Re-watching the 2009 movie for the first time after answering this question about shield collisions, I noticed the following:

Enterprise is about to drop out of warp in Vulcan space.

Captain Pike: Raise shields, red alert.

Enterprise drops out of warp, encounters the debris field of the other star fleet vessels and suffers hull damage due to a low velocity graze against a piece of debris even though its shields are up and fully charged.

The shields are capable of pushing interstellar dust out of the way at high impulse (which is relativistic), and surviving photon torpedo detonations.

So what happened?

  • 9
    Uh... the director goofed?
    – bobbyalex
    Commented Jan 25, 2012 at 10:18
  • 7
    @BobbyAlexander: That was in the script, so the writer goofed.
    – Tango
    Commented Jan 25, 2012 at 15:39
  • Shields don't deflect the dust, that's the job of the main deflector dish. It may not have been up and working yet, or the debris was simply too large for the deflector to handle.
    – Jeff
    Commented Jan 25, 2012 at 18:01
  • @Jeff: I've been waiting for someone who knows the distinction. They keep calling the shields deflector shields and then they also refer to the deflector/s (the latter of which I originally understood to mean the forward-facing dish structure in TOS and TNG). But some of the dialogue in VOY and DS9 has had me confused.
    – HNL
    Commented Jan 26, 2012 at 3:12
  • 1
    It's cooler to see obliterated panelling and collapsed framing than it is to see something bounce harmlessly off an energy barrier (with an obligatory bridge shot of panels exploding and sparks everywhere to suggest a collision). Like most things in ST 2009, the reason could quite simply be theatrical.
    – Chad Levy
    Commented Jan 26, 2012 at 7:37

6 Answers 6


I think the shield technology is a little different than the later ellipsoid ones. It is an energy field applied to the hull that deflects energy weapons. In Star Trek 6 you can see torpedoes hitting the hull even though the shields are up, but they cause little damage compared to later when the shields are down.

  • That is a good point, further confirmed by the shield displays on the Enterprise and Reliant in ST2 (an array of lights that outline the ship, rather than surround it in an oval).
    – Xantec
    Commented Jan 25, 2012 at 15:13
  • 1
    i'm pretty sure if you look carefully in some TNG episodes, or possible ST:Generations, you see a hull-hugging field on display panels - but the representation in a fight still seems to be ellipsoid.
    – HorusKol
    Commented Jan 25, 2012 at 21:59
  • 1
    According to Mr. Scott's Guide to the Enterprise (not canon, but still nifty), the shields are just outside the hull and are made by scanning a block of diburnium-osmium alloy (from TOS: That Which Survives) and projecting it just beyond the hull. This is referenced on a display graphic in STID (24 second mark in this video: under where the display says "shield strength" vimeo.com/72019454 ) Commented Jan 18, 2014 at 22:27
  • Watching the Enterprise getting pummeled during the Battle at Boreth all detonations were on the hull surface, however when the shooting began the long shot showed detonations on both sides (sect 31 & Enterprise) hitting a shield wall. Such Sweet Sorrow II
    – Vogon Poet
    Commented Oct 16, 2019 at 2:18

I'd have to watch that scene again - but it could be that the debris was already inside the shield's surface area.

In other Star Trek material (particularly TNG, but other series, too), shields appear to be ellipsoid shells around the ship, so it is possible that the debris was already inside as the shield was powering up.

An alternative explanation is that the shield technology at the time of the movie isn't as good as the other time periods we see in Star Trek (it is set prior to TOS).

  • 2
    I doubt it. Pike gave the shields up order well ahead of time and they had been maneuvering through the debris field for at least 20 seconds before they encountered the piece that they ended up rubbing nacelles with.
    – HNL
    Commented Jan 25, 2012 at 10:21
  • 3
    maybe they work like Dune shields - slow objects can pierce them ;) of course, there's no canon to support this
    – HorusKol
    Commented Jan 25, 2012 at 10:26
  • 1
    Ah! Yes. I totally forgot about this. A lot of shields (including Goa'uld shields) work this way. If you edit your answer and no one else can come up with a better answer, I will accept this explanation.
    – HNL
    Commented Jan 25, 2012 at 10:29
  • 3
    I'm not sure it really is acceptable - AFAIK there is no canon to support it...
    – HorusKol
    Commented Jan 25, 2012 at 10:37
  • I agree with @HorusKol - if anything, the shield precursor seen in ENT 1x22, Vox Sola, shows the opposite.
    – Izkata
    Commented Jan 25, 2012 at 13:01

I don't believe there are canonical examples of starships plowing through fields of ship-sized debris and expecting the shields to handle it for them. Maybe this is just because captains prefer to preserve their shield power, but it's certainly plausible that shields just aren't meant to handle that sort of thing.


