Development of the variable emittance thermal suite for the space technology 5 microsatellite

Abstract

Abstract. The advent of very small satellites, such as nano and microsatellites, logically leads to a requirement for smaller thermal control subsystems. In addition, the thermal control needs of the smaller spacecraft/instrument may well be different from more traditional situations. For example, power for traditional heaters may be very limited or unavailable, mass allocations may be severely limited, •and fleets of nano/microsatellites will require a generic thermal design as the cost of unique designs will be prohibitive. Some applications may require significantly increased power levels while others may require extremely low heat loss for extended periods. Small spacecraft will have low thermal capacitance thus subjecting them to large temperature swings when either the heat generation rate changes or the thermal sink temperature changes. This situation, combined with the need for tighter temperature control, will present a challenging situation during transient operation. The use of "off-the-shelf' commercial spacecraft buses for science instruments will also present challenges. Older thermal technology, such as heaters, thermostats, and heat pipes, will almost certainly not be sufficient to meet the requirements of these new spacecraft/instruments. They are generally too heavy, not scalable to very small sizes, and may consume inordinate amounts of power. Hence there is a strong driver to develop new technology to meet these emerging needs. Variable emittance coatings offer an exciting alternative to traditional control methodologies and are one of the technologies that will be flown on Space Technology 5, a mission of three microsatellites designed to validate "enabling" technologies. Several studies have identified variable emittance coatings as applicable to a wide range of spacecraft, and to potentially offer substantial savings in mass and/or power over traditional approaches. This paper discusses the development of the variable emittance thermal suite for ST-5. More specifically, it provides a description of and the infusion and validation plans for the variable emittance coatings.

Light modulation in phase change disordered metamaterial - A smart cermet concept

“…The demonstrated, Fig. 3, change in emissivity from 0.8 to 0.1 (DƐ ¼ 0.7), or 0.94 to 0.1 (DƐ ¼ 0.84) using VO 2 coatings, is unprecedented with conventional variable emissivity coatings used in space applications [16,17].…”

The electrical resistivity and thermal infrared properties of La1−xSrxMnO3 compounds

“…While active thermal control components, such as louvers, are favorable in dealing with the temperature fluctuation, their drawbacks of being bulky and complex prevent their popular use. With recent trend towards the miniaturization of satellites, the production of new generations of micro-and nano-satellites critically demands the compact and efficient thermal technology [2]. To meet this requirement, advanced active thermal control materials and devices such as variable emittance thermal control coatings (VEC) [3][4][5], micro-electro-mechanical (MEMS) louvers and electrostatic thermal switches [6,7] are vigorously researched.…”

Variable Emissivity Surfaces for Micro and Nanosatellites

“…The MEMS VES has overall emissivity modulation ∆ε ≈ 0.4 due to the limited louver packing density and weighs app. 30 kg/m 2 , including holders and control circuits [6]. Electrostatic radiator is similar to MEMS thermal switch with ∆ε ≈ 0.5 [6].…”

“…30 kg/m 2 , including holders and control circuits [6]. Electrostatic radiator is similar to MEMS thermal switch with ∆ε ≈ 0.5 [6]. Other proposed solutions include electrophoretic and electrochromic coatingssandwich structures which change their emissivity under the influence of electric current and/or temperature.…”