Recursos de colección

Archivo Digital UPM (107.543 recursos)

This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.

Materia = Astronomía

Mostrando recursos 1 - 20 de 41

  1. Frozen orbits for scientific missions using rotating tethers

    Urrutxua, Hodei; Peláez Álvarez, Jesús; Lara, M.
    We derive a semi-analytic formulation that permits to study the long-term dynamics of fast-rotating inert tethers around planetary satellites. Since space tethers are extensive bodies they generate non-keplerian gravitational forces which depend solely on their mass geometry and attitude, that can be exploited for controlling science orbits. We conclude that rotating tethers modify the geometry of frozen orbits, allowing for lower eccentricity frozen orbits for a wide range of orbital inclination, where the length of the tether becomes a new parameter that the mission analyst may use to shape frozen orbits to tighter operational constraints.

  2. Orbital debris mitigation through deorbiting with passive electrodynamic drag

    Zanutto, Denis; Lorenzini, Enrico C.; Mantellato, Riccardo; Colombatti, Giacomo; Sánchez Torres, Antonio
    The increase of orbital debris and the consequent proliferation of smaller objects through fragmentation are driving the need for mitigation strategies. The issue is how to deorbit the satellite with an efficient system that does not impair drastically the propellant budget of the satellite and, consequently, reduces its operating life. We have been investigating, in the framework of a European-Community-funded project, a passive system that makes use of an electrodynamics tether to deorbit a satellite through Lorentz forces. The deorbiting system will be carried by the satellite itself at launch and deployed from the satellite at the end of its...

  3. Assessment of "mobile mapping system": A GIS-based support methodology

    Herrero Tejedor, Tomás Ramón; Conejo Calvo, Miguel; Pérez Martín, Enrique; López-Cuervo Medina, Serafín
    In this article, the authors examine the current status of different elements that integrate the landscape of the municipality of Olias del Rey in Toledo (Spain). A methodology for the study of rural roads, activity farming and local hunting management. We used Geographic Information Technologies (GIT) in order to optimize spatial information including the design of a Geographic Information System (GIS). In the acquisition of field data we have used vehicle "mobile mapping" instrumentation equipped with GNSS, LiDAR, digital cameras and odometer. The main objective is the integration of geoinformation and geovisualization of the information to provide a fundamental tool...

  4. Power density of a bare electrodynamic tether generator

    Bombardelli, Claudio
    The maximum performance of bare electrodynamic tethers as power generating systems under OML-theory is analyzed. Results show that best performance in terms of power density is achieved by designing the tether in such a way to increase ohmic impedance with respect to plasma contact impedance, hence favoring longer and thinner tethers. In such condition the corresponding optimal value of the load impedance is seen to approach the ohmic impedance of the conducting tether. At the other extreme, when plasma contact impedance dominates (which is not optimal but can be relevant for some applications) optimum power generation is found by matching...

  5. Adaptive scheme for Accurate orbit propagation

    Bau, Giulio; Bombardelli, Claudio; Peláez Álvarez, Jesús
    Two extensions of the fast and accurate special perturbation method recently developed by Peláez et al. are presented for respectively elliptic and hyperbolic motion. A comparison with Peláez?s method and with the very efficient Stiefel- Scheifele?s method, for the problems of oblate Earth plus Moon and continuous radial thrust, shows that the new formulations can appreciably improve the accuracy of Peláez?s method and have a better performance of Stiefel-Scheifele?s method. Future work will be to include the two new formulations and the original one due to Peláez into an adaptive scheme for highly accurate orbit propagation

  6. Dynamic stabilization of L2 periodic orbits using attitude-orbit coupling effects

    Peláez Álvarez, Jesús; Bombardelli, Claudio; Lara, M.; Lucas, Fernando R.; Sanjurjo Rivo, Manuel; Curreli, D.; Lorenzini, Enrico C.; Scheeres, D.
    Numerical explorations show how the known periodic solutions of the Hill problem are modified in the case of the attitude-orbit coupling that may occur for large satellite structures. We focus on the case in which the elongation is the dominant satellite?s characteristic and find that a rotating structure may remain with its largest dimension in a plane parallel to the plane of the primaries. In this case, the effect produced by the non-negligible physical dimension is dynamically equivalent to the perturbation produced by an oblate central body on a masspoint satellite. Based on this, it is demonstrated that the attitude-orbital...

  7. Energy Analysis of Bare Electrodynamic Tethers

    Sanjurjo Rivo, Manuel; Peláez Álvarez, Jesús
    The design of an electrodynamic tether is a complex task that involves the control of dynamic instabilities, optimization of the generated power (or the descent time in deorbiting missions), and minimization of the tether mass. The electrodynamic forces on an electrodynamic tether are responsible for variations in the mechanical energy of the tethered system and can also drive the system to dynamic instability. Energy sources and sinks in this system include the following: 1) ionospheric impedance, 2) the potential drop at the cathodic contactor, 3) ohmic losses in the tether, 4) the corotational plasma electric field, and 5) generated power...

