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- Ion thrusters are the most common primary engine powering satellites through orbital maneuvers today.
- But to travel from low-Earth orbit (LEO) to farther orbits—or even the Moon—requires a different kind of ion thruster capable of achieving escape velocity and orbital capture maneuvers.
- Using technology originally developed for NASA’s upcoming lunar space station, the space agency has miniaturized its high-power solar electric tech into an engine that could make more complex satellites and planetary missions possible.
The history of space travel is filled with impressive sizzle reels of fire-breathing chemical engines launching monumental rockets skyward toward the Moon, Mars, and beyond. While these massive devices are marvels of human engineering, the real workhorses of the space industry are the immensely less-gargantuan ion thrusters.
These engines are as old as rocketry itself—Soviet and German rocket leaders first dreamed up their future uses more than a century ago. And today, these electric propulsion systems power the swarms of satellites around Earth that make modern life possible. Unlike chemical rockets that throw out gasses for propulsion, ion engines are powered by individual atoms, which makes them much more fuel efficient and allows satellites to operate for longer.
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However, they’re not perfect. In the future, spacecraft will need to perform high-velocity propulsive maneuvers—such as achieving escape velocity and orbital capture—that current ion engines can’t deliver. That’s why NASA developed the H71M sub-kilowatt Hall-effect thruster, a next-generation ion engine that can supply a velocity change.
The propulsion system must operate using low power (sub-kilowatt) and have high-propellant throughput (i.e., the capability to use a high total mass of propellant over its lifetime) to enable the impulse required to execute these maneuvers. While commercial ion thrusters are good enough for most LEO satellites, these engines only use “10% or less of a small spacecraft’s initial mass in propellant,” according to NASA. The H71M thruster uses 30 percent, and could operate for 15,000 hours.
“Small spacecraft using the NASA-H71M electric propulsion technology will be able to independently maneuver from low-Earth orbit (LEO) to the Moon or even from a geosynchronous transfer orbit (GTO) to Mars,” NASA wrote on its website regarding the new ion thruster. “The ability to conduct missions that originate from these near-Earth orbits can greatly increase the cadence and lower the cost of lunar and Mars science missions.”
The creation of this thruster grew from NASA’s work on the Power and Propulsion Element for Gateway, NASA’s planned lunar orbital space station. The team essentially miniaturized the high-power solar electric technologies that will make that lunar mission possible into a package that could provide thrust for smaller space missions.
One of the first spacecraft companies that will use this next-gen technology is SpaceLogistics, a space subsidiary of Northrop Grumman. The company’s NGHT-1X Hall-effect thrusters are based on NASA’s technology, and will allow its Mission Extension Pod (MEP)—which, as its name suggests, is essentially a satellite repair vehicle—to reach geosynchronous Earth orbit, where it’ll attach itself to a larger satellite. Acting as a “propulsion jet pack,” the MEP will act as an ion-powered symbiote that extends the larger satellite’s mission by at least six years.
If all goes well, this small-yet-mighty thruster could enable planetary missions once considered impossible to pull off.
