This paper assesses the application of small ion-propelled spacecraft of about 200 kg launch mass to low-cost interplanetary missions, for which very high velocity increments (ΔV) are required. Here, the "low cost" criterion eliminates the utilisation of the launcher for the attainment of escape velocity, thereby implying the use of an ion propulsion system for orbit-raising from an initial low Earth orbit or from the geostationary transfer orbit. The sample missions considered were to rendezvous with a wide range of asteroids; they require a total ΔV of the order of 10-12 km/s. Although the performance of the solar array is critical, recent advances in solar cell technology have enabled considerable progress to be made in this area. Other relevant advances include improved batteries, attitude and orbit control sensors, and communications systems. Gridded ion thrusters are essential, owing to the need for very high values of specific impulse. They allow a very large number of target bodies to be accessible within a launch mass of 200-250 kg.
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