Deep Space 1: When Ion Propulsion Became Operational

Transcripción

Ion propulsion is built for a long, patient push. Instead of producing a large burst of thrust, an ion engine accelerates charged particles and gradually builds spacecraft velocity with high efficiency. Deep Space 1 turned that principle into an operational test. The mission soon faced a serious problem. On 11 November 1999, its star tracker failed. The spacecraft needed that tracker to point the ion engine and its instruments, so the failure threatened the mission. There was no replacement hardware. Over the next five months, the operations team devised a new attitude-control system in flight, allowing the spacecraft to operate without the tracker and continue toward Comet Borrelly. The engine kept working. On 18 December 2001, it was finally switched off after operating for 16,265 hours and delivering 4.3 kilometres per second of total delta-V, the change in velocity produced by the spacecraft’s own propulsion. Deep Space 1’s restrained legacy is not simply that an ion engine ran for a long time. It mattered because the propulsion system operated as part of a complete spacecraft, not merely in a laboratory test.