Sentinel-1
Earth observation satellite From Wikipedia, the free encyclopedia
Earth observation satellite From Wikipedia, the free encyclopedia
Sentinel-1 is the first of the Copernicus Programme satellite constellations conducted by the European Space Agency.[4] The mission was originally composed of a constellation of two satellites, Sentinel-1A and Sentinel-1B, which shared the same orbital plane. Two more satellites, Sentinel-1C and Sentinel-1D are in development. Sentinel-1B was retired following a power supply issue on December 23, 2021, leaving Sentinel-1A the only satellite of the constellation currently operating.[5] Sentinel-1C is currently planned to launch in the final quarter of 2024.[6]
Model of a Sentinel-1 (radar antenna missing) | |||
| Manufacturer |
| ||
|---|---|---|---|
| Operator | European Space Agency | ||
| Applications | Land and sea monitoring, natural disasters mapping, sea ice observations, ships detection | ||
| Specifications | |||
| Spacecraft type | Satellite | ||
| Constellation | Active: 1 | ||
| Launch mass | 2,300 kg (5,100 lb) | ||
| Dry mass | 2,170 kg (4,780 lb) | ||
| Dimensions | 3.9 m × 2.6 m × 2.5 m (13 ft × 8.5 ft × 8.2 ft) | ||
| Power | 5.9 kilowatts (5,900 W)[2] | ||
| Batteries | 324 Ah | ||
| Design life | 7 years (12 years of consumables) | ||
| Production | |||
| Status | Active | ||
| On order | 4 | ||
| Built | 4 | ||
| Launched | 2 | ||
| Operational | 1 | ||
| Retired | 1 | ||
| Maiden launch | Sentinel-1A (3 April 2014)[3] | ||
| Last launch | Sentinel-1B (25 April 2016) | ||
| Related spacecraft | |||
| Subsatellite of | Copernicus Programme | ||
| |||
The first satellite, Sentinel-1A, launched on 3 April 2014, and Sentinel-1B was launched on 25 April 2016. Both satellites lifted off from the Guiana Space Centre in Kourou, French Guiana, and each on a Soyuz rocket.[7] Sentinel-1C and 1D are in development.[8] An equipment failure on Sentinel-1B in December 2021 accelerated work on Sentinel-1C,[9] originally planned to launch in December 2023.[10]
The satellites have a Sun-synchronous, near-polar (98.18° inclination) orbit.[11] Their orbits have a 12-day repeat cycle and complete 175 orbits per cycle (having a 98.6 minute orbital period). The satellites operate at 693 km (431 mi) altitude, with 3-axis altitude stabilization.
The European Space Agency and European Commission's policies makes Sentinel-1's data easily accessible. Various users can acquire the data and use it for public, scientific, or commercial purposes for free.
 | This section may be too technical for most readers to understand. (May 2024) |
Sentinel-1 spacecraft are designed to carry a C-band synthetic-aperture radar (C-SAR) instrument which provides a collection of data in all-weather, day or night, as well as an SDRAM-based Data Storage and Handling Assembly (DSHA).[12]
The single C-SAR instrument with its electronics provides 1 dB radiometric accuracy with a central frequency at 5.405 GHz.[11] This instrument has a spatial resolution down to 5 m (16 ft) and a swath of up to 410 km (250 mi).[13] The data collected in C-SAR was made to be continuous after the termination of a previous mission (Envisat mission).[14]
The DSHA has an active data storage capacity of about 1,443 Gbit (168 GiB), receiving data streams from SAR-SES over two independent links gathering SAR_H and SAR_V polarization, with a variable data rate up to 640 Mbit/s on each link, and providing 520 Mbit/s X-band fixed-user data-downlink capability over two independent channels towards ground.
Sentinel-1 has four operational modes and four types of data products available. All data levels are publicly available for free online within 24 hours of observation.[15]
The four operational modes offered by Sentinel-1 are:[11][16][17]
The four types of data products offered by Sentinel-1 are:[16]
There are a wide range of applications for the data collected via the Sentinel-1 mission. A few of these uses include marine and land monitoring, emergency response due to environmental disasters, and economic applications. A major goal of the mission was to provide C-Band SAR data.[14] Sentinel-1 provides continuity of data from the ERS and Envisat missions, with further enhancements in terms of revisit, coverage, timeliness and reliability of service. Recently, Sentinel-1 has worked in conjunction with SMAP to help achieve a more accurate measure of soil moisture estimates.[18] Observations from both instruments show to be complementary of each other as they combine data of soil moisture contents.
A summary of the main applications of Sentinel-1 include:[19]
The C-SAR instrument is capable of measuring land subsidence through the creation of interferometric synthetic-aperture radar (InSAR) images. The analysis of phase changes between two or more synthetic aperture radar images taken at different times is able to create maps of the digital elevation and measure the land surface deformation of an area. High spatial (20m) and temporal (6 days) resolutions allow Sentinel-1 to improve on current InSAR techniques and provide systematic continuity to the data.[20]
Shortly after the August 2014 South Napa earthquake, data collected by Sentinel-1A was used to develop an interferometric synthetic-aperture radar, or InSAR, image of the affected region. The Sentinel-1 satellites are expected to make analysis of earthquakes using InSAR techniques quicker and simpler.[21]
The prime contractor of the mission is Thales Alenia Space Italy, with whole system integration and also with production of platform Spacecraft Management Unit (SMU) and payload Data Storage and Handling Assembly (DSHA). Sentinel-1A was constructed in Rome, Italy. Other technologies such as the T/R modules, the C-band synthetic-aperture radar antenna, the advanced data management and transmission subsystems, and the on-board computer, were developed in L'Aquila and Milan.[22] The C-SAR instrument is the responsibility of Astrium Gmbh.
The ground segment prime contractor is Astrium with subcontractors Telespazio, WERUM, Advanced Computer Systems and Aresys. Final test verification of the satellite was completed at Thales Alenia Space's clean rooms in Rome and Cannes.[22]
Examples of images produced from Sentinel-1 data.
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