Swarm accelerometer data processing from raw accelerations to thermospheric neutral densities

The Swarm satellites were launched on November 22, 2013, and carry accelerometers and GPS receivers as part of their scientific payload. The GPS receivers do not only provide the position and time for the magnetic field measurements, but are also used for determining non-gravitational forces like drag and radiation pressure acting on the spacecraft. The accelerometers measure these forces directly, at much finer resolution than the GPS receivers, from which thermospheric neutral densities can be derived. Unfortunately, the acceleration measurements suffer from a variety of disturbances, the most prominent being slow temperature-induced bias variations and sudden bias changes. In this paper, we describe the new, improved four-stage processing that is applied for transforming the disturbed acceleration measurements into scientifically valuable thermospheric neutral densities. In the first stage, the sudden bias changes in the acceleration measurements are manually removed using a dedicated software tool. The second stage is the calibration of the accelerometer measurements against the non-gravitational accelerations derived from the GPS receiver, which includes the correction for the slow temperature-induced bias variations. The identification of validity periods for calibration and correction parameters is part of the second stage. In the third stage, the calibrated and corrected accelerations are merged with the non-gravitational accelerations derived from the observations of the GPS receiver by a weighted average in the spectral domain, where the weights depend on the frequency. The fourth stage consists of transforming the corrected and calibrated accelerations into thermospheric neutral densities. We present the first results of the processing of Swarm C acceleration measurements from June 2014 to May 2015. We started with Swarm C because its acceleration measurements contain much less disturbances than those of Swarm A and have a higher signal-to-noise ratio than those of Swarm B. The latter is caused by the higher altitude of Swarm B as well as larger noise in the acceleration measurements of Swarm B. We show the results of each processing stage, highlight the difficulties encountered, and comment on the quality of the thermospheric neutral density data set.Astrodynamics & Space Mission

Design status of ASPIICS, an externally occulted coronagraph for PROBA-3

The "sonic region" of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like conditions over long observation times. The space-borne coronagraphs flown so far provided a continuous coverage of the external parts of the corona but their over-occulting system did not permit to analyse the part of the white-light corona where the main coronal mass is concentrated. The proposed PROBA-3 Coronagraph System, also known as ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), with its novel design, will be the first space coronagraph to cover the range of radial distances between ~1.08 and 3 solar radii where the magnetic field plays a crucial role in the coronal dynamics, thus providing continuous observational conditions very close to those during a total solar eclipse. PROBA-3 is first a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future European missions, which will fly ASPIICS as primary payload. The instrument is distributed over two satellites flying in formation (approx. 150m apart) to form a giant coronagraph capable of producing a nearly perfect eclipse allowing observing the sun corona closer to the rim than ever before. The coronagraph instrument is developed by a large European consortium including about 20 partners from 7 countries under the auspices of the European Space Agency. This paper is reviewing the recent improvements and design updates of the ASPIICS instrument as it is stepping into the detailed design phase

Development of ASPIICS: a coronagraph based on Proba-3 formation flying mission

This paper presents the recent achievements in the development of ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), a solar coronagraph that is the primary payload of ESA's formation flying in-orbit demonstration mission PROBA-3. The PROBA-3 Coronagraph System is designed as a classical externally occulted Lyot coronagraph but it takes advantage of the opportunity to place the 1.4 meter wide external occulter on a companion spacecraft, about 150m apart, to perform high resolution imaging of the inner corona of the Sun as close as similar to 1.1 solar radii. Besides providing scientific data, ASPIICS is also equipped with sensors for providing relevant navigation data to the Formation Flying GNC system. This paper is reviewing the recent development status of the ASPIICS instrument as it passed CDR, following detailed design of all the sub-systems and testing of STM and various Breadboard models. ASPIICS is built by a large European consortium including about 20 partners from 7 countries under the auspices of the European Space Agency

East Europe\u27s cinema industries since 1989: financing structure and studios

Desetletne izkušnje vzhodnoevropske tranzicije je mogoče povzeti v nekaj temeljnih ugotovitvah o viharnem in globokem preoblikovanju kulturn administracije. Vzhodnoevropska kulturna industrija je bila v začetku devetdesetih let prva izpostavljena velikemu zmanjšanju sredstev in odpravi vnaprej zagotovljenega financiranja. Še posebej je bil prizadet film. V vseh vzhodnoevropskih državah je bila filmska proizvodnja podvržena nepremišljenim strukturnim spremembam ter pogosto protislovnim ukrepom v upravljanju in financiranju. Drobljenje proizvodnih postopkov je pri mnogih povzročilo ustvarjalno krizo. Značilni problemi so nepoštena konkurenca, poglabljanje generacijskega prepada ter zaton celovečernih, dokumentarnih in animiranih filmov. Hkratna kriza v filmski distribuciji in prikazovanju je pripeljala do upadanja števila gledalcev vseh vzhodnoevropskih filmov, čeprav so hkrati nekateri vzhodnoevropski filmi poželi mednarodna priznanja. Spremembe v vzhodnoevropskem filmu so potekale v obodbju negotovosti zahodnoevropskih kulturnih politik, ki so jih vodila vse bolj protiameriška čustva. Nastanek investicijskih skladov, kot sta Media 95 in Euroimage, je bil reakcija na triumf komercialnega filma. Pod vplivom prevlade ideje "novega evropskega filma" nad "nacionalnim filmom" so se povečale tudi subvencije v vzhodnoevropske studie. Članek podrobneje obravnava spremembe v vzhodnoevropski filmski proizvodnji, konec nacionalnih kinematografij, probleme koprodukcij, zlasti v povezavi z Evroimage, komercialno financiranje,odnos med domačo in tujo filmsko distribucijo in prikazovanjem ter filmske festivale.The decade worth of the East European transition allows us to sum up important lessons of the stormy and profound transformation in cultural administration. The East European cultural industries were the first ones to suffer massive cuts and withdrawal of secure funding early in the 1990s. Cinema was affected most notably. In all of the East European countries filmmaking underwent volatile structural changes and was subjected to often contradictory undertakings in administration and financing. The crumbling production routines caused a creativity crisis in many filmmakers. Problems included unfair competition, deepening generation gap, and decline in feature,documentary and animation output. The concurrent crisis in distribution and exhibition led to a sharp drop in box office indicators for all productions carrying an East European label. At the same time some East European films enjoyed an international critical acclaim internationally. The volatility in East European cinema coincided with a clearly articulated period of insecurity in West European cultural policies, driven by a growing anti-American sentiment. The establishment of such pan-European funding bodies as Media 95 and Euroimage came as a reaction to the overwhelming triumphof commercialism in cinema. The share of international subsidies for filmmaking in poverty-stricken Eastern European studios quickly increased as the concept of "national cinema" gave way to a "new European" one. The article focuses on the following topics: changes in East European production schemes, the end of national cinemas, issues of co-producing with focus on Euroimage, media and commercial financing, the questions of domestic versus foreign film distribution and exhibition, and festivals

ASPIICS: an externally occulted coronagraph for PROBA-3. Design evolution

PROBA-3 is a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future ESA missions. PROBA-3 will fly ASPIICS (Association de Satellites pour l’Imagerie et l’Interferometrie de la Couronne Solaire) as primary payload, which makes use of the formation flying technique to form a giant coronagraph capable of producing a nearly perfect eclipse allowing to observe the sun corona closer to the rim than ever before. The coronagraph is distributed over two satellites flying in formation (approx. 150m apart). The so called Coronagraph Satellite carries the camera and the so called Occulter Satellite carries the sun occulter disc. This paper is reviewing the design and evolution of the ASPIICS instrument as at the beginning of Phase C/D