  8. Dynamic stabilization of L2 periodic orbits using attitude-orbit coupling effects

    Peláez Álvarez, Jesús; Bombardelli, Claudio; Lara, M.; Lucas, Fernando R.; Sanjurjo Rivo, Manuel; Curreli, D.; Lorenzini, Enrico C.; Scheeres, D.
    Numerical explorations show how the known periodic solutions of the Hill problem are modified in the case of the attitude-orbit coupling that may occur for large satellite structures. We focus on the case in which the elongation is the dominant satellite’s characteristic and find that a rotating structure may remain with its largest dimension in a plane parallel to the plane of the primaries. In this case, the effect produced by the non-negligible physical length is dynamically equivalent to the perturbation produced by an oblate central body on a mass-point satellite. Based on this, it is demonstrated that the attitude-orbital coupling of a...

  9. Space Debris Removal with an Ion Beam Shepherd Satellite: target-plasma interaction

    Merino, Mario; Ahedo Galilea, Eduardo; Bombardelli, Claudio; Urrutxua, Hodei; Pélaez Álvarez, Jesús; Summerer, L.
    A novel concept for active space debris removal known as Ion Beam Shepherd (IBS) which has been recently presented by our group is investigated. The concept makes use of a highly collimated ion beam to exert the necessary force on a generic debris to modify its orbit and/or attitude from a safe distance in a controlled manner, without the need of docking. After describing the main characteristics of the IBS system, some of the key aspects of thruster plasma and its interaction with the debris are studied, namely, (1) the modeling of the expansion of an plasma beam, based on the...

  10. Can Jupiters be found by monitoring Galactic bulge microlensing events from northern sites?

    Tsapras, Yiannis; Street, Rachel A.; Horne, Keith; Penny, Alan; Clarke, Fraser; Deeg, Hans; Garzon, Francisco; Kemp, Simon; Zapatero Osorio, Maria Rosa; Oscoz Abad, Alejandro; Madruga Sánchez, Santiago; Eiroa, Carlos; Alcione, Mora; Alberdi, Antxon; Cameron, Andrew; Davies, John K.; Ferlet, Roger; Grady, Carol; Harris, Allan W.; Palacios, Javier; Quirrenbach, Andreas; Rauer, Heike; Schneider, Jean; Winter, Dolf de; Merin, Bruno; Solano, Enrique
    In 1998 the EXPORT team monitored microlensing event light curves using a charge-coupled device (CCD) camera on the IAC 0.8-m telescope on Tenerife to evaluate the prospect of using northern telescopes to find microlens anomalies that reveal planets orbiting the lens stars. The high airmass and more limited time available for observations of Galactic bulge sources make a northern site less favourable for microlensing planet searches. However, there are potentially a large number of northern 1-m class telescopes that could devote a few hours per night to monitor ongoing microlensing events. Our IAC observations indicate that accuracies sufficient to detect...

  11. Singularities around w=-1

    Fernández Jambrina, Leonardo
    In this talk we would like to analyse the appearance of singularities in FLRW cosmological models which evolve close to w = -1, where w is the barotropic index of the universe. We relate small terms in cosmological time around w = -1 with the correspondent scale factor of the universe and check for the formation of singularities.

  12. Resources to introduce Inquire Based Scientic Education in Secondary and High School

    Gómez de Castro, Ana Inés; Lozano Bright, Carmen; Martínez Rodríguez-Osorio, Ramón; Calvo Ramón, Miguel; Organero, Faustino; Blay Serrano, Pere; López Martínez, Fátima
    The global Hands-on Universe association is producing and distributing free resources world- wide to implement Inquire Based Scienti?c Education (IBSE) at secondary and high school levels. The materials are inspired in astronomical research and space exploration. The association is implementing the Galileo Teacher Training Program world-wide. In this contribution, a summary on the most recent resources being implemented by HOU-Espa~na and developed with Spanish participation is presented.

  13. Evidence for a disaggregation of the universe.

    Alfonso-Faus, Antonio
    Combining the kinematical definitions of the two dimensionless parameters, the deceleration q(x) and the Hubble t 0 H(x), we get a differential equation (where x=t/t 0 is the age of the universe relative to its present value t 0). First integration gives the function H(x). The present values of the Hubble parameter H(1) [approximately t 0 H(1)≈1], and the deceleration parameter [approximately q(1)≈−0.5], determine the function H(x). A second integration gives the cosmological scale factor a(x). Differentiation of a(x) gives the speed of expansion of the universe. The evolution of the universe that results from our approach is: an initial...

