Ion Beam Shepherd for Contactless Space Debris Removal
  A novel concept for contactless active removal of large space debris is proposed exploiting the use of a high-speed targeted ion beam. The ion beam shepherd spacecraft (IBS) is equipped with an electric propulsion system generating a quasi-neutral plasma pointed against the space debris to remotely modify its orbit without physical contact with the latter. The beam shepherd must be equipped with a secondary propulsion system which counteracts the reaction force exerted by the ion beam hence keeping the distance between the space debris constant throughout the deorbit (or reorbit) process. A preliminary analysis of the concept is provided highlighting the expected performance and the main technologicals challenges. The concept has the potential of making large debris removal operations possible in the near future. 
C. Bombardelli, and J. Pelaez
physics.space-ph math.OC