In the battle of Scarif one of the Star Destroyers gets disabled. The rebels then decide to push it into another one which causes them both to tear each other apart.

The other Star Destroyer is still working correctly at this point and so should still have its shields up.

How come the shields didn't protect it against the collision?

  • 1
    Shields seem to be most effective against laser impacts and small objects (debris, for example) and least effective against large physical objects such as other ships.
    – Valorum
    Dec 23, 2016 at 9:40
  • 1
    Star Wars shields seem to be completely ineffective unless they're being used as a plot device to prevent you from blowing up a space station.
    – user40790
    Dec 27, 2016 at 17:33

2 Answers 2


There are two (or three) types of shields in the Star Wars universe: ray shields, particle shields, and "concussion shields." I've not personally experienced the difference between a "concussion shield" and the others, but the difference between a ray shield and a particle shield are discussed in the original Star Wars.

DODONNA Only a precise hit will set up a chain reaction. The shaft is ray-shielded, so you'll have to use proton torpedoes.

Capital ships battle each other with massive waves of turbolaser attacks and missile launches; the other ship scatters the turbolasers with ray-shields (which wouldn't be an impediment to proton torpedoes).

That's all canon. But canon doesn't discuss particle shielding, so I need to dip into Legends. The good news is that the Legends explanation makes sense.

Particle Shields blocked EVERY physical object, from both directions. To launch fighters or even their own missiles, the particle shields would need to be down. You'd only bring them up in heavy debris, or when you cease launching ships/weapons, or for very specific areas (like the bridge, where you would have strong particle shields).

In short, during active combat, Star Destroyers depend on localized shielding around weak points and their armor to protect themselves from combat damage from particle-type weapons. The ray weapons are kept at bay because they could tear through the armor, letting the missiles get to the juicy bits inside.

The Hammerhead corvette strikes the Star Destroyer, which was both disabled and still in combat, amidships, where there would be no particle shielding. The other ship, still being in combat, likely had it's particle shields down.

But for some reason, the Star Destroyers were orbiting criminally close to each other! Once the active Star Destroyer realized they were about to be rammed by the other ship, they had no time to generate a strong particle shield, even if they were in a frame of mind to give the order. The maneuver was completely unexpected.

Even if they had thrown up a particle shield, the particle shield would have to deflect a 1.6 kilometer long vessel. It's not designed for that. Missile banks, sure. Starfighters, no problem. Star Destroyers ramming you? Not on your life.

The planetary shield they run into is also a particle shield. It's why the ships couldn't get through when they closed the ring. Two star destroyers smashing into that brought that shield down, so I'd expect one star destroyer to be plenty to tear through any particle shield that the other ship could throw up.

  • Legends can't decide if particle shields are one way or two. It's standard that missiles, starfighters, and ships can't get through particle shields, but many times ships are both "shielded" and firing their own lasers. So either the shields can be tuned to allow the ship's weapons out, or they're only partially covering the ship, allowing fire out "around" the shields (that would make Han's "angle the deflector" make sense). In either case, the rammed SD had no chance to defend itself, and neither did the other ship.
    – Zoey Green
    Dec 23, 2016 at 20:46
  • Didnt ALMOST the same thing happen during the empire strikes back? (asteroid scene where two star destroyers damaged each other while trying to capture one single small transport?)
    – Thomas
    Dec 24, 2016 at 7:40
  • One thing that might be worth considering is that the shields of one Star Destroyer could actually increase the damage of a collision to the other ship, by trying to deflect it (and thus exerting a force on it). So both Star Destroyers might have had their shields up for protection, which might only increase the damage to both ships.
    – Adamant
    Dec 25, 2016 at 19:27
  • @Adamant the disabled Star Destroyer definitely didn't have particle shields up, as the Hammerhead Corvette was able to hit the hull directly (it would have slammed into the particle shields before then). Remember, it was hit by huge ion blasts and disabled. However, the other ship COULD have thrown it's shields up. One thing which happens in Legends a lot is that Particle Shields are fixed in place by the shield generator mounts, and a big enough explosion rips the shield generators from their mounts. I like that mental image.
    – Zoey Green
    Dec 25, 2016 at 19:56
  • "There are two (or three) types of shields in the Star Wars universe: ray shields, particle shields, and "concussion shields." I've not personally experienced the difference between a "concussion shield" and the others" Any personal experience with other kinds of shields? :-)
    – RichS
    Jun 20, 2017 at 2:41

Um, because it was hit by a flipping six-million tonne star destroyer? While the ships shields are effective against energy weapons I doubt it has much hope against a massive object crashing into it. In Empire Strikes Back for example we see a star destroyer collide with an asteroid which demolishes the conning tower.

  • 4
    This has the makings of a good answer if you actually wanted to make it into one.
    – Valorum
    Dec 25, 2016 at 19:31

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