  Current spacecraft mass are mostly fuel, this is dictated by the lack of
fueling stations in space and also by the Tsiolkovsky rocket equation which
defines the mass ratio needed to escape earths gravity. The Tsiolkovsky rocket
equation gives a relationship between the mass ratio and the final velocity in
multiples of the exhaust speed, and dictates a high mass ratio for current
exhaust speeds. A relativistic motor exchanging momentum and energy with the
electromagnetic field may mitigate such considerations, enabling efficient
interplanetary travel. In this paper we will discuss the advantages and
challenges of this novel mover for space transportation.
