando il curriculum dei loro studi universitari attraverso un reale,
In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) ca... more In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) carried out a two-site observation campaign devoted to the autonomous orbit determination of objects in the geosynchronous region. Two 40 cm aperture Ritchey-Chrétien devices were employed: the f/7.5 ``Collepardo Automatic Telescope'' (CAT, located in Collepardo, Italy) and a f/5 tube of the ``Observatori Astronòmic de Mallorca'' (OAM, located in Mallorca, Spain). The baseline between the sites is 916 km. 3 s long, 1 minute apart exposures were simultaneously taken in sidereal tracking mode, looking at the same arcs of the GEO ring; the fields of view allowed to see a few satellites in two successive frames from both sites, thus providing two positions: the Lambert theorem has been exploited to determining the orbits. A first order approximation of the targets angular motion has been used to fix synchronism errors. Of course, the longer the time interval between positions, the lower the effect of measurements errors. Nevertheless, the only way to have quite distant points would be tracking the satellite, which is typically not suitable for a surveillance campaign, thus not interesting from a practical standpoint. Currently, in the Measurement Working Group of the Inter-Agency Space Debris Co-ordination Committee (IADC), the orbits of the objects detected during GEO optical observation campaigns, are estimated under the assumption of null eccentricity. This is the only way, if one telescope is used and if only a few observations are available. Obviously, the hypothesis of circular orbit provides excellent results for actually geostationary satellites and definitely incorrect estimates for high eccentricity objects. The systematic cooperation of couples of observatories, would provide good orbit determination, for instance, for GTO debris. In the paper the results of the orbit determination from the September 2003 campaign are reported. More in detail, the outcomes of some classical methods for solving the Lambert theorem, are compared with the least squares improved solutions, with the circular orbit assumption results and with the TLEs.
Advances in Space Research, 2006
This chapter deals with the design of the EduSAT microsatellite: a small educational satellite de... more This chapter deals with the design of the EduSAT microsatellite: a small educational satellite developed by the Group of Astrodynamics of University of Roma “Sapienza” (GAUSS), on the basis of its previous experience. The UNISAT program (UNIversity SATellite) started at School of Aerospace Engineering of Roma in the early nineties. The EduSAT Project is funded and coordinated by Italian Space Agency with the aim to promote space education among high school students and to support the qualification and scientific careers of young people (university students, PhD students and young researchers). Another target of this program is to develop a small space mission for low cost scientific experiments and technological tests in orbit. The launch of EduSAT microsatellite is scheduled in 2010: a cluster launch in Low Earth Orbit, performed by Russian-Ukrainian DNEPR Launch Vehicle. This chapter synthesizes project motivations, program organization and describes system architecture and satellite main subsystems design.
Acta Astronautica, 2009
... The UNISAT program: Lessons learned and achieved results. ... The spacecraft is stabilized us... more ... The UNISAT program: Lessons learned and achieved results. ... The spacecraft is stabilized using a passive magnetic attitude control and the orbit is not actively ... following scientific and technological payloads: Maximum Peak Power Tracking system to drive solar array working ...
Advances in Space Research, 2004
... been definitely, though not intentionally, detected by astronomers in the last decades, dedic... more ... been definitely, though not intentionally, detected by astronomers in the last decades, dedicated observations of space debris have never ... In other words, our frames processed by someone with full access to the catalogue, might result in a successful correlation with the ...
SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di I... more SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di Ingegneria Aerospaziale dell'Università di Roma "La Sapienza", dal gruppo di ricerca GAUSS (Gruppo di Astrodinamica dell' Università degli Studi "la Sapienza"). Lo scopo fondamentale del programma è impartire agli studenti un'educazione di tipo pratico, completando il curriculum dei loro studi universitari attraverso un reale,
Advances in Space Research, 2010
In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) ca... more In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) carried out a two-site observation campaign devoted to the autonomous orbit determination of objects in the geosynchronous region. Two 40 cm aperture Ritchey-Chrétien devices were employed: the f/7.5 ``Collepardo Automatic Telescope'' (CAT, located in Collepardo, Italy) and a f/5 tube of the ``Observatori Astronòmic de Mallorca'' (OAM, located in Mallorca, Spain). The baseline between the sites is 916 km. 3 s long, 1 minute apart exposures were simultaneously taken in sidereal tracking mode, looking at the same arcs of the GEO ring; the fields of view allowed to see a few satellites in two successive frames from both sites, thus providing two positions: the Lambert theorem has been exploited to determining the orbits. A first order approximation of the targets angular motion has been used to fix synchronism errors. Of course, the longer the time interval between positions, the lower the effect of measurements errors. Nevertheless, the only way to have quite distant points would be tracking the satellite, which is typically not suitable for a surveillance campaign, thus not interesting from a practical standpoint. Currently, in the Measurement Working Group of the Inter-Agency Space Debris Co-ordination Committee (IADC), the orbits of the objects detected during GEO optical observation campaigns, are estimated under the assumption of null eccentricity. This is the only way, if one telescope is used and if only a few observations are available. Obviously, the hypothesis of circular orbit provides excellent results for actually geostationary satellites and definitely incorrect estimates for high eccentricity objects. The systematic cooperation of couples of observatories, would provide good orbit determination, for instance, for GTO debris. In the paper the results of the orbit determination from the September 2003 campaign are reported. More in detail, the outcomes of some classical methods for solving the Lambert theorem, are compared with the least squares improved solutions, with the circular orbit assumption results and with the TLEs.
Journal of Spacecraft and Rockets, 2008
ABSTRACT
Journal of Spacecraft and Rockets, 2008
ABSTRACT
The increasing population of space debris and NEO objects is becoming a severe threat for all the... more The increasing population of space debris and NEO objects is becoming a severe threat for all the on-ground and in-space infrastructure, because of the risk of potential collisions that may seriously damage these active systems. It is therefore of paramount importance to maintain updated catalogues containing estimates of the orbital parameters of objects belonging to the whole trackable population. Space Surveillance activities, such as in-orbit collision avoidance and re-entry campaigns, are typical based on publicly available orbital parameters (TLE), accessible only for catalogued and unclassified space objects. Unfortunately, TLEs are generally characterized by a few days or even faster degradation, which makes the information provided not completely reliable: object positions may be affected by errors of the order of several kilometers, mainly in the in-track direction, making the orbital prediction unreliable both at short (few hours in the specific case of objects at the end...
Aerospace
In recent years, the increase in space activities has brought the space debris issue to the top o... more In recent years, the increase in space activities has brought the space debris issue to the top of the list of all space agencies. The fact of there being uncontrolled objects is a problem both for the operational satellites in orbit (avoiding collisions) and for the safety of people on the ground (re-entry objects). Optical systems provide valuable assistance in identifying and monitoring such objects. The Sapienza Space System and Space Surveillance (S5Lab) has been working in this field for years, being able to take advantage of a network of telescopes spread over different continents. This article is focused on the re-entry phase of the object; indeed, the knowledge of the state of the object, in terms of position, velocity, and attitude during the descent, is crucial in order to predict as accurately as possible the impact point on the ground. A procedure to retrieve the light curves of orbiting objects by means of optical data will be shown and a method to obtain the attitude ...
