Development of a Small Satellite Remote Sensing Payload for Passive Limb Sounding of the Atmospheric Oxygen Emission

The Mesosphere/ Lower Thermosphere (MLT) is the region of the atmosphere in the altitude range from 60 km to 110 km. This region becomes more and more important for climate predictions and weather forecasts with the extension of simulation models to higher altitudes. The global dynamics of the MLT is driven by gravity waves. Gravity waves are generated in the lower atmosphere and transport momentum to the MLT, where these waves break and dissipate. The resulting gravity wave drag influences the wind fields and, thus, the global circulation in this region. However, gravity waves are not yet sufficiently well represented in global circulation models, because their scales are often below the grid size of the simulation models, requiring that gravity waves are parameterized. The parameterization is one of the major uncertainties in current simulation models. Thus, observational data are required to better understand the underlying processes and to constrain gravity waves in the global circulation models. However, current gravity wave observing satellites for the MLT exceeded their operational lifetimes and succeeding missions are sparse. The observational gap in the near future is already conceivable. The goal of this work is to propose a novel satellite mission with the corresponding remote sensing instrument that can reduce the data gap through a low-cost, agile, and scalable satellite. The satellite is based on the 3U CubeSat form factor that limits the mass to 4 kg and the launch volume to 34cm x 10 cm x 10 cm. CubeSats are nano satellites that can be launched on many different rockets through a standardized interface that eases the access to space. The here proposed AtmoCube-1 mission is described on a conceptual level. The focus of this work lies on the development of the remote sensing instrument that enables the characterization of gravity waves through temperature soundings in the MLT with a limb viewing geometry. The instrument measures the oxygen atmospheric band emission around 762 nm with a high spectral resolution in a small bandwidth to derive the kinetic temperature in the MLT from the temperature dependence of individual rotational fine structure lines. Thereby, the instrument uses a monolithic and temperature stabilized Fourier-transform spectrometer of the type Spatial Heterodyne Spectrometer that is characterized by a high resolving power and a high etendué at a small form factor. Thus, this instrument can be miniaturized to fit into the volume of a CubeSat. The development of the instrument and of the satellite mission started with this work. Accordingly, the specification of the satellite instrument is a major part of this work, followed by the actual development of the instrument within the mission AtmoHIT. The Atmospheric Heterodyne Interferometer Test (AtmoHIT) is an experiment on-board the sounding rocket REXUS 22 that was launched in Kiruna, Sweden, in March 2017, within the Rocket/Ballon Experiments for University Students program. AtmoHIT had the goal to verify the satellite instrument under near-space conditions by measuring the oxygen atmospheric band. The temperature stabilized design of the spectrometer has been verified in a thermal vacuum chamber test before the flight, where also the operations in the temperature range from -20 degC to 46 degC have been confirmed. Vibration tests indicated that the instrument can sustain the loads during the flight, which was demonstrated with the successful rocket flight campaign. The campaign showed also that the instrument operates under near-space conditions. The oxygen atmospheric band was measured, demonstrating the functionality of the instrument. An anomaly occurred during the separation of the payload module and the rocket motor that resulted in a strongly tumbling payload. Thus, the goal of temperature sounding in the MLT could not be fulfilled. Nevertheless, the sounding rocket campaign was deemed successful, because it showed that the instrument performed as expected. This work concludes by a discussion of the major results from the instrument development and possible enhancements to the instrument. The here developed methods and design tools are already employed in the related projects AtmoSHINE and AtmoWINDS that eventually lead to the launch of the AtmoCube-1 satellite.</p

Study on a miniaturized satellite payload for atmospheric temperature measurements

