Spaceflight Insider

Modified XR‑5 Hall thruster operates successfully on orbit

United Launch Alliance Atlas V 551 rocket at Cape Canaveral Air Force Station Space Launch Complex 41 photo credit Carleton Bailie SpaceFlight Insider

Photo Credit: Carleton Bailie / SpaceFlight Insider

The improved XR‑5 Hall Thruster (designated the XR‑5A) has passed initial orbital validation testing on the United States Air Force’s X-37B spacecraft on the AFSPC-5 mission. The Orbital Test Vehicle mission 4 (OTV-4) is still on orbit, with the XR‑5A Hall Thruster experiment being carried out as part of a collaborative effort with the Air Force Research Laboratory, Space and Missile Systems Center, and Rapid Capabilities Office.

“The GEO Comsat market has embraced the use of five kilowatt Hall Thrusters, and Aerojet Rocketdyne not only has the only flight-proven five kilowatt Hall Thruster, we now have the only flight-tested, second-generation five kilowatt Hall Thruster,” said Eileen Drake, chief executive officer and president at Aerojet Rocketdyne. “Satellite customers are very risk adverse, as many GEO Comsats have operational lives exceeding 15 years. So we are very pleased to bring a second generation product to market that provides our customers with that higher level of reliability and confidence.”

Aerojet Rocketdyne’s Upgraded XR-5A Hall Thruster Demonstrates Successful On-Orbit Operation

The XR-5A Hall Thruster. Photo Credit: Aerojet Rocketdyne

The XR‑5A Hall Thruster is an enhanced version of the XR‑5 Hall Thruster. While each of these are five-kilowatt class Hall thrusters, the XR-5A is considered to have improved range and performance.

According to Aerojet Rocketdyne, the XR‑5A maintains most of the design and flight heritage from the original XR‑5, with only minor modifications. These changes included a modification to the outer pole extending around the cathode and a change to the cathode position itself.

To date, 16 of these thrusters have been delivered, with 12 of them being sent aloft so far. Aerojet Rocketdyne decided to incorporate improvements after an initial low-rate production and flight programs had been conducted.

So far, Aerojet Rocketdyne has received orders for 64 flight thrusters. The company hopes that it will receive additional orders from both government and commercial customers.

The AFSPC-5 mission lifted off from Cape Canaveral Air Force Station’s Space Launch Complex 41 in Florida on May 20, 2015, atop an Atlas V 501.



Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

Reader Comments

Egh, XR-5… Still waiting for the XR-12 and XR-20! Where are my heavy interplanetary missions? :-p 😀


There’s no profitable market for an XR-12 or 20!

Out of curiosity, how much do they sell an XR5 for?

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