Sentinel-1A: pinpoint precision in remote sensing of Earth
Data received from Sentinel-1A is showing the high degree of precision in measuring the deformations of the earth’s surface. An example is the Gulf of Naples with the mapping of Vesuvius, the Phlegraean Fields and the island of Ischia.
Launched on April 3, 2014, Sentinel-1A, the first satellite in the European environmental monitoring programme Copernicus, which sees Finmeccanica playing a significant role, has already been providing important information for a month as demonstration of the enormous steps taken in remote sensing by satellite field.
Designed and integrated by Thales Alenia Space, the first Sentinel in the programme is actually able to take measurements of the deformations in the earth’s surface with millimetric precision: a great improvement in performance in terms of the quality and availability of the data observed.
From a comparison of the data coming from satellites launched in the Nineties, ERS 1/2 and Envisat with the data from Sentinel-1A, researchers at the Institute for the Electromagnetic Sensing of the Environment (IREA) have seen a great increase in the quality and availability of the data necessary for mapping of the Earth’s surface and its deformation.
This is particularly evident when comparing maps showing the average speed of deformation generated with the data acquired by the satellites Sentinel-1A and Envisat over the area of the Gulf of Naples with its three active volcano complexes –Vesuvius, the Phlegraean Fields and the island of Ischia.
The maps obtained with the data from Sentinel-1A, able to cover a wider expanse of territory, clearly show the lowering of the summit of Vesuvius, only partially visible with measurements previously taken by ERS and Envisat. Furthermore, there is a clear improvement in the spatial density of the measurement points on the Phlegraean Fields, characterised by a continuous rise.
To achieve this, the scientists have used the Interferometric Synthetic Aperture Radar (InSAR) technique. This uses the combination of two or more radar images captured at different times. If something on the earth has changed between the captures, the deformation of the ground is shown as a continuous sequence of coloured stripes called "interferograms". Shortly, with the launch of Sentinel-1B, the "twin" satellite of Sentinel-1A , the mapping of the deformation of the surfaces will further improve. The two satellite systems will halve data acquisition times (revisit times), reducing the “passage period” to six days.
Observing to protect planet Earth
The Copernicus mission satellites Sentinel-1A and 1B, entirely designed, integrated and tested by Thales Alenia Space Italia as prime contractor, acquire images of the Earth between 20 and 250 kilometres wide, with a resolution of between 5 and 25 metres. The satellites are equipped with a synthetic aperture radio in band C (SAR) to provide users with continuous images, day and night, under all weather conditions.
The European Copernicus Satellite Programme
Previously known as GMES (Global Monitoring for Environment and Security) Copernicus is the new European satellite Earth Observation and Monitoring Programme, today the most ambitious project ever undertaken in this field and expected to provide accurate, timely and easily accessible information to improve the management of the environment, understand and mitigate the effects of climatic change and ensure civil security.
Copernicus is controlled by the European Commission in conjunction with the European Space Agency (ESA) and with the European Environmental Agency (AEA). In the programme, Finmeccanica plays a primary role proving a fundamental partner both in systems development and in the various satellite applications of the programme.