Laboratory measurements of realistic space-aged surfaces and the development of a Monte Carlo simulation to model radiative transfer in a passively cooled space telescope

Sullivan, Mark (2001). Laboratory measurements of realistic space-aged surfaces and the development of a Monte Carlo simulation to model radiative transfer in a passively cooled space telescope. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fd05

Abstract

I investigate the effects of bombardment upon the surface properties, and subsequently the equilibrium temperatures of, the telescope’s components.

Extensive directional measurements have been made of the surface properties of gold samples at two wavelengths (0.633μm and 10.6μm), with both vertically and horizontally polarised radiation and at ambient temperature and ~80K.

Apart from pristine planar gold samples, an extensive program of two types of hypervelocity bombardment was used to simulate micrometeorite impact degradation of space-aged surfaces in order to investigate the effects of long-term exposure to space.

Laboratory efficiency was enhanced with the development and semi-automation of the measurement process.

Careful modelling of radiation exchange in a telescope system with respect to direction, wavelength and temperature has given a clearer view of the behaviour of surfaces within a spacecraft configuration and offers insight into advantageous design.

The main conclusions are as follows.

1. For an initially specular surface to develop a significant diffuse component, exposure to bombardment in space might have to exceed about 10 yrs.

2. When a significant diffuse component develops, the effect on telescope temperature could be significant, and also the effect on which part of a heatshield is dominant in the heat exchange.

3. The telescope temperature is sensitive to spacecraft geometry and very sensitive to conduction between heatshield and telescope.