If you were in space do you maintain momentum forever?

In space there is no matter to stop the momentum or motion of body through friction. This means excluding the gravitational pulls and also the random floating junk in space one could float on infinitely with a small thrust of fuel. Also another interesting fact, due to this lack of matter or vacuum astronauts are trained for the case of a jet pack losing all fuel away from the shuttle to hold the pack against there feet and kick off of it to create this endless momentum back towards the shuttle. This lack of matter and gravity allows for equal dispersion of force sending both objects though different masses of at an equal velocity in opposite directions sending the astronaut back to the shuttle :)