Watching the TNG theme, I've noticed an odd pattern in the aft-ventral hull of the Enterprise-D:

kind of a jagged line running through the bottom of the ship just ahead of where the nacelles connect

It can be clearly seen 48 seconds into the opening sequence at high resolution .

It always looked to me like a place where the ship could split apart, like with Saucer separation. So, can Galaxy-class Starships like the Enterprise-D eject/separate their warp nacelles from the stardrive section? Or is this just a random feature of the model?

I know it never happened in the series' canon, so feel free to include other sources.

  • 3
    My TNG Tech Manual is in a box somewhere so I can't give a proper answer, but I believe the nacelles would detach at the point where they are mounted to the pylons. Commented Nov 23, 2017 at 7:04
  • 2
    I don't think "eject" is an appropriate term, as this would wrongly suggest the nacelles are inside. Try "disconnect."
    – jpmc26
    Commented Nov 23, 2017 at 14:14
  • 2
    @jpmc26, jettison. Commented Dec 5, 2017 at 6:36
  • “We need more speed! Jettison the warp nacelles!” “But Captain—“ “Damnit Lieutenant, they’re just weighing us down.” Commented Feb 5, 2022 at 12:41

3 Answers 3


They had the capability to detatch individual nacelles:

Ed Whitefire's original blueprints for the Enterprise-D, which were used as a basis for Rick Sternbachs official version, contain "Warp Nacelle Emergency Disconnects". These are, however, at the top of each pylon and not where the image in the question shows.(Click for full image)

Warp Nacelle Emergency Disconnect (Explosive Bolts)

From the official Rick Sternbach drawings, we see the Warp Nacelle Emergency Disconnects have been removed, however he's kept the same design for the explosive bolts, although hasn't labelled them. (Again, click to embiggen)

As further outlined in the comments from the Technical Manual, the nacelles could be ejected at a speed of 30m/sec. Note in the official drawing above the ten explosive latches which were marked on the original as "explosive bolts".

Official ones don't contain them

But only saucer separation is seen on screen:

After a warp core breach, where LaForge confirms there's nothing he can do, the separation sequence for the warp core begins:

LAFORGE: Coolant leak! We have a coolant leak, everybody. Let's go. Let's get out of here. ...Everybody out! Let's move! ...Let's move! Let' go! Bridge, we have a new problem. We're five minutes from a warp core breach. There's nothing I can do.

[Enterprise-D bridge]

RIKER: Deanna, evacuate everyone to the saucer section. Mister Data, prepare to separate the ship

After everyone has been evacuated into the saucer section, Data completes the ejection and confirms so:

[Enterprise-D bridge]

DATA: One minute to warp core breach.
RIKER: Begin separation sequence. Full impulse power once we're clear. Warp core is going critical.
DATA: Separation complete.
TROI: Engaging impulse engines.
DATA (OC): Core breach in progress.
COMPUTER VOICE: Primary stabilisers off-line. Engaging secondary systems.
RIKER: Report!
TROI: Helm controls are off-line!
DATA: Oh, shit...
(on the viewscreen Data has realised the saucer section is hurtling towards the planet)

Still of Stardrive section exploding and saucer section

  • 1
    Oddly enough neither diagram has anything corresponding to the feature indicated in the OP's image. I suppose it could be part of the cargo loading doors or the shield grid though, as shown in the Rick Sternbach drawings.
    – N. Virgo
    Commented Nov 23, 2017 at 12:47
  • 9
    Ejecting the nacelles wouldn't solve a warp core breach, would it? The core isn't in the nacelles, it's in main engineering. That said, I'm pretty sure the idea of "ejecting the warp core" was covered in canon as well: as I understand it, the core could be ejected without affecting the nacelles at all. Commented Nov 23, 2017 at 15:28
  • 3
    @DanielPryden I never said Ejecting the nacelles would solve a warp core breach. The saucer separation would protect from the warp core breach, the fact that the nacelles could eject was a separate point. You’re right the warp core does seem to be able to eject separately.
    – Edlothiad
    Commented Nov 23, 2017 at 15:50

Yes according to the TNG Tech Manual pg 63.

The emergency separation system would be used in the event that a catastrophic failure occurred in the PIS , or if a nacelle damaged in combat or other situation could not be safely retained on its support pylon. Ten explosive structural latches can be fired driving the nacelle up and away at 30m/sec.

  • 2
    Since it refers to a single nacelle, the join must be where the nacelle meets the superstructure. i.sstatic.net/TKeIb.png
    – Valorum
    Commented Nov 23, 2017 at 8:27
  • 1
    Hmmmm tbh that system must have been a complete and utter fail. I've seen a LOT of episode where a narcelle is damaged and NO ejection happened....aside from the ship blowing up and the narcelle parts flying away then.......
    – Thomas
    Commented Nov 23, 2017 at 8:30
  • 1
    “at 30m/sec”, hmm… Let’s hope it will be a slow emergency then.
    – Holger
    Commented Nov 23, 2017 at 16:24
  • 2
    @Holger I think it means the nacelles themselves would be ejected away from the ship at 30m/s relative to the ship's own movement, rather than that being the top speed the ship could be moving at to perform the action. I feel like it'd be neat to see that happen as a last-ditch alternative to a ship ramming a Borg cube or somesuch, if the ship ejected the nacelles then did a hard brake. Commented Nov 23, 2017 at 18:33
  • 2
    @AytAyt sadly not true. in TNG with the time loop where an old starship came out of a timewarp it always hit (only) the narcelle and......enterprises warp drive destabilized and exploded within seconds after that
    – Thomas
    Commented Nov 23, 2017 at 19:31

To add to what others have said, it would be reasonable for Galaxy class starships to have some emergency ability to discard warp nacelles. Galaxy class starships have a similar configuration to Constitution class starships like the Enterprise.

In "The Apple" the Enterprise is being pulled down to a planet:

KIRK: Status report, Scotty.

[Planet surface]

SCOTT: No change, Captain. The orbit is decaying along computed lines. No success with the warp drive. We're going down and we can't stop it.


KIRK: I'm sick of hearing that word can't. Get that ship out of there.


SCOTT: Sir, we're doing everything within engineering reason.


KIRK: Then use your imagination. Tie every ounce of power the ship has into the impulse engines. Discard the warp drive nacelles if you have to, and crack out of there with the main section, but get that ship out of there!


SCOTT: Sir, I'm going to switch over everything but the life-support systems and boost the impulse power, but that's just about as dangerous.

This indicates that Constitution class starships have provisions for emergency separation from the warp nacelles.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.