Ion Drive
Entry updated 16 September 2024. Tagged: Theme.
A common item of sf Terminology derived from a long only theoretical means of Rocket propulsion proposed by Konstantin Tsiolkovsky in 1911. Chemically fuelled rockets are hampered by the necessity of carrying large burdens of fuel. Other systems, including the ion drive, propose using much lighter fuels, compensating for the decrease in the mass available for propulsion by ejecting it at correspondingly higher velocities. Ions (charged particles) can be accelerated to enormous velocities using a magnetic field, and so would seem an ideal fuel. Also, since all elements can be ionized, albeit with varying degrees of difficulty, ion-drive rockets could theoretically make use of pretty well any substance to hand. Although an ion drive would produce only a small acceleration because of the relatively tiny masses involved, this could be maintained for months or years (assuming a suitably inexhaustible Power Source), so that very high terminal velocities could be achieved. The first successful test in space of such a system was in 1964 with NASA'S SERT (Space Electric Rocket Test) probe, which did not enter orbit; the propellant was ionized mercury and the electric power was derived from solar cells. The first successful orbital test of an ion engine was the ATS-4 flight on 10 August 1968. Practical applications have included NASA's manoeuvrable Deep Space 1 space craft launched in 1998, using ionized xenon as propellant.
There is a surprisingly early sf appearance of the ion drive concept in Donald W Horner's By Aeroplane to the Sun: Being the Adventures of a Daring Aviator and his Friends (1910). Ion drives are also mentioned by name in "The Equalizer" (March 1947 Astounding) by Jack Williamson, "In the Still Waters" (June 1955 Fantastic Universe) by Lester del Rey, Trivana I (1966) by R Cox Abel and Charles Barren, and Tau Zero (June-August 1967 Galaxy as "To Outlive Eternity"; exp 1970) by Poul Anderson. Twenty-first century appearances include Pandora's Star (2004) by Peter F Hamilton and Polity Agent (2006) by Neil Asher. [PN/DRL]
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