The dynamics of asteroid deflection and manipulation using mass ejection are examined. First, a linearized small angular velocity and inertia tensor deviation model for close-to-principal-axis rotators is developed. The model is then applied to launching boulders off of asteroid surfaces, proving that the principal-axis-rotator characteristic can be kept while removing material off the surface. Mass ejections for asteroid deflection are presented and examined. This method, dubbed mass driver deflection, uses small discrete launches of masses off an asteroid to prevent its collision with Earth. By using material from the asteroid itself, such as boulders or regolith deposits, mass driver deflection substantially reduces the required mass of the deflection system. The analysis in the paper seeks to optimize the deflection efforts while minimizing unwanted effects on the deflected asteroid’s state: both rotational and orbital. The results show that deflection is possible in timeframes of several years in a variety of scenarios and that the deflection effects on the asteroid behavior do not pose a risk of disrupting the asteroid in a catastrophic way.