Electric Propulsion for Small Spacecraft

Roald Sagdeev
East-West Science Center, University of Maryland, College Park

The role of electric thrusters in spacecraft propulsion is constantly evolving and expanding as new missions, covering the entire spectrum of spacecraft size and power, continue to be developed. A large number of such missions can significantly benefit from the performance characteristics of electric propulsion. We have considered different classes of scenarios (LEO, HEO, GEO and even baseline deep space missions). Such analysis brings together the issues of delivery orbit optimization (including the radiation issue), compatibility of s/c bus with the electric propulsion system and the choice of most appropriate version of electric thrusters, ranging from sub-kW (~350W) thrusters for orbital maneuvering of small s/c inside Mars system to 1.5 kW thrusters for orbit raising of small telecommunication satellites from GTO to GEO. One of the critical issues is how small can the satellite be, and still accommodate the electric propulsion module (is there a critical mass of electrically propelled satellites for currently available and realistic thrusters?)

As specific examples we have elaborated conceptual designs for several baseline missions:

• Mars/Phobos/Deimos orbiter (lander) with all the maneuvers within Mars system (after getting to initial capture orbit) performed by electric thruster;
• Small sat in HEO with flexible orbital parameters and inclination;
• Small telecom sat in GEO;
• Small LEO sat released by Space Station or Shuttle, capable of raising orbit up to an altitude of a few thousand miles and return ("boomerang"-type mission).