ELECTRIC PROPULSION

Now the overwhelming majority of satellites use electric propulsion, but when Mr. Martin was researching the subject in the 1970s not a single satellite used it. Electric propulsion uses electricity -- typically from solar panels -- to first ionize atoms (so that they have an electrical charge) and then accelerate those ions out through a nozzle to provide thrust. Because they use 90% less propellants than chemical rockets, they reduce the weight of spacecraft, enabling longer mission lifetimes and reduced launch weight and cost. It is used for low-thrust applications such as station-keeping, orbit raising and deep-space missions.