An Italian Company Builds the First Known Propellantless Space-Propulsion System
35 comments
·November 14, 2025beloch
hinkley
Am I correct in thinking that in some cases gyroscopic orientation results in turning 270° the “wrong way” to cancel out net gyroscope speed due to friction losses?
Retric
Article is light on details but there’s a few options such as using sunlight or earths magnetic field to move around without propellent tanks near earth.
hbrav
This article is quite frustrating, since all that it really tells me is that their system "generates thrust without using any propellant and without expelling reaction mass, by directly converting electrical energy into thrust through controlled electromagnetic impulses".
That's rather non-specific. My first thought was that they're using photon momentum, but thinking about that a little harder rules it out. The ratio of energy to momentum doesn't change with any properties of the photon (they're both proportional to frequency) so there's nothing to really develop there: so long as you waste very little power as heat, you might as well be shining a well-collimated flashlight.
Options 3 and 4 from [this paper](https://arxiv.org/pdf/2510.21743), _magnetic sails_ and _solar sails_, seem more promising. Is that what Genergo are doing? I have no idea. The article doesn't tell me.
drillsteps5
I remember in the 80s, after mostly having given up on perpetuuum mobile, bunch of people were trying to invent something like this, using vibration etc which worked on Earth but would not in a vacuum... Looks like a new generation took the baton. Like this guy:
https://www.popularmechanics.com/space/rockets/a65924333/eng...
An Engineer Says He’s Found a Way to Overcome Earth’s Gravity
This new propulsion system could rewrite the rules of spaceflight—not to mention completely defy conventional physics.
"In 2001, British Electrical Engineer Roger Shawyer first introduced the “impossible drive,” known as the EmDrive. It was called “impossible” because its creator purported that the drive was reactionless, meaning no propellant required—in other words, it defied the known laws of physics (specifically, the conservation of momentum)."
cjameskeller
Link to relevant patent: https://patents.google.com/patent/US11462985B2/en
BurningFrog
> "Genergo’s system generates thrust without using any propellant and without expelling reaction mass, by directly converting electrical energy into thrust through controlled electromagnetic impulses."
Anyone have a clue how this might work?
verzali
Maybe its possible to generate motion using the Earth's magnetic field under the right circumstances, though I'm not sure if that's really feasible. Or they might be able to create a very small thrust by emitting photons, but that must be very very small if its actually the case.
buildbot
Generating matter somehow via E/c^2=m?
(I don't think you can do this but I'm not a physicist...)
jfengel
You don't need to go that far. Light has momentum, and you can use that directly. It has the maximum possible specific impulse.
https://en.wikipedia.org/wiki/Photon_rocket
However, it requires a lot of energy and we are nowhere near a practical model. It's also not "propellant-less"; the photons are the propellant.
philipkglass
Known physics allows for it:
https://en.wikipedia.org/wiki/Pair_production
If you have a source of energy on the spacecraft, like a solar panel, you could theoretically convert some of that energy to particle pairs with mass. But this is such an inefficient process (and so inherently low-mass with any practical energy source) that I doubt the claimed thruster could work this way.
Terr_
My money's on fake woo-woo.
At first—like many others here—I thought it might just be a terribly-written explanation for a device that uses Earth's magnetic field, so that the planet itself is the "reaction mass" being pushed around... but I'm not seeing that in a quick patent search for the company.
Instead, there's a bunch of stuff that seems like perpetual-motion-machine crankery, where their "motor" depends on a oscillating some mass back and forth inside a chamber using special frequencies and "waveforms", which somehow imparts some acceleration which they explain as "generating mass."
Perhaps did use Earth's magnetic field through pure experimental error, and they either haven't realized it or think they can bilk investors by presenting it as something new.
_________
https://patents.google.com/patent/US11462985B2/en :
> The inertial mass of an object varies with the variation of its magnetic field and therefore a variation of inertia can be created which leads to the generation of mass by varying the magnetization of the motor and its constituent elements (at given times, as explained above).
> [...] the variation of “mass” is generated by the overmagnetization or undermagnetization of the motor itself in conjunction with given “shocks” or interactions between the magnetic piston and the two buffer magnets [...]
https://patents.justia.com/patent/11462985 :
> [In] general the motor or the moving system according to the present invention consists of an electromagnetically charged body which moves within a delimited volume of space being accelerated and decelerated electromagnetically in controlled manner during its movement within said volume of space.
> Such accelerations/decelerations generate a force on the volume inside which the mass moves and allow the volume of space to move.
verzali
I think you are right. Either they have accidentally used the Earth's field somehow, or they are mistaking other effects (drag, perturbations...) for a thrust.
a-priori
They say it works "by directly converting electrical energy into thrust through controlled electromagnetic impulses", so I assume it's reacting against the Earth's magnetic field using the Lorentz force?
Terr_
Their patents don't say anything about an external magnetic field, so at best they've accidentally rediscovered it through experimental error and don't know it yet.
drillsteps5
That would be "using Earth's magnetic field to create propulsion" and obviously would not work in deep space.
a-priori
Yes but they also don't seem to claim it does. The use cases they talk about are orbital station-keeping and de-orbiting of satellites. So that implies near-Earth use.
nickff
I suspect that you’re right, but I believe that I heard something about a similar ‘drive’ being used on some sort of telescope satellite in the past (though I can’t remember the specifics).
visviva
Impossible claim with no evidence offered - curious why this is on the front page.
Sanzig
I am highly skeptical. A reactionless thruster is the holy grail of propulsion systems, but there are no known physics which permit it to work. A photon rocket would allow momentum exchange without mass consumption, but a quick look at the math shows it would be infeasible (hundreds of megawatts per newton).
My guess is this works at all, it is inadvertently expelling reaction mass somehow, such as ablating off small amounts of volatiles from polymer parts (like an inefficient version of a pulsed plasma thruster).
I'd love to be wrong, but this very much falls into the "extraordinary claims" category for me.
wat10000
1. No info given about how this system works.
2. No info about how it supposedly produces thrust.
3. No numbers given except for number of hours tested in orbit. No thrust or power consumption figures.
4. Violates pretty widely accepted law of physics.
Yeah, I'm ever so slightly skeptical.
maremmano
It so happens that a friend of a friend of mine works at this company. I'll ask for some details.
snow_mac
This is amazing. I wonder how it works. I would be cool if they published it.
Satellites once used propellant for attitude control. When the propellant was used up, the satellite lost the ability to maintain or change orientation. Very much as this article describes, control moment gyroscopes took over because they didn't require propellant. They operate on the same principles that let a cat land on it's feet by twisting about as it falls.
However, there's a key difference between attitude control and movement. Changing your orientation doesn't involve changes in net kinetic energy, momentum, etc.. Changing speed (i.e. What a propulsion system does) does involve changes in these quantities, so Newtonian conservation laws come into play.
>"Genergo’s system generates thrust without using any propellant and without expelling reaction mass, by directly converting electrical energy into thrust through controlled electromagnetic impulses."
If this isn't hogwash, it might be something similar to an ion engine. i.e. It does operate by expelling propellant, but what it uses as propellant is background dust and ions, accelerated to a high velocity by electric fields and expelled.
If, as the site claims, this technology is currently working and produces non-negligible thrust, it could be very useful. They need to be very clear about what this is though, since vague and unscientific sounding claims will not attract clients.