Projecte llegit
Títol: Interferometric Error Model for Precise Orbit Determination of Geostationary Satellites
Director/a: NICOLÁS ÁLVAREZ, JORGE
Departament: TSC
Títol: Interferometric Error Model for Precise Orbit Determination of Geostationary Satellites
Data inici oferta: 28-01-2021 Data finalització oferta: 28-09-2021
Estudis d'assignació del projecte:
GR ENG SIS TELECOMUN
| Tipus: Individual | |
| Lloc de realització: |
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| Segon director/a (UPC): BROQUETAS IBARS, ANTONI | |
| Paraules clau: | |
| interferometry, precise orbit determination, remote sensing, radar, python, geosynchronous satellites | |
| Descripció del contingut i pla d'activitats: | |
| Background: Low Earth Orbit Synthetic Aperture Radars (LEOSAR) present a main drawback regarding their revisit time of several days or weeks. At most, they can only provide an image of the same area of the planet per week. To mitigate this limitation, Geosynchronous Synthetic Aperture Radars (GEOSAR) missions will be able to provide permanent monitoring over wide areas of the planet. GEOSAR presents a main challenge: it requires unprecedented orbit determination precision. We have to demonstrate that we can get this precision before launching any spacecraft. We have designed and built a ground interferometer in the UPC-D3 building in order to track non-cooperative geostationary telecommunication satellites.
The student will work in the context of some on-going remote sensing missions: The European Space Agency (ESA) has selected Hydroterra in the call for its 10th Earth Explorer. Hydroterra will help scientists unravel the details of the daily water cycle. In the event of a natural disaster, they would be able to predict the development of floods and emergency services will be able to safely evacuate the citizens before the water rise. NASA Jet Propulsion Laboratory (JPL) has a keen interest in the presented technique and has contacted us to join their team in an emerging snow remote sensing mission. Goal: The project consists of retrieving geostationary satellite orbits from experimental interferometric measurements. The student will code an Extended Kalman Filter in Python in order to estimate the satellite position. They will work with different datasets of observables: single- satellite and three-satellite tracking. Finally, the uncertainty of the estimated solution with respect to the true position of the satellite must be determined. |
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| Overview (resum en anglès): | |
| The G-CLASS / Hydroterra project is being considered, among other options, by the European Space Agency (ESA) as the tenth Earth Explorer mission to use a Synthetic Aperture Radar to carry out studies of the Earth¿s surface to ensure the safety of citizens. The aim of the mission is to observe, monitor and understand the processes involved in the Earth¿s water cycle. In this way, it will be possible to monitor water and prevent catastrophes such as floods or droughts. In addition, it can also be applied to different events related to the Earth¿s crust such as earthquakes or volcanoes.
Otherwise, this mission is possible thanks to Synthetic Aperture Radar (SAR). However, the drawback is that for now they work in LEO orbit and have a long revisit period, that is, they take a long time to return to the same place for monitoring. It is for this reason that GEO orbit has been considered for this type of satellite, with the intention of extending its area of vision. But in order to be able to put this type of radar into orbit, it is necessary to accurately track its trajectory. A group of researchers at the Universitat Polit `ecnica de Catalunya is working on the concept of orbital determination of a satellite in GEO orbit, with the intention of bringing this project to a successful conclusion. To this end, a small-performance interferometer model was designed and built, with the intention of improving it for the future, in the D3 building of Campus Nord, UPC in Barcelona. The main purpose of this model is to receive the signal from the satellites that make up the ASTRA 19.2ºE constellation, at a distance of about 36000 km above the Earth¿s surface, in order to be able to work on the tracing of their orbits. On the other hand, it is not the interferometer that is in charge of estimating the orbit, but the program that does the post-processing of the signal. This program is developed by the software team of the research group at the Universitat Polit `ecnica de Catalunya. Although there is a model working today, it needs to be greatly improved in order to increase its accuracy. In this work, we will study the non-idealities of the medium through which the signal received by the interferometer travels, which generates errors that the developed program does not take into account at the moment. By means of this error model it will be possible to avoid variations in the received signal that will generate errors when estimating the location of the satellite. |
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