Air Force

Hall thruster

The Air Force Research Laboratory (AFRL), Space and Missile Systems Center (SMC), and Rapid Capabilities Office (RCO) are collaborating to host a Hall thruster experiment onboard the X-37B flight vehicle (Boeing). The experiment will be hosted on Orbital Test Vehicle (OTV) mission 4, the fourth flight of the X-37B reusable space plane.

In a testing procedure, the X-37B Orbital Test Vehicle taxis on the flightline in June 2009 at Vandenberg Air Force Base, California (Courtesy photo)
In a testing procedure, the X-37B Orbital Test Vehicle taxis on the flightline in June 2009 at Vandenberg Air Force Base, California (Courtesy photo)

The first three OTV flights have accumulated a total of 1,367 days of on-orbit experimentation prior to successful landings and recoveries at Vandenberg Air Force Base, California. The X-37B program performs risk reduction, experimentation, and concept of operations development for reusable space vehicle technologies, and it is administered by RCO.

The Hall thruster that will fly on the X-37B experiment is a modified version of the units that have propelled SMC’s first three Advanced Extremely High Frequency (AEHF) military communications spacecraft. A Hall thruster is a type of electric propulsion device that produces thrust by ionizing and accelerating a noble gas, usually xenon. While producing comparatively low thrust relative to conventional rocket engines, Hall thrusters provide significantly greater specific impulse, or fuel economy. This results in increased payload carrying capacity and a greater number of on-orbit maneuvers for a spacecraft using Hall thrusters rather than traditional rocket engines.

This experiment will enable in-space characterization of Hall thruster design modifications that are intended to improve performance relative to the state-of-the-art units onboard AEHF. The experiment will include collection of telemetry from the Hall thruster operating in the space environment as well as measurement of the thrust imparted on the vehicle. The resulting data will be used to validate and improve Hall thruster and environmental modeling capabilities, which enhance the ability to extrapolate ground test results to actual on-orbit performance. The on-orbit test plans are being developed by AFRL and administered by RCO.

The experiment has garnered strong support from AFRL senior leadership. «Space is so vitally important to everything we do», said Major General Tom Masiello, AFRL commander. «Secure comms, Intelligence, Surveillance and Reconnaissance (ISR), missile warning, weather prediction, precision navigation and timing all rely on it, and the domain is increasingly contested. A more efficient on-orbit thruster capability is huge. Less fuel burn lowers the cost to get up there, plus it enhances spacecraft operational flexibility, survivability and longevity».

Dr. Greg Spanjers, the AFRL Space Capability Lead and Chief Scientist of the Space Vehicles Directorate, added, «AFRL is proud to be able to contribute to this research teamed with our partners at SMC, RCO, NASA, Boeing, Lockheed Martin, and Aerojet Rocketdyne. It was great to see our Government-Contractor team identify an opportunity and then quickly respond to implement a solution that will offer future Air Force spacecraft even greater capabilities».

The first X-37B Orbital Test Vehicle waits in the encapsulation cell of the Evolved Expendable Launch vehicle April 5, 2010, at the Astrotech facility in Titusville, Florida. Half of the Atlas V five-meter fairing is visible in the background. The Hall thruster being tested on this flight provide significantly greater specific impulse, or fuel economy and may lead to increased payload carrying capacity and a greater number of on-orbit maneuvers for a spacecraft using Hall thrusters rather than traditional rocket engines (Courtesy photo)
The first X-37B Orbital Test Vehicle waits in the encapsulation cell of the Evolved Expendable Launch vehicle April 5, 2010, at the Astrotech facility in Titusville, Florida. Half of the Atlas V five-meter fairing is visible in the background. The Hall thruster being tested on this flight provide significantly greater specific impulse, or fuel economy and may lead to increased payload carrying capacity and a greater number of on-orbit maneuvers for a spacecraft using Hall thrusters rather than traditional rocket engines (Courtesy photo)

 

Facts

Length 29 feet, 3 inches/8.91 m
Height 9 feet, 6 inches/2.90 m
Wing Span 14 feet, 11 inches/4.55 m
Experiment Bay Size 7 feet/2.13 m by 4 feet/1.22 m
Launch Weight 11,000 pounds/4,990 kg
Orbit Range 110-500 miles/177-805 km above Earth