About ISRO Recent Events ISRO Centres Programmes Decade Plan Space Science International Sponsored Research Space Services Commercial Training Facilities Resources Contact Us   April 12,1999 Critical Deployments on INSAT-2E Completed A major critical operation of deploying the 14m long solar sail and boom on the North face of INSAT-2E was successfully completed this morning (April 12, 1999). The deployment took place in two stages - first by firing an explosive device to release the sail-boom assembly and later operating a motor for about 15 minutes to ensure a controlled deployment. At the time of launch, the sail-boom assembly is kept compactly packed which just occupies about 1/50th of its final deployed length. The boom is made of ultra light-weight glass fibre structure weighing about 3.5 kg. The sail measuring 2 m across and 5 m tall weights less than a kilogram. INSAT-2E carries a meteorological payload, which requires the detector to be maintained at an extremely low temperature. This precludes the use of solar arrays symmetrically on both north and south faces. To counteract the torque generated by the sun's radiation falling on the solar array on the south side, the solar sail mounted on a boom is incorporated in the design of INSAT-2E on the north side. The sail and boom were indigenously designed, developed and manufactured at ISRO Satellite Centre, Bangalore, followed by extensive testing in simulated zero-gravity conditions. This deployment was preceded by turning on the momentum wheels onboard the satellite, and running them up to a speed of 4800 revolutions per minute. The momentum wheels are used for maintaining the precise orientation of the satellite required for the communication and meteorological payloads. With this, the satellite is in the 3-axis stabilised final configuration with earth orientation, and the stage is set for turning on the payloads.