  Thermal control is of critical importance for normal operation of spacecraft.
Given thermal radiation is the only means of heat dissipation in space, an
efficient thermal control approach for spacecraft is to coat the radiator with
a tunable-emittance "skin" that can tune its heat dissipation according to
various thermal conditions. The existing schemes solely relying on far-field
thermal radiation, which are based on mechanical, electrochromic or
thermochromic working principles, are difficult to combine the advantages of
all-solid-state structure, actively and accurate tuning, and large tuning range
of heat flux. In this work, we propose a near-field radiation assisted (NFRA)
smart skin for thermal control which can tune the heat rejection accurately and
in a large range. It contains a metal-insulator-semiconductor (MIS) structure,
where the carrier distribution in the semiconductor layer can be electrically
altered. In this way, the near-field heat flux, and ultimately the skin
emission power expressed using effective emittance, can be controlled as a
function of the applied voltage. The variation range of the effective emittance
can exceed 0.7 when adjusting the applied voltage from -10 V to 100 V with our
preliminary design. This work opens a new way of smart skin design for active
spacecraft thermal control.
