346,462 research outputs found

    Radiometric Model and Inter-Comparison Results of the SGLI-VNR On-Board Calibration

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    The Second Generation Global Imager (SGLI) on Global Change Observation Mission Climate (GCOM-C) satellite empowers surface and atmospheric measurements related to the carbon cycle and radiation budget, with two radiometers of Visible and Near Infrared Radiometer (SGLI-VNR) and Infrared Scanning Radiometer (SGLI-IRS) that perform a wide-band (380 nm12 m) optical observation not only with as wide as a 11501400 km field of view (FOV), but also with as high as 0.250.5 km resolution. Additionally, polarization and along-track slant view observations are quite characteristic of SGLI. It is important to calibrate radiometers to provide the sensor data records for more than 28 standard products and 23 research products including clouds, aerosols, ocean color, vegetation, snow and ice, and other applications. In this paper, the radiometric model and the first results of on-board calibrations on the SGLI-VNR, which include weekly solar and light-emitting diode (LED) calibration and monthly lunar calibration, will be described. Each calibration data was obtained with corrections, where beta angle correction and avoidance of reflection from multilayer insulation (MLI) were applied for solar calibration; LED temperature correction was performed for LED calibration; and the GIRO (GSICS (Global Space-based Inter-Calibration System) Implementation of the ROLO (RObotic Lunar Observatory) model) model was used for lunar calibration. Results show that the inter-comparison of the relative degradation amount between these three calibrations agreed to within 1% or less

    3Cat-3/MOTS nanosatellite mission for optical multispectral and GNSS-R Earth Observation: concept and analysis

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    The 3Cat-3/MOTS (3: Cube, Cat: Catalunya, 3: 3rd CubeSat mission/Missió Observació Terra Satèl·lit) mission is a joint initiative between the Institut Cartogràfic i Geològic de Catalunya (ICGC) and the Universitat Politècnica de Catalunya-BarcelonaTech (UPC) to foster innovative Earth Observation (EO) techniques based on data fusion of Global Navigation Satellite Systems Reflectometry (GNSS-R) and optical payloads. It is based on a 6U CubeSat platform, roughly a 10 cm × 20 cm × 30 cm parallelepiped. Since 2012, there has been a fast growing trend to use small satellites, especially nanosatellites, and in particular those following the CubeSat form factor. Small satellites possess intrinsic advantages over larger platforms in terms of cost, flexibility, and scalability, and may also enable constellations, trains, federations, or fractionated satellites or payloads based on a large number of individual satellites at an affordable cost. This work summarizes the mission analysis of 3Cat-3/MOTS, including its payload results, power budget (PB), thermal budget (TB), and data budget (DB). This mission analysis is addressed to transform EO data into territorial climate variables (soil moisture and land cover change) at the best possible achievable spatio-temporal resolution.Peer ReviewedPostprint (published version

