Once in space, far enough from objects to be more or less free from?
Perpetual motion, essentially yes. A perpetual motion machine? definitely not. As soon as you try to use this motion to do any work, it starts draining away. This is why perpetual motion machines are not possible, and will never be possible, period. The best you can hope for is a machine that derives new energy from quantum vaccum fluctuations or some other such handwavium, and that wouldnt be a perpetual motion machine, it would be a quantum vacuum battery. Also, it might destroy the universe. If you like handwavium, you might enjoy my free award-winning scifi sampler.