Experiences from Thermal Balance Tests on Indian Remote Sensing Satellite (IRS-1A)

Prior to successful launch of IRS-1A, two different thermal balance tests were carried out, one on the Structure Thermal Model using heater pad technique and second on Engineering Model, using solar simulation technique. The temperature match was found to be better for extreme cold case in STM test and for EOL case in solar simulation test and not so good for other cases. An attempt was made to find out the reasons for this mismatch, but the exact reason could not be ascertained. The flight temperatures were predicted, based on solar simulation test data, which matches well with on orbit data.