The startup will be designing prototype thrusters to test low-cost alternative fuel sources such as iodine.
Electric propulsion solutions startup Phase Four recently won a contract with the U.S. Air Force to develop and test alternative propellants for its Maxwell thrusters. The company revealed in early April that it had received a $750,000 Phase 2 Small Business Innovation Research (SBIR) grant from the U.S. Air Force’s AFWERX program, which funds technological innovations. Phase Four will be using the funding to develop a prototype version of the thruster that will test the use of iodine as an alternative fuel source. If successful, these thrusters are expected to eventually replace the Air Force’s existing electric propellants for both its commercial and defense systems.
“There is a growing need for more options for advanced electric in-space propulsion, to provide satellites with better maneuverability and operability in space at an affordable cost, and propellant flexibility could provide new options for in-space propulsion,” shared Dan Eckhardt, electric propulsion lead at the U.S. Air Force Research Laboratory.
According to Phase Four’s CTO, Umair Siddiqui, iodine presents more advantages over traditional propellants such as xenon and krypton. This is because iodine is four times denser, eliminating the need for high-pressure storage and making it more ideal for microsatellites. This means it is possible to store more fuel onboard a spacecraft, which can increase a satellite’s maneuvering range in orbit. More reserve fuel also allows for end-of-life disposal maneuvers when it’s time for disposal. Similarly, the absence of high-pressure storage can decrease the risk of debris incidents while simultaneously offering a significantly more cost-effective fuel solution.
“Well over 50% of the cost of that unit is tied up on the fluid side: the storage tank, the high-pressure valves, and the cost of xenon,” noted Beau Jarvis, the chief executive of Phase Four.
The only drawback when it comes to using iodine as a propellant is its tendency to corrode thruster components. While iodine can be temporarily used for a legacy electric propulsion system, it still has a relatively short life span because it eventually corrodes the cathode, according to Jarvis. This makes it challenging to use iodine for commercial applications. However, this isn’t a problem for the Maxwell, which uses radiofrequency technology instead of cathodes to generate thrust.
As space explorations continue to expand, the demand for efficient, low-cost technologies is becoming more apparent. “We need to manufacture at scale and implement new technologies that lower the cost, shorten lead times and improve the quality of mass manufactured space hardware,” said Jarvis.
Phase Four will also be working with other government agencies to enhance the Maxwell RF Thruster’s performance for long-duration missions. The new thruster design is expected to make it smaller, lighter and less costly compared to the current legacy electric propulsion systems used by the Air Force. Phase Four’s RF technology can also utilize both traditional sources and newer fuel alternatives, such as water, air and iodine, allowing for more flexibility. In addition to that, RF electronics developed by smartphone and wireless charging companies can provide more low-cost technical systems and components.
According to Phase Four, these kinds of improvements can enable both government and commercial space operators to deploy satellites at a lower cost while also speeding up processes for critical missions. The startup recently tested its xenon Maxwell thrusters on two satellites that were onboard the SpaceX Transporter-1 rideshare mission back in January. Jarvis shared that the thrusters’ performance matched what the company observed in the lab during testing and flight qualification.
Phase Four is currently ramping up production and will be launching as many as 10 thrusters before the end of the year. Two more Maxwell thrusters are set to launch in May or June 2021.
For more information, visit https://www.phasefour.io/.
