Astrodynamical Space Test of Relativity using Optical Devices I (ASTROD I) - A class-M fundamental physics mission proposal for Cosmic Vision 2015-2025: 2010 Update

This paper on ASTROD I is based on our 2010 proposal submitted for the ESA call for class-M mission proposals, and is a sequel and an update to our previous paper [Experimental Astronomy 23 (2009) 491-527; designated as Paper I] which was based on our last proposal submitted for the 2007 ESA call. In this paper, we present our orbit selection with one Venus swing-by together with orbit simulation. In Paper I, our orbit choice is with two Venus swing-bys. The present choice takes shorter time (about 250 days) to reach the opposite side of the Sun. We also present a preliminary design of the optical bench, and elaborate on the solar physics goals with the radiation monitor payload. We discuss telescope size, trade-offs of drag-free sensitivities, thermal issues and present an outlook. ASTROD I is a planned interplanetary space mission with multiple goals. The primary aims are: to test General Relativity with an improvement in sensitivity of over 3 orders of magnitude, improving our understanding of gravity and aiding the development of a new quantum gravity theory; to measure key solar system parameters with increased accuracy, advancing solar physics and our knowledge of the solar system; and to measure the time rate of change of the gravitational constant with an order of magnitude improvement and the anomalous Pioneer acceleration, thereby probing dark matter and dark energy gravitationally. It is envisaged as the first in a series of ASTROD missions. ASTROD I will consist of one spacecraft carrying a telescope, four lasers, two event timers and a clock. Two-way, two-wavelength laser pulse ranging will be used between the spacecraft in a solar orbit and deep space laser stations on Earth, to achieve the ASTROD I goals.Comment: 15 pages, 11 figures, 1 table, based on our 2010 proposal submitted for the ESA call for class-M mission proposals, a sequel and an update to previous paper [Experimental Astronomy 23 (2009) 491-527] which was based on our last proposal submitted for the 2007 ESA call, submitted to Experimental Astronom

Quando a fotografia (já) fazia os antropólogos sonharem: O jornal La Lumière (1851-1860)

Na efervescente metade do século XIX, marcada pela febre da ordem e do progresso, da racionalidade e das luzes, os antropólogos-naturalistas franceses descobrem, ao lado de muitos outros cientistas, as possibilidades heurísticas que a fotografia ofereceria à "visão" que eles tinham da "antropologia", a saber essa tentativa de mapeamento da "espécie humana", das raças e, dentre elas, dos tipos humanos, numa perspectiva claramente evolucionista. O jornal La Lumière (1851-1867), primeira publicação francesa dedicada à "Fotografia, às Artes e às Ciências", foi parcialmente reimpresso em 1995. Mergulhando nas colunas desse semanário, o leitor, além de adquirir uma idéia das origens da antropologia francesa, descobre as profissões de fé que se erguem em torno do novo suporte técnico e da nova "retina do cientista". Descobre, também, como essa prótese instaura uma nova ordem do olhar e levanta, em termos de uma epistemologia do conhecimento, um interessante questionamento em torno de dois outros meios de representações figurativas nos círculos antropológicos da época: os desenhos e as moldagens.In the effervescent half ot the nineteenth century, characterized by an order-and-progress fever, a blind belief on rationality and on enlightment, French anthropologists-naturalists discover, besides many other scientists, the heuristic possibilities photography could offer their "vision" of "anthropology" as an effort to outline, from an evolucionist point of view, "human species" and races as a whole, and, amidst them, the different types of human beings. La Lumière (1850-1867), the first French journal concentrated on "Photography, Arts and Sciences", has partly been reprinted in 1995. By diving into the columns of this weekly journal, the reader not only gets into contact with the origins of French anthropology, but also discovers the conceptions and beliefs these early scientists shared regarding the new "retina" and technical support photography represented for them. And the reader also discovers how this protesis brings about a new order of seeing, and arises, in terms of an epistemology of knowledge, an interesting questioning regarding two other means of figurative representations usual in the anthropological circles of that time: drawings and mouldings of plaster