The atmospheric temperature reflects the thermal balance of the atmosphere and is a valuable indicator of climate change. It has been widely recognized that the atmospheric gravity wave activity has a profound effect on the large-scale circulation, thermal and constituent structures in the mesosphere and lower thermosphere (MLT). Temperature distribution in this region is an essential component to identify and quantify gravity waves. Observation from remote sensing instruments on satellite platforms is an effective way to measure the temperature in the MLT region. A miniaturized satellite payload is developed to measure the atmospheric temperature in the MLT region via observing the O2A-band emission. Following a Boltzmann distribution, the relative intensities of the emission lines can be used to derive the temperature profile. Based on the spatial heterodyne spectroscopy, this instrument is capable of resolving individual emission lines in the O2A-band for the spatial and spectral information simultaneously. The monolithic and compact feature of this spectrometer makes it suitable for operating on satellite platforms. In this work, the characterization of the instrument is investigated for the purpose of simultaneously measuring multiple emission lines of the O2A-band. The instrument is explored through a series of experimental methods, providing characteristics of the instrument and evaluation of its performance. In spatial and spectral domain, Level- 0 and Level-1 data processors are developed to convert the raw data to the calibrated spectral radiance for further temperature and gravity wave characterization. Within this framework, the performance of the utilized detector is evaluated along with its radiation tolerance in space environment. In the processor, the detector artifacts are corrected based on the measurements in laboratory or in space. The radiometric response of the instrument is characterized on a pixel-by-pixel basis using a blackbody. An interferogram distortion correction algorithm is developed to correct for the spatial and phase distortion induced by the detector optics. Further, localized phase distortion correction is implemented to correct for the remaining phase error. Unwanted ghost emission lines are removed based on two dimensional Fourier transform. In the spectral domain, the processing steps mainly consist of wavelength calibration and instrument spectral response correction, including filter response correction and modulation efficiency correction. As an in-orbit verification, the AtmoSHINE instrument was successfully deployed in space on 22th of December, 2018. In the first test phase, the functionality and the performance of the instrument in space were verified. The detector dark current measurement in orbit is consistent with the ground-based results. Based on the the calibration procedures and the developed data processing algorithms, the O2A-band emission lines can be successfully resolved. A cross-verification of the AtmoSHINE limb radiance profile with other satellite payload measurements indicates that the radiometric performance of the instrument is within the expectation. The retrieved temperature parameters are studied with respect to different number of samples and different objective functions in the optimization. This work verifies the ability of the instrument to derive the atmospheric temperature in the MLT region and its potential application in gravity wave detections

Large space structures and systems in the space station era: A bibliography with indexes (supplement 05)

Bibliographies and abstracts are listed for 1363 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and July 31, 1992. Topics covered include technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion and solar power satellite systems

The science case for the EISCAT_3D radar

The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere (the ionosphere). The mainland radars were constructed about 30 years ago, based on technological solutions of that time. The science drivers of today, however, require a more flexible instrument, which allows measurements to be made from the troposphere to the topside ionosphere and gives the measured parameters in three dimensions, not just along a single radar beam. The possibility for continuous operation is also an essential feature. To facilitatefuture science work with a world-leading IS radar facility, planning of a new radar system started first with an EU-funded Design Study (2005–2009) and has continued with a follow-up EU FP7 EISCAT_3D Preparatory Phase project (2010–2014). The radar facility will be realised by using phased arrays, and a key aspect is the use of advanced software and data processing techniques. This type of software radar will act as a pathfinder for other facilities worldwide. The new radar facility will enable the EISCAT_3D science community to address new, significant science questions as well as to serve society, which is increasingly dependent on space-based technology and issues related to space weather. The location of the radar within the auroral oval and at the edge of the stratospheric polar vortex is also ideal for studies of the long-term variability in the atmosphere and global change. This paper is a summary of the EISCAT_3D science case, which was prepared as part of the EU-funded Preparatory Phase project for the new facility. Three science working groups, drawn from the EISCAT user community, participated in preparing this document. In addition to these working group members, who are listed as authors, thanks are due to many others in the EISCAT scientific community for useful contributions, discussions, and support

Design of a generic end-to-end mission performance simulator and application to the performance analysis of the FLEX/Sentinel-3 mission

