Sentinel-1 is the first of the

Copernicus Programme Copernicus is the European Union's Earth observation programme coordinated and managed for the European Commission by the European Union Agency for the Space Programme in partnership with the European Space Agency (ESA), the EU Member States. ...

satellite constellation conducted by the

European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...

. This mission was originally composed of a constellation of two satellites,

Sentinel-1A Sentinel-1A is a European radar imaging satellite launched in 2014. It is the first Sentinel-1 satellite launched as part of the European Union's Copernicus programme. The satellite carries a C-band Synthetic Aperture Radar which will provide ...

and

Sentinel-1B Sentinel-1 is the first of the Copernicus Programme satellite constellation conducted by the European Space Agency. This mission was originally composed of a constellation of two satellites, Sentinel-1A and Sentinel-1B, which shared the same orbit ...

, which shared the same orbital plane. Two more satellites, Sentinel-1C and Sentinel-1D are in development. Sentinel-1B has been retired, leaving Sentinel-1A the only satellite of the constellation. The Sentinel-1 satellites carry a C-band

synthetic-aperture radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide fine ...

instrument which provides a collection of data in all-weather, day or night. This instrument has a spatial resolution of down to 5 m and a swath of up to 400 km. The satellites orbit a Sun synchronous, near-polar (98.18°) orbit. The orbit has a 12-day repeat cycle and completes 175 orbits per cycle. 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 The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximatel ...

Kourou Kourou () is a commune in French Guiana, an overseas region and department of France in South America. Kourou is famous for being the location of the Guiana Space Centre, the main spaceport of France and the European Space Agency (ESA). It i ...

French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...

, and each on a

Soyuz Soyuz is a transliteration of the Cyrillic text Союз (Russian and Ukrainian, 'Union'). It can refer to any union, such as a trade union (''profsoyuz'') or the Union of Soviet Socialist Republics (Сою́з Сове́тских Социалис� ...

rocket. Sentinel-1C and 1D are in development with Sentinel-1C set for launch in April 2023. There are a wide range of applications for the data collected via the Sentinel-1 mission. A few of these uses include sea 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. Recently, Sentinel-1 has worked in conjunction with

SMAP SMAP was a Japanese boy band, composed of Masahiro Nakai, Takuya Kimura, Goro Inagaki, Tsuyoshi Kusanagi, and Shingo Katori. The group was created in 1988 by music producer Johnny Kitagawa, founder of Johnny & Associates, originally as a six-pi ...

to help achieve a more accurate measure of soil moisture estimates. Observations from both instruments show to be complementary of each other as they combine data of soil moisture contents. The ESA 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.

Instruments

Sentinel-1 spacecraft are designed to carry the following instruments: * A single C-band

(C-SAR) with its electronics. This instrument provides 1 dB radiometric accuracy with a central frequency at 5.405 GHz. The data collected in C-SAR was made to be continuous after the termination of a previous mission (Envisat mission). * An

SDRAM Synchronous dynamic random-access memory (synchronous dynamic RAM or SDRAM) is any DRAM where the operation of its external pin interface is coordinated by an externally supplied clock signal. DRAM integrated circuits (ICs) produced from the ...

-based Data Storage and Handling Assembly (DSHA), with an active data storage capacity of about 1,443

Gbit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented ...

(168

GiB The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...

), 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 The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxim ...

fixed-user data-downlink capability over two independent channels towards ground.

Characteristics

Specifications of the Sentinel-1 satellites: * 7 year lifetime (12 years for consumables) * Launcher:

* Near-polar (98.18°) Sun-synchronous orbit * altitude * 12-day repeat cycle * 175 revolutions per cycle * 98.6 minute orbital period * 3-axis altitude stabilization * launch mass * dimensions

Operational/acquisition modes

Sentinel-1 has four operational modes: * Strip Map (SM) Mode features spatial resolution and an swath. ** The sole uses of SM are to monitor small islands as well as emergency management for extraordinary events upon request ** Offers data products in single (HH or VV) or double (HH + HV or VV + VH) polarization * Interferometric Wide Swath (IW) Mode features spatial resolution and a swath. ** IW is the main operational mode over land ** IW accomplishes

interferometry Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...

through burst synchronization ** Offers data products in single (HH or VV) or double (HH + HV or VV + VH) polarization * Extra Wide Swath (EW) Mode features spatial resolution and a swath. ** EW is used mainly to monitor wide coastal areas for phenomena such as shipping traffic and potential environmental hazards like oil spills or changes in sea ice. ** Offers data products in single (HH or VV) or double (HH + HV or VV + VH) polarization * Wave (WV) Mode features resolution and a low data rate. It produces sample images along the orbit at intervals of . ** This is the main operational mode over open ocean. ** Offers data products only in single (HH or VV) polarization

Data products

Sentinel-1 has four types of data products: * Raw Level 0 data * Processed Level 1 Single Look Complex (SLC) data: ** Complex images with phase and amplitude of specified areas * Ground Range Detected (GRD) Level 1 data: ** Only systematically distributed multi-looked intensity * Level 2 Ocean (OCN) data: ** Systematically distributed data of ocean's geophysical parameters All data levels are publicly available for free online within 24 hours of observation.

