How does ion propulsion compare with chemical propulsion? Does it make the spacecraft go any faster?
Under the circumstances for which ion propulsion is appropriate, it can push a spacecraft up to about ten times as fast as chemical propulsion. Because the ion propulsion system, although highly efficient, is very gentle in its thrust, it cannot be used for any application in which a rapid acceleration is required. With patience, the ion propulsion system on DS1 imparts about 3.6 km/s to the spacecraft. To undertake the same mission with a chemical propulsion system would require a more expensive launch vehicle and a larger spacecraft to accommodate a large tank for the chemical propellants.