Quando a fotografia (já) fazia os antropólogos sonharem: O jornal La Lumière (1851-1860)

In the effervescent half ot the nineteenth century, characterized by an order-and-progress fever, a blind belief on rationality and on enlightment, French anthropologists-naturalists discover, besides many other scientists, the heuristic possibilities photography could offer their vision of anthropology as an effort to outline, from an evolucionist point of view, human species and races as a whole, and, amidst them, the different types of human beings. La Lumière (1850-1867), the first French journal concentrated on Photography, Arts and Sciences, has partly been reprinted in 1995. By diving into the columns of this weekly journal, the reader not only gets into contact with the origins of French anthropology, but also discovers the conceptions and beliefs these early scientists shared regarding the new retina and technical support photography represented for them. And the reader also discovers how this protesis brings about a new order of seeing, and arises, in terms of an epistemology of knowledge, an interesting questioning regarding two other means of figurative representations usual in the anthropological circles of that time: drawings and mouldings of plaster.Na efervescente metade do século XIX, marcada pela febre da ordem e do progresso, da racionalidade e das luzes, os antropólogos-naturalistas franceses descobrem, ao lado de muitos outros cientistas, as possibilidades heurísticas que a fotografia ofereceria à visão que eles tinham da antropologia, a saber essa tentativa de mapeamento da espécie humana, das raças e, dentre elas, dos tipos humanos, numa perspectiva claramente evolucionista. O jornal La Lumière (1851-1867), primeira publicação francesa dedicada à Fotografia, às Artes e às Ciências, foi parcialmente reimpresso em 1995. Mergulhando nas colunas desse semanário, o leitor, além de adquirir uma idéia das origens da antropologia francesa, descobre as profissões de fé que se erguem em torno do novo suporte técnico e da nova retina do cientista. Descobre, também, como essa prótese instaura uma nova ordem do olhar e levanta, em termos de uma epistemologia do conhecimento, um interessante questionamento em torno de dois outros meios de representações figurativas nos círculos antropológicos da época: os desenhos e as moldagens.8912

Caractérisation de T2L2 (transfert de temps par lien laser) sur le satellite d'altimétrie d'océans Jason 2 et télémétrie laser micrométrique

