I bet one of the best things we make for low friction are the gyroscopes in the old inter-continental ballistic missiles. They have air bearings and, once spinning, are designed to continue until, if not the end of the world, at least for the lifetime of the gyroscope. The earth going around the sun sounds like a pretty good candidate for something with no friction, so maybe you are right in that it is a perpetual motion machine. You see, space is not a vacuum. It is almost empty, but there are still small particles whizzing around, as well as larger things like meteorites.
Many particles come from the sun.
However, the effect is tiny. Copyright 1996, Washington University. All rights reserved.