IRS P4 (OCEANSAT-1)
India entered an elite club of commercial satellite launching nations when their PSLV rocket blasted off from a southern seaport with two international payloads on May 26, 1999. This was the first time an Indian launch vehicle carried more than one payload. This was also the fourth successful launch of the PSLV in a row.
One of the launched satellites was OCEANSAT-1 (IRS-P4), which is the first Indian satellite dedicated fully for the study of oceans. It carries the Ocean Colour Monitor (OCM) and the Multi-frequency Scanning Microwave Radiometer (MSMR). The satellite is helpful in the study of oceanographic phenomenon such as sea temperature, sea surface height, rain over oceans and would be useful in measuring various ocean parameters.
OceansAt-1: The specifications of OCM and MSMR payloads
IRS-P6 (RESOURCESAT-1)
The heaviest earth-observation spacecraft launched by ISRO so far, RESOURCESAT-1 was launched into an 817 km sun-synchronous polar orbit on board PSLV-C5 On October 17, 2003. It is the most advanced satellite built by ISRO, bringing continuity to the current IRS 1C and 1D programmes. RESOURCESAT-1 carries three sensors that deliver an array of spectral bands and resolutions ranging from 5.8 metres to 60 metres. Data products derived from RESOURCESAT-1 can be used for advanced applications in vegetation dynamics, crop yield estimates, disaster management support etc. In addition, RESOURCESAT-1 has 120 Gigabits of on-board memory that allows for out-of-contact imaging. Scheduled to last for five years, RESOURCESAT is the tenth spacecraft of ISRO in the IRS series.
Improved features
IRS-P6 has several improved features over its predecessors. These include availability of 5.8 m spatial resolution in 3 bands from LISS-IV camera, improved LISS III with MIR band information at 23.5 m resolution as other Visible and NIR bands. In addition, the AWiFS provides data in the same spectral channels as LISS-III at about 56m resolution with 10-bit radiometry, 5-day revisit and scene coverage of 740 km for regional studies. Unique to IRS-P6 is the availability of simultaneous multi-spectral data at 3 spatial resolutions from the same platform with scene coverage varying from 576 sq km to 1,9,600 sq km to 5,42,000 sq km.
