Is Motion in space completely with out friction??

Do you think that motion of a satellite in space is completely constant and only accelerated?
If you do then you are wrong.
There is also retardation. It is not due to any gravitational pull of sun or earth but due to the thermal radiation(heat) from the satellite it self.
This is called thermal friction
Any body that generates thermal radiation undergoes deceleration in outer space. Its effect may be minimal or negligible on earth conditions but it clearly making its mark in outer space…..