University of Cranfield
All radar satellites so far have been in low Earth orbit (LEO). Images from these satellites are used for applications ranging from mapping forestry to measuring the movement of glaciers and even Earth’s tectonic plates. Using LEO however means that we can’t observe changes happening faster than about a week. Also, the atmosphere distorts images slightly and this complicates their use for very precise measurements.
An alternative to LEO is geosynchronous orbit (GEO). GEO is already used by weather satellites to take visible images using the Sun’s illumination. Weather satellites produce frequent images over wide areas, but GEO has not been used so far for radar. Calculations and some initial experiments show that radar imaging from GEO is possible. This project’s aims are to resolve some of the remaining technical problems, especially the processing needed to form good images, and to evaluate potential applications for GEO radar.
GEO radar could play a valuable role in monitoring natural hazards, weather and climate. One particular application would be to survey large areas for ground motion, e.g. landslide risk, subsidence and earthquakes. Another role may be measuring soil moisture: the frequent images mean that daily changes can be observed directly which will help early detection of drought or flood risks. GEO radar should also be much more responsive in cases of natural disasters: images will be available within hours whatever the weather, day and night.
A by-product of imaging from GEO will be maps of the Earth’s atmosphere showing either humidity distribution or the state of the ionosphere. These data are valuable in themselves and will help with weather forecasting and climate studies. They may even help us to forecast space weather from the changes we will be able to detect in the ionosphere.Having measurements of the atmosphere as we image from GEO means that the atmosphere’s effects can be removed, so GEO radar images could be used directly for precise measurements of changes at Earth’s surface.
Although not yet demonstrated, the potential benefits of GEO radar justify this research which may lead to valuable new services from space.
This project is being lead by the University of Cranfield