honeycomb equipment panels were thermally coupled to provide a nearly isothermal equipment panel irrespective of the location of heat-dissipating components and subsystems.

The axially grooved aluminium ammonia heat-pipes were developed by the ISRO Satellite Centre, (ISAC) Bangalore. Both single vapour core and double vapour core axially grooved aluminium ammonia heat pipes have been developed. These
heat-pipes were used in GSAT-1, launched in April 2001 and they will be used again in GSAT-2, to be launched by GSLV-D2 in 2003. Embedded heat-pipe panels employing double vapour core heat-pipes will be used in INSAT-3A, which is also slated for launch in 2003.

With the continuous requirement of heat-pipes for the forthcoming satellites, the technology for the heat-pipes was transferred under a contract to M/s Elbeam Devices Limited, an Avasarala Group Company in March 2001 with ISRO providing technical and financial assistance for establishing fabrication and testing facilities for space grade heat pipes. The contract has borne fruit with space-worthy double core axially grooved aluminium ammonia heat-pipes having been successfully fabricated and undergone all the acceptance tests.

Communication hardware

At a brief function held on October 30, 2002 at Antariksh Bhavan, Bangalore, Bharat Electronics Ltd. (BEL), Bangalore, formally handed over Invar Filters to ISRO. These sophisticated precision components are to be used in the communication transponders of INSAT-3E and follow-on satellites. The Invar Filters were the first batch of space qualified components being fabricated by BEL under a contract with ISRO's Space Applications Centre, Ahmedabad.

BEL is also making C-band and Ku-band receivers for ISRO's communication satellites, which involve the use of microwave integrated circuits that need to be assembled under a clean environment. ISRO had transferred the technology for the Invar Filters and Receivers to BEL and also trained its personnel for their production. Besides this, ISRO has funded the setting up of specific facilities required for building space hardware, in addition to allowing BEL to use ISRO's facilities like the Electron Beam Welding facility. Besides satellite components, BEL will also be supplying ground terminal equipment like Mobile Satellite Services reporting terminals and L-band Demodulators to ISRO. It is expected that BEL will supply space hardware worth about Rs. 200 Crore in the next five years.