Wellweathered

When Columbia arrived in the OPF on 26 January 1990, a few days after her return from the record-breaking STS-32 mission, one of the first tasks was removal of the

LDEF satellite. It had remained inside her payload bay during the long ferry flight back to KSC from Edwards Air Force Base, closely monitored by a set of environmental sensors. Although excited LDEF scientists were able to photograph their precious payload through Columbia's aft flight deck windows while at Edwards, it was not until it was back at KSC that they could get their hands on it properly.

After removal from the Shuttle, it was placed in a specially built LDEF Assembly and Transportation System (LATS) which trundled it firstly to the Operations and Checkout Building and later, on 1 February, to the Spacecraft Assembly and Encapsulation Facility (SAEF). Once it was safely inside the latter, the laborious job of removing the 86 experiment trays could get underway in earnest. For the next two months, engineers and scientists measured radiation levels, conducted an infrared video survey, observed contaminants - including micrometeoroids - and took over 10,000 photographs of the LDEF's exterior.

The satellite was intact, but certainly well-weathered after almost six years in space. Clear evidence existed of 'pitting', in which micrometeoroids had punched into her outermost surfaces, and some erosion to a Kevlar-foil thermal-protection cover on her space-facing end. ''I think the conclusion that we all came away with,'' said William Kinard, ''is that you have to be cautious in designing a spacecraft.'' Organic materials such as Mylar, Kapton, paint binders and bare composites showed severe erosion caused by exposure to atomic oxygen.

'Coated' composite materials generally survived and maintained their mechanical properties, but due to the extended mission a few of the thin polymeric films and blanketing materials were virtually destroyed; these had deposited debris onto adjacent surfaces of the satellite. A low-density particulate cloud was also spotted by Columbia's crew, trailing in the LDEF's wake. Many of the satellite's surfaces had a light-brown discoloration, although the leading face tended to be cleaner than the others. The data would aid designers when planning the structure of the space station's habitable modules and electricity-generating solar-cell arrays.

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