A year of firsts for electric propulsion
By David Y. Oh and Patrick Neumann |December 2023
The Electric Propulsion Technical Committee works to advance research, development and application of electric propulsion for satellites and spacecraft.
In November, operators at NASA’s Jet Propulsion Laboratory fired the Hall Effect thrusters, or HETs, on the Psyche spacecraft, the first time HETs have been used in interplanetary space. Built at JPL, Psyche was launched in October from NASA’s Kennedy Space Center in Florida.
In February, SpaceX launched the first of its Starlink V2 Mini satellites. These next-generation spacecraft are equipped with HETs that operate on argon, instead of the krypton propellant on previous Starlinks. Shortly after launch, the satellites turned on their 4.2-kilowatt thrusters, the first time argon HETs have been operated in space.
In May, the 100th BHT-350 HET built by Massachusetts-based Busek was sent to orbit during a launch of 16 OneWeb satellites. Over 100 units are now operating in space aboard spacecraft in OneWeb’s Gen1 broadband constellation.
In other satellite news, the Gravity Space-1 satellite in August maneuvered to geostationary orbit via thrust vectoring with Austria-based Enpulsion’s NANO AR3 electric thruster. In June, ExoTerra of Colorado demonstrated its Halo micro-HET in orbit. In March, the water resistojet system built by Pale Blue Inc. of Japan was operated for the first time on the EYE nano satellite as part of the STAR SPHERE project by Sony Corp. In June, Neumann Space of South Australia launched the first center-triggered pulsed cathodic arc thruster.
In ground-based research, researchers from Imperial College London, URA Thrusters of the U.K. and Aliena Pte Ltd. of Singapore for the first time operated a HET with water electrolyzed into hydrogen for the cathode and oxygen for the main thruster. University of Michigan researchers demonstrated a tenfold increase in power density for a HET operating at 45 kW on xenon and alternative propellants. Under NASA’s Evolutionary Xenon Thruster project, thrust levels of a gridded-ion thruster were doubled by incorporating modifications to increase beam uniformity in the thruster.
At the Jet Propulsion Lab, researchers developed a heaterless hollow cathode made of lanthanum hexaboride (LaB6) that radiatively heats the thermionic insert with a high-voltage discharge to an internal refractory metal tube. This technology eliminates arcing and has been used to reliably start LaB6 cathodes capable of discharge currents up to 50-300 amperes. In March, an air-breathing microwave plasma cathode was tested at the University of Surrey with a low-power xenon cylindrical HET. Researchers observed stable thruster operation on both xenon and air at thruster discharge powers of 100-300 watts.
In Massachusetts in January and May, students from Olin College, Wellesley College and Brandeis University fired a Hall thruster at 200-600 W, the first fully undergraduate team to design and operate a steady-state electric propulsion thruster.
Looking to future flights, Northrop Grumman in June secured orders for the last of three planned Mission Extension Pods. These all-electric “jet packs” would attach to satellites in geostationary orbit and maneuver them via NGHT-1X thrusters to extend their lifetimes. At Safran, the PPS 5000 5-kW HET saw a sharp increase in orders and production rates. Busek delivered the first two BET-MAX electrospray systems for launch.
In October, the Japan Aerospace Exploration Agency, JAXA, completed testing of its 6-kW-class HET. A unit is scheduled to launch in 2025 aboard Engineering Test Satellite-9.
Qualification and production of flight hardware began for the first element of NASA’s planned Lunar Gateway space station, the Power and Propulsion Element. Provided by Maxar, the PPE will have 48 kW of electric propulsion distributed among HETs provided by Aerojet Rocketdyne and Busek. In June, the second 13-kW integrated string test was completed at NASA’s Glenn Research Center in Ohio, and Aerojet Rocketdyne and NASA in July completed acceptance testing of the first 12-kW Hall thruster.
Overall, the future looks bright with electric propulsion continuing to expand across the solar system.