ettore perozzi - Academia.edu (original) (raw)

Papers by ettore perozzi

Small Satellites Systems and Services, 1993

ABSTRACT Long-Period Comets are possibly the best preserved primitive bodies of the Solar System ... more ABSTRACT Long-Period Comets are possibly the best preserved primitive bodies of the Solar System because of the limited number, if not any, of passages close to the Sun, thus minimizing the consequences following the onset of cometary activity. The unpredictability of their appearance and the short time spent inside the inner planetary region impose heavy constraints (e.g. limited time from comet discovery to launch) when trying to plan a space mission toward a long-period comet. The reduced cost and overall complexity introduced by studying small satellite missions allowed to draw realistic scenarios. The appearance of comet Hale-Bopp in July 1995 is therefore used to investigate in a real case the feasibility of the proposed LOCO (Long Period Comet Observer) mission. It is found that if all preliminary studies are already carried out at the time of comet appearance, a sufficient timespan is left to prepare and launch a small spacecraft to encounter Hale-Bopp at the descending node of its orbit. A preliminary spacecraft design is presented, some general considerations on the problem of having to wait for a long-period comet to appear are discussed and alternative scenarios are proposed.

VizieR Online Data Catalog, Jul 1, 2016

Abstract. We investigate the arrangements of periodic orbits in a restricted, circular, 3-dimensi... more Abstract. We investigate the arrangements of periodic orbits in a restricted, circular, 3-dimensional 3-body problem in which the primaries are the Sun and the Earth, and the massless body represents the Moon. By fixing the duration of the periodic orbits to a multiple of the synodic lunar month, we set up a numerical procedure that systematically finds all the periodic orbits of given duration, not only close to the current lunar orbit, i.e. at low eccentricity and low inclination, but also far from it. 1.

&lt;p&gt;The advent of new wide field, ground-based and multiwavelength space bas... more &lt;p&gt;The advent of new wide field, ground-based and multiwavelength space based sky surveys will lead to a large amount of data that needs to be efficiently processed, archived and disseminated. In addition, differently from astrometric observations which have a centralized data repository acting under IAU mandate (the MPC), the outcome of ground-based NEO observations devoted to NEO physical characterization are sparsely distributed. It appears then desirable to have data on NEO physical characterization available through a centralized access able to guarantee their long-term archiving, as well as to ensure the maintenance and the evolution of the corresponding data products. &amp;#160;&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;Within the NEOROCKS EU project (&amp;#8220;The NEO Rapid Observation, Characterization and Key Simulations&amp;#8221; - SU-SPACE-23-SEC-2019 from the Horizon 2020), as part of WP5 (Data Management) activities, we propose the implementation of a unique NEO Physical Properties database hosting all different data products resulting from NEO observations devoted to physical characterization, in order to ensure an efficient data products dissemination and their short/long-term storage and availability. The NEOROCKS database, will be designed by means of an EPNCore derived data model (see [1]) ready for the EPN-TAP service implementation, and thus able to store, maintain and regularly update all different levels of processing, from raw data to final products (e.g. size, rotation, spectral type) beyond the duration of the project as an reliable source of services and data on NEO physical properties hosted at ASI SSDC.&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;The NEOROCKS database will import NEO orbital elements from the Near-Earth Object Dynamics Site (NEODyS), while NEO physical parameters will be partly provided by NEOROCKS users, partly imported from external data source. In particular, the NEO physical properties database available at the ESA NEO Coordination Center, hosting since 2013 the legacy of the European Asteroid Research Node (EARN) and which will host Solar System Objects (SSO) NEO physical properties in the Gaia DR3 expected for the second half of 2021, will be imported and integrated into the NEOROCKS Physical Properties Database. Thus, a single query interface will allow to display both dynamical and physical properties of any given NEO, or to search for samples within the NEO population satisfying certain requirements (e.g. targets for astronomical observations and mission analysis).&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;: The LICIACube team acknowledges financial support from Agenzia Spaziale Italiana (ASI, contract No. 2019-31-HH.0 CUP F84I190012600).&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;[1] Erard S., Cecconi B., Le Sidaner P., Berthier J., Henry F., Molinaro M., Giardino M., Bourrel N., Andre N., Gangloff M., Jacquey C., Topf F. 2014. The EPN-TAP protocol for the Planetary Science Virtual Observatory (2014). Astronomy And Computing, vol. 7-8, p. 52-61, ISSN: 2213-1337, doi: 10.1016/j.ascom.2014.07.008&lt;/p&gt;