The exact behavior of shields varies through the canon. It's generally accepted that shields block high-energy transmissions (phasers, disruptors, transporter beams), and "high-velocity" physical objects (photon torpedoes, asteroids, even smaller ships). However, there are also instances of a ship's shields holding back powerful but slow-moving physical barriers, such as the gate into the Dyson's Sphere in the TNG episode "Relics". So, one would think with shields at full that a collision with a piece from another ship would leave the debris worse off than the shielded ship.

In addition to deflector shields, most Federation ships have a deflector array. This array is highly configurable, and so can do basically anything the scriptwriters need, but its primary purpose is to push away large physical objects while the ship is underway; it's the ship's "icebreaker", shoving aside particulate matter, asteroids, etc while the ship is moving, especially at warp. It's supposed to work in much the same way as the full shields, but is generally lower-power in "shield" form, requiring a "beam" to push higher-mass objects. It's logical, given the difficulty involved in locking transporters on to a moving target, that the deflector array would simply be overwhelmed. The very large ship remnant that Enterprise specifically has to dodge is also half the size of the Enterprise herself; at some point the act of using any sort of beam to shove away a hunk half as heavy as yourself without any change in your direction or velocity would offend our Newtonian-oriented sensibilities.

The in-universe answer would probably be that the deflectors, both the full shields and the array, is simply overwhelmed by the sheer size and number of debris objects that must be shunted aside. Why they're still effective at near-full power after that, to absorb one of the Narada's missiles, is anyone's guess. The out-of-universe answer is that it's more visually engaging to see a piece of flotsam the size of an aircraft carrier gouge out a few panels of the brand-new Enterprise's saucer, with or without shields. Typical Rule of Cool.


I've always attributed this to the size of the debris that collided with the ship. As you mentioned, the shields (augmented by the navigational deflector) are capable of deflecting interstellar dust, even at high velocities.

But dust has a relatively low mass, meaning the energy required to move it out of the way is not very high (relatively speaking). The destroyed starship debris on the other hand, IIRC, was a large section of a secondary hull, a piece of the saucer section. The energy required to deflect this would have been orders of magnitude greater. Also, we don't know what velocity the Enterprise was traveling at, whether it was moving at full impulse or some fraction. This would have played a large part in how effective the shields would have been as well.

Finally, remember back to the movie Nemesis. In the final battle the Enterprise is struck by a large section of a Romulan ship. It is not unreasonable to assume that the Enterprise-E from the 24th century, built to battle all the baddies of its age, would have had vastly superior shielding technology. Yet even with that advantage, the shields were only just able to deflect that piece of debris.

  • It was traveling at minimal impulse -- it took about two seconds to traverse the length of the nacelle.
    – HNL
    Commented Jan 25, 2012 at 14:45
  • @HNL How did you arrive at that? The debris field above Vulcan would not have been motionless. The destroyed ships would have been in motion at the time of their demise, if not because of Nero's ship then because they were trying to get to the planet to begin evacuation. As it is not possible to know the velocity of the debris it is impossible to calculate Enterprise's velocity based on how long it took the ship to traverse the field.
    – Xantec
    Commented Jan 25, 2012 at 14:56
  • True, but for kinetic energy of impact, only relative velocity is considered.
    – HNL
    Commented Jan 25, 2012 at 15:33
  • @HNL And mass of the objects.
    – Xantec
    Commented Jan 25, 2012 at 15:49

The Enterprise in this episode is a new and untried ship with an inexperienced crew.

The shields are designed to protect the hull of the starship, so a piece of another starship of the same design could possibly breach the shields, as the shields are designed to protect against energy weapons and foreign materials, Another Federation starship could pass through this, theoretically.

  • 1
    That's not the way shields work in this universe. Shuttles and torpedoes, even of another Federation ship, cannot penetrate shields from the outside in.
    – KeithS
    Commented Mar 3, 2012 at 0:30
  • Come on that is not how shields work think back to the wrath of khan all of the torpedos, phaser blasts, etc. were stopped by the Enterprise NCC-1701's shields and dealt damage to their shields and this was set after that movie. Commented Jun 27 at 19:46

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