Acta Astronautica, 2014
ABSTRACT The space debris is a challenging problem for the human activity in the space. Observati... more ABSTRACT The space debris is a challenging problem for the human activity in the space. Observation campaigns are conducted around the globe to detect and track uncontrolled space objects. One of the main problems in optical observation is obtaining useful information about the debris dynamical state by the images collected. For orbit determination, the most relevant information embedded in optical observation is the precise angular position, which can be evaluated by astrometry procedures, comparing the stars inside the image with star catalogs. This is typically a time consuming process, if done by a human operator, which makes this task impractical when dealing with large amounts of data, in the order of thousands images per night, generated by routinely conducted observations. An automated procedure is investigated in this paper that is capable to recognize the debris track inside a picture, calculate the celestial coordinates of the image׳s center and use these information to compute the debris angular position in the sky. This procedure has been implemented in a software code, that does not require human interaction and works without any supplemental information besides the image itself, detecting space objects and solving for their angular position without a priori information. The algorithm for object detection was developed inside the research team. For the star field computation, the software code astrometry.net was used and released under GPL v2 license. The complete procedure was validated by an extensive testing, using the images obtained in the observation campaign performed in a joint project between the Italian Space Agency (ASI) and the University of Bologna at the Broglio Space center, Kenya.
Remote Sensing
This paper presents the HORUS mission, aimed at multispectral and multiangle (nadir and off-nadir... more This paper presents the HORUS mission, aimed at multispectral and multiangle (nadir and off-nadir) planetary optical observation, using Commercial Off-The-Shelf (COTS) instruments on-board a 6-Unit CubeSat. The collected data are characterized by a sub-kilometer resolution, useful for different applications for environmental monitoring, atmospheric characterization, and ocean studies. Latest advancements in electro-optical instrumentation permit to consider an optimized instrument able to fit in a small volume, in principle without significant reduction in the achievable performances with respect to typical large-spacecraft implementations. CubeSat-based platforms ensure high flexibility, with fast and simple components’ integration, and may be used as stand-alone system or in synergy with larger missions, for example to improve revisit time. The mission rationale, its main objectives and scientific background, including the combination of off-nadir potential continuous multiangle c...
Journal of Spacecraft and Rockets, 2007
IEEE Transactions on Aerospace and Electronic Systems, 2011
SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di I... more SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di Ingegneria Aerospaziale dell'Università di Roma "La Sapienza", dal gruppo di ricerca GAUSS (Gruppo di Astrodinamica dell' Università degli Studi "la Sapienza"). Lo scopo fondamentale del programma è impartire agli studenti un'educazione di tipo pratico, completando il curriculum dei loro studi universitari attraverso un reale,
In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) ca... more In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) carried out a two-site observation campaign devoted to the autonomous orbit determination of objects in the geosynchronous region. Two 40 cm aperture Ritchey-Chrétien devices were employed: the f/7.5 ``Collepardo Automatic Telescope'' (CAT, located in Collepardo, Italy) and a f/5 tube of the ``Observatori Astronòmic de Mallorca'' (OAM, located in Mallorca, Spain). The baseline between the sites is 916 km. 3 s long, 1 minute apart exposures were simultaneously taken in sidereal tracking mode, looking at the same arcs of the GEO ring; the fields of view allowed to see a few satellites in two successive frames from both sites, thus providing two positions: the Lambert theorem has been exploited to determining the orbits. A first order approximation of the targets angular motion has been used to fix synchronism errors. Of course, the longer the time interval between positions, the lower the effect of measurements errors. Nevertheless, the only way to have quite distant points would be tracking the satellite, which is typically not suitable for a surveillance campaign, thus not interesting from a practical standpoint. Currently, in the Measurement Working Group of the Inter-Agency Space Debris Co-ordination Committee (IADC), the orbits of the objects detected during GEO optical observation campaigns, are estimated under the assumption of null eccentricity. This is the only way, if one telescope is used and if only a few observations are available. Obviously, the hypothesis of circular orbit provides excellent results for actually geostationary satellites and definitely incorrect estimates for high eccentricity objects. The systematic cooperation of couples of observatories, would provide good orbit determination, for instance, for GTO debris. In the paper the results of the orbit determination from the September 2003 campaign are reported. More in detail, the outcomes of some classical methods for solving the Lambert theorem, are compared with the least squares improved solutions, with the circular orbit assumption results and with the TLEs.