Monthly Notices of the Royal Astronomical Society, 2019

The distinction between active and inactive small bodies in the Solar System has become more blen... more The distinction between active and inactive small bodies in the Solar System has become more blended in recent years, with the discovery of objects exhibiting a transient nature. The assumption of activity (past or present) for a small body can be achieved indirectly by its identification as the parent of a meteor shower. In this framework, the near-Earth object (NEO) 2009 WN25 represents an interesting case study. The target, recovered in 2015, is the likely progenitor of a complex stream of meteor shower, and its peculiar high-eccentricity, high-inclination orbit, with an aphelion as far as Jupiter, is responsible for the meteoroid long-term stability. We investigated the physical characteristics of 2009 WN25, by obtaining spectral observations from ESO-NTT and ESO-VLT to constrain its surface composition. We also compared the observed spectra with meteorite data present in the RELAB database and obtained from other laboratories. We found for 2009 WN25 a primitive D-type composition, in agreement with being a cometary progenitor. The low-albedo nature we derived implies a km-sized body, making it one of the few D-type NEOs in this size range. The two spectra we obtained have a similar spectral slope in the 0.5-0.9 μm range, suggesting a possible homogeneous surface. Finally, by comparison with meteorite data we found an association with an unaltered sample of the rare meteorite Tagish Lake. All these evidences strongly support the association with the meteoroid stream.

Astronomy & Astrophysics, 2018

Aims. We present observations of 523676 (2013 UL10), a centaur orbiting between Jupiter and Uranu... more Aims. We present observations of 523676 (2013 UL10), a centaur orbiting between Jupiter and Uranus that is dynamically similar to the few tens of active centaurs that are currently known. Methods. We analysed visible BVR images of the centaur obtained at the Telescopio Nazionale Galileo (La Palma, Canary Islands, Spain) to investigate the weak comet-like activity and to derive information on the nucleus surface colours and size. Results. Centaur 523676 (2013 UL10) is the only centaur known so far that has both comet-like activity and red surface colours: its nucleus has a colour index [B – R] = 1.88 ± 0.11. The nucleus R magnitude (R = 20.93 ± 0.09) allowed us to derive an upper limit for its nucleus size of D ≤ 10 km. We estimated its dust production rate to be Qd ~ 10 kg s−1 at 6.2 au (just after its perihelion passage), resulting in a timescale for the surface blanketing process τB of approximately tens of years, which is very short with respect to typical dynamical lifetime insi...

Nature, 1999

Neptune has a collection of incomplete narrow rings, known as ring arcs, which should in isolatio... more Neptune has a collection of incomplete narrow rings, known as ring arcs, which should in isolation be destroyed by differential motion in a matter of months. Yet since ®rst discovered 1 by stellar occultations in 1984, they appear to have persisted 2±6 , perhaps through a gravitational resonance effect involving the satellite Galatea 6±8. Here we report ground-based observations of the ring arcs, obtained using an adaptive optics system. Our data, and those obtained using the Hubble Space Telescope (reported in a companion paper 9), indicate that the ring arcs are near, but not within the resonance with Galatea, in contrast to what is predicted by some models. Our data set consists of nine 600-s exposures taken at the Canada±France±Hawaii telescope in Hawaii between 11:44 and 13:15 UT on 6 July 1998, using a 1.72-mm ®lter. After standard¯at-®elding and background subtraction, each image was deconvolved with an estimated point-spread function, clearly revealing some of the small inner satellites, namely Proteus, Larissa and Galatea, and more marginally, Despina. Neptune's centre was determined to within half a pixel (,0.017 arcsec) using both the motion of the satellites and the planet cloud cover. To enhance the signal-to-noise ratio, each pixel in individual images was rotated into Neptune's equatorial plane according to the orbital motion at the corresponding point, so as to show the neptunian system at a prescribed time, namely 12:29:39 UT (Earth time). A median ®lter was then applied when co-adding the nine images, while bright pixels near the planet were masked out. On this ®nal image, Proteus, Larissa, Galatea and the arcs are detected, while Despina is lost in the glare of the planet (Fig. 1). Small differences were found between the observed orbital phases of the satellites and those predicted from Voyager observations 10,11 .

Meteoritics & Planetary Science, 2017

The present near-Earth asteroids (NEA) discovery rate has surpassed 1500 objects per year, thus c... more The present near-Earth asteroids (NEA) discovery rate has surpassed 1500 objects per year, thus calling for extensive observation campaigns devoted to physical characterization in order to define successful mitigation strategies in case of possible impactors. A tool is presented which, through a prioritization algorithm, aims to optimize the planning and the execution of NEA physical observations. Two ranking criteria are introduced, Importance and Urgency, accounting for the need of satisfying the two basic observational modes for physical characterization, that is, rapid response and large observing programs, aimed at selecting targets for exploration and mitigation space missions. The resulting tool generates a daily table of observable targets and it can also be run as a stand-alone tool in order to provide future observing opportunities at a specific date of interest. It has been developed and implemented within the framework of the NEOShield-2 EU/HORIZON 2020 Project; the output of the prioritization algorithm is publicly available, in tabular format, on the NEOShield-2 NEO Properties Portal (http:// www.neoshield.net/the-neoshield-project/project-activities/neo-properties-portal), reachable from the main page of the Project website (http://www.neoshield.eu).

