755 research outputs found

    A Bloody Tradition: Ethnic Cleansing in World War II Yugoslavia

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    When World War II began, a climate for mass violence already existed. The author examines the history of ethnic cleansing, cultural cleansing, mass murder, and genocide in Yugoslavia – Serbia, Croatia, Bosnia-Hertzegovena, and Kosovo – and finds that the historical atrocities are alive in active memory today. With a new awareness of the consequences of ethnic hatred, people can study their own histories cleansed of myth and nationalist delusions so that wars that unleash ethnic violence can be stopped before these excesses erupt

    Mg II line profiles of the Mira S Carinae

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    High-dispersion IUE observations obtained to investigate the evolution of the shock structure of the Mira S Carinae (S Car) produced, despite very limited phase coverage, a set of five spectra of the Mg II h and k lines. There is significant emission from both the h and k lines at velocities of -150 km/sec relative to the stellar photosphere. The h-to-k ratio of the Mg II doublet remains below the theoretically predicated values of 2:1 to 1:1, and shows a smooth dependence on the optical phase. Archival studies of other Miras (e.g., R Car) indicate that S Car is not unique in possessing unusual and highly variable Mg II h and k line profiles

    The International X-ray Observatory

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    The International X-ray Observatory (IXO) is a joint ESA-JAXA-NASA effort to address fundamental and timely questions in astrophysics: What happens close to a black hole? How did supermassive black holes grow? How does large scale structure form? What is the connection between these processes? To address these questions IXO will employ optics with 3 sq m collecting area and 5 arc sec angular resolution - 20 times more collecting area at 1 keV than any previous X-ray observatory. Focal plane instruments will deliver a 100-fold increase in effective area for high-resolution spectroscopy, deep spectral imaging over a wide field of view, unprecedented polarimetric sensitivity, microsecond spectroscopic timing, and high count rate capability. The mission is being planned for launch in 2021 to an L2 orbit, with a five-year lifetime and consumables for 10 years.Comment: 6 pages, 3 figures, for conference "X-ray Astronomy 2009 Present status, multi-wavelength approach and future perspectives

    A Small Spacecraft Swarm Deployment and Stationkeeping Strategy for Sun-Earth L1 Halo Orbits

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    Spacecraft orbits about the Sun-Earth librarian point L1 have been of interest since the 1950s. An L1 halo orbit was first achieved with the International Sun-Earth Explorer-3 (ISEE-3) mission, and similar orbits around Sun-Earth L1 were achieved in the Solar and Heliospheric Observatory (SOHO), Advanced Composition Explorer (ACE), Genesis, and Deep Space Climate Observatory (DSCOVR) missions. With recent advancements in CubeSat technology, we envision that it will soon be feasible to deploy CubeSats at L1. As opposed to these prior missions where one large satellite orbited alone, a swarm of CubeSats at L1 would enable novel science data return, providing a topology for intersatellite measurements of heliophysics phenomena both spatially and temporally, at varying spatial scales.The purpose of this iPoster is to present a flight dynamics strategy for a swarm of numerous CubeSats orbiting Sun-Earth L1. The presented method is a coupled, two-part solution. First, we present a deployment strategy for theCubeSats that is optimized to produce prescribed, time-varying intersatellite baselines for the purposes of collectingmagnetometer data as well as radiometric measurements from cross-links. Second, we employ a loose controlstrategy that was successfully applied to SOHO and ACE for minimized stationkeeping propellant expenditure. Weemphasize that the presented solution is practical within the current state-of-the-art and heritage CubeSat technology,citing capabilities of CubeSat designs that will launch on the upcoming Exploration Mission 1 (EM-1) to lunar orbitsand beyond. Within this iPoster, we present animations of the simulated deployment strategy and resulting spacecrafttrajectories. Mission design parameters such as total v required for long-term station keeping andminimum/maximum/mean spacecraft separation distances are also presented
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