Sentinel-1A Environmental Monitoring Satellite, France
Sentinel-1A is an Earth observation satellite developed as part of the European Copernicus programme, previously known as European Global Monitoring for Environment and Security (GMES) programme.
The Sentinel-1A programme was initiated and developed by a joint venture comprising of the European Space Agency (ESA), European Commission and the European Environmental Agency (EEA).
The satellite will collect and evaluate environmental data on Earth for civil safety and humanitarian needs.
The Sentinel-1A is the first in twin satellite Sentinel-1 constellation, whose main objectives will include land and ocean monitoring. Sentinel-1B, the second in the pair, was launched in April 2016.
The Sentinel-1 satellites will provide services by covering main shipping routes across Europe and Canada.
Sentinel-1A design and development
The prime manufacturing and integration contract for the Sentinel-1A satellite was awarded to Thales Alenia Space (TAS). The contractual scope included developing T/R modules and Electronic Front Ends for synthetic aperture radar (SAR) antenna and an advanced data handling subsystem.
Astrium was awarded a contract to supply C-band SAR payload for the satellite. Astrium delivered the radar instrument system to TAS for the integration with Sentinel-1A satellite in October 2013.
The satellite was transported to Europe's Spaceport in French Guiana in February 2014 with the help of Antonov An-124 transport plane, and underwent further tests and pre-launch operations before it was launched on 3 April 2014.
The satellite was based on the Piattaforma Italiana Multi Applicativa (PRIMA) bus manufactured by TAS. It had a launch mass of 2,300kg and will orbit Earth at an altitude of about 700km. It carries a deployable solar array and will be placed in Sun-synchronous near polar orbit.
The satellite will provide services orbiting around the planet for seven years. It will fly over the north and south poles of the Earth in each orbit. The radar instrument within the satellite will observe the Earth and record data round-the-clock.
Environmental monitoring satellite missions
Sentinel-1A will support a broad range of environmental tasks on Earth, such as surveillance of maritime environment, monitoring the Arctic sea-ice extent and oil spills, landslides and floods.
It will also provide rapid and latest data for assistance for carrying out reconnaissance and operational support activities in the event of natural disasters.
It will benefit by providing routine sea-ice mapping, ship detection for maritime security and monitoring land-surface for motion risks. It will also render mapping for forest, water and soil management, for supporting humanitarian aid in crisis situations.
Communication systems on the Sentinel satellite
Sentinel-1A features a single C-band SAR payload. The SAR features an active electronic antenna measuring 12.30m by 0.90m. It will have beam wavelength of 6cm.
It is capable of obtaining night imagery and detecting small movements on the ground with two modes of operation, which include interferometric wide swath and extra-wide swath modes.
The first mode will image the Earth in swaths of 250km diameter with a ground resolution ranging between 5m and 25m, while the second mode will image the planet in swaths of 400km diameter with ground resolution ranging between 25m and 100m.
It also includes two manual operated modes, including a strip map mode with swaths of 80km and wave mode with swaths of 20km.
The communication system also includes large data storage with a capacity of 1,410GB. It is equipped with 520MB/s capacity X-band downlink, to obtain quick data in the event of natural disasters.
Launch vehicle for the European satellite
Arianespace was awarded with a contract to provide launch service and solutions for the Sentinel-1A satellite in December 2010.
The satellite was launched on a Soyuz rocket from Guiana Space Centre located at Europe's Spaceport in French Guiana on 3 April 2014.
Sentinel-1A ground control station
The ground segment of the Sentinel series satellites comprises of three elements, which include GSC core ground segment, the GSC collaborative ground segment and the GMES contributing missions ground segment.
DLR was awarded with a contract to provide Laser Communication Terminal (LCT), which will transmit data from the Sentinel-1A satellite to the European Data Relay Satellite (EDRS) using an optical laser link to transmit data back to the ground facility.
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