\n<\/p>\n
Down on the ground, death equals stillness \u2013 but not in space. Abandoned satellites are prone to tumble in unpredictable ways and an ESA project with the Astronomical Institute of the University of Bern\u00a0sought to better understand this behaviour.<\/p>\n
ESA\u2019s Clean Space initiative\u00a0has plans to remove dead satellites from highly trafficked orbits. The preferred method of \u2018Active Debris Removal\u2019 involves grabbing the target object, in which case knowledge of its precise orientation and motion will be vital. So the need is clear to understand the tumbling that almost all satellites and rocket bodies undergo after their mission end-of-life.<\/p>\n
The project combined optical, laser ranging and radar observations to refine an existing \u2018In-Orbit Tumbling Analysis\u2019 computer model, aiming to identify, understand and predict the attitude motion of a fully defunct satellite within a few passes. More than 20 objects were observed during a two-year campaign.<\/p>\n
The long list of perturbation triggers includes \u2018eddy currents\u2019 as internal magnetic fields interact with Earth\u2019s magnetosphere, drag from the vestigial atmosphere, gravity gradients between the top of an object and its bottom, outgassing and fuel leaks, the faint but steady push of sunlight \u2013 known as \u2018solar radiation pressure\u2019 \u2013 micrometeoroid and debris impacts, even the sloshing of leftover fuel.<\/p>\n
Among the study findings was rocket bodies and satellites in lower orbits are mostly influenced by gravity gradients and eddy currents, while up at geostationary altitudes, satellites with large solar panels are sensitive to solar radiation pressure.<\/p>\n
The project was supported through ESA\u2019s General Support Technology Programme, developing promising technologies for space.<\/p>\n
Find out more here.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n