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Satellites once used propellant for attitude control. When the propellant was used up, the satellite lost the ability to maintain or change orientation. Very
by beloch 11mo ago
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.
- Retric 11mo agoArticle 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.
- hinkley 11mo agoAm 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?
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- Terr_ 11mo agoTheir patents don't mention the Earth's magnetic field or ambient material, so I'd go with "hogwash". https://news.ycombinator.com/item?id=45932763 https://news.ycombinator.com/item?id=45932763
- ravi-delia 11mo agoPropellant is still used for rotation control. Reaction wheels can "saturate" if they compensate for rotation more in one direction than the other on net, so propellant is needed to get them back down. Ion engines, generally speaking, do not use background dust. They still carry propellant, they just eject it electromagnetically. An photon engine, basically just a laser pointed backwards, uses pure electricity to produce thrust. But of course the numbers all work out, since photons have momentum. They're extremely weak though, even lasers of staggering power produce very little force. There's no way you could put one on a satellite
- DarmokJalad1701 11mo ago> Reaction wheels can "saturate" if they compensate for rotation more in one direction than the other on net, so propellant is needed to get them back down. Torque Rods can be used to desaturate wheels without needing any propellant https://en.wikipedia.org/wiki/Magnetorquer https://en.wikipedia.org/wiki/Magnetorquer This is widely used in smaller satellites operating in Earth orbit. However, this doesn't mean that TFA isn't BS.
- amluto 11mo agoIt’s surely hogwash. I like how it’s “validated” but does not mention power consumption or measured thrust. For what it’s worth, one can very straightforwardly produce thrust using electromagnetism: just shine any sort of light out the back of your spaceship. This is called a photon rocket, and it works because light has momentum. Very little momentum: thrust = power / c. It’s only worth doing if energy is free in the way that light hitting a solar sail is free or if you power it with something absurdly energy-dense like antimatter.
- ahazred8ta 11mo agoIt could be a legitimate conductive tether system. These have flown on the space shuttle and cubesats: see TEPCE and MiTEE. https://en.wikipedia.org/wiki/Electrodynamic_tether https://en.wikipedia.org/wiki/Electrodynamic_tether But the 'pulses' make it sound like EmDrive hogwash.