INSAT-3D is a meteorological satellite that was built by the Indian Space Research Organization for operation by Insat. The satellite is based on the I-2K satellite bus that was modified as INSAT-3D does not feature an additional communications payload which was the case for previous satellites that are part of that constellation.
The satellite is 2.4 by 1.6 by 1.5 meters with a total liftoff mass of 2,120 Kilograms. It features a single deployable solar array that provides power to the satellite. The vehicle is three-axis stabilized. Its main propulsion system is centered around a Liquid Apogee Motor, LAM. It provides a thrust of 440 Newtons and uses Mixed Oxides of Nitrogen as fuel and Unsymmetrical Dimethylhydrazine as oxidizer.
The engine operates and an mixture ratio (O/F) of 1.65 and has a nozzle ratio of 160. The engine’s injector is a co-axial swirl element made of titanium while the thrust chamber is constructed of Columbium alloy that is radiatively cooled. The engine is certified for long firings of up to 3,000 seconds. The Propellants are stored in spherical tanks that are pressurized with Helium.
The meteorological payload of the satellite consists of a 6 Channel Imager, 19 Channel Sounder along with Data Relay Transponder and Satellite Aided Search & Rescue payloads. The satellite has an expected lifetime of 7 years.
It will be stationed at 82 degrees East covering India. The satellite’s mission is “to provide an operational, environmental & storm warning system to protect life & property and also to monitor earth’s surface and carryout oceanic observations and also provide data dissemination capabilities.”