Papers by Luciano Anselmo
cosp, 2010
A previous study (Pardini C., Anselmo L, Moe K., Moe M.M., Drag and energy accommodation coeffici... more A previous study (Pardini C., Anselmo L, Moe K., Moe M.M., Drag and energy accommodation coefficients during sunspot maximum, Adv. Space Res., 2009, doi:10.1016/j.asr.2009.08.034), including ten satellites with altitudes between 200 and 630 km, has yielded values for the energy accommodation coefficient as well as for the physical drag coefficient as a function of height during solar maximum conditions. The
International Institute of Space Law, 1994
A space mission is described which consists of a rigid spin-axis-stabilised spacecraft with two s... more A space mission is described which consists of a rigid spin-axis-stabilised spacecraft with two small, high-density masses free-falling inside. The gravitational attraction of the masses dominates all perturbations, providing a miniature "planet-satellite" system that can only be realised in space. Unlike any celestial two-body system, the masses can be weighed on Earth before launch. Thus, monitoring their motion by means
42nd COSPAR Scientific Assembly, Jul 1, 2018
40th COSPAR Scientific Assembly, 2014
Passive laser-ranged satellites, launched for geodynamics and geophysics purposes, not only have ... more Passive laser-ranged satellites, launched for geodynamics and geophysics purposes, not only have contributed to significant measurements in space geodesy that enabled, among several aspects, a deeper knowledge of the Earth's geopotential (both in its static and dynamic behavior), as well as of the geocenter motion and GM value up to the definition of the terrestrial reference frame, but they also provided an outstanding test bench to fundamental physics, as in the case of the first measurement of the Lense-Thirring precession on the combined nodes of the two LAGEOS satellites, or in the case of the total relativistic precession of the argument of pericenter of LAGEOS II. Indeed, the physical characteristics of such satellites -- such as their low area-to-mass ratio -- as well as those of their orbits, and the availability of high-quality tracking data provided by the International Laser Ranging Service (ILRS), allow for precise tests of gravitational theories. The aim of LARASE (LAser RAnged Satellites Experiment) is to go a step further in the tests of the gravitational interaction in the field of Earth, i.e. in the weak-field and-slow motion limit of general relativity, by the joint analysis of the orbits of the two LAGEOS satellites and that of the most recent LARES satellite. One of the key ingredients to reach such a goal is to provide high-quality updated models for the perturbing non-gravitational forces acting on the surface of such satellites. A large amount of Satellite Laser Ranging (SLR) data of LAGEOS and LAGEOS II has been analyzed using a set of dedicated models for satellite dynamics, and the related post-fit residuals have been analyzed. A parallel work is on-going in the case of LARES that, due to its much lower altitude, is subject to larger gravitational and non-gravitational effects; the latter are mitigated in part by its much lower area-to-mass ratio. Recent work on the data analysis of the orbit of such satellites will be presented together with the development of some new refined models to account for the impact of the subtle and complex non-gravitational perturbations. The general relativistic effects leave peculiar imprint on the satellite orbit, namely in the secular behavior of its three Euler angles. Recent results will be provided together with updated constraints on non-Newtonian gravitational dynamics. The measurement error budget will be discussed, emphasizing the role of the modeling of gravitational and, especially, non-gravitational forces on the overall precise orbit determination quality, as well as on future new measurements and constraints of the gravitational interaction. <P /
The Medium Earth Orbit (MEO) region is becoming increasingly exploited as the number of navigatio... more The Medium Earth Orbit (MEO) region is becoming increasingly exploited as the number of navigation constellations grows with the advent of the European GALILEO and the Chinese COMPASS systems. There is the need for an effective disposal strategy of satellites at endof-life able to prevent any possible damage of operational satellites. This strategy has to take into account the known instability of nearly circular disposal orbits in MEO. These orbits show an increase of the eccentricity that could lead to dangerous crossings of the operational orbits. The nature of this instability, linked to luni-solar resonances, is briefly recalled. Then the effect of different disposal strategies on the long term evolution of the MEO environment is analyzed. It is shown how the disposal of satellites at end-of-life into well separated storage zones, above the constellations operational orbits, is capable of limiting the collision risk for operational satellites to very low values for long time spans (200 years). Moreover, a disposal into eccentric orbits not only keeps the collision risk to very low values, but also has the advantage of reducing the lifetime of the disposed satellites, thus freeing the orbital environment from the uncontrolled spacecraft.
