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Herkimer Jitty August 1 2010 02:54 AM

Shields and Screens
For the sake of argument, TWOK-onwards Trek is erased from history.

What's the difference between "screens" and "shields"? Are they part of the same system? A layered defense?

The TOS/TMP defenses seem a bit more complicated than "press a button and a magic bubble pops up", but I can't for the life of me figure out how exactly to put it together.

If there's some commonly-accepted fanon tech about this, I promise I won't shout at other posters (or the mods).

Mister_Atoz August 1 2010 05:19 AM

Re: Shields and Screens
As I see it, the "Deflector Screens" would extend outward from the vessel to deflect incoming projectiles and energy weapons. Anything that gets through this screen would then be absorbed by the skin tight energy shield before penetrating the hull. The "shields" then, in the traditional sense, would be more of a last ditch effort.

I guess I would see the "screen" as being an active defense, while the shields are a passive one.

Captain Robert April August 1 2010 07:37 PM

Re: Shields and Screens
^ What he said.

Timo August 1 2010 08:06 PM

Re: Shields and Screens
Roddenberry's memo to Jon Povill vis--vis forcefield terminology, Oct. 13, 1977 (from the Reeves-Stevens book ST Phase II - the Lost Series, p.50), contained these pieces of wisdom:

"FORCEFIELD SCREEN - a defensive or protective field which envelops or surrounds a vessel, person or object. A FS can also be called simply a 'forcefield', still means the same thing. We never use the term 'forcefield shield' as 'shield' refers to a single plane of forcefield protection as opposed to protection which envelops or surrounds [the target]." The memo then mentions the automated operation of the forcefields, the ability to drop sections of the forcefields, the ability to use communicators or transporters through weak forcefields, and the idea that the helmsman controls the forcefields.

"DEFLECTORS or DEFLECTOR SHIELDS - another kind of vessel protection which are the responsibility of the weapons and armament officer. Unlike a forcefield, a deflector shield does not surround the vessel. It is a single plane of protection as the term shield would indicate. Deflector shields can be many, and thrown up in manuy difrections, and they generally supplement the forcefield shields." The idea is that the strong shields can only be held up against attacks from so many directions, and a clever and determined enemy can get around them eventually.

"DEFLECTOR BEAM - this is solely a navigational device. It is never referred to simply as a 'deflector'." It's then described as in the TNG Tech Manual, as a forward-pointing "sweeper" beam for clearing the flightpath.

The terminology in that memo is somewhat confusing and contradictory, even though the ideas on the various sorts of protective fields are nicely developed. Whether the above was still in vogue when TMP dialogue was written is debatable, but it seems to fit the onscreen material pretty well.

Timo Saloniemi

kkozoriz1 August 2 2010 01:16 AM

Re: Shields and Screens
In TWOK we see this graphic when shields first go up. An enhanced network of lines in the area around the bridge.

When the prefex code is used to drop Reliant's shields, we see this.

Based on what Timo posted I'd say the latter shows the screens as they surround the vessel. The former example is a shield, an extra layer of protection around certain areas. We only saw the bridge, there are probably others.

keekwai August 2 2010 12:40 PM

Re: Shields and Screens
I guess "Deflector Screens" are called "screens" because one of their main functions is to deflect or "screen" out dust particles and micro meteorites. Just like a fly screen on your window screening out flies?

You wouldn't want to hit a fly at full impulse power!

I'm not sure .. but are the deflector shields used when traveling at warp? Or only with Impulse/Sub Light speeds?

If they are .. are they necessary? (during warp)

Do dust and micro meteorites exist in that bubble of "Warp space" surrounding the ship?

Is the "warp bubble" alone sufficient to push small objects away that are in normal space?

Mister_Atoz August 2 2010 12:55 PM

Re: Shields and Screens

keekwai wrote: (Post 4287664)
If they are .. are they necessary? (during warp)

There is a reference to "Main Shields" and "Navigation Shields" in TNG, (Outrageous Okona?)

I really wish they had stuck with Deflector and Shields as being two separate systems. They started doing that in TMP, dabbled with it in TWOK, and even brought it up again in early TNG.

I still choose to take the term "Deflector Shields" as describing two different systems that work together in tandem. I've always maintained that the "bubble" effect we sometimes see are the deflectors at work, while the skin tight fields are the shields.

On a separate note, I really think the introduction of point defense systems in the new 'Star Trek' (what three digit short form are we using for that?)...I've mentally retconned it into all previous trek.

keekwai August 2 2010 01:05 PM

Re: Shields and Screens

Mister_Atoz wrote: (Post 4287681)
I've always maintained that the "bubble" effect we sometimes see are the deflectors at work, while the skin tight fields are the shields.

That's not the "bubble" I was referring to. I'm talking about the bubble of "different space/time" or "warp space" the ship is in when traveling at warp speed.

Would the deflectors be necessary during warp flight to deflect dust and other particles from punching a hole through the hull?

Mister_Atoz August 2 2010 01:38 PM

Re: Shields and Screens
I understood that you were referring to the warp bubble, I should have clarified. I think the existence of "navigation shields" is probably enough to assume the warp bubble will not deflect dust particles.

keekwai August 2 2010 01:56 PM

Re: Shields and Screens
I'm thinking that as the only things existing in the "space/time bubble" or "warp space"would be warp powered ships .. there wouldn't be any dust, cows or telephone boxes in there to deflect.

Unless some madman strapped a couple of nacelles onto a cow.

Mister_Atoz August 2 2010 04:20 PM

Re: Shields and Screens
but then wouldn't a starship be able to fly right through an object in normal space such as a planet? there wouldn't be a need for a navigational deflector, or hell even a need to plot a course since star ships could just "tunnel" trough anything in their path.

