Radar Imaging Satellite 1 or RISAT-1, was an Indian

remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

built by the

Indian Space Research Organisation The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman ...

and operated by National Technical Research Organisation . The second

RISAT RISAT (Radar Imaging Satellite) is a series of Indian radar imaging reconnaissance satellites built by ISRO. They provide all-weather surveillance using synthetic aperture radars (SAR). The ''RISAT'' series are the first all-weather Earth obs ...

satellite to be launched, it used a C-band 5.35

GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

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 ...

(SAR) for

Earth observation Earth observation (EO) is the gathering of information about the physical, chemical, and biological systems of the planet Earth. It can be performed via remote-sensing technologies (Earth observation satellites) or through direct-contact sensors ...

. The launch of RISAT-1 came several years after that of

RISAT-2 RISAT-2, or Radar Imaging Satellite-2 was an Indian radar imaging reconnaissance satellite that was part of India's RISAT programme. It was built by Indian Space Research Organisation (ISRO) and successfully launched aboard a PSLV-CA launch veh ...

, which carried an Israeli-built

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 ...

radar. The RISAT-2 mission was prioritised over RISAT-1 following the

2008 Mumbai attacks The 2008 Mumbai attacks (also referred to as 26/11, pronounced "twenty six eleven") were a series of Terrorism, terrorist attacks that took place in November 2008, when 10 members of Lashkar-e-Taiba, an Islamist terrorist organisation from P ...

, resulting in RISAT-1 being delayed by several years.

Satellite description

RISAT-1 had a mass at liftoff of , making it the heaviest Earth observation satellite to be launched by India, and the heaviest satellite to be launched using a

Polar Satellite Launch Vehicle The Polar Satellite Launch Vehicle (PSLV) is an expendable medium-lift launch vehicle designed and operated by the Indian Space Research Organisation (ISRO). It was developed to allow India to launch its Indian Remote Sensing (IRS) satellites ...

. It had the capability to take images of

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

during day and night, as well as in cloudy conditions. The satellite is equipped with a 160 × 4

Mbit/s In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multi ...

data handling system, 50 Newton-metre-second reaction wheels, and a phased array antenna with dual polarisation. The mission has an approximate cost of ;the spacecraft itself cost to develop, and a further to launch. The satellite had a design life of five years. The satellite was used for natural resources management, primarily agriculture planning and forestry surveys, as well as to predict and prevent

flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...

ing. It was used for monitoring paddy plantations and yields in the

kharif Kharif crops, also known as monsoon crops or autumn crops, are domesticated plants that are cultivated and harvested in India, Pakistan and Bangladesh during the Indian subcontinent's monsoon season, which lasts from June to November depending o ...

season and to assist India's food security planning. Pictures from RISAT-1 was used to estimate the number of hectares being farmed in India, to assess crop health and predict total yield. They was also used to identify wreckage from aircraft which go down in forested areas. RISAT-1 was not designed as a

surveillance satellite A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. The ...

, given its reliance on the C-band.

Instrument

Its synthetic-aperture radar (SAR-C) has a resolution of 3 m to 50 m. It also supports a spotlight mode for prolonged focus on a given geographical area at a resolution of 1 m. Most of the design and the installation of basic instrument subsystems for the satellite was conducted in 2010.

Mission history

Launch

RISAT-1 was launched at 00:17 UTC (05:47 IST) on 26 April 2012 by a

, flight number C19, flying in the XL configuration with extended length solid strap-on boosters. The launch, which was the third flight of the PSLV-XL configuration, took place from the First Launch Pad of the

Satish Dhawan Space Centre Satish Dhawan Space Centre - SDSC (formerly Sriharikota Range - SHAR) is a rocket launch centre (spaceport) operated by Indian Space Research Organisation (ISRO). It is located in Sriharikota, Tirupati district of Andhra Pradesh. Sriharikota R ...

Sriharikota Sriharikota is a Barrier island off the Bay of Bengal coast located in the Shar Project settlement of Tirupati district in Andhra Pradesh, India. It houses the Satish Dhawan Space Centre, one of the two satellite launch centres in India (the o ...

Andhra Pradesh Andhra Pradesh (, abbr. AP) is a state in the south-eastern coastal region of India. It is the seventh-largest state by area covering an area of and tenth-most populous state with 49,386,799 inhabitants. It is bordered by Telangana to the ...

. The launch marked the twenty-first flight of the PSLV, and its nineteenth successful launch. After launch RISAT-1 was placed in 470 x 480 km orbit with near 97°

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

. In next two days, RISAT-1 raised its orbital altitude using on-board propulsion to place itself into its operational

sun-synchronous orbit A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...

of 536 km with 06:00

Local Time of Equator Crossing Local may refer to: Geography and transportation * Local (train), a train serving local traffic demand * Local, Missouri, a community in the United States * Local government, a form of public administration, usually the lowest tier of administrat ...

. The satellite began its normal operations with a repetitive cycle of 25 days.

Incidents

On 30 September 2016,

Joint Space Operations Center The Combined Space Operations Center (CSpOC) is a U.S.–led multinational space operations center that provides command and control of space forces for United States Space Command's Combined Force Space Component Command. The CSpOC is located at ...

identified a debris generating event near RISAT-1. The event created 16 pieces out of which 15 decayed and one was catalogued on 6 October 2016 under NORAD ID: 41797 and COSPAR ID: 2012-017C and decayed on 12 October 2016. Cause of this event remains unknown. A month later on 3 November 2016, RISAT-1 data was declared unavailable on ESA's Copernicus Space Component Data Access portal due satellite outage. Satellite was experiencing anomalies but ISRO denied they were related to fragmentation event.

End of mission

On 26 July 2017, Department of Space released names of its operational satellites in a reply to a Parliamentary query and RISAT-1 was not included in the list. Later in Annual Report 2017-18 of Department of Space, RISAT-1 was declared non-operational.

References

{{Orbital launches in 2012 Spacecraft launched in 2012 Earth observation satellites of India Space synthetic aperture radar 2012 in India