EGU General Assembly Conference Abstracts, Apr 1, 2017
Acta Astronautica, Sep 1, 2023
EGU General Assembly Conference Abstracts, Apr 1, 2018
In 2007 three space debris detection tests were performed in the framework of a monitoring progra... more In 2007 three space debris detection tests were performed in the framework of a monitoring program carried out by the Istituto Nazionale di Astrofisica-INAF-in collaboration with the Italian Space Agency-ASI. The observations were made by using the bistatic radar technique. The INAF 32 m radiotelescope located at Medicina (Bologna, Italy) was used as receiver whereas the Ukrainian 70 m parabolic antenna located at Evpatoria was utilized as transmitter. The aim of the experiment was to test the sensitivity of the Medicina-Evpatoria radar system in space debris detection, and to validate and optimize the hardware setup. Measurements were mainly carried out on inactive satellites and catalogued space debris. However the search for new fragments in LEO was also performed during the campaign. This paper reports on results of these observations.
Acta Astronautica, Nov 1, 2017
The laser-ranged satellite LARES is expected to provide new refined measurements of relativistic ... more The laser-ranged satellite LARES is expected to provide new refined measurements of relativistic physics, as well as significant contributions to space geodesy and geophysics. The very low area-to-mass ratio of this passive and extremely dense satellite was chosen to reduce as much as possible the disturbing effects of non-gravitational perturbations. However, because of its height, about 1450 km compared with about 5800-5900 km for the two LAGEOS satellites, LARES is exposed to a much stronger drag due to neutral atmosphere. From a precise orbit determination, analyzing the laser ranging normal points of LARES over a time span of about 3.7 years with the GEODYN II (NASA/GSFC) code, it was found an average semi-major axis decay rate of 0.999 m per year, corresponding to a non-conservative net force acting nearly opposite to the velocity vector of the satellite and with a mean along-track acceleration of 1.444 10 11 m/s 2. By means of a modified version of the SATRAP (ISTI/CNR) code, the neutral drag perturbation acting on LARES was evaluated over the same time span, taking into account the real evolution of solar and geomagnetic activities, with five thermospheric density models (JR-71, MSIS-86, MSISE-90, NRLMSISE-00 and GOST-2004). All of them provided consistent results, well within their acknowledged uncertainties. Moreover, when the same models (JR-71 and MSIS-86) were used within GEODYN II in a least-square fit of the tracking data, the differences between the average drag coefficients estimated with SATRAP and GEODYN were of the order of 1% or less. Unlike what happened for the two LAGEOS, where Yarkovsky thermal drag and charged particle drag were the leading causes, it was found that neutral atmosphere drag alone was able to explain most (98.6%) of the observed semi-major axis decay of LARES. The remaining 1.4%, corresponding to an average along-track acceleration of about 2 10 13 m/s 2 (i.e. 1/70 of neutral drag), was probably linked to thermal thrust effects. It was 50%, or less, of the value previously reported in the literature, but further and more detailed investigations, including the detection of the signature of the periodic terms, will be needed in order to characterize such smaller nongravitational perturbation.
Journal of The Astronautical Sciences, Mar 1, 2000
Acta Astronautica, Sep 1, 2016
Abstract A new ranking index was developed and applied to a wide set of rocket body families, cha... more Abstract A new ranking index was developed and applied to a wide set of rocket body families, characterized by stage dry masses greater than 500 kg and by the presence of at least 5 stages abandoned in LEO. The upper stages selected accounted for more than 80% of the unclassified rocket bodies in LEO and nearly 95% of the associated dry mass. The detailed results obtained for 657 objects clearly identified the most critical altitude-inclination bands and stage models, to be targeted first if and when a debris remediation strategy including the active removal of intact abandoned objects were deemed necessary. Apart from the evaluation of the criticality regarding the long-term evolution of the debris environment, resulting in a priority listing for optimal active removal, the application of the new ranking index is not limited to debris remediation. In fact, if applied before launch to spacecraft and rocket bodies to be disposed in orbit, at the end of mission, it would provide an additional debris mitigation analysis tool for evaluating competing disposal options. Concerning the rocket bodies abandoned in LEO, 274 resulted to have a criticality equal or larger than the average intact object abandoned in an 800 km sun-synchronous orbit. Among them, 243 belonged to the Russian Federation and Ukraine, 25 to China, 5 to Europe and 1 to Japan. In addition to being concentrated in relatively few and narrow altitude-inclinations bands, the most numerous rocket body families often present a quite uniform distribution in right ascension of the ascending node, which is especially convenient for multiple target removal missions.
