One thing that confuses me about Star Wars Episode V: The Empire Strikes Back is that the resistance had shield generators on Hoth that were powerful enough to make airborne assault by the Star Destroyers infeasible (thus the whole saga with the AT-ATs).

If they have such powerful shields, why not put them on a ship of their own (or a small asteroid) and make any resistance by the empire futile?

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    I don't think there are any canon numbers on the shield generator used at Echo Base (or the one used by the Empire on the forest moon of Endor), but presumably the size and power requirements of such a strong shield would preclude a design which used one on a starship. There are always tradeoffs...if the Rebels managed to put one on a starship it would probably be immobile and unable to generate enough extra power to fire a turbolaser.
    – Null
    Commented May 27, 2015 at 2:16

2 Answers 2


The answer is power generation. Any ground-based shield will have more power available than a starship. The shield technology is the same, but ground-based stations can use more (and more varied) power supplies, and don't have to worry about propelling the generator, its fuel, and armor/weaponry around.

The Star Destroyers could have battered down Echo Base's shield - there's no question. That's the purpose of the Imperial Star Destroyer - they were designed to batter down planetary (or area) shields and damage planetary installations (in addition to their role in space combat, of course). The shield was only a delaying tactic. It prevented the Empire from destroying the base from orbit in a few shots. Destroying the base from orbit would have required them to sustain a bombardment for a significant period (how long is unknown, but certainly longer than the ground assault took).

The point of the ground assault was speed - they wanted to seize the base with as much data and material intact as possible, and capture as many Rebels as possible. They wanted to force the Rebels to lose valuable resources or even more valuable personnel in an attempt to evacuate those resources.

The shield (and Rouge Squadron's snowspeeder hampering maneuvers) bought the Rebellion time to load the transports and escape aboard them. Had the Empire taken enough time to batter down the shield, the Rebels would have had enough time to load more of their heavy equipment (which you can hear Luke ordering abandoned in ESB).

By rushing the base, Vader and the Empire also hoped that the Rebellion, in their haste to escape, would fail to completely erase their databases and wipe or destroy their remaining equipment. The Empire had extremely skilled data analysts, and any bit of data they could recover would help pinpoint other Rebel bases/operatives/plans.

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    A note to this answer. The shield is only half the size of a shield required for a ship of the same size. To create a shield capable of protecting a ship the same way, you would need twice as many generators as were shown on Hoth, which is a considerable amount of power. Also, Vader wanted the rebels (Luke most notably) alive because at this point he knew his son was becoming a prominent figure in the rebellion and could possibly be found with the rebels on Hoth.
    – MAF
    Commented May 27, 2015 at 15:25
  • Not to mention the greatest consumer of power on a star ship of any kind will be life support (heating/cooling, oxygen generation, artificial gravity, etc). Planetside, on most planets anyhow, it doesn't consume nearly as much power.
    – BBlake
    Commented May 27, 2015 at 20:32
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    @BBlake: Seriously? You think that life support (climate control, air circulation, light, and carbon dioxide scrubbing) which we can do in our space shuttles today will use more energy than powering weapons that can pulverize asteroids and send ships moving FTL? I expect life support uses very little power.
    – Jeff
    Commented May 28, 2015 at 13:17
  • Absolutely. Take one example from Star Trek Voyager. They encounter the insane hologram Dajaren, who killed the 6 "organics" on his ship. One of his complaints was about their inefficiency. He makes the comment that "life support uses 59.2 percent of the ship's power." From a practical standpoint, 02/CO2 and light are minor and circulation is a little more, but still minor. Heating to keep out the surrounding absolute freezing of space is more, but probably still not a major pull. The big draws would be artificial gravity/inertial dampers. Gotta keep your crew from being turned into goo.
    – BBlake
    Commented May 28, 2015 at 14:44
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    @BBlake: Voyager's technical explanations are bull. Considering that ships which are completely without power in Star Trek routinely have artificial gravity, it can't use that much power. I'll buy that artificial gravity and inertial compensation takes more power than life support does today, but it cannot compare to the energy needed to power the engines, weapons, and shields. Besides, you can't use Trek dialog as explanations for Star Wars ;-)
    – Jeff
    Commented May 28, 2015 at 15:01

Since power generation isn't much of an issue in the Star Wars universe, I would assume in this case it is more an issue of access to the technology/parts. Even access to "no questions asked" transport is expensive because of Imperial controls. Given that the Empire wants to control everything, it's unlikely they would let military-grade shield technology be readily available. Think about stealth technology for planes, where hackers have been arrested for allegedly trying to sell stolen information to the Chinese. It's conceivable that the Rebellion could get its hands on the technology to protect one base, but multiple ships? That becomes much less feasible. Even in ESB, they most likely lose the shield generators as they flee Hoth.

  • Then why doesn't the Empire have ultra-powerful shields on their warships? It's because of power generation.
    – Null
    Commented Jun 2, 2015 at 2:04

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