IRS-1A, Indian Remote Sensing satellite-1A, the first of the series of indigenous state-of-art

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 Ear ...

satellites, was successfully launched into a polar

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 ...

on 17 March 1988 from the

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

Cosmodrome at

Baikonur Baikonur ( kk, Байқоңыр, ; russian: Байконур, translit=Baykonur), formerly known as Leninsk, is a city of republic significance in Kazakhstan on the northern bank of the Syr Darya river. It is currently leased and administered ...

. IRS-1A carries two sensors, LISS-1 and LISS-2, with resolutions of and respectively with a swath width of about during each pass over the country. Undertaken 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 o ...

(ISRO). It was a part-operational, part-experimental mission to develop Indian expertise in satellite imagery.

History

The availability of

Landsat The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to La ...

imagery created a lot of interest in the science community. The

Hyderabad Hyderabad ( ; , ) is the capital and largest city of the Indian state of Telangana and the ''de jure'' capital of Andhra Pradesh. It occupies on the Deccan Plateau along the banks of the Musi River, in the northern part of Southern Indi ...

ground station A ground station, Earth station, or Earth terminal is a terrestrial radio station designed for extraplanetary telecommunication with spacecraft (constituting part of the ground segment of the spacecraft system), or reception of radio waves f ...

started receiving Landsat data on a regular basis in 1978. The Landsat program with its design and potentials was certainly a great model and yardstick for the IRS programme. IRS-1A was the first remote sensing mission to provide imagery for various land-based applications, such as agriculture, forestry, geology, and hydrology. The mission's long-term objective was to develop indigenous remote sensing capability.

Satellite description

The

satellite bus A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held. Bus-derived satellites are opposed to specially produced satellites. Bus- ...

, measuring 1.56 m x 1.66 m x 1.10 metres, had the payload module attached on the top and a deployable

solar panels A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...

stowed on either side.

Attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...

was provided by four- momentum wheels, two magnetic torques, and a thruster system. Together, they gave an estimated accuracy of better than ± 0.10° in all three axes.

Instruments

IRS-1A carried two "Linear Imaging Self-Scanning Sensor", LISS-1 and LISS-2, with a

spatial resolution In physics and geosciences, the term spatial resolution refers to distance between independent measurements, or the physical dimension that represents a pixel of the image. While in some instruments, like cameras and telescopes, spatial resolut ...

of and respectively. The three-axis-stabilised Sun-synchronous satellite carried LISS sensors which performed " push-broom" scanning in visible and

near-infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from arou ...

bands to acquire images of the

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 sur ...

. Local equatorial crossing time (ECT) was fixed at around 10:30 of the morning.

Launch

IRS-1A was launched on 17 March 1988, at 06:43:00 UTC. It had a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any el ...

of , an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any el ...

of , an

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

of 99.01°, and an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting pla ...

of 102.7 minutes.

Mission

IRS-1A was operated in a

. IRS-1A successfully completed its mission on 1 July 1992 after operating for 4 years.

References

External links

ISRO IRS-1A link
{{Orbital launches in 1988 Earth observation satellites of India Spacecraft launched in 1988 1988 in India India–Soviet Union relations 1988 in the Soviet Union