Published 7/25/2011

My Piece of Space Shuttle History

A sample of the silica insulation developed for the “tiles” that formed a critical part of the space shuttle’s Thermal Protection System came my way in the early 1980s. I’ve saved it all these years as a reminder of the technology (particularly five-axis machining) that made space shuttle flight possible.

Mark Albert

Editor Emeritus, Modern Machine Shop

This piece of space shuttle tile is more than a souvenir. It reminds Mark of what machining technology has done to advance space exploration. This explanation was enclosed with the sample.

In the early 1980s, five-axis machining was not the commonplace capability it is today. In fact, it was at the frontier of metalworking technology. Yet, it helped get the space shuttles back to Earth without burning up in the atmosphere.

When the space shuttle program first got off the ground, much attention was paid to the novel technology invented so that the orbiters could be reused, mission after a mission. The remarkable insulation tiles made of silica seemed to capture the popular imagination more than other innovations—maybe because the fiery reentries of the earlier manned space capsules were such a dramatic part of the media coverage surrounding those missions.

The Thermal Protection System developed for the space shuttles was different. It had to survive the tremendous heat of reentry. Tiles of the silica insulation were a prominent part of this system. Demonstrations of their heat resistant capability were vivid—a red-hot piece of insulation being held in a bare hand, for example.

A major challenge to installing these tiles was shaping them to fit the aerodynamic contour of the orbiter’s exterior. Most of the tiles had to be machined on three- or five-axis machine tools. Creating the toolpaths involved interpreting 3D wireframe designs on DEC MicroVAX “minicomputers,” which were a big advancement compared to the mainframe systems generally used for complex NC programming tasks. Reportedly, silica billets were machined with end mills faced with industrial diamonds. Machine spindles operated at speeds as fast as 10,000 rpm—a very high figure at the time.

Today, five-axis machining is highly affordable and accessible. Our Five-Axis Machining Zone is a handy resource for exploring the many applications for five-axis machining to meet opportunities created by the heating up of the current economy.