Browsing by Author "Hobbs, Stephen E."
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Item Open Access G-CLASS: geosynchronous radar for water cycle science - orbit selection and system design(IET, 2019-11-28) Hobbs, Stephen E.; Guarnieri, Andrea Monti; Broquetas, Antoni; Calvet, Jean-Christophe; Casagli, Nicola; Chini, Marco; Ferretti, Rossella; Nagler, Thomas; Pierdicca, Nazzareno; Prudhomme, Christel; Wadge, GeoffThe mission geosynchronous – continental land atmosphere sensing system (G-CLASS) is designed to study the diurnal water cycle, using geosynchronous radar. Although the water cycle is vital to human society, processes on timescales less than a day are very poorly observed from space. G-CLASS, using C-band geosynchronous radar, could transform this. Its science objectives address intense storms and high resolution weather prediction, and significant diurnal processes such as snow melt and soil moisture change, with societal impacts including agriculture, water resource management, flooding, and landslides. Secondary objectives relate to ground motion observations for earthquake, volcano, and subsidence monitoring. The orbit chosen for G-CLASS is designed to avoid the geosynchronous protected region and enables integration times of minutes to an hour to achieve resolutions down to ∼20 m. Geosynchronous orbit (GEO) enables high temporal resolution imaging (up to several images per hour), rapid response, and very flexible imaging modes which can provide much improved coverage at low latitudes. The G-CLASS system design is based on a standard small geosynchronous satellite and meets the requirements of ESA's Earth Explorer 10 call.Item Open Access Geosynchronous continental land-atmosphere sensing system (g-class): persistent radar imaging for earth science(IEEE, 2018-11-05) Hobbs, Stephen E.; Monti-Guarnieri, A.More frequent imaging of Earth system processes is recognised as one of the emerging needs in Earth observation. Conventional low Earth orbit satellites are limited in their ability to provide this, whereas satellites in geosynchronous orbit can in principle provide continuous imaging. A new mission de- sign has been developed from studies for a previous geosynchronous radar mission concept (GeoSTARe) to improve its technical feasibility and geographical coverage, and to rein- force its science focus. This new mission (Geosynchronous - Continental Land Atmosphere Sensing System (G-CLASS)) is presented. G-CLASS is in fact a family of missions: we present a version focussed on the diurnal water cycle - G-CLASS:H2O - for which geosynchronous radar has great potential. G-CLASS:H2O is being developed as a proposal for ESA’s Earth Explorer programme.Item Open Access Machine vision and scientific imaging for autonomous air vehicles (UAV).(Cranfield University, 2008-08) Jameson, Pierre-Daniel; Cooke, Alastair K.; Hobbs, Stephen E.This thesis outlines the necessary requirements to determine an Unmanned Aerial Vehicles (UAV’s) pose relative to a lead aircraft or target, thus enabling a UAV to successfully follow a lead aircraft or target. The use of Machine Vision for Autonomous navigation has been investigated and two flight scenarios were chosen for analysis. Firstly, following a manoeuvring lead aircraft, and secondly, maintaining a steady heading behind a target/lead aircraft (as would be required for in-flight refuelling). In addition, the author has performed a literature review of current research in this field which is significantly dominated by eventual military requirements in order to improve UAV endurance. In addition, experimental work towards developing a passive vision based navigation system has been undertaken. It is hoped that after further research and development this will lead to an eventual flight trial using the flight dynamics department’s UAV’s. The experimental work has been performed using both equipment and software already available within the department and furthermore, it has enabled an analysis of the department’s currently available capabilities for passive visual navigation to be undertaken. Key points for further work have been outlined for the future advancement of the visual navigation project.Item Open Access Towards in-orbit hyperspectral imaging of space debris(2023-01-26) Hobbs, Stephen E.; Felicetti, Leonard; Leslie, Cameron; Rowling, Samuel; Brydon, George; Dhesi, Mekhi; Harris, Toby; Chermak, Lounis; Soori, UmairSatellites are vulnerable to space debris larger than ~1 cm, but much of this debris cannot be tracked from the ground. In-orbit detection and tracking of debris is one solution to this problem. We present some steps towards achieving this, and in particular to use hyperspectral imaging to maximise the information obtained. We present current work related to hyperspectral in-orbit imaging of space debris in three areas: scenario evaluation, a reflectance database, and an image simulator. Example results are presented. Hyperspectral imaging has the potential to provide valuable additional information, such as assessments of spacecraft or debris condition and even spectral “finger-printing” of material types or use (e.g. propellant contamination). These project components are being merged to assess mission opportunities and to develop enhanced data processing methods to improve knowledge and understanding of the orbital environment.