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IRS-1A
IRS-1A is the first satellite in the IRS constellation. It was launched from Baikonur cosmodrome, Khazakhstan. It operated in sun-synchronous near polar orbit at an inclination of 99 degrees at an altitude of 904 km. One orbit around the earth took about 103 minutes and the satellite made 14 orbits per day. The 22 day repetivity ensured repeated collection of data of the same geographical area at the same local time. The equatorial crossing time for IRS-1A in the descending node was 9:40 AM.
It had two types of cameras known as Linear Self Scanning Sensors (LISS-I and LISS-II). LISS-I had a spatial resolution of 72.5m with a swath of 148 km on ground. LISS-II had two separate imaging sensors LISS-IIA and LISS-IIB with spatial resolution of 36.25m each. They were mounted on the spacecraft in such a way so as to provide a composite swath of 146.98 km on ground. Both LISS-I and LISS-II operated in four spectral bands covering visible and near infrared region. It had following payload and orbital parameters
Orbit |
Polar Sun synchronous |
Altitude |
904 Km |
Inclination |
99 degrees |
Local Time |
9:40 A.M |
Repetivity |
22 Days |
Orbits/day |
14 |
Period |
103 minutes |
Sensors |
LISS-I, LISS-II |
LISS - I Sensor Characteristics:
Sensor |
LISS-1 |
Resolution |
72.5 m |
Swath |
148 km |
Repetivity |
22 days |
Spectral Bands |
0.45 - 0.52 microns (B1)
0.52 - 0.59 microns (B2)
0.62 - 0.68 microns (B3)
0.77 - 0.86 microns (B4) |
LISS - II Sensor Characteristics:
Sensor |
LISS - II |
Resolution |
36.25 m |
Swath |
74 x 2 km |
Repetivity |
22 days |
Spectral Bands |
0.45 - 0.52 microns (B1)
0.52 - 0.59 microns (B2)
0.62 - 0.68 microns (B3)
0.77 - 0.86 microns (B4) |
Products :
Sensor |
Resolution(m) & No. of Bands
|
Coverage
km x km |
Data Products |
Type |
Media |
Scale of Photo products |
LISS-I |
72.5
(four) |
148 x 174 |
Full scenes |
Digital, FCC |
1:250,000 |
LISS-II |
36.25
(four) |
74 x 87
28 x 28 |
Full Scenes
Geocoded
(15'x15') |
Digital, FCC
Digital, FCC |
1:125,000
1: 50,000 |
With a designed life of three years, the satellite provided excellent data during 1988 – 1991. |
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