    The Global Precipitation Measurement (GPM) Mission: Overview and U.S. Status

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    The Global Precipitation Measurement (GPM) Mission is an international satellite mission designed to unify and advance precipitation measurements from a constellation of research and operational microwave sensors. NASA and JAXA will deploy the GPM Core Observatory carrying an advanced radar-radiometer system to serve as a physics observatory and a transfer standard for inter-calibration of constellation radiometers. The GPM Core Observatory is scheduled for launch in July 2013. NASA will provide a second radiometer to be flown on a partner-provided GPM Low-Inclination Observatory to enhance the near real-time monitoring of hurricanes and mid-latitude storms. JAXA will also contribute data from the Global Change Observation Mission-Water (GCOM-W) satellite. Additional partnerships are under development to include microwave radiometers on the French-Indian Megha-Tropiques satellite and U.S. Defense Meteorological Satellite Program (DMSP) satellites, as well as cross-track scanning humidity sounders on operational satellites such as the NPP, POES, JPSS, and MetOp satellites, which are used to improve the precipitation sampling over land. Brazil has in its national space plan for a GPM low-inclination radiometer, and data from Chinese and Russian microwave radiometers could potentially become available through international collaboration under the auspices of the Committee on Earth Observation Satellites (CEOS) and Group on Earth Observations (GEO). The current generation of global rainfall products combines observations from a network of uncoordinated satellite missions using a variety of merging techniques. GPM will provide "next-generation" precipitation data products characterized by: (1) more accurate instantaneous precipitation measurement (especially for light rain and cold-season solid precipitation), (2) more frequent sampling by an expanded constellation of microwave radiometers including operational humidity sounders over land, (3) intercalibrated microwave brightness temperatures from constellation radiometers within a unified framework, and (4) physical-based precipitation retrievals from constellation radiometers using a common a priori cloud/hydrometeor database constructed from GPM Core sensor measurements. As a science mission with integrated application goals, GPM will (1) provide new measurement standards for precipitation estimation from space, (2) improve understanding of precipitation physics, the global water cycle variability, and freshwater availability, and (3) advance weather/climate/hydrological prediction capabilities to directly benefit the society. An overview of the GPM mission concept, NASA program status, science activities in the United States, as well as a wide range of international scientific collaborations in radiometer inter-calibration, retrieval algorithm development, and ground validation will be presented

    Enabling Hybrid Architectures and Mesh Network Topologies to Support the Global Multi-Domain Community

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    The turn of the new decade also represents the dawn of a new shift in domain operations. Concepts such as “Space Dial Tone,” reliable global access to internet, on-demand Earth observation, and remote sensing, while still not fully realized, are no longer purely imaginative. These concepts are in high demand and are coupled with the goals of Global Multi-Domain Operations (MDO). Small satellites (smallsats) have emerged as functionally reliable platforms, driving the development of next-generation satellite constellations. To achieve the potential of tomorrow’s technology, these constellations must embrace space mission architectures based on interoperable, open-system constructs such as hybrid architectures and mesh network topologies. This paper presents the full timeline for realization of multi-node, disparate (sovereign, coalition, commercial, etc.) multi-domain (Space, Air, Maritime, Land, and Cyber) systems to support future space mission architectures. It identifies and discusses the underlying technologies needed to bring new “system-of-systems” concepts to operational capability. Technologies to be discussed include: message-agnostic physical/protocol “Bridges”; Machine-to-Machine (M2M) data sharing enabled through Electronic Data Sheet (EDS) standards; and, new concepts related to Artificial Intelligence (AI) enabled human decision making. Tying these technologies together effectively will positively impact the smallsat market and fundamentally change mission architectures in the near future

    3D Online Visualization and Synergy of NASA A-Train Data Using Google Earth

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    This poster presentation reviews the use of Google Earth to assist in three dimensional online visualization of NASA Earth science and geospatial data. The NASA A-Train satellite constellation is a succession of seven sun-synchronous orbit satellites: (1) OCO-2 (Orbiting Carbon Observatory) (will launch in Feb. 2013), (2) GCOM-W1 (Global Change Observation Mission), (3) Aqua, (4) CloudSat, (5) CALIPSO (Cloud-Aerosol Lidar & Infrared Pathfinder Satellite Observations), (6) Glory, (7) Aura. The A-Train makes possible synergy of information from multiple resources, so more information about earth condition is obtained from the combined observations than would be possible from the sum of the observations taken independentl