Astrophysics and Space Science Library, 1985

The Long-Term Evolution Project (LTEP), realized in collaboration by the IAS-Reparto di Planetolo... more The Long-Term Evolution Project (LTEP), realized in collaboration by the IAS-Reparto di Planetologia (Rome, Italy) and the Astronomical Institute of SAV (Bratislava, Czechoslovakia), has been developed with the aim of giving a general insight into the dynamical evolution of short-period comets. The motion of all the known short-period comets has been investigated over a long time span (over 800 years) taking care, as far as possible, to eliminate the sources of possible discrepancies within the computations. An internally consistent data-set and an atlas of orbital evolutions are the first outputs of this project. The main characteristics of the LTEP are discussed, together with some general remarks on its importance for cometary studies, its limitations and the future developments.

Astrophysics and Space Science Library, 1985

All the known short-period comets have been followed by numerical integration over a time span of... more All the known short-period comets have been followed by numerical integration over a time span of 821 years, from 1585 to 2406. A preliminary survey of the results of these integrations has shown some interesting features, which become recognizable thanks to the length of the time interval covered, not negligible if compared with the typical evolutionary time scale of comets moving in short-period orbits. Interesting phenomena that have been recognized include: (1) captures from, or ejections into, very elongated ellipses, with perihelia of the parking orbits close to the orbit of Jupiter and aphelia within or beyond the region of outer planets; (2) passages of comets from the control of Saturn to that of Jupiter; (3) orbital evolutions controlled mainly by Saturn; (4) librations of comets around low-order resonances; (5) repeated close approaches of comets to Jupiter, often with the comet being captured as a temporary satellite; (6) an almost perfect coincidence of two comet orbits just before a close approach to Jupiter, suggesting their genetic relationship.

Exploration of Halley’s Comet, 1988

Halley-type comets, usually referred to as those with revolution periods of 20 to 200 yr, can be ... more Halley-type comets, usually referred to as those with revolution periods of 20 to 200 yr, can be dynamically defined by the values of their Tisserand invariants with respect to Jupiter, which account for the processes that brought these comets into the present orbits. Long-term integrations of their motion show oscillations of their heliocentric elements when the comets are far from the Sun and the centre of their motion is the barycentre of the solar system. The shift from barycentric to heliocentric motion is also responsible for the major changes of orbital elements within a single revolution which, in the case of direct orbits, may follow regular libration patterns with typical periods of 350–400 yr. This is the reason for the concentration of periods around 70 yr. Some examples of this behaviour and a short discussion of its importance for the dynamical history of Halley-type comets are presented.

ABSTRACT The SIMONE (Spacecraft Intercept Missions to Objects Near Earth) concept has recently be... more ABSTRACT The SIMONE (Spacecraft Intercept Missions to Objects Near Earth) concept has recently been developed as part of an ESA-funded study (Near Earth Objects Space Mission Preparation). The SIMONE study, led by QinetiQ, with scientific aspects led by the Open University's Planetary and Space Sciences Research Institute, is to help understand the diversity of the NEO population using a fleet of microsatellite-class (~120 kg) interplanetary spacecraft with solar electric propulsion. The low cost approach (<50 MEuro for the first and 30 MEuro for subsequent spacecraft) allows a fleet of spacecraft to be deployed for the budget of a typical interplanetary mission. Each spacecraft will rendezvous with a different Near-Earth Object to perform key physical, morphological and compositional measurements relevant to NEO risk assessment as well as scientific investigation. We present the main features of the spacecraft design, measurement objectives, payload, target NEOs and mission operations.

The NEOShield-2 (2015-2017) project has been recently approved by the European Commission in the ... more The NEOShield-2 (2015-2017) project has been recently approved by the European Commission in the framework of the Horizon 2020 programme with the aim i) to study specific technologies and instruments to conduct close approach missions to NEOs or to undertake mitigation demonstration, and ii) to acquire in-depth information of physical properties of the population of small NEOs (50-300 m), in order to design mitigation missions and assess the consequences of an impact on Earth. The Italian scientific community is widely involved in this project.

Invariant Manifolds, Lagrangian Trajectories and Space Mission Design.- Chaos and Diffusion in Dy... more Invariant Manifolds, Lagrangian Trajectories and Space Mission Design.- Chaos and Diffusion in Dynamical Systems Through Stable-Unstable Manifolds.- Regular and Chaotic Dynamics of Periodic and Quasi-Periodic Motions.- Survey of Recent Results on Weak Stability Boundaries and Applications.- On the Accessibility of the Moon.- Optimal Low-Thrust Trajectories to the Interior Earth-Moon Lagrange Point.- On the Use of the Earth-Moon Lagrangian Point L 1 for Supporting the Manned Lunar Exploration.- Manifolds and Radiation Protection.- Three-Body Invariant Manifold Transition with Electric Propulsion.- From Sputnik to the Moon: Astrophysics and Cosmology from Space.- Space Exploration: How Science and Economy may Work Together.

Small Satellites Systems and Services, 1993

VizieR Online Data Catalog, Jul 1, 2016

Monthly Notices of the Royal Astronomical Society, 2019

Astronomy & Astrophysics, 2018

Nature, 1999

Meteoritics & Planetary Science, 2017

Astrophysics and Space Science Library, 1985

Exploration of Halley’s Comet, 1988