Search Results

Manned space systems have many requirements for the monitoring of vital life support systems such as the cabin air quality and the quality of the recycled water supply. Infrared spectroscopy probes the characteristic vibrational and rotational modes of chemical bonds in molecules to provide information about both the chemical composition and the bonding configuration of a sample. The significant advantage of the IR spectral technique is that it can be used with minimal consumables to simultaneously detect a large variety of chemical and biochemical species with high chemical specificity. To date, relatively large Fourier Transform (FT-IR) spectrometers employing variations of the Michelson interferometer have been successfully employed in space for various IR spectroscopy applications. However, FT-IR systems are mechanically complex, bulky (> 15 kg), and require considerable processing.

This paper describes a new approach to spacecraft thermal control based on a passive thin-film smart radiator device (SRD) that employs a variable heat-transfer/emitter structure. The SRD employs an integrated thin-film structure based on V1-x-yMxNyOn that can be applied to existing Al thermal radiators. The SRD operates passively in response to changes in the temperature of the space structure. The V1-x-yMxNyOn exhibits a metal/insulator transition with temperature, varying from an IR transmissive insulating state at lower temperatures, to a semiconducting state at higher temperatures. Dopants, M and N, are employed to tailor the thermo-optic characteristics and the transition temperature of the passive SRD. The transition temperature can be preset over a wide range from below -30°C to above 68°C using suitable dopants. A proprietary SRD structure has been developed that facilitates emissivities below 0.2 to dark space at lower temperatures to reduce heater requirements.

This paper presents experimental results regarding a new approach to smart radiator devices (SRD) employing a smart, integrated thin-film structure based on V1-x-yMxNyOn that can be applied to existing thermal blankets such as Kapton or to thermal radiators such as Al. The smart coating facilitates thermal control by dynamically modifying the thermo-optic characteristics of the underlying substrate in response to the ambient temperature and/or a control voltage. This methodology has significant advantages over competitive technologies in terms of weight, cost, structural simplicity, and integration with the space structure. The effective emissivity of the film/substrate structure can be reduced dynamically by changing the behavior of the smart coating from insulator to metallic. High quality VO2 films have been prepared using a hybrid reactive laser ablation technique.

Infrared (IR) spectroscopy probes the characteristic vibrational and rotational modes of chemical bonds in molecules to provide direct information about both the chemical composition and the bonding configuration of a sample. The significant advantage of the IR spectral technique is that it can be used with minimal consumables to simultaneously detect a large variety of different chemical and biochemical species with high chemical specificity. Currently, various VIS/NIR grating spectrometers are employed to cover the spectral range between 0.3 and about 2.2 (μm. Bulk-optic Fourier Transform (FT)-IR spectrometers employing variations of the Michelson interferometer are generally used to provide spectral measurements above 2.5 (μm. The FT-IR systems tend to be mechanically complex, bulky (>15 kg), and require considerable processing, maintenance and recalibration. For space-based systems, the important drivers are reliability, power consumption, mass and simplicity of operation.

MPB has developed advanced smart radiator devices (SRDs) for passive, dynamic thermal control of space structures and payloads. The SRDs employ a nano-engineered, integrated thin-film structure based on V1-x-yMxNyOn. Dopants, M and N, tailor the transition temperature characteristics of the tuneable IR emittance. This paper describes the progress in MPB's smart thermal radiator towards its validation as an efficient thermal control device for space environment. A set of environmental tests were performed in order to validate the coating resistance and performance stability in space. The tests included random vibration, thermal shock, and accelerated aging. In addition, the thermo-optic characteristics after exposure to Atomic Oxygen (AO) in a simulated LEO environment were similar to the “as deposited” characteristics. Preliminary radiation tests, comparable to 3 years in a GEO environment, indicate very low change in emissivity and solar absorptance relative to the initial values.

Manned space systems have many requirements for the monitoring of vital life support systems including quality of cabin air and the recycled water supply, as well as direct monitoring of vital indicators of astronaut health. Infrared (IR) spectroscopy is an attractive monitoring technique because it requires minimal consumables while providing relatively high chemical specificity for the detection of a wide variety of biochemicals using the characteristic vibrational modes of chemical bonds. For space-based systems, the important drivers are reliability, power consumption, mass and simplicity of operation. MPB has advanced its IOSPEC™ technology for miniature integrated IR spectrometers to provide performance comparable to large bench-top IR systems but in a compact and ruggedized footprint weighing under 2.5 kg.