Under the viewscreen on many Federation starships, there are a series of lights that constantly run through a chase or 'marching ants' pattern. What's the reason for these lights? Are they status indicators or some part of the viewscreen projection system?

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    I believe they are an intricate artistic methodology referred to by the specialists as "oooouuuu SHINY" Commented Oct 12, 2012 at 1:19
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    I always thought they were indicators - at least on the original series - of something having to do with the sensors, indicating they were operating; I have no particular information to back up that theory though.
    – eidylon
    Commented Oct 12, 2012 at 2:37
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    Those are Blinkenlights en.wikipedia.org/wiki/Blinkenlights (How to add links in comments?) Commented Oct 12, 2012 at 22:07
  • @user1129682 Looky here Commented Apr 30, 2017 at 19:51
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    It evolved from KITT
    – Peter
    Commented Jun 26 at 15:21

4 Answers 4


According to the (Paramount-approved) McMaster Bridge Blueprints, the lights under the TOS viewscreen relate to the ship's sensors, presumably confirming that the viewer is working correctly.

enter image description here

As to their purpose in TNG, the simple truth seems to be that they're utterly useless and exist solely to create a mental linkage between TOS and TNG for fans

"While creating these designs with Herman Zimmerman, we heard a tremendous amount of angst among the fans that we were 'replacing their [original] show,'" Probert says. "So I included clues that hopefully would calm their concerns." Those clues include chasing lights below the viewscreen, and a ship's diagram and dedication plaque similar to those from TOS. "Instead of being at the back of the bridge, they're on either side, near the front," he adds. "Just above the food replicators — which were never used."

Star Trek: The Next Generation 365


Almost everyone looks towards the main viewscreen, so it's almost certainly all about Red Alert. A whole bunch of other unnecessary/unused lights on the bridge also exist that only turn on during emergencies:

RedAlert on the Bridge (Actually, the one above the door may usually be on, but without a color tint. I just quickly circled some Red Alert lights from TNG 1x21, The Arsenal of Freedom)

I have no doubt those running lights do the same. There could be some important extra information conveyed through them (perhaps it's a battery meter for antimatter reserves?), but I don't recall the lights ever actually being mentioned in the series.

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    I take it NOBODY who designed the Enterprise ever read Three-Mile Island postmortem report? Commented Oct 12, 2012 at 1:56
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    @DVK Nor do I know what you're referring to...
    – Izkata
    Commented Oct 12, 2012 at 1:58
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    If I recall correctly, they found that the Three Mile Island Nuclear Reactor Accedent was at least in part caused by HCI design flaws, including "too many indicators". Commented Oct 12, 2012 at 2:02
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    In other words, Don't Design Your Warship Or Nuclear Plant Like It's A Geocities Page lesson of design. Commented Oct 12, 2012 at 2:03
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    @DVK Ahh... In that case, I must disagree. It looks like there were too many different indicators, and one that was particularly badly designed, that appeared to be giving conflicting information. Star Trek's Red Alert lights are all over the ship, but have exactly one meaning - the ship is in danger. It's a good way to make sure everyone knows to get to safety, and stay there.
    – Izkata
    Commented Oct 12, 2012 at 2:09

Well, it was my belief that in the original series (TOS), the chase lights have 2 modes. The first one being 2 lights next to each other - alternating left and right, and the more common line left to right. In Star Trek IV it switches to the format we see today. In TNG, DS9 and VOYAGER they are the equivalent to the CPU lights on a modern PC. Note that in Star Trek IV and later that only have one mode: 2 lights moving outwards towards the middle. Note that Voyager has 2 sets of chase lights: one under the view screen and one above the view screen.

enter image description here

In the unaired pilot of TOS, it had this view screen
enter image description here

And here is the NX-01 view screen
enter image description here

And in the JJ Abrams reboot, they don't even have chase lights. enter image description here

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    That's because in the reboot lens flare takes the place of chase lights. Commented Nov 11, 2012 at 4:53

The chase light sequence might be there to give a coarse visual cue to the crew manning the viewer-facing bridge stations as to at which position the sensors are in their scan cycle.

Now you would think that in a 23rd+ century starship sensor scans should happen at a much higher frequency. However, we do know that a full scan cycle can actually last several seconds:

O'BRIEN: The original Enterprise used an old-style duotronic sensor array. If we wait for just the right point in the scan cycle, we can decloak the Defiant for almost three seconds without being detected.

(from DS9: Trials and Tribble-ations)

There are indications that the scan cycle speed is adjustable. For example, in the teaser of Balance of Terror, we see very leisurely chasing lights, while in Spock's Brain, the sequence is much faster than 3 seconds. So it's possible the scan cycle speed was kept low when a fast sweep was not needed, e. g. to conserve energy.

This could also mean that with the more modern ships such as the Enterprise D, "standard mode" was quite slow (though faster than 3 seconds) but could be set much faster if needed (though I don't remember seeing fast chasers in TNG).

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