The diagram on the right is a blown-up illustration of the high-speed oxygen turbo pump. Running through the center of the engine is the turbine shaft, which is held in place by the bearings that the Steel Research Group at Northwestern University has worked on. These bearings are subjected to extremely high loads -- the turbine spins at 30,000 rpm, the bearings are unlubricated, and they are cooled by liquid oxygen. "For the lifetime that's desired for this part," says Greg Olson, "and the margin of safety that's required, it would be highly desirable to double both the fracture-toughness and the stress-corrosion-resistance."
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