958 research outputs found

    Diwata-2: Earth Observation Microsatellite with a Compact Bus System, ElectronicallyTunable Multi-spectral Imager, and Amateur Radio Communications Capability

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    The microsatellite Diwata-2 was launched into the 600-km Sun-Synchronous Orbit (SSO) last October 29, 2018. It has a low-power, low-complexity, compact bus structure, capable of Earth observation and remote sensing mission through a 5-meter resolution Near-Infrared (NIR) High Precision Telescope (HPT) and a 125-meter resolution Space-borne Multispectral Imager (SMI) with two Liquid Crystal Tunable Filters (LCTF). The LCTF operates as an electronic-based band reconfiguration filter allowing for more than 600-channels of wavelength variation. As a secondary mission, Diwata-2 has full-duplex FM voice communications capability via a non-board module utilizing the amateur radio band at a 5W power requirement from mobile ground users. The structure has a 500-mm cubic external dimension, with JAXA’s Payload Attached Fairing (PAF) rocket interface and deployment mechanism. Deployable solar array panels (DSAP) were also introduced to increase the power generation capabilities of the microsatellite. The importance of detailed structural-mechanical models for finite-element analysis allowed for accurate structural simulation results. The observed accuracy is within 5-Hz for the first two modes compared to the actual vibration test results. Lastly, strict management of in-flight procedures allowed for consistent satellite performance, while modification of satellite maneuver based on imaging observation results improved target pointing accuracy to within 5-km

    CHES: a space-borne astrometric mission for the detection of habitable planets of the nearby solar-type stars

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    The Closeby Habitable Exoplanet Survey (CHES) mission is proposed to discover habitable-zone Earth-like planets of the nearby solar-type stars (∼10 pc\sim 10~\mathrm{pc} away from our solar system) via micro-arcsecond relative astrometry. The major scientific objectives of CHES are: to search for Earth Twins or terrestrial planets in habitable zones orbiting 100 FGK nearby stars; further to conduct a comprehensive survey and extensively characterize the nearby planetary systems. The primary payload is a high-quality, low-distortion, high-stability telescope. The optical subsystem is a coaxial three-mirror anastigmat (TMA) with a 1.2 m1.2 \mathrm{~m}-aperture, 0.44∘×0.44∘0.44^{\circ} \times 0.44^{\circ} field of view and 500 nm−900 nm500 \mathrm{~nm}-900 \mathrm{~nm} working waveband. The camera focal plane is composed of 81 MOSAIC scientific CMOS detectors each with 4 K×4 K4 \mathrm{~K} \times 4 \mathrm{~K} pixels. The heterodyne laser interferometric calibration technology is employed to ensure micro-arcsecond level (1 μ\muas) relative astrometry precision to meet the requirements for detection of Earth-like planets. CHES satellite operates at the Sun-Earth L2 point and observes the entire target stars for 5 years. CHES will offer the first direct measurements of true masses and inclinations of Earth Twins and super-Earths orbiting our neighbor stars based on micro-arcsecond astrometry from space. This will definitely enhance our understanding of the formation of diverse nearby planetary systems and the emergence of other worlds for solar-type stars, and finally to reflect the evolution of our own solar system.Comment: 39 pages, 37 figures, Invited Review, accepted to Research in Astronomy and Astrophysic

    Telecommunications and data acquisition systems support for Voyager missions to Jupiter and Saturn, 1972-1981, prelaunch through Saturn encounter

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    The Deep Space Network has supported the Voyager Project for approximately nine years, during which time implementation, testing, and operational support was provided. Four years of this time involved testing prior to launch; the final five years included network operations support and additional network implementation. Intensive and critical support intervals included launch and four planetary encounters. The telecommunications and data acquisition support for the Voyager Missions to Jupiter and Saturn are summarized

    Formation Flight in Low-Earth-Orbit at 150 m Distance - AOCS In-Orbit Experience

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    Space physics missions handbook

