Launched April 24, 1990, on STS-31/Discovery, the Hubble Space Telescope (HST) opened the universe to astronomers with a resolving power calculated to be ten times better than any ground-based telescope. Orbiting 375 miles above Earth, the HST archives 3 to 5 gigabytes of data and delivers between 10 and 15 gigabytes to astronomers all over the world daily.

The HST was the first scientific spacecraft that was specifically designed for routine servicing by spacewalking astronauts. To that end, Endeavour launched December 2, 1993, to rendezvous with the HST and repair its faulty optics (discovered after STS-31, three years earlier).

Topping the primary servicing task list was the replacement of the HST's solar arrays. Excessive flexing, caused by the extreme changes between cold darkness and warm daylight, was thought to be compromising the structural integrity of the arrays.

The European Space Agency (ESA) had provided HST's deployable solar arrays, and as such ESA was returned a damaged array after it was returned to Earth on STS-61 (the second array was jettisoned when it couldn't be fully retracted due to kink in the framework).

After studying the array for the effects of long duration exposure to space, ESA cut samples of the solar cells and embedded them within lucite for presentation to VIPs and program participants. The above cells are from one such presentation.