Advances in Space Research, 2006
This chapter deals with the design of the EduSAT microsatellite: a small educational satellite de... more This chapter deals with the design of the EduSAT microsatellite: a small educational satellite developed by the Group of Astrodynamics of University of Roma “Sapienza” (GAUSS), on the basis of its previous experience. The UNISAT program (UNIversity SATellite) started at School of Aerospace Engineering of Roma in the early nineties. The EduSAT Project is funded and coordinated by Italian Space Agency with the aim to promote space education among high school students and to support the qualification and scientific careers of young people (university students, PhD students and young researchers). Another target of this program is to develop a small space mission for low cost scientific experiments and technological tests in orbit. The launch of EduSAT microsatellite is scheduled in 2010: a cluster launch in Low Earth Orbit, performed by Russian-Ukrainian DNEPR Launch Vehicle. This chapter synthesizes project motivations, program organization and describes system architecture and satellite main subsystems design.
Acta Astronautica, 2009
... The UNISAT program: Lessons learned and achieved results. ... The spacecraft is stabilized us... more ... The UNISAT program: Lessons learned and achieved results. ... The spacecraft is stabilized using a passive magnetic attitude control and the orbit is not actively ... following scientific and technological payloads: Maximum Peak Power Tracking system to drive solar array working ...
Advances in Space Research, 2004
... been definitely, though not intentionally, detected by astronomers in the last decades, dedic... more ... been definitely, though not intentionally, detected by astronomers in the last decades, dedicated observations of space debris have never ... In other words, our frames processed by someone with full access to the catalogue, might result in a successful correlation with the ...
SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di I... more SOMMARIO - Il programma di ricerca e didattica UNISAT viene portato avanti, presso la Scuola di Ingegneria Aerospaziale dell'Università di Roma "La Sapienza", dal gruppo di ricerca GAUSS (Gruppo di Astrodinamica dell' Università degli Studi "la Sapienza"). Lo scopo fondamentale del programma è impartire agli studenti un'educazione di tipo pratico, completando il curriculum dei loro studi universitari attraverso un reale,
Advances in Space Research, 2010
In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) ca... more In September 2003 the Group of Astrodynamics of the University of Rome ``La Sapienza'' (GAUSS) carried out a two-site observation campaign devoted to the autonomous orbit determination of objects in the geosynchronous region. Two 40 cm aperture Ritchey-Chrétien devices were employed: the f/7.5 ``Collepardo Automatic Telescope'' (CAT, located in Collepardo, Italy) and a f/5 tube of the ``Observatori Astronòmic de Mallorca'' (OAM, located in Mallorca, Spain). The baseline between the sites is 916 km. 3 s long, 1 minute apart exposures were simultaneously taken in sidereal tracking mode, looking at the same arcs of the GEO ring; the fields of view allowed to see a few satellites in two successive frames from both sites, thus providing two positions: the Lambert theorem has been exploited to determining the orbits. A first order approximation of the targets angular motion has been used to fix synchronism errors. Of course, the longer the time interval between positions, the lower the effect of measurements errors. Nevertheless, the only way to have quite distant points would be tracking the satellite, which is typically not suitable for a surveillance campaign, thus not interesting from a practical standpoint. Currently, in the Measurement Working Group of the Inter-Agency Space Debris Co-ordination Committee (IADC), the orbits of the objects detected during GEO optical observation campaigns, are estimated under the assumption of null eccentricity. This is the only way, if one telescope is used and if only a few observations are available. Obviously, the hypothesis of circular orbit provides excellent results for actually geostationary satellites and definitely incorrect estimates for high eccentricity objects. The systematic cooperation of couples of observatories, would provide good orbit determination, for instance, for GTO debris. In the paper the results of the orbit determination from the September 2003 campaign are reported. More in detail, the outcomes of some classical methods for solving the Lambert theorem, are compared with the least squares improved solutions, with the circular orbit assumption results and with the TLEs.
Journal of Spacecraft and Rockets, 2008
ABSTRACT
Journal of Spacecraft and Rockets, 2008
ABSTRACT