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Antennae on modern telecoms satellites are subject to extra heating by illumination of both direct sunlight and reflection from the optical solar reflectors (OSRs). One method to decrease the temperature of the transponders is to modify the direction of the reflected light from the OSRs. OSRs with a large diffuse component of reflectance have been successfully manufactured. In this paper, we describe the manufacture and characterisation of the optical properties of these diffuse OSRs.

There has been concern that the use of natural gas in engines designed for gasoline fuelling can give rise to excessive temperatures. This is based on experience of exhaust valve recession, high piston temperatures and hot exhaust systems with conversions in New Zealand. In order to establish some data this work has measured exhaust gas temperatures, piston, exhaust valve and cylinder head temperatures in a single cylinder research engine. The data show that at wide open throttle and with the engine tuned to similar operating conditions (ie. the same fuel-air ratio and MBT spark timing), the natural gas fuelled engine generally has lower surface temperatures within the combustion chamber and lower exhaust gas temperatures than the gasoline fuelled engine. When the engine is operated at the same load on the two fuels the combustion chamber temperatures were similar for the two fuels.