---
title: "Spacecraft electric propulsion"
chunk: 2/4
source: "https://en.wikipedia.org/wiki/Spacecraft_electric_propulsion"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:55:41.016044+00:00"
instance: "kb-cron"
---

In West Germany, electric-propulsion development also proceeded from 1960 at German Aerospace Center (DLR) institutes in Stuttgart and Braunschweig and at the University of Giessen. At Gießen, Horst Löb's group began development of radio-frequency ion thrusters of the RIT type, which use radio frequency fields rather than physical electrodes to ionize propellant, starting with the conception, laboratory model, and first tests of the RIT-10; the prototype was further improved through the 1960s and transferred to industry for qualification in 1970. A June 1960 decree of the Central Committee and Council of Ministers (No. 715-296), declassified after the Soviet period, directed the development of "space electric rocket engines". This included ion and electroplasma thrusters with target specific impulse of 5,000-10,000 seconds, a measure of propellant efficiency, assigning work to OKB-1, the Kurchatov Institute, and other named bureaus as part of a broader 1960-1967 Soviet Union space development plan. In 1964, Ernst Stuhlinger published Ion Propulsion for Space Flight, characterized by Choueiri as the first comprehensive book on electric rocket technology, marking the field's transition into a serious engineering discipline.
On 20 July 1964, two electrostatic ion engines were tested in space in the Space Electric Rocket Test (SERT I), and the mercury electron-bombardment engine produced thrust in flight. SERT I was the first spacecraft to incorporate electric propulsion; its mercury electron bombardment ion engine, which ionizes mercury vapor by bombarding it with electrons and then accelerates the resulting ions electrically, ran for 31 minutes, becoming the first electric engine to operate in space. A 1966 NASA Lewis Research Center overview stated that electric-propulsion spacecraft then under study could not be expected to take off from Earth and therefore would need to be launched to Earth orbit by chemical rockets before beginning low-thrust operation. The 30 November 1964 Zond 2 mission to Mars from the Soviet Union marked the first planetary use of electric propulsion. Following the Zond 2 demonstration, pulsed plasma thruster development was transferred from the Kurchatov Institute to OKB Fakel, whose "Globus" pulsed propulsion unit flew in 1968. The follow-on Space Electric Rocket Test II (SERT II), launched on 3 February 1970, was the first long-duration operation of ion thrusters in space; its two mercury electron-bombardment engines accumulated over 5 months and 3.5 months of continuous operation respectively, and after intermittent restarts, one thruster logged over 11 years of total operation through 1981.
Alongside ion engine development, a distinct line of electromagnetic thruster research was advancing in the Soviet Union. In the 1960s, A. I. Morozov proposed the stationary plasma thruster (SPT), a Hall-effect device that accelerates ionized propellant using perpendicular electric and magnetic fields. Within decades, hundreds would fly in space.
The first SPT was tested in orbit aboard a Meteor spacecraft in 1972, with corrective propulsion units operating on further Meteor missions through 1980.

=== 1980s ===
Commercial electrothermal propulsion entered operational satellite service during this period. Hydrazine resistojets, electric thrusters that heat propellant before expelling it, began commercial geostationary north-south orbital station-keeping, used to maintain orbital position, with Intelsat V in 1980.

=== 1990s ===

The end of the Cold War opened access to previously restricted Soviet electric propulsion technology. U.S. electric propulsion specialists traveled to Russia in 1991 to evaluate the Russian SPT-100 at the Scientific-Research Institute of Thermal Processes in Moscow and at Fakel in Kaliningrad using U.S. instrumentation. Brophy's subsequent JPL report said the measured performance appeared close to the advertised values, and noted claims that more than fifty lower-power SPT units had already flown on Russian spacecraft. The report laid out a second program phase in which thrusters would be brought to the United States for testing toward possible Western use. That work fed into the later Ballistic Missile Defense Organization Russian Hall Electric Thruster Technology (RHETT) effort to move Hall thruster technology toward Western operational use.
Electric-propulsion work matured across the decade. Hydrazine-based arcjet rockets were deployed in 1993 on Telstar 401, extending electrothermal electric propulsion into higher-performance commercial geostationary use.
Alongside these experimental programs, electric propulsion was also entering routine commercial service. Commercial electric propulsion also entered Western geostationary satellite operations in the 1990s, as Hughes Boeing 601HP communications satellites began using gridded xenon ion thrusters (XIPS) for station-keeping in 1997. After initial Russian usage from the 1970s, beginning in the 1990s qualified SPT units entered service on American and European spacecraft as well. European electric propulsion programs reached similar milestones in the years that followed. The Gießen RIT line later reached flight application on the European Space Agency's Artemis satellite, launched in 2001, which carried two German RIT-10 thrusters for station-keeping. By the late 1990s, ESA was already positioning solar electric primary propulsion as a key technology for future deep-space missions through SMART-1, whose PPS-1350-G Hall thruster was later developed in the CNES Stentor satellite program and adapted from a geostationary station-keeping design.
By the late 1990s, electric propulsion had moved from experimental and military programs into routine commercial satellite operations, particularly for geostationary station-keeping, orbit raising, and related orbit-control maneuvers. Deep Space 1 became the first U.S. space mission to use an ion thruster as its primary means of propulsion through 1998, validating NASA's NSTAR solar electric propulsion system in long-duration flight.

=== 21st century ===