The Indian Space Research Organisation, or ISRO, is celebrating the successful launch on April 20 of two satellites, both with different purposes, known as RISAT-2 and ANUSAT. Of these, with RISAT, India has for the first time acquired an “eye in the sky” capability, which can watch any form of border infiltration, whether day and night, rain, snow or shine. (It is also expected to help India’s disaster management preparedness.)

The RISAT, an acronym for radar imagery satellite, could be said to belong to the class of high-tech spy satellites. Its technology is noticeably updated: it has “synthetic aperture radar” technology. ISRO’s earlier launches used optical remote sensing technology; with this they graduate to microwave payloads. SAR is an active sensor, which helps to gather accurate information about the target — dielectric constant, roughness, and geometry, enabling target identification through fog and haze (and clouds). In the past, cross-border infiltration has taken place during times when bad weather could be used as a shield; this should help cut that down. (Also, for the first time information on soil moisture will be made available, which is helpful for agriculture.)

ANUSAT, in contrast, designed by Chennai-based Anna University, and is a 40-kg “micro-satellite”. ISRO’s intention with the launch is to involve universities, to promote and encourage intra-disciplinary technologies. (There are plans afoot with students from IIT-Kanpur and Mumbai.) It carries a digital store and forward payload for amateur communication.

It has been widely reported that this satellite has been put in orbit because of the pressing security requirements post-26/11. However, what needs to be emphasised that no country in the world has yet reached a stage where it can launch satellites on demand. Besides, satellites aren’t precisely available “off-the-shelf”. ISRO has been working on indigenous SAR technology for years, and intends to launch RISAT-1 soon; that is expected to be a 1,780-kg satellite, and would become a major milestone in the country’s remote sensing capabilities, with a C-band SAR payload that can operate in a multi-polarisation and multi-resolution mode. However, the integration of this satellite appears to have been delayed; RISAT-2 might have been launched as a stopgap arrangement.

... contd.