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    The purpose of this handbook is to provide background data on current, approved, and planned missions, including a summary of the recommended candidate future missions. Topics include the space physics mission plan, operational spacecraft, and details of such approved missions as the Tethered Satellite System, the Solar and Heliospheric Observatory, and the Atmospheric Laboratory for Applications and Science

    Tracking and Data System Support for the Mariner Venus/Mercury 1973 Project

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    The Tracking and Data System, which provided outstanding support to the Mariner Venus/Mercury 1973 project during the period from January 1970 through March 1975 are chronologically described. In the Tracking and Data System organizations, plans, processes, and technical configurations, which were developed and employed to facilitate achievement of mission objectives, are described. In the Deep Space Network position of the tracking and data system, a number of special actions were taken to greatly increase the scientific data return and to assist the project in coping with in-flight problems. The benefits of such actions were high; however, there was also a significant increase in risk as a function of the experimental equipment and procedures required

    Mariner Venus-Mercury 1973 project. Volume 2: Extended mission-Mercury 2 and 3 encounters

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    The Mariner Venus/Mercury 1973 mission operations Extended Mission is described. The activities are summarized from shortly after Mercury I through the end of mission. The operational activities are reported by Mission Operations Systems functions providing a brief summary from each discipline. Based on these experiences recommendations for future projects are made

    Calibration and performance of the Galileo solid-state imaging system in Jupiter orbit

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    The solid-state imaging subsystem (SSI) on the National Aeronautics and Space Administration’s (NASA’s) Galileo Jupiter orbiter spacecraft has successfully completed its 2-yr primary mission exploring the Jovian system. The SSI has remained in remarkably stable calibration during the 8-yr flight, and the quality of the returned images is exceptional. Absolute spectral radiometric calibration has been determined to 4 to 6% across its eight spectral filters. Software and calibration files are available to enable radiometric, geometric, modulation transfer function (MTF), and scattered light image calibration. The charge-coupled device (CCD) detector endured the harsh radiation environment at Jupiter without significant damage and exhibited transient image noise effects at about the expected levels. A lossy integer cosine transform (ICT) data compressor proved essential to achieving the SSI science objectives given the low data transmission rate available from Jupiter due to a communication antenna failure. The ICT compressor does introduce certain artifacts in the images that must be controlled to acceptable levels by judicious choice of compression control parameter settings. The SSI team’s expertise in using the compressor improved throughout the orbital operations phase and, coupled with a strategy using multiple playback passes of the spacecraft tape recorder, resulted in the successful return of 1645 unique images of Jupiter and its satellites

    Mariner Mars 1971 project. Volume 3: Mission operations system implementation and standard mission flight operations

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    The Mariner Mars 1971 mission which was another step in the continuing program of planetary exploration in search of evidence of exobiological activity, information on the origin and evolution of the solar system, and basic science data related to the study of planetary physics, geology, planetology, and cosmology is reported. The mission plan was designed for two spacecraft, each performing a separate but complementary mission. However, a single mission plan was actually used for Mariner 9 because of failure of the launch vehicle for the first spacecraft. The implementation is described, of the Mission Operations System, including organization, training, and data processing development and operations, and Mariner 9 spacecraft cruise and orbital operations through completion of the standard mission from launch to solar occultation in April 1972 are discussed

    Underwater Vehicles

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    For the latest twenty to thirty years, a significant number of AUVs has been created for the solving of wide spectrum of scientific and applied tasks of ocean development and research. For the short time period the AUVs have shown the efficiency at performance of complex search and inspection works and opened a number of new important applications. Initially the information about AUVs had mainly review-advertising character but now more attention is paid to practical achievements, problems and systems technologies. AUVs are losing their prototype status and have become a fully operational, reliable and effective tool and modern multi-purpose AUVs represent the new class of underwater robotic objects with inherent tasks and practical applications, particular features of technology, systems structure and functional properties
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