Engineers from Aerojet Rocketdyne and NASA have started the multiyear qualification testing of the most powerful solar electronic propulsion (SEP) thrusters. These engines are expected to radically change propulsion in space, according to a press release from NASA.
For decades, space propulsion research has relied on chemical engines to generate millions of pounds of thrust. The emphasis has been on making bigger and more powerful rockets to take us further in our space travels. This is a standard even with the most advanced methane-powered rocket engines. However, it is not necessarily the most efficient way to move about in space.
Chemical propulsion requires spacecraft to carry large quantities of propellants aboard the spacecraft. This is especially true if they have to make the return journey back to Earth. Electric propulsion can drastically reduce the amount of fuel required on spacecraft. It can also increase travel speeds. This makes it critical for future space missions.
In an electric space propulsion system, electricity is used to ionize inert gases such as Xenon or Krypton. A magnetic or electrostatic field is then used to accelerate these ions and push them out of the thruster to generate high speeds.
The electricity used to ionize gases can be generated from sunlight which is abundantly available across the solar system. Electric propulsion engines will also permit spacecraft to change their speeds and trajectories mid-way throughout the space mission.
NASA has already experimented with SEP for its Dawn mission. However, now NASA is preparing to demonstrate the most-powerful version of an SEP. The SEP will be tested on the Power and Propulsion Element (PPE) of the lunar Gateway which will orbit the Moon.
The Gateway is a sixty-kilowatt spacecraft. Fifty kilowatts will be dedicated to propulsion. Aerojet Rocketdyne has constructed an electric propulsion system that has been named the “Advanced Electric Propulsion System” (AEPS). At twelve kilowatts, the AEPS is twice as powerful as the most advanced electric propulsion system ever built. However, it still needs to undergo qualification testing before it can become part of the PPE on the Gateway.
In order to accomplish this, NASA and Aerojet have started testing on one of the qualification units. These units are identical to the thruster that will fly on the Gateway in 2025. After verification that the thruster is built correctly, engineers will expose it to extreme shock, vibration, and temperature. This will simulate conditions during the launch and flight of the Artemis Mission.
A second qualification unit will be made available in 2024. It will undergo testing that mimics orbit raising and transition to lunar orbit maneuvers. All tests are being conducted in the massive vacuum chambers at the NASA Glenn Research Center.
Rohit Shastry is the lead AEPS engineer. He said, “This testing campaign is a big deal. It’s kind of the final leg before we test the thrusters that will actually fly on Gateway.”
The comprehensive test will include 23,000 hours of operation of the thrusters during a four-year period. The thrusters that will be installed on the PPE of the Gateway will actually be launched prior to the wear tests being completed.
Clayton Kachele is the AEPS project manager at NASA Glenn. He said in a press release, “With NASA missions, launch dates are critical. In this case, NASA is trying to expedite the process, and we’re doing it intelligently. We will complete a few thousand hours of wear testing to prove successful operations before PPE launches. We’ll then complete the final 15,000 hours or so to fully qualify AEPS for future customers."