Maintes aspects de notre vie moderne reposent sur des réseaux d une échelle mondiale et composés d éléments synchronisés, comme l internet et des système de navigation. Aujourd hui, des nouvelles générations d horloges atomiques, comme des fontaines atomiques et des horloges optiques, déterminent les exigences envers les dispositifs qui permettent l établissement de ces réseaux synchronisés, ou échelles de temps. Le schéma de T2L2 (Transfert de Temps par Lien Laser), basé sur la technologie de la télémétrie laser sur satellite (SLR), représente un moyen radicalement nouveau pour la synchronisation d horloges de demain. L expérience T2L2 fut accepté par le CNES en 2005 en tant que instrument passager sur le satellite d altimétrie des mers Jason 2, afin de prouver le concept et la performance visée d un transfert de temps optique. Après une phase de développement courte, l instrument spatial fut livré par les partenaires industriels début 2007. La partie majeure de ce travail de thèse traite la caractérisation intégrale de l instrument spatial T2L2. A cette fin, un banc de test de haute complexité fut développé à l Observatoire de la Côte d Azur (OCA); il inclut tous éléments importants du schéma opérationnel de T2L2, comme l irradiation par laser et autres sources, des horloges et la simulation de la géométrie. Ce moyen rendait possible de reproduire l utilisation de l instrument spatial T2L2 sur le satellite, dans un environnement de laboratoire. Ceci permettait la caractérisation de l instrument spatial à deux égards: Premièrement, on obtenait des données substantielles pour la calibration de l instrument; elles sont essentielles pour l utilisation et l exploitation sans faille de T2L2 car elles permettent une configuration optimale des paramètres de l instrument dépendant sur les conditions dominantes. D autre part, on dispose des données pour l établissement des tableaux ou algorithmes de correction pour le traitement des données brutes venant du satellite. Le deuxième volet est l évaluation de la performance en métrologie temps / fréquence de l instrument de vol T2L2: Les campagnes d essai permettaient de prouver que l instrument respecte les exigences dans tous les aspects importants du transfert de temps envisagé. Par ailleurs, une analyse approfondie de tout le schéma était mené, incluant la performance de l instrument spatial ainsi que celle du segment sol (c est-à-dire, une station de télémétrie laser). A l aide de ce moyen, le bilan d erreurs , on a pu démontrer la performance finale de tout le transfert de temps: Avec une stabilité de quelques picosecondes, en intégrant sur un passage du satellite de quelques centaines de secondes, T2L2 permettra de comparer les horloges les plus avancés d aujourd hui, incluant les fontaines atomiques. L exactitude absolue d un transfert de temps fut déterminé à moins que 50 ps en configuration vue commune. Par conséquent, T2L2 permettra, quelques semaines après son lancement au 20 juin de cette année, d effectuer des transfert de temps d un niveau de précision et exactitude jamais atteint; ceci, en revanche, contribuera à des applications scientifiques et technologiques de haut niveau. La deuxième partie du document présent est orienté autour l extension de la technologie de télémétrie laser et T2L2 à un autre domaine d application, la mesure absolue et de très haute résolution de distances en espace. Deux équipes complémentaires de l Observatoire de la Côte d Azur avait démarré une collaboration en 2005, nommé ILIADE, afin de réunir leurs compétences respectives en interférométrie et mesure de temps de vol. Cet objectif devra être atteint en utilisant un laser de peigne de fréquences qui avait gagné de l attention publique à cause de la remise du prix Nobel à ses inventeurs en 2005. Le peigne de fréquences devra permettre d effectuer des mesures de temps de vol sur la porteuse optique modulée (les impulsions laser) en parallèle avec une mesure interférométrique sur les raies de fréquence. Un pas important vers la faisabilité de cet approche est d atteindre le seuil de la longueur d onde par la datation et la mesure de phase à haute cadence. Mon travail porte sur la caractérisation de l équipement de détection et datation de haute bande passante qui sera employé à cette fin. On put démontrer que ce niveau de performance en mesure de distance est effectivement à la portée de la technologie d aujourd hui. Le schéma d ILIADE rendra possible d effectuer des mesures de distance au même niveau de performance que l horloge connectée sur le peigne de fréquence, c est-à-dire au niveau d au moins 10 15, ainsi permettant des précisions d un micron sur un million de kilomètres et ceci d une façon exacte (alors donnant un nombre avec 15 chiffres significatifs). Une telle performance en télémétrie permettra la recherche de gravité anomale en espace, des nouvelles types de géodésie terrestre et planétaire et une métrologie hyperfine pour des futures télescopes spatiales.Many aspects of our modern life rely on global networks of highly synchronized elements, such as the internet and navigation systems. Today, new generations of atomic clocks, such as atomic fountains and optical clocks push the requirements on the devices that permit the establishment of these precisely synchronized networks or time scales. The T2L2 (Time Transfer by Laser Link) scheme, based on the technology of satellite laser ranging (SLR), is a radically new means for tomorrow s clock synchronization. The T2L2 experiment was accepted in 2005 by CNES to fly as a passenger instrument on the ocean altimetry satellite Jason 2, in order to prove the concept and the aimed performance of optical time transfer. After a short development phase, the instrument was delivered by the industrial partners beginning 2007. The main part of this work treats the thorough characterization of the T2L2 flight instrument. For this purpose, a highly complex test bed has been developed by the Observatoire de la Côte d Azur (OCA), including all important elements of the T2L2 operation scheme, such as laser and other luminous irradiation, clocks and geometry simulation. By this means, the operation of the T2L2 instrument aboard the satellite could be reproduced in a laboratory environment. This allowed the detailed characterization in two respects: First, we obtained substantial data for the calibration of the instrument which are essential for the proper operation and exploitation of T2L2. Thus, they permit on the one hand an optimum configuration of instrumental settings depending on the prevailing conditions. On the other hand, we are able to establish high fidelity correction tables or algorithms for the processing of the raw data. The second aspect is the evaluation of the performance of the T2L2 flight instrument in terms of time / frequency metrology: The performed test campaigns allowed to prove that the instrument meets the imposed requirements in all important aspects of the envisaged time transfer. Further, a detailed analysis of the whole scheme, including the performance of the space instrument as well as of the ground segment (i.e. a satellite laser ranging station) has been performed. By means of this error budget we could demonstrate the final performance of the whole laser-based time transfer: With a time stability of some picoseconds when integrating over a satellite pass of some hundred seconds, T2L2 will be able to compare today s most advanced clocks such as atomic fountains. The absolute accuracy has been determined to be less than 50 ps in common view configuration. Hence T2L2 will permit, starting few weeks after its launch on June 20 of this year, to perform time transfer on a precision and accuracy level never reached before, what will allow, in its turn, remarkable scientific and technological applications. The second part of the present document is oriented to the extension of the technology used for SLR and T2L2 to another field of application, the high-resolution measurement I of absolute distances in space. Two complementary teams of the Observatoire de la Côte d Azur started in 2005 a collaboration, named ILIADE, in order to unify their respective competences in interferometry and time of flight measurement. This goal shall be reached by the use of frequency combs that have recently gained much public attention due to the award of the Nobel Prize to its inventors in 2005. The frequency comb promises to perform time-offlight measurements on the modulated optical carrier wave (the pulses) and simultaneously interferometry on the comb frequency lines. An important step towards the feasibility of this approach is to reach the threshold of the wavelength by event timing and phase measurement at very high rates. My work comprises the characterization of some ultra-high bandwidth opto-electronic and timing equipment to be employed at that purpose. We could show that this level of performance in distance measurement is effectively coming into the reach of today s technology. The ILIADE scheme would allow to perform distance measurements on the same level of performance as the clock connected to the used frequency comb, that is to say on the order of at least 10 15, meaning for instance a micrometer over one million kilometers, and this in an absolute manner (i.e. giving a number with 15 significant digits). Such an advanced performance in terms of ranging will enable the search of anomalous gravity in space, new types of Earth and planetary geodesy and high-fidelity metrology of future space telescopes.NICE-BU Sciences (060882101) / SudocSudocFranceF

