Space

NASA's X3 ion thruster smashes records in test firings

The X3 thruster being tested at the NASA Glenn Research Center, firing at 50 kilowatts
The X3 thruster being tested at the NASA Glenn Research Center, firing at 50 kilowatts
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The X3 thruster broke three records during vacuum-chamber testing in July and August, paving the way for eventual missions to Mars
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The X3 thruster broke three records during vacuum-chamber testing in July and August, paving the way for eventual missions to Mars
The X3 thruster being tested at the NASA Glenn Research Center, firing at 50 kilowatts
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The X3 thruster being tested at the NASA Glenn Research Center, firing at 50 kilowatts

A human settlement on Mars is rapidly moving from science fiction to fact, with Elon Musk envisioning Battlestar Galactica-style fleets blasting off to the Red Planet in coming decades. That scenario is now one step closer, as engineers from NASA and the University of Michigan have successfully tested the X3, a thruster designed to get us to Mars. And it's broken several records in the process.

The X3 is one of three Mars engine prototypes currently in development. It is what's known as a Hall thruster, which uses electric and magnetic fields to ionize gases like xenon and expels the ions to produce thrust. The technique is much cleaner, safer and more fuel efficient than traditional chemical rockets, but the trade off is relatively low thrust and acceleration.

"Mars missions are just on the horizon, and we already know that Hall thrusters work well in space," says Alec Gallimore, lead engineer on the X3's development. "They can be optimized either for carrying equipment with minimal energy and propellant over the course of a year or so, or for speed — carrying the crew to Mars much more quickly."

In the recent tests, the X3 broke three different records previously set by other Hall thrusters, a very promising step towards manned Mars missions. Most importantly of course is thrust: the X3 blasted off with 5.4 newtons of force, smashing the previous record of 3.3 newtons. On top of that, the engine also managed an operating current of 250 amperes, which is more than double that of the previous record, and ran at 102 kilowatts of power, just edging out the previous record of 98 kW.

The X3 thruster broke three records during vacuum-chamber testing in July and August, paving the way for eventual missions to Mars
The X3 thruster broke three records during vacuum-chamber testing in July and August, paving the way for eventual missions to Mars

The tests were conducted over 25 days in July and August this year in a vacuum chamber at the NASA Glenn Research Center. Since the thruster gives off quite a bit of exhaust, which can then interfere with readings, this particular vacuum chamber is apparently the only one in the US that can properly test the X3. A specially-built stand was also needed to support its 500 lb (227 kg) weight.

Before the thruster can be fired up, it takes about 20 hours to pump the air out of the chamber to achieve a vacuum similar to that in space. The tests are slow-going: if anything goes wrong, air has to be pumped back in gradually before any repairs can be made, and then it takes another 20 hours to get it back to a vacuum to resume testing.

While these tests were conducted using separate power supplies, the X3 will eventually have its own unit, currently being developed by Aerojet Rocketdyne. Once this is up and running, further tests are set to take place at the same facility in the first half of 2018, with the team aiming to run the thruster for 100 hours.

Source: University of Michigan

10 comments
Grunchy
102 kW is about 135 horsepower. 5.4 N of thrust is about 1.2 lbf. So that's a lot of power to sustain in space, maybe the solar collectors capture that much power. It would be useful to know what is the kg/hr expel rate for the motor, it would give us an idea how much Xenon propellant they would need to bring. What ever happened to the reactionless motor?? That's the anomaly we all want to hear about!
McDesign
Grunchy - I agree - the numbers don't seem to work out for input power vs. output thrust
El Bonko
"What ever happened to the reactionless motor??" Turns out it was illegal. Unless someone lobbies to change Newton's laws of motion, it won't be getting off the ground anytime soon.
ljaques
I got just under 48in/lb of thrust, or 3.98ft/lb. How does that tiny bit of thrust move thousands of pounds of spacecraft and any speed at all? I know, over time, it adds up, but what about the stop at the end? I'm having trouble wrapping my brain around this one. Evidently, converting light into electricity and somehow ionizing an unknown quantity of gas is extremely inefficient. 102kW = 136.784hp, and converts to just under 4 pounds of push? Wow! I guess I'll have to read this from cover to cover. http://pepl.engin.umich.edu/pdf/2014_Florenz_Thesis.pdf
Paul Muad'Dib
Compared to a conventional rocket engine this engine is quite compact and probably weighs a lot less too.
Buellrider
I can understand going to Mars but living there seems like a death sentence to me. No green earth. All work, no play. What is the upside for any individual signing on to that stark life? I can easily see going to some lush paradise of a planet that is full of life and adventure but Mars by all known accounts is dead and the only adventure would be just keeping from going mad after awhile.
b@man
I think most of us know by now that "we" are well beyond this silly technology, and that stuff like this is just a way to syphon off money into black projects.
Robert Schreib
Dear Sirs, Back in the 1960s, DARPA was experimenting with chemically powered laser rifles. But they encountered a problem of 'laser beam 'Repercussion'. That is, when they aimed the laser rifle at a mirror or reflective surface, a kinetic recoil would knock the rifle out of the hands of the soldier. anyway, could this 'Repercussion' effect be used to improve the velocity and fuel efficiency of the Hall Thruster or related ionic drive propulsion systems? If we put a set of laser beams projectors around the expulsion end of this thruster, with the laser frequency-synched to the electric charge of the Argon ions, forming a kind of solid hologram tunnel or cone about it, could that make this thing a LOT faster?
Douglas Bennett Rogers
102 KW/5 N = 20 KM/s. This is how fast you will go if 66% of your mass is propellant. This is several times as much as a chemical rocket.
b@man
Just more of the same medieval rocket tech, when we have had anti-gravity for over 60 years. We have even discovered flying spiders that use anti-gravity. When will we force our government to get away from this silly and reveal the truth?
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