Acedia

The work in the exhibition investigated signs and symbols of acedia in Western art from the Renaissance onwards. The images were juxtaposed with quotations from Gustave Flaubert’s The Temptation of St. Antony (1874), ‘The legend of St Julian the hospitaller’ (from ‘Trois Contes’ (1877)), and Pierre de Marivaux’s ‘Apology of Nothing’ (‘L’eloge du rien’, from the novel ‘Pharsamon ou Les Folies romanesques'(1737)). The work signified ideas of idleness and boredom through objects and situations, reinterpreting the iconography of the deadly sins. Using the resources of the Warburg Institute in London, Richon’s research included a systematic enquiry into the iconography of acedia, as well as related texts from Renaissance studies. The work translated signs and symbols of acedia while expanding the visual vocabulary for a contemporary understanding of the relevance of idleness. The analogue photographs were conceived as melancholic images that referred to something that is lost, absent or inscrutable. Melancholia is understood as a particular attraction for reading signs and symbols that have gradually lost their meaning and function, and that are now haunting the contemporary landscape of representations. Research into acedia was developed through a critical reading of the concept of the image-as-appearance in Plato’s Sophist, in Richon’s article, ‘The sophist and the photograph’, published in Philosophy of Photography (2010). His essay, ‘Acedia – on dreaming and idleness’ was published in the book Seeing for Others (2012). The exhibition ‘Acedia’ was reviewed in Art in America (2013) and Elephant (Winter 2012–13)

The Scott-Magat Polymer Theory for Determining Onset of Precipitation of Dissolved Asphaltene in the Solvent + Precipitant Solution

This article has been published in an open access journal and is also available at http://www.benthamscience.com/open/totherj/articles/V002/13TOTHERJ.pdfInternational audienceThe Scott-Magat polymer theory, which assumes that polymers have heterogeneous structure and takes into account the polydispersity in the molecular weight of polymers, is a method to model asphaltene precipitation conditions. The traditional Scott-Magat polymer theory based models assume that the precipitated phase consists of asphaltene only. In the present work, we introduce a model based on the Scott-Magat polymer theory assuming that the precipitated phase consists of asphaltene and non-asphaltene components and the oil phase is free of asphaltene (Due to low concentration of asphaltene in the oil phase). It is shown that the latter model is similar to a previously reported thermodynamic model in the literature based on the Flory-Huggins polymer theory (R. Cimino, S. Correra, P.A. Sacomani, C. Carniani, "Thermodynamic Modelling for Prediction of Asphaltene Deposition in Live Oils", SPE 28993, Presented at the SPE International Symposium on Oilfield Chemistry held in San Antonio, TX, USA, 14-17 February 1995), in which it is assumed that asphaltene has a homogeneous structure and the precipitated phase consists of asphaltene and non-asphaltene components and the oil phase is free of asphaltene

Anima(l)

Approaching visual allegory from a contemporary point of view, the photographs in this exhibition included contemporary still lives and portraits of living animals taken in a studio setting. The work reflected upon the animate and the inanimate, and the way in which a tension between the two is created by the use of photography. It remains ambiguous whether the animal is used to play a role, or if it remains alien to the intended staging. In her review of the exhibition in Frieze magazine (2009), Sarah James described the allegorical affect: ‘All of [Richon’s] photographs appear to connote highly specific meanings, yet refuse to give anything away. They are more parodies of allegories than allegories themselves, invested in the aesthetic of ambivalence and promising a narrative content or meaning that might unfold over time or, equally, never materialize.’ Richon’s methodology pairs a systematic and rigorous use of lighting, colour, shadows and iconographic references with a studio setting that enables a staging of a comparative taxonomy. The photographic image is here endowed with a particular type of thoughtfulness: it is an image that proposes an indeterminate state between activity and passivity, movement and stillness, denotation and connotation. The exhibition was well reviewed, receiving substantial coverage in Frieze and Studio International. Richon was invited to present his research in a paper, ‘The animal, mimicry and the mouth’ at the International Symposium ‘The Animal Gaze Returned’ at London Metropolitan University (2011), and was included in the group show ‘The Animal Gaze Returned’ at Sheffield Hallam University (2013). Works from the exhibition were also shown in group shows, including ‘Teaching Photography’ at the Museum Folkwang, Essen (2010) and ‘Le Bestiaire Imaginaire’, Palais Lumière, Evian (2010–11)

EUVE/XTE orbit decay study

The Explorer Platform (EP) program currently comprises two missions, the Extreme Ultraviolet Explorer (EUVE) and the X-ray Timing Explorer (XTE), each of which consists of a scientific payload mounted to the EP. The EP has no orbit maintenance capability. The EP with the EUVE payload will be launched first. At the end of the EUVE mission, the spacecraft will be serviced by the Space Transportation System (STS), and the EUVE instrument will be exchanged for the XTE. The XTE mission will continue until reentry or reservicing by the STS. Because the missions will be using the EP sequentially, the orbit requirements are unusually constrained by orbit decay rates. The initial altitude must be selected so that, by the end of the EUVE mission (2.5 years), the spacecraft will have decayed to an altitude within the STS capabilities. In addition, the payload exchange must occur at an altitude that ensures meeting the minimum XTE mission lifetime (3 years) because no STS reboost will be available. Studies were performed using the Goddard Mission Analysis System to estimate the effects of mass, cross-sectional area, and solar flux on the fulfillment of mission requirements. In addition to results from these studies, conclusions are presented as to the accuracy of the Marshall Space Flight Center solar flux predictions

