Abstract

Thermal management problems of large space systems will receive increasing attention during the next decade. Large Space Platforms will be developed which will carry multidisciplinary instruments of diverse thermal and power requirements. Energy levels of the order of 250 kW will result in significant heat rejection, acquisition and transport requifements. These systems will transport multi-kilowatt loads over distances of possibly hundreds of meters. Current thermal distribution systems on large spacecraft, such as the Shuttle and Spacelab, utilize pumped fluid loops that circulate the coolant between a series of user stations and a single rejection point. This usually involves complex plumbing and controls with a significant power penalty and limited reliability. The majority of future instruments will require very narrow temperature limits to be maintained at or near room temperature conditions. In order to provide heat transport at near isothermal conditions, systems-such as those utilizing two phase flow will be required. This can be accomplished by taking advantage of the heat of vaporization and condensation of common working fluids, at little or no expenditure of power and minimal temperature variation. Thus, a “thermal buss” or utility can be developed into which a user can reject or extract heat, depending on conditions. In this manner components can be coupled together within the system, with excess heat being transferred from warmer to cooler regions.

The paper will discuss the results of a recent survey to determine the thermal requirements of almost one hundred potential astrophysics and astronomy instruments. Material was gathered on such parameters as temperature requirements, power dissipations, environmental fluxes, heat rejection or addition and general description. These data were used to form conceptual designs for the thermal utility. Current and future research and development plans, which will establish the readiness of such a system will also be discussed.