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I wanted to know if we can thrust a rocket from earth using electric power? If yes, how and has anyone tried to do that?

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tldr; No, our current technology is far too weak.

Electrostatic Thrusters

The term 'electric power' when it comes to engines can mean a few things, but the closest we currently have in spaceflight to a pure 'electric engine' are Electrostatic thrusters. These essentially use electricity to power electromagnets that accelerate charged particles backwards at tremendous velocities to produce thrust (some achieve ~30km/s exhaust velocity).

The reason we can't launch from earth is that these produce thrusts measured in Millinewtons. Typical rocket engines produce thrust in the range of hundreds of Kilonewtons - 100 million times more thrust.

You wouldn't be able to lift a paperclip off the ground with an electrostatic thruster, let alone a rocket.

They do have their uses however:

A type of electrostatic thruster know as an Ion Engine is quite popular for use on deep space probes. The combination of relatively lightweight vehicles and the ability to fire the engine continuously for weeks or months at a time means that Ion Engines can be incredibly effective. See Hayabusa and Dawn for examples of Ion-propelled spacecraft.

Another thing worth noting is that our current electric propulsion technology is almost completely ineffective inside an atmosphere - the thrust and efficiency attainable are drastically worse than in vacuum.

VASIMR

The Variable Specific Impulse Magnetoplasma Rocket is under development and testing. It is in a category known as Plasma Propulsion Engines and is able to vary its efficiency as a trade-off for thrust (low-thrust, high–specific impulse or relatively high-thrust, low–specific impulse).

Data shows it is able to produce thrust on the order of Newtons at similarly high efficiencies as Ion Engines. If this technology becomes a reality, it has enormous potential for orbital and interplanetary spaceflight.

Others

There are many other types of electrical propulsion, but all still suffer the exact same problem as electrostatic thrusters; far too little thrust for surface launches.

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  • $\begingroup$ Do you think we can go more faster with fuel thrusters or electric thrusters ? $\endgroup$ – Taher May 22 '18 at 13:47
  • $\begingroup$ Speed is difficult to define in space since you always need to measure it relative to something. However, all other factors being equal, and ignoring engineering challenges, electric thrusters can go much faster than chemical engines. This is because they typically have a much higher efficiency for a given amount of fuel. It will take you a very, very, very long time though. $\endgroup$ – Jack May 22 '18 at 13:55
  • $\begingroup$ Is it worth including VASIMR in this answer? I think they're still working on the prototypes for that. Shouldn't change the overall conclusion. $\endgroup$ – Erin Anne May 22 '18 at 21:03
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    $\begingroup$ You should add railgun. It's again a 'No', but for reasons completely different than others: nothing would survive such acceleration. $\endgroup$ – SF. May 24 '18 at 8:58
  • $\begingroup$ @SF. Feel free to add another answer on railguns, I was mainly focusing on engine-like propulsion. $\endgroup$ – Jack Jun 8 '18 at 10:36
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The one thing which could conceivably fit your question and have a positive reply is an electromagnetic catapult. This would be an evacuated tube, typically hundreds of kilometers long, in which magnetic fields were used to accelerate a payload (which could be a rocket) to escape velocity (or a bit faster to allow for the energy lost to air resistance after leaving the tunnel). The end of the tunnel is typically on a mountaintop so that the tunnel can bend upwards in its final miles, and to reduce air resistance. Nothing like this has ever been built, but design studies exist. One I remember hearing about (sorry, no link) would need about 15GW of power for about 90 seconds to launch a 1 metric ton payload at 10g.

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Short answer : No. We do not have storage capacity of energy in either electric or chemical form that would allow to convert back the chemical energy into electric energy if required, and allow us to propell a rocket into space..

Current achievements & Future work : But what does it mean to use electric power to propell a rocket? The general accepted examples are the electrostatic and hall thrusters used in ion & plasma propulsion.

But since we do not have the capability of propelling spacecrafts into orbit using such low thrust devices, I will introduce you to the unique case of the Electron launch vehicle.

The Electron launch vehice is truly fascinating since, they are using only electric power from batteries to power their propellent feed pump for their multiple Rutherford engines in two stages with an additional third stage with a Curie engine. The launch vehicle is able to achieve 303 seconds of specific impulse using RP-1/LOX combination. Which is amazing. This is the best example of using electricity powered propulsion for launch vehicles in current time.

Space travel is difficult, there is no shortcuts, there is only compromise.

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No. Electric power has a very low thrust. It would require an enormous amount of energy to lift, far beyond even the most concentrated engine today.

The closest is the Electron Rocket, which uses batteries to run the turbopumps vs exhaust from the rocket that most systems today use. But that still isn't really electric, only one portion of the rocket is electric.

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Beam Powered Propulsion - firing a laser up the rear end of a vehicle to heat some reaction mass - is a proposed method for both launch to space and in space. It would be electrically powered. Variants of beam powered propulsion include giving added push to solar sails and electric thrusters using power beamed to the spacecraft (to PV panels) rather than carried on board, but for launch to space the thermal rocket types would be needed.

