Project Title:
Variable Emissivity Electrochromic Panels for Control of Radiant Energy Transfer
09.04-9450
Variable Emissivity Electrochromic Panels for Control of Radiant Energy Transfer
in Spacecraft
EIC Laboratories Inc.
111 Downey Street
Norwood
MA
02062
Rauh
David R.
NAS8-37259
Amount:
MSFC
NAS8-35267
Abstract:
Heat transfer in the space environment is largely a radiative process. The emissivities of the surface linking the payload to the space environment are
key to the problem of temperature stabilization and control in orbiting spacecraft.
The purpose of the proposed research effort is to develop thin film coatings which
have variable thermal emissivities and variable solar absorptivities. The development
of such coatings will provide a means of actively controlling heat transfer between
orbiting spacecraft and the space enviroment. Modulation of the emittance and absorptance
is achieved by the passage of a small DC electric current and is based on the concept
of electrochromism. The Phase I program was successful in demonstrating the principle
of variable thermal emittance (e = 0.06-0.75) and variable solar absorptance (as
= 0.32-0.98) switching in thin films of WO3. In addition, the concept of a solid-state
five-layer electrochromic coatings was formulated and optical switching experiments
showed
that variable emittance/absorptance coatings could undergo a large number of switching
cyles without degradation. The Phase II program is intended to develop electrochromic
coatings to the point of commercialization. To accomplish this objective, the Phase
II program will include: fabrication of variable emittance and variable absorptance
solid-state thin film coatings, demonstration of long-term optical switching, determination
of design parameters for thermal engineers, development of magnetron sputtering process,
and delivery to NASA of optimized variable thermal emittance and variable solar absorptance
electrochromic coatings.