Document Type

Presentation

Journal/Book Title/Conference

25th Annual Thermal and Fluids Analysis Workshop (TFAWS) 2014

Publisher

National Aeronautics and Space Administration

Publication Date

8-4-2014

First Page

1

Last Page

26

Abstract

The Precision Tracking Space System (PTSS) was a constellation of infrared (IR) sensors planned by the US Missile Defense Agency (MDA) to observe and track ballistic missile objects in flight. The PTSS program funded testing to characterize the parasitic heat loads expected on the actively-cooled multi-band IR sensor assembly, a subassembly within the optical telescope, thereby reducing uncertainty in the cooler heat lift requirements and system power budget. A detailed flight-like thermal analog of the sensor assembly, including designed conductances, surface treatments, and multi-layer insulation, was tested in a fixture that simulated its flight interfaces with a controllable interface temperature. A heat flow sensor, located at the flight cold-head attachment point, provided heat lift measurements. Testing was performed with various boundary conditions and a least squares fit was used to discriminate between the conduction and radiation parasitic heat load components. This knowledge was used to correlate a detailed thermal model built in Thermal Desktop that could then be used to accurately predict flight heat lift and perform system level design trades. This document presents a detailed description of the testing, test results, model correlation methodology and results, and lessons learned.

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