The International Laser Ranging Service (ILRS) provides range measurements of passive satellites ... more The International Laser Ranging Service (ILRS) provides range measurements of passive satellites around the Earth through the powerful Satellite Laser Ranging (SLR) technique. These very precise measurements of the distance between an on-ground laser station and a satellite equipped with cube corner retro-reflectors (CCRs) make possible precise tests and measurements in fundamental physics and, in particular, in gravitational physics. The LAGEOS (NASA 1976) and LAGEOS II (NASA/ASI 1992) satellites are outstanding examples of very good test particles because of their very low area-to-mass ratio as well as the high quality of their tracking data and, consequently, of the precise orbit determination (POD) we can obtain after a refined modeling of their orbit. The aim of our research program LARASE (LAser RAnged Satellites Experiment) is to go a step further in testing gravitation in the field of Earth by means of the joint analysis of the orbits of the two LAGEOS satellites together with that of the most recently launched LARES (ASI, 2012) satellite. Therefore, our work falls in the so-called weak field and slow motion (WFSM) limit of Einstein's general relativity (GR) where, in terms of Newtonian physics, relativistic effects appear as two new fields to be added to the classical gravitational field: the gravitoelectric and the gravitomagnetic fields. A fundamental ingredient to reach such a goal is to provide high-quality updated models for the perturbing non-gravitational perturbations (NGP) acting on the surface of these satellites. In fact, regardless of their minimization thanks to a smaller value for the area-to-mass ratio, the subtle and complex to model perturbing effects of the NGP play a crucial role in the POD of the considered satellites, especially in the case of the thermal thrust effects. A large amount of SLR data of LAGEOS and LAGEOS II has been worked out using a set of dedicated models for the satellite dynamics and the related post-fit residuals have been analyzed. A parallel work was performed with LARES, although at a preliminary stage. Our recent work on the orbit modeling and on the data analysis of the orbit of such satellites is presented and discussed.
Acta Astronautica, May 1, 2016
This paper addresses the problem of ranking the upper stages in orbit in order to evaluate their ... more This paper addresses the problem of ranking the upper stages in orbit in order to evaluate their potential detrimental effects on the debris environment over the long-term, and the relative advantage of having them actively de-orbited. To do so, a new ranking scheme is introduced, applicable to any object in low Earth orbit (LEO) and able to prioritize the target objects potentially most critical for the future preservation of the LEO protected region. Applying the proposed approach, it was found, for instance, that the 22 most massive upper stages abandoned in LEO, at the beginning of 2015, are on the whole equivalent to several hundred average intact objects in sun-synchronous orbit, regarding their latent detrimental effects on the debris environment over the next 200 years. Most of them could therefore be the top priority targets of any worldwide coordinated effort for active removal and the prevention of new collisional debris. The ranking scheme was also applied to other main models of rocket bodies currently in orbit, trying to identify the combinations of orbital elements and upper stage types requiring particular attention. Highlights The upper stages abandoned in orbit were categorized in detail in terms of number, mass and orbital distribution. The types contributing to a significant amount of the mass and number in LEO were identified. A new ranking index was applied to estimate their long-term criticality for the orbital debris environment. The ranking obtained could also be used for active removal priority listing.
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Papers by Luciano Anselmo
In this paper, the environmental criticality of the Italian satellites in LEO, from the orbital debris point of view, was evaluated addressing the following issues:
• Their residual lifetime;
• The probability of impact with other objects;
• The probability of catastrophic fragmentation;
• The number of expected fragments in case of catastrophic collisional breakups;
• The possible interference with the orbit of the International Space Station;
• An overall ranking, using a criticality index developed by the authors.
The results obtained not only represented an updated assessment for the Italian objects launched until the summer of 2017, but also a guide for planning and conducting future missions in LEO in a way as safe and sensible as possible.
After a short historical introduction, the criteria used for the definition of potentially risky space objects are presented and discussed, together with the lessons learned during previous reentry campaigns. The activity carried out for Mir is then described in detail, highlighting the end products needed for the civil protection emergency planning.
Mir was never declared a risk space object in Italy and only a limited alert status was activated, ready to switch to full emergency if needed. However, the event represented a useful training opportunity and a good example of international cooperation, paving the way for the future end-of-life disposal of large low earth spacecraft.
The problem was assessed, to assist tether systems design, by detailed numerical computations of the average impact rate of artificial debris, taking into account the specific geometric properties of tethers as debris targets, when compared to typical satellites.
The results obtained confirm that, for single-strand tethers in low earth orbit, the probability to be severed by orbital debris and meteoroid impacts is quite significant, making necessary the adoption of innovative designs for long duration missions.