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A computer based data acquisition and power control system has been designed and installed for conducting thermal test at 4M thermal vacuum chamber of ISRO Satellite Centre(ISAC), Bangalore, INDIA. The system consists of four main units viz. Temperature Signal Processing Unit(TSPU), Power and Control Unit(PACU), Spacecraft telemetry and thermal vacuum chamber facility data interface unit and Data Processing Unit(DPU). The system has capability of monitoring 512 thermocouple channels, 700 spacecraft telemetry thermal related parameters, facility parameters including chamber Vacuum level, chamber contamination level using Quartz Crystal Monitor data and 128 numbers of heat-flux/temperature control channels. TSPU and PACU are VME based system. DPU is based on Pentium processor with hot redundancy using Redundant Array Of Inexpensive Disks(RAID) to takeover in case of failure of a server. All the subsystem and their peripherals are networked using TCP/IP on Ethernet.

This paper discusses about the software ‘ISCP’ developed for thermodynamic design and analysis of Stirling cycle cryocooler. The model is based on second order analysis method which assumes the various parasitic losses as independent of each other. The specifications of the cooler are arrived at using the Design Module of the software after performing various optimizations. The analysis module performs both dynamic and thermodynamic analyses.

“Tinned Copper Braid” is planned to be used in IRS-1C spacecraft for the thermal control of the detector of the “Middle Infra Red” (MIR) band of LISS III Camera. The thermal conductance of the braid was evaluated experimentally in the temperature range of -65°C to +35°C by employing the calorimetric technique. The measured thermal conductance of the 215mm long copper braid varies from 0.051 to 0.056 W/°C at different temperatures in the specified range. An error estimation has been performed which shows a maximum uncertainty of better than ± 5% on the conductance value measured.

Thermal control materials of different types are being used on the spacecraft for temperature control viz. Thermal control tapes, Thermal control paints, Anodised surfaces and Optical solar reflectors. This paper covers the measurement of emittance at different temperatures on various Optical Solar Reflectors ( OSR ) both rigid and flexible types. The rigid OSRs evaluated are OCLI - USA, PPE - UK and ISRO - INDIA. The flexible OSR is from SHELDAHL - USA. The emittance of the OSRs were measured in the temperature range 223K - 373K using steady state calorimetric method. Measurements were done on a square sample with OSRs affixed on each face. The sample has a built in heater and an evacuated low temperature radiation receiver is used for the test environment. Experimental results, temperature dependence of the total hemispherical emittance relation for each of these OSRs and error estimation are presented in this paper.

Integral black anodizing and gold plating on Mg-Li alloys were developed for spacecraft thermal control applications. The influence of various process conditions have been investigated to optimise the process. The deposits were characterized by morphological studies, adhesion test, thickness measurement, microhardness evaluation and porosity inspection. The space worthiness of the coatings has been evaluated by humidity, thermal cycling, and thermovacuum tests and measurement of optical properties. The high solar absorptance and infrared emittance (αs = 0.95, εIR = 0.93) value of black anodic film showed that these can be effectively utilized to improve heat radiation characteristics. The gold coating on the other hand provides the infrared emittance as low as 0.03, is extremely suitable in minimising the radiative coupling with other components within the spacecraft.