I think we must assume objects in "real space" can effect starships travelling at warp.

I usually think of the "warp field" as being more of an area of "compressed" normal space through which the vessel travels, and not some other dimension all together.

Nuadu August 2 2010 05:03 PM

Re: Shields and Screens

kkozoriz1 wrote: (Post 4286951)
In TWOK we see this graphic when shields first go up. An enhanced network of lines in the area around the bridge.

When the prefex code is used to drop Reliant's shields, we see this.

Based on what Timo posted I'd say the latter shows the screens as they surround the vessel. The former example is a shield, an extra layer of protection around certain areas. We only saw the bridge, there are probably others.

Or...for a different perspective - take a look at TMP!

Here, we have the scene were the Enterprise was being attacked by V'Ger for the first time. We see Chekov's station and the shield display clearly shows a "bubble" while the system is energized.

Then, some time later, after Chekov returns to his post after recovering from being zapped by the plasma probe, we see the same shield display, but now with NO bubble. The shields were now down due to the ship being inside the cloud.

I doubt many may have caught this, so i wanted to share it here!

publiusr August 2 2010 07:02 PM

Re: Shields and Screens

kkozoriz1 wrote: (Post 4286951)

When the prefex code is used to drop Reliant's shields, we see this.

I think that was more to prevent folks beaming over a boarding party. In Mr. Scotts Guide, we see a skin tight method. In TNG, we see the bubble around the ship. In some lines in the ST:TMP, we hear both deflectors force fields and force shields, so there are layers as well.

One way to explain why weapons that are so powerful to an unguarded surface affect ships less might be to say this.

1.) Ship hulls are very sturdy,

2.) defenses are absolute, with no destructive power really getting through at all, but only on a suicide basis. In other words, it is the shields that explode from within after being overloaded in nulling out weapons fire after a brief delay, but paying the price destructively from within--accidental chubb' armor.

And since SFX folk use explosive squibs from within models to show what looks to be something outside trying to come in--you can use that for evidence, I guess.

We have transporter emitters, so I might beam scatter anti-matter as it comes in in a lower tech, shield tie in so to reduce damge from incoming weapons in as many way as we can. Heck , the SFB Andomedans absorb incoming fire--but only to a point.

Timo August 3 2010 10:34 AM

Re: Shields and Screens
In the end, do we really have individual lines that would confirm the existence of both shields and screens? Or both shields and deflectors? Or other such combinations?

Or is it just that different people at different times would use different names for the same thing?

Let's do a proper list... Starting with


Early on in the V'Ger encounter, "navigational deflectors" are mentioned as a separate syste. Later, Decker prepares for entering the V'Ger cloud:


"Recommend defensive posture, screens and shields."
So screens and shields are two separate protective systems. Or are they? Screens are never again mentioned in this movie, nor in other movies. Perhaps Decker recommended keeping an eye on the viewscreens while huddling behind protective shields?

Soon thereafter, Kirk and Chekov have this exchange when preparing for V'Ger's first plasma bolt:


Kirk: "Forcefields up. ...Deflectors now!"
Chekov: "Forcefields and deflectors up full, Captain."
So forcefields and deflectors are two separate protective systems. Or are they? After the hit, Scotty has this to say:


"We cannot hold full power on forcefields. Deflector power is down seventy percent!"
Perhaps these aren't separate defenses - perhaps forcefields are the things that power up the deflectors? Perhaps you first create the forcefields, then (at Kirk's "Now!") you use them to create deflectors?

The situation then develops further:


Kirk: "Engineering! What's happening to our forcefields?"
Scotty: "Our shields cannot handle another attack!"
So forcefields and shields are the same protective system. Or are they? We don't know if Scotty was answering Kirk's question, or ignoring it and putting forth some more pressing fact. In any case, apart from Decker's earlier recommendation, this is the only time shields are mentioned in the movie.


All mentions of shields are of shields alone, never of "shields and screens" or "shields and deflectors" or "shields and forcefields". Indeed, screens are never mentioned (except in the viewscreen context), nor are deflectors. At the first encounter with Khan, Saavik tells her underlings to energize "defece fields", and we then learn that this is not the same as raising shields.


Shields are mentioned as the sole defensive system. No deflectors, screens or forcefields.


Apart from shields, "heat shields" are used during the slingshot flights past the Sun. No other protective technologies are mentioned.


Apart from Scotty mentioning a "blowscreen", the terminology is again solely about shields.


Apart from the ships' shields, there is the "magnetic shield" or "beaming shield" over the prison camp.


The "deflector" plays a big part in the prologue; curiously, it's never referred to as "navigational" here. Apart from that, it's all shields again.


The "deflector" dish is again important, but not said to be "navigational". Apart from ship shields, there is a "forcefield" covering the opening in that room where Picard shows&tells Sloan that they're in space. No connection with or separation from shields is expressed.


Forcefields are used for creating holograms and for sealing the caves in which our heroes hide. Again, there's no "cross-phrasing".


Both heroes and villains use forcefields for sealing holes in their ships. The rest is all shields.

The bottom line? Only TMP has any lines (or even pairs of lines) combining two types of defensive system designation, thus separating or sometimes equating them. We get the following possibilities:

shields =/= screens
forcefields =/= deflectors
forcefields = shields

Both deflectors and shields are credited with repelling V'Ger's first attack. Screens aren't credited with anything.

Timo Saloniemi

kkozoriz1 August 3 2010 12:37 PM

Re: Shields and Screens
In TWOK Saavik says "Energize defense fields" and we see the area around the bridge highlighted on one of the displays as seen here.

So now we have defense fields added to the mix.

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