  14. Quantization of the universe as a black hole.

    Fullana i Alfonso, Mariùs Josep; Alfonso-Faus, Antonio
    It has been shown that black holes can be quantized by using Bohr’s idea of quantizing the motion of an electron inside the atom. We apply these ideas to the universe as a whole. This approach reinforces the suggestion that it may be a way to unify gravity with quantum theory.

  15. Red Nacional de Estaciones de Referencia GPS (ERGPS)

    Sánchez Sobrino, José A.; Cano Villaverde, Miguel A.; Prieto Morin, Juan Francisco; Quirós Donate, Rafael; Valdés Peres de Vargas, Marcelino
    El Instituto Geográfico Nacional, por medio del Área de Geodesia, está llevando a cabo el establecimiento de una Red de Estaciones Permanentes GPS que permitan obtener coordenadas muy precisas, así como sus campos de velocidades en un Sistema de Referencia Global (ITRFxx). Dichas estaciones pertenecen a la Red de Estaciones Permanentes de EUREF (EUropean REference Frame) y constituyen el orden cero de la Geodesia Española.

  16. El Proyecto REGENTE

    Regidor Gutiérrez, Jose; Prieto Morin, Juan Francisco; Sanz Mejía, José Manuel; Quirós Donate, Rafael; Barbadillo Fernández, Antonio
    Con el fin de establecer una cartografía europea unificada, se hace indispensable la conversión de las coordenadas de los Marcos de los Sistemas Geodésicos Nacionales al Marco ETRF89, lo cual sólo es posible a través de la determinación de transformaciones y superficies de ajuste desde uno a otro marco. Tal determinación requiere el conocimiento de ambas clases de coordenadas en un número muy elevado de estaciones uniformemente distribuidas, debiendo este número ser tanto mayor cuantas más irregularidades presente el Marco local. En el caso de la Península y Archipiélagos, el IGN decidió resolver el problema mediante el Proyecto REGENTE (Red Geodésica...

  17. Asymptotic solution for the two-body problem with constant tangencial acceleration

    Bombardelli, Claudio; Bau, Giulio; Peláez Álvarez, Jesús
    An analytical solution of the two body problem perturbed by a constant tangential acceleration is derived with the aid of perturbation theory. The solution, which is valid for circular and elliptic orbits with generic eccentricity, describes the instantaneous time variation of all orbital elements. A comparison with high-accuracy numerical results shows that the analytical method can be effectively applied to multiple-revolution low-thrust orbit transfer around planets and in interplanetary space with negligible error.

  18. Prácticas de Topografía con el Observatorio Robotizado Montegancedo

    Prieto Morin, Juan Francisco; Velasco Gomez, Jesus; Valbuena, José Luís; Sebastian y Zuñiga, Jose Maria; Sánchez Moreno, Francisco Manuel; Cedazo León, Raquel; López, Diego
    En el programa formativo del actual Ingeniero Técnico en Topografía está presente la Astronomía Geodésica o de Posición con el fin de que el futuro profesional conozca los elementos de astronomía necesarios para poder calcular coordenadas latitud y longitud de puntos sobre la superficie terrestre, así como el acimut de direcciones a otros puntos a partir de observaciones a las estrellas. Aunque los métodos astronómicos se van sustituyendo por los métodos por observaciones a satélites (GNSS), ciertos conocimientos astronómicos son necesarios para poder comprender tanto los sistemas de referencias celestes y terrestres, como las observaciones geodésicas y geofísicas. Dentro de este programa formativo juegan un papel fundamental la realización de prácticas en las que el alumno...

  19. Monitorización gps del paso del ciclón Vince por la península ibérica

    Seco, A.; García, R.; Ramírez, F.; Prieto, E.; García, B.; Miqueleiz, L.; Prieto Morin, Juan Francisco; Yagüe, C.; González, P. J.; Fernández, J.
    Se exponen aquí los desarrollos llevados a cabo para la monitorización del paso del Ciclón Vince, primer ciclón tropical documentado que alcanza la Península Ibérica, a través de las señales GPS de receptores en tierra durante el evento.

  20. Red GPS Fiduciaria Nacional de España

    Sánchez Sobrino, José A.; Cano Villaverde, Miguel A.; Prieto Morin, Juan Francisco; Quirós Donate, Rafael; Valdés Peres de Vargas, Marcelino
    El Instituto Geográfico Nacional, por medio del Área de Geodesia, está llevando a cabo el establecimiento de una Red de Estaciones Permanentes GPS que permitan obtener coordenadas muy precisas, así como sus campos de velocidades en un Sistema de Referencia Global (ITRFxx). Dichas estaciones pertenencen a la Red de Estaciones Permanentes de EUREF (EUropean REference Framen) y constituyen el órden cero de la Geodesia Española.

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