According to the answer on Why do shields in Star Trek "wear out"? the TNG technical manual says the Defense Shields are basically form fitting. And this aligns with what I remember of TOS, mainly the hacking scene from Wrath of Kahn, with the lights on the shield display fitting around the ship display.

But in TNG and forward, I remember the shields being very bubble like, especially during phaser strikes. Is there any out of universe explication for the difference? Any in universe changes to shield tech or explication?

  • 2
    well we know they can expand and retract the shields, as they are able to encompass other ships inside of their shields should they want. From reading that answer, it appears that if the shield were directly on the hull, any leak through from the shield immediately hits the hull, whereas if the shield is in a bubble, it allows for deflection, or secondary layers of shielding to block residual mater passing through the shield before hitting the hull.
    – Himarm
    Commented Mar 20, 2015 at 14:35
  • @Himarm exactly, that's one of the scenes I remember best, but I'm not sure if it was the defense or the navigational shields
    – user16696
    Commented Mar 20, 2015 at 15:10
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    Well, TNG was set about 80 years after The Wrath of Khan, technology was bound to change
    – Izkata
    Commented Mar 20, 2015 at 15:58
  • Oh dear...do we have any ENT experts on hand? Knowing whether or not they had form-fitting shields back then would give us a clue - if they did, it's simply an advancement in shielding technology.
    – Zibbobz
    Commented Mar 20, 2015 at 17:51
  • 3
    @Zibbobz The NX-1 didn't have "shields", they had "polarized hull plating". Commented Mar 20, 2015 at 19:36

2 Answers 2


I think this question stems from the poor wording of the quote. The easiest way to explain it is that rather than the shield emitter emitting a perfectly spherical shield (which would obviously cut through the structure of the ship), the inner edge of the shield fits against the ship, with the outer edge forming the familiar bubble shape outside.

You can see this most clearly in Star Trek V, with this representation of the shields being raised and lowered.

enter image description here

By the time of TNG, it seems that improvements in shield tech allowed them to project a more even structure, forming the more familiar "bubble" shape around the ship.

  • Why would it cut through the structure?
    – Pioneer
    Commented Aug 9, 2015 at 11:58

I've always been under the impression that shields, like the warp field, could be configured into different shapes and sizes.

Perhaps the strongest and most energy-efficient shield configuration is tight against the hull of the ship, but there are definitely times when it's necessary to extend the shields of a starship to protect, say, a shuttle that is under attack.

It makes sense that when you extend the shield's range, it loses the form-fitting contours of the hull and becomes more bubble-like (somewhat similar to a latex glove being inflated like a balloon).

There's also the possibility that the hull-hugging shape is the idle configuration, but when the ship is being hit with a tractor beam or some such, it distends and either expands or becomes spherical.

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