Applications

Sentinel-1 will provide continuity of data from the ERS and

Envisat Envisat ("Environmental Satellite") is a large inactive Earth-observing satellite which is still in orbit and now considered space debris. Operated by the European Space Agency (ESA), it was the world's largest civilian Earth observation satell ...

missions, with further enhancements in terms of revisit, coverage, timeliness and reliability of service. A summary of the main applications of Sentinel-1 include: * Marine monitoring ** Sea-ice levels and conditions ** Ocean oil spills ** Ship activity ** Marine winds * Land monitoring ** Agriculture ** Forestry **Subsidence ***The C-SAR instrument is capable of measuring land subsidence through the creation of

interferometric synthetic-aperture radar Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing. This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface defor ...

(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 S1 to improve on current InSAR techniques and provide systematic continuity to the data. * Emergency response ** Flooding ** Landslide and volcanic ** Earthquakes *** Shortly after the August

2014 South Napa earthquake The 2014 South Napa earthquake occurred in the North San Francisco Bay Area on August 24 at . At 6.0 on the moment magnitude scale and with a maximum Mercalli intensity of VIII (''Severe''), the event was the largest in the San Francisco Bay Are ...

, data collected by Sentinel-1A was used to develop an

, or InSAR, image of the affected region. The Sentinel-1 satellites are expected to make analysis of earthquakes using InSAR techniques quicker and simpler.

Industrial

The prime contractor of the mission is

Thales Alenia Space Thales Alenia Space () is a Franco-Italian aerospace manufacturer. A joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (33%), the company is the largest satellite manufacture ...

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. The C-SAR instrument is the responsibility of

Astrium Astrium was an aerospace manufacturer subsidiary of the European Aeronautic Defence and Space Company (EADS) that provided civil and military space systems and services from 2006 to 2013. In 2012, Astrium had a turnover of €5.8 billion and 18 ...

Gmbh. The ground segment prime contractor is Astrium with subcontractors

Telespazio Telespazio Spa is a European spaceflight services company founded in 1961. It is a joint venture owned by Leonardo (67%) and Thales Group (33%) headquartered in Rome. Telespazio provides services that include the design and development of space s ...

, 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.

Spacecraft

– launched on 3 April 2014 *

– launched on 25 April 2016, unavailable due to a power issue since 23 December 2021, mission end declared 3 August 2022 * Sentinel-1C – development contract signed with Thales Alenia Space of Italy in December 2015; launch scheduled for April 2023 * Sentinel-1D – development contract signed with Thales Alenia Space of Italy in December 2015; launch scheduled for the second half of 2024

Gallery

Examples of images produced from Sentinel-1 data. File:Thunderstorms over Estonia on a Copernicus Sentinel-1 synthetic aperture radar image.jpg, Thunderstorms over Estonia.

False colour False color (or pseudo color) refers to a group of color rendering methods used to display images in color which were recorded in the visible or non-visible parts of the electromagnetic spectrum. A false-color image is an image that depicts ...

RGB image of VV-, VH- and VV+VH-polarisation backscatter. File:Lake Success, California ESA373671.jpg, Lake Success region, California. False colour RGB image of scans from two different dates. File:Alert, Canada ESA375402.jpg, Ice movement in Alert, Canada. False colour RGB image of scans from three different months. File:Ground Deformation from Chilean Volcanic Eruption Shown by Satellite Radar Image.png,

InSAR Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing. This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface defo ...

image displaying the ground deformation after the eruption of

Calbuco Calbuco is a city and commune in southern Chile administered by the Municipality of Calbuco. Administratively Calbuco belongs to the Llanquihue Province of Los Lagos Region. The origin of the city was the Spanish Fort Calbuco founded in 1603, an ...

volcano in Chile. File:Larsen-C crack interferogram ESA376365.jpg, Interferometry reveals a crack in the

Larsen Ice Shelf The Larsen Ice Shelf is a long ice shelf in the northwest part of the Weddell Sea, extending along the east coast of the Antarctic Peninsula from Cape Longing to Smith Peninsula. It is named after Captain Carl Anton Larsen, the master of the No ...

, Antarctica.