    The Integrated Carbon Observation System in Europe

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    Since 1750, land-use change and fossil fuel combustion has led to a 46% increase in the atmospheric carbon dioxide (CO2) concentrations, causing global warming with substantial societal consequences. The Paris Agreement aims to limit global temperature increases to well below 2 degrees C above preindustrial levels. Increasing levels of CO2 and other greenhouse gases (GH6s), such as methane (CH4) and nitrous oxide (N2O), in the atmosphere are the primary cause of climate change. Approximately half of the carbon emissions to the atmosphere are sequestered by ocean and land sinks, leading to ocean acidification but also slowing the rate of global warming. However, there are significant uncertainties in the future global warming scenarios due to uncertainties in the size, nature, and stability of these sinks. Quantifying and monitoring the size and timing of natural sinks and the impact of climate change on ecosystems are important information to guide policy-makers' decisions and strategies on reductions in emissions. Continuous, long-term observations are required to quantify GHG emissions, sinks, and their impacts on Earth systems. The Integrated Carbon Observation System (ICOS) was designed as the European in situ observation and information system to support science and society in their efforts to mitigate climate change. It provides standardized and open data currently from over 140 measurement stations across 12 European countries. The stations observe GHG concentrations in the atmosphere and carbon and GHG fluxes between the atmosphere, land surface, and the oceans. This article describes how ICOS fulfills its mission to harmonize these observations, ensure the related long-term financial commitments, provide easy access to well-documented and reproducible high-quality data and related protocols and tools for scientific studies, and deliver information and GHG-related products to stakeholders in society and policy.Peer reviewe

    AMSR2 Soil Moisture Product Validation

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    The Advanced Microwave Scanning Radiometer 2 (AMSR2) is part of the Global Change Observation Mission-Water (GCOM-W) mission. AMSR2 fills the void left by the loss of the Advanced Microwave Scanning Radiometer Earth Observing System (AMSR-E) after almost 10 years. Both missions provide brightness temperature observations that are used to retrieve soil moisture. Merging AMSR-E and AMSR2 will help build a consistent long-term dataset. Before tackling the integration of AMSR-E and AMSR2 it is necessary to conduct a thorough validation and assessment of the AMSR2 soil moisture products. This study focuses on validation of the AMSR2 soil moisture products by comparison with in situ reference data from a set of core validation sites. Three products that rely on different algorithms were evaluated; the JAXA Soil Moisture Algorithm (JAXA), the Land Parameter Retrieval Model (LPRM), and the Single Channel Algorithm (SCA). Results indicate that overall the SCA has the best performance based upon the metrics considered

    Extension of earth orbits using low-thrust propulsion

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    The primary motivation for the utilization of space for environmental science, and in-particular Earth Observation, is the unique vantage point which a spacecraft can provide. For example, a spacecraft can provide a global dataset with a much higher temporal resolution than any other platform. Earth Observation spacecraft are increasingly focused on a single primary application, typically conducted from a small set of classical orbits which limits the range of vantage points and hence the type of observations which can be made. The next generation of innovative Earth Observation spacecraft may however only be enabled through new orbit options not considered in the past. The objective of the study was therefore to enlarge the set of potential Earth orbits by considering the use of low-thrust propulsion to extend the conventional Molniya orbit. These new orbits will use existing, or near-term low-thrust propulsion technology to enable new Earth Observation science and offer a radically new set of tools for mission design. Continuous low-thrust propulsion was applied in the radial, transverse and normal directions to vary the critical inclination of the Molniya orbit, while maintaining the zero change in argument of perigee condition. As such the inclination can be freely altered from the expected critical inclination of 63.4 deg, to, for example 90 deg, creating a Polar-Molniya orbit. Analytical expressions were developed which were then validated using a numerical model, to show that not only was the argument of perigee unchanged but all other orbital elements were also unaffected by the applied low-thrust. It was shown that thrusting in the transverse direction allowed the spacecraft to achieve any inclination with the lowest thrust magnitude in any single direction; this value was however found to be further reduced by combining both radial and transverse thrust. Real-time continuous observation of the Arctic Circle is then enabled using current electric propulsion technology, with fewer spacecraft than the traditional Sun-synchronous polar orbit, and at reduced range than a 'pole-sitter'. Applications of such an orbit would include more accurate Arctic weather predictions and severe weather event warnings for this region
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