The Earth Science Afternoon Constellation Contingency Procedures

The Earth Science Afternoon Constellation comprises NASA missions Aqua, Aura, CloudSat and the Orbiting Carbon Observatory (OCO), the joint NASA/CNES mission CALIPSO and the CNES mission PARASOL. Both NASA and CNES offices are responsible for ensuring that contingency plans or other arrangements exist to cope with contingencies within their respective jurisdictions until the conclusion of all Afternoon Constellation operations. The Mission Operations Working Group, comprised of members from each of the missions, has developed the high-level procedures for maintaining the safety of this constellation. Each contingency situation requires detailed analyses before any decisions are made. This paper describes these procedures, and includes defining what constitutes a contingency situation, the pertinent parameters involved in the contingency analysis and guidelines for the actions required, based on the results of the contingency analyses

Launch Window Trade Analysis for the James Webb Space Telescope

The James Webb Space Telescope (JWST) is a large-scale space telescope mission designed to study fundamental astrophysical questions ranging from the formation of the universe to the origin of planetary systems and the origins of life. JWSTs orbit design is a Libration Point Orbit (LPO) around the Sun-Earth/Moon (SEM) L2 point for a planned mission lifetime of 10.5 years. The launch readiness period for JWST is from Oct 1st, 2018 November 30th, 2018. This paper presents the first launch window analysis for the JWST observatory using finite-burn modeling; previous analysis assumed a single impulsive midcourse correction to achieve the mission orbit. The physical limitations of the JWST hardware stemming primarily from propulsion, communication and thermal requirements alongside updated mission design requirements result in significant launch window within the launch readiness period. Future plans are also discussed

James Webb Space Telescope Orbit Determination Analysis

The James Webb Space Telescope (JWST) is designed to study and answer fundamental astrophysical questions from an orbit about the Sun-Earth/Moon L2 libration point, 1.5 million km away from Earth. This paper describes the results of an orbit determination (OD) analysis of the JWST mission emphasizing the challenges specific to this mission in various mission phases. Three mid-course correction (MCC) maneuvers during launch and early orbit phase and transfer orbit phase are required for the spacecraft to reach L2. These three MCC maneuvers are MCC-1a at Launch+12 hours, MCC-1b at L+2.5 days and MCC-2 at L+30 days. Accurate OD solutions are needed to support MCC maneuver planning. A preliminary analysis shows that OD performance with the given assumptions is adequate to support MCC maneuver planning. During the nominal science operations phase, the mission requires better than 2 cm/sec velocity estimation performance to support stationkeeping maneuver planning. The major challenge to accurate JWST OD during the nominal science phase results from the unusually large solar radiation pressure force acting on the huge sunshield. Other challenges are stationkeeping maneuvers at 21-day intervals to keep JWST in orbit around L2, frequent attitude reorientations to align the JWST telescope with its targets and frequent maneuvers to unload momentum accumulated in the reaction wheels. Monte Carlo analysis shows that the proposed OD approach can produce solutions that meet the mission requirements

Libration Orbit Eclipse Avoidance Maneuver Study for the James Webb Space Telescope Mission

Mission analysis of libration orbit trajectories at Sun-Earth/Moon L2 typically includes predictions of lunar and Earth eclipses during the mission life-time. The NASA James Webb Space Telescope (JWST) trajectory, by design, avoids these eclipses by pruning its launch window. In an off-nominal scenario where an eclipse is predicted, a maneuver strategy is needed. In this paper, trade studies are examined for JWST that characterize the burn magnitude, location, and epochs of multiple maneuver plans to avoid an eclipse. The results enable analysts to explore the space of feasible maneuver strategies during routine operations

Analysis For Monitoring the Earth Science Afternoon Constellation

The Earth Science Afternoon Constellation consists of Aqua, Aura, PARASOL, CALIPSO, Cloudsat, and the Orbiting Carbon Observatory (OCO). The coordination of flight dynamics activities between these missions is critical to the safety and success of the Afternoon Constellation. This coordination is based on two main concepts, the control box and the zone-of-exclusion. This paper describes how these two concepts are implemented in the Constellation Coordination System (CCS). The CCS is a collection of tools that enables the collection and distribution of flight dynamics products among the missions, allows cross-mission analyses to be performed through a web-based interface, performs automated analyses to monitor the overall constellation, and notifies the missions of changes in the status of the other missions

Mid-Course Correction Contingency Analysis for the James Webb Space Telescope

This investigation details two analyses performed as part of an early orbit contingency operations study related to the James Webb Space Telescopes limited ability to maneuver in a sunward direction. First, contingency planning developed by the Flight Dynamics Team and shared with the Science and Operations Center to quickly assess the available timeline in the event of a delayed mid-course correction maneuver is presented. Second, the methods for recovering from a maneuver over-burn using observatory geometry to exploit the solar radiation pressure perturbation contributions from the large sunshield as well as adjusting the maneuver campaign to recover the observatory are examined