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Jack's answer explains why deep space engines are unsuited for launch pretty well, and those are indeed what we think about when talking about electric engines. However, this may not give the full picture.

There are essentially two problems with launching an electric rocket:

  • Engine thrust

Ion engines and VASIMR lack the thrust needed for rocket launch. VASIMR may be enough for launching from asteroids, current ion engines not even that. However, there are other electric engines: resistojets and arcjets. While not studied for rocket launch, those can theoretically have the necessary thrust for a rocket. They essentially work like nuclear-thermal engines: heat an inert propellant with external power instead of with a chemical reaction. It can theoretically reach higher exhaust velocity than nuclear-thermal, in fact, giving it better Isp - however this often means lower thrust, and a nuclear-thermal launch rocket would already be hard to do.

On the other hand, similarly to nuclear-thermal being usable as an air-breather, those also could be. Again, hard to do, not unlike Skylon, but doable, and theoretically with good performances - if you can also solve the second problem.

  • Energy source

The problem with those electrothermal engines is that they require a lot of energy. According to the rocket power equation, for a given power, thrust is inversely proportional to exhaust velocity. Those engines have a high exhaust velocity in order to have better Isp, so to have enough thrust for launch, they need much, much more power. Ion engines are a more extreme example of this. The logical extreme would be a photon rocket.

Obviously, chemical energy is out: you would have even less energy than with a chemical engine, due to losses, and you would still have the mass of the empty batteries to lug around. Even superconducting solenoid batteries wouldn't help much, as those are limited by chemical binding energy (to prevent the solenoid to burst under Lorentz forces).

So you need a nuclear reactor, with its vastly superior energy density. Note that while you can reach higher temperatures (nuclear-thermal is limited to "don't melt the reactor" temperatures) and thus exhaust velocity and Isp, you need big, possibly red-hot radiators to evacuate waste heat from the nuclear generator. You can use some of it to pre-heat the propellant, but by nature not all of it (or you would basically have a nuclear-thermal engine anyway).

Another option is to have an electrically-powered laser or maser on the ground (or in orbit), that transmits energy to the rocket through the beam. In most cases, it directly heats propellant (which, again, can be air when in the atmosphere). A few designs have the craft turn it back into electricity, but this is more to power a helicopter, not a rocket.

The advantage is that the craft itself is cheaper, lighter and has good performances. The drawback is the need for big external installations, that your neighbour may see as weapons. Then again, some would also see this as an advantage.

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  • $\begingroup$ +1 You make some good points here, but I have to say that resistojets and arcjets could still only produce in the range of ~1N of thrust. That's several orders of magnitude less that what would be needed to lift their own mass off Earth, let alone any payload. $\endgroup$ – Jack Apr 26 at 18:42
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It's a research topic, but it might be possible to send a beam of say microwave radiation of significant power (fractions of gigawatt) to a rocket, capture this power rather efficiently as a form of electricity and use it to accelerate a moving mass so that thrust will be more than gravity. Not many details are available now.

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The answer is YES, shockingly. Most people are likely taught that ion propulsion does not have enough thrust to ever lift its power supply. That used to seem correct. However, I have worked on the problem for 19 years. The result is US Patent No.10,119,527, the Self contained Ion Powered Aircraft. It is a very lightweight ion propelled aircraft that does indeed lift its power supply for nearly 2 minutes so far, as of 9-5-2019. If you are still interested, you can google ion propelled aircraft and onboard power or ionocraft. There are 6 public flight footage videos, and a website that are should be obvious. It has been demonstrated to many officials that it works as shown.

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  • $\begingroup$ "lift(ing) its power supply for nearly 2 minutes" does not a rocket make, however the OP hasn't clearly stated that it needs to go to space. $\endgroup$ – uhoh Sep 5 at 8:31
  • $\begingroup$ You need to add some links to your answer, not have people search for themselves. $\endgroup$ – Hobbes Sep 5 at 19:46
  • $\begingroup$ Here are the links to the YouTube channel and a website, where there is lots of straight forward information. I hope people find this is helpful youtube.com/channel/UC_trtRcbCLO9Q2CzbKAya3w?view_as=subscriber www.electronairllc.org Thanks for asking! $\endgroup$ – Ethan Krauss Sep 6 at 9:55
  • $\begingroup$ In response to "lift(ing) its power supply for nearly 2 minutes" does not a rocket make, however the OP hasn't clearly stated that it needs to go to space.": There are currently commercially available solar cells that would allow the craft to fly as long as there is sunlight. It can also carry a very small propellant tank. I wouldn't argue that it can reach space, since their isn't enough data yet. It does seem like it could be possible in the future. It depends mostly on propellant usage. $\endgroup$ – Ethan Krauss Sep 6 at 21:21

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