Thermal Design Solutions for Space Exposed P/L’s and Pointing Systems on the ISS Express Pallet 2001-01-2431
The use of the truss of the International Space Station (ISS) for the accommodation of several experiments, in the frame of the “Early opportunity for ISS utilization”, will have a lot of advantages such as the possibility of human or robotics intervention, the recovery of the experiment at the end of its life, visual inspection of the items and cost reduction with respect to an installation on a dedicated satellite.
However, from the user point of view, the ISS generates a great number of disturbances and severe environmental conditions for the experiments providing constraints and affecting the performances in different areas (thermal, mechanical, and avionics).
The present paper will discuss the thermal aspects (disturbances, constraints and performances) concerning three different projects, developed by Alenia Spazio Turin plant, that will be mounted on the truss of the ISS: Hexapod, Coarse Pointing Device (CPD) and Sky Polarization Observatory (SPOrt).
Hexapod and CPD are two pointing systems designed to give different pointing capabilities to the payloads mounted on them. Their main requirements are thermal stability and reduction of local temperature gradients to ensure the Payloads required pointing accuracy.
SPOrt is a radiometer designed to observe the Cosmic Microwave Background (temperature near 0 K). Its main thermal requirement is to maintain the four sensors (one for each antenna) at a cryogenic temperature by means of pulse tube cryocoolers.
A common problem for all ExPA payloads is the management of thermal interfaces with the Express Pallet Adapter (ExPA)
Purpose of the paper is:
Provide description of thermal design of the pointing systems and Experiments;
- Highlight the problems related to the thermal interface management with the ISS and the Payloads and provide approach to their solution
- Provide description of the analytical tools/models used for the design