Astrodynamical Space Test of Relativity Using Optical Devices I (ASTROD I)—A class-M fundamental physics mission proposal for Cosmic Vision 2015–2025

ASTROD I is a planned interplanetary space mission with multiple goals. The primary aims are: to test general relativity with an improvement in sensitivity of over three orders of magnitude, improving our understanding of gravity and aiding the development of a new quantum gravity theory; to measure key solar system parameters with increased accuracy, advancing solar physics and our knowledge of the solar system; and to measure the time rate of change of the gravitational constant with an order of magnitude improvement and the anomalous Pioneer acceleration, thereby probing dark matter and dark energy gravitationally. It is an international project, with major contributions from Europe and China and is envisaged as the first in a series of ASTROD missions. ASTROD I will consist of one spacecraft carrying a telescope, four lasers, two event timers and a clock. Two-way, two-wavelength laser pulse ranging will be used between the spacecraft in a solar orbit and deep space laser stations on Earth, to achieve the ASTROD I goals. A second mission, ASTROD (ASTROD II) is envisaged as a three-spacecraft mission which would test General Relativity to 1 ppb, enable detection of solar g-modes, measure the solar Lense–Thirring effect to 10 ppm, and probe gravitational waves at frequencies below the LISA bandwidth. In the third phase (ASTROD III or Super-ASTROD), larger orbits could be implemented to map the outer solar system and to probe primordial gravitational-waves at frequencies below the ASTROD II bandwidth