La Observación de la Tierra mediante técnicas de teledetección con instrumentos ópticos en satélite tiene como objetivo monitorizar los procesos bio-geofísicos en la superficie y atmósfera terrestre, adquiriendo datos a diferentes longitudes de onda del espectro electromagnético. Con el fin de asegurar el mantenimiento de las observaciones y las capacidades para entender el sistema Tierra, nuevas misiones satelitales están siendo desarrolladas por agencias espaciales nacionales e internacionales así como organizaciones de investigación. En este contexto, los simuladores de misiones espaciales (E2ES por sus siglas en inglés, End-to-End Mission Performance Simulator) ofrecen a los científicos e ingenieros un marco único para entender el impacto de la configuración del instrumento en los productos finales de la misión y, por tanto, acelerar el desarrollo de una misión desde la fase conceptual hasta el lanzamiento. Al mismo tiempo, estas herramientas permiten definir una metodología para la consolidación de los requisitos y la evaluación de la actuación de estas misiones satelitales, estableciendo criterios para la selección de una misión por las diferentes agencias espaciales. Mientras que el concepto de un E2ES es simple, el diseño de nuevos E2ES y la evolución de los ya existentes tienen una falta de guias y metodología estandarizadas, lo cual se traduce en un caro y complejo proceso de re-ingeniería. Esta tesis cubre dos objetivos principales. Por un lado, se pretende armonizar el trabajo hecho en el campo de los E2ES durante las últimas décadas y proponer una serie de guias y metodologías para desarrollas E2ES para misiones satelitales futuras con instrumentos ópticos pasivos. El primer objetivo es por tanto "Diseñar un simulador de misión genérico que pueda ser fácilmente adaptado para reproducir la mayoría de misiones satelitales, presentes y futuras, con sensores ópticos pasivos". Por otro lado, la misión FLEX/Sentinel-3 de la ESA se usa para validar, a través de la implementación de su propio E2ES, el diseño de la arquitectura genérica tratada en el punto anterior. De este modo, el E2ES para la misión FLEX permite evaluar la actuación de la misión para la obtención de la fluorescencia inducida por radiación solar emitida por la vegetación terrestre. La misión FLEX/Sentinel-3 es una candidata óptima para esta tarea de validación dada la complejidad de la misión (p.ej. vuelo en tandem, multi-plataforma/-instrumento, múltiples rangos y resoluciones espectrales, observaciones multi-angulares, sinergia de productos). El segundo objetivo de esta tesis es por tanto "Evaluar la misión FLEX para la la observación de la emisión de fluorescencia emitida por la vegetación usando un E2ES desarrollado de acuerdo con una arquitectura genérica". La razón fundamental tras esta Tesis es promocionar el uso de una arquitectura genérica común para los E2ES que permita comparar misiones satelitales en procesos de selección competitiva como los Earth Explorer de la ESA así como acelerar el análisis de los requisitos técnicos y el rendimiento de la misión a nivel científico. Particularmente, esto se muestra mediante la implementación de esta arquitectura genérica para el caso específico de la misión FLEX/Sentinel-3 demostrando que: (1) la misión es capaz de obtener con la precisión requerida la emisión de fluorescencia por la vegetación ; y (2) el concepto de esta arquitectura genérica es apto para reproducir la complejidad de la misión FLEX/Sentinel-3 y por tanto se espera que esta metodología pueda ser también aplicable para un gran abanico de misiones ópticas pasivas. Esta base lógica se consigue a partir de una categorización de varias misiones satelitales y la identificación y análisis de los elementos principales que afectan en el rendimiento de la misión e impactan en la arquitectura de un simulador de misión. La arquitectura genérica para E2ES propuesta se valida mediante la implementación del E2ES de la misión FLEX/Sentinel-3 de la ESA teniendo en cuenta ambos satélites, sus instrumentos, y evaluando con este E2ES el rendimiento de la misión FLEX. En esta Tesis, los capítulos 1 y 2 introducen los principales temas de esta Tesis y definen los conceptos básicos. Los capítulos 3 al 5 describe el diseño de la arquitectura genérica para los E2ES en misiones ópticas pasivas. Finalmente, el capítulo 6 resume los principales resultados y las conclusiones derivadas de esta Tesis.Earth observation by satellite optical remote sensing aims to monitor bio-geophysical processes happening in the Earth surface and the atmosphere by acquiring data at different wavelengths of the electromagnetic spectrum. In order to ensure sustained observations and capabilities to fill scientific gaps in our current understanding of the Earth system, new satellite missions are being developed by national and international space agencies and research organisations. In this context, End-to-End Mission Performance Simulator (E2ES) tools offer scientists and engineers a unique framework to understand the impact of instrument configuration in the final mission products and to accelerate the mission development from concept to deployment. At the same time, these cost-effective and flexible tools are capable of defining a methodology for the consolidation of requirements and performance assessment of these new satellite missions, setting the criteria for mission selection by the various space agencies’ programme boards. While the concept of an E2ES is simple, the design of new E2ES and the evolution of existing ones lack from a standard methodology and guidelines, which translates into a complex and costly re-engineering process. This Thesis covers two main objectives. On the one hand, it aims to harmonize the work done in the field of E2ES during the last decades and to propose a set of guidelines or methodology to develop E2ES for future remote sensing satellite passive optical missions. The first main objective, therefore, is: ’To design a generic end-to-end mission performance simulator that can be easily adapted to reproduce most present or future passive optical spaceborne instruments’. On the other hand, the ESA’s FLEX/Sentinel-3 tandem mission is used to validate, through the implementation of its E2ES, the designed generic E2ES architecture and to evaluate the performance of the FLEX mission for the retrieval of Sun-induced fluorescence. The FLEX/Sentinel- 3 mission is optimally suitable for this validation task due to the complexity of the mission (e.g. tandem flight, multi-platform/-instrument mission, multiple spectral ranges and resolutions, multi-angular observations, synergy of products). The second main objective, therefore, is: ’To evaluate the FLEX mission for Sun-induced fluorescence retrievals using a newly developed E2ES in agreement with the designed generic E2ES architecture.’. The rationale behind this Thesis is promoting the use of a common generic E2ES architecture that allows comparing missions in competitive selection process (e.g., ESA’s Earth Explorers) and speeding-up the analysis of the mission technical requirements and scientific performances. Particularly, this is shown by implementing this generic E2ES architecture for the specific case of FLEX/Sentinel-3 mission demonstrating that: (1) the mission is capable of retrieving Sun-induced fluorescence within the required accuracy; and (2) the conceptual generic E2ES architecture is suitable toreproduce the complexity of the FLEX/Sentinel-3 tandem mission and thus it is expected to be also applicable for a wide range of passive optical missions. This rationale is achieved by categorising several satellite missions to identify and analyse the main elements that affect the mission performance and impact the simulator architecture. The proposed generic E2ES architecture is validated by implementing the ESA’s FLEX/Sentinel-3 E2ES, both satellites and their instruments, and testing it through the performance assessment of the FLEX mission products. In this Thesis, Chapters 1 and 2 introduce the main research questions and sets the background concepts. Then Chapters 3–5 describe the design of a generic E2ES architecture for passive optical missions. Finally, Chapter 6 summarizes the main results and conclusions derived in this Thesis

The science case for the EISCAT_3D radar

The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere (the ionosphere). The mainland radars were constructed about 30 years ago, based on technological solutions of that time. The science drivers of today, however, require a more flexible instrument, which allows measurements to be made from the troposphere to the topside ionosphere and gives the measured parameters in three dimensions, not just along a single radar beam. The possibility for continuous operation is also an essential feature. To facilitatefuture science work with a world-leading IS radar facility, planning of a new radar system started first with an EU-funded Design Study (2005–2009) and has continued with a follow-up EU FP7 EISCAT_3D Preparatory Phase project (2010–2014). The radar facility will be realised by using phased arrays, and a key aspect is the use of advanced software and data processing techniques. This type of software radar will act as a pathfinder for other facilities worldwide. The new radar facility will enable the EISCAT_3D science community to address new, significant science questions as well as to serve society, which is increasingly dependent on space-based technology and issues related to space weather. The location of the radar within the auroral oval and at the edge of the stratospheric polar vortex is also ideal for studies of the long-term variability in the atmosphere and global change. This paper is a summary of the EISCAT_3D science case, which was prepared as part of the EU-funded Preparatory Phase project for the new facility. Three science working groups, drawn from the EISCAT user community, participated in preparing this document. In addition to these working group members, who are listed as authors, thanks are due to many others in the EISCAT scientific community for useful contributions, discussions, and support

Izaña Atmospheric Research Center. Activity Report 2015-2016

This report is a summary of the many activities at the Izaña Atmospheric Research Center to the broader community. The combination of operational activities, research and development in state-of-the-art measurement techniques, calibration and validation and international cooperation encompass the vision of WMO to provide world leadership in expertise and international cooperation in weather, climate, hydrology and related environmental issues

International program for Earth observations

During the 1990 summer session of the International Space University, graduate students of many different countries and with various academic backgrounds carried out a design project that focused on how to meet the most pressing environmental information requirements of the 1990's. The International Program for Earth Observations (IPEO) is the result of the students labor. The IPEO report examines the legal and institutional, scientific, engineering and systems, financial and economic, and market development approaches needed to improve international earth observations and information systems to deal with environmental issues of global importance. The IPEO scenario is based on the production of a group of lightweight satellites to be used in global remote sensing programs. The design and function of the satellite is described in detail

Innovation in smallholder farming in Africa: recent advances and recommendations: Proceedings of the International Workshop on Agricultural Innovation Systems in Africa (AISA)

In the wake of a series of recent international events and initiatives focusing on understanding and fostering innovation1, there is growing awareness and interest in applying and making sense of the Agricultural Innovation Systems (AIS) concepts and perspectives and what they offer for understanding and supporting innovation systems, processes and networks. This has particular relevance for African agriculture as it faces several challenges, such as increasing and intensifying food production in a sustainable way and nourishing its fast-growing population, adapting to the consequences of climate change, and finding its rightful place in an increasingly global and complex international scene. Several initiatives and programmes seeking answers to these questions jointly organised a series of events during a Week on Agricultural Innovation in Africa (WAIA) held in Nairobi, Kenya, on 25–31 May 2013, of which the international workshop on Agricultural Innovation Systems in Africa (AISA) on 29–31 May was a major part. Another key event during this week, was the Eastern African Farmer Innovation Fair (EAFIF) held on 28–29 May, which was linked to AISA