35

It's an occurrence common enough to be routine:

"Captain, they have locked on phasers."
"Shields up! Go to red alert."

It makes sense that the captain would be the one who decides to go to red alert — and, for that matter, who makes tactical decisions regarding the shields. (As the answers to this question suggest, automated responses aren't necessarily dependable under all circumstances.)

My question is... why aren't the shields up all the time unless there's a reason for them not to be? Shields don't preclude maneuverability, communications, sensors, weapons use... pretty much anything except transporting, landing a shuttlecraft, and getting shot. And presumably there's a range of situations in which the ship could be damaged before the captain could get two syllables in, and before the security officer could get two LCARS pokes in.

The out-of-universe reasoning is obvious: ordering the shields to be activated allows the captain to inform the audience, in no uncertain terms, that s___ just got real. But is there an in-universe justification? A reason that shields on a starship should be raised as necessary, rather than lowered as necessary?

Sneftel
  • 532
  • 1
  • 5
  • 13
  • 20
    Save energy? Would be my guess. – kjw Aug 27 '15 at 21:14
  • 46
    The same reason you don't walk around with your fists raised all day, just in case someone tries to punch you in the face: it's unnecessary, tiring, inefficient, cumbersome, and can come off as threatening to others. – Nerrolken Aug 27 '15 at 21:15
  • @kjw The various ST vessels never seemed to be at much of an energy deficit (initial ST:VOY difficulties notwithstanding). Is there evidence that keeping them up all the time would have caused a hardship? – Sneftel Aug 27 '15 at 21:17
  • 19
    @Nerrolken True, but I do drive around with my seat belt fastened, just in case I crash. It's probably unnecessary, and it's definitely cumbersome. It's not tiring, and AFAIK neither are shields. And it doesn't seem like it would be threatening, for the same reason other drivers don't assume my wearing a seatbelt means I intend to demolition-derby them. – Sneftel Aug 27 '15 at 21:20
  • 20
    @Sneftel Remember, the shields aren't the only defensive system on the ship. Your seatbelt is equivalent to the deflector dish, which is designed to protect against random impacts and cosmic radiation, etc, and which is pretty much always on. But the shields are a much bigger draw on the ship's engines, and they're simply not necessary 99.9999% of the time. During a war I'm sure they WOULD be up more often, but even the Enterprise's crazy adventures don't have them taking major ship-to-ship fire very often. – Nerrolken Aug 27 '15 at 21:25
  • @Nerrolken You make a good point about the deflector dish. But I don't remember anybody out-and-out saying that the shields were a significant-to-the-point-of-affecting-tactics energy draw, and they seem to raise their shields in response to Unusual Subspace Anomalies as well as ship-to-ship aggression, so I don't see why they wouldn't keep them up by default, purely as a matter of pragmatism. – Sneftel Aug 27 '15 at 21:30
  • Are you asking "Why do captains wait so long before raising shields in scenarios where they could plausibly need them", or are you asking why they literally are not on all of the time? – Phyneas Aug 27 '15 at 21:31
  • @Phyneas Literally all the time (other than when there's a specific reason for them not to be). – Sneftel Aug 27 '15 at 21:32
  • 2
    Non-canon, of course, but as an example of one possible reason: in the classic Star Trek computer game flying at warp uses a lot more energy if your shields were up. – Harry Johnston Aug 27 '15 at 22:14
  • Just don't as about the lack of safety harnesses aka seat belts :) – user23715 Aug 27 '15 at 22:18
  • @user23715 Nah, that's adequately covered by the Rule Of Cool (Ensigns Flying Across The Bridge). – Sneftel Aug 27 '15 at 22:23
  • It looks really dumb to my mind whenever operating at warp. We already know full well, if you operate at warp without shields you will tear your ship to shreds just encountering dust. So, I'm inclined to go with bad writing. – Joshua Aug 28 '15 at 03:18
  • 2
    In the original series, the shields are seemingly activated automatically, if the sensors detect a danger to the ship. The usual line is something like this from Zulu: "Captain, the shields just activated.". – Jost Aug 28 '15 at 09:41
  • 9
    Given that energy management is often depicted during battles ("divert all power to aft shields") it's reasonable to assume that the shields are a considerable energy drain. There's no indication that it would be "free" to keep them on. – Moyli Aug 28 '15 at 09:43
  • @Moyli: Well, there's presumably a strong drain when they are actually hit, instead of just maintained up. – Deduplicator Aug 28 '15 at 10:46
  • 1
    @Deduplicator But why would you then need to divert power to shields before you're hit? – Moyli Aug 28 '15 at 10:47
  • @Moyli: You decide where the power has to come from before you need it, or there's too little, thus the shield breaks when stressed. Also, revving it up above baseline presuably means less endurance but more stability. – Deduplicator Aug 28 '15 at 11:09
  • @Deduplicator Sorry, but that's stretching it pretty far... – Moyli Aug 28 '15 at 13:17
  • You can't beam through the shields. I'd guess that at a random point in time a Starfleet vessel is much more likely to want to beam down / over / accross an away party than to defend against hostile weapons fire. – Jonathan Cast Aug 28 '15 at 21:55
  • IRC there is a Star Fleet rule that shields have to be raised already when encountering any unknown vessel (or at least one that doesn't answer hailing frequencies?). Our favourite captains have a tendency to always ignore that rule (often with someone citing it to them) until it's too late ... – Hagen von Eitzen Aug 29 '15 at 09:48
  • 2
    I'm a bit late to the party here, but it's not very diplomatic to raise shields. Numerous times characters infer hostility through raised shields. It really is like saying "I don't trust you buddy!" (They probably shouldn't be trusting, but the Starfleet way is to maintain an open stance at first I think). – ThruGog Aug 30 '15 at 15:17

6 Answers6

59

Presumably, to save power.

While how deflector shields work exactly is covered up in technobabble, in the Star Trek: The Next Generation Technical Manual, it states that shields do have a limit to how long they can be operated:

The deflector system utilizes one or more graviton polarity source generators whose output is phase-synchronized through a series of subspace field distortion amplifiers.... Heat dissipation on each generator is provided by a pair of liquid helium coolant loops with a continuous-duty rating of 750,000 MJ. Four backup generators are located in each hull, providing up to twenty-four hours of service at 65% of nominal rated power.

Emphasis mine.

And, pure speculation here: It may also be due to the same reason away teams don't wear protective gear, Starfleet is of peaceful exploration, it doesn't really help your case when if you're talking to a Klingon bird of prey that your shields are raised, like you're expecting them to suddenly attack.

Community
  • 1
SpaceIsBig42
  • 1,129
  • 11
  • 11
  • 8
    Good one. So the manual is suggesting that if they kept the shields on as often as possible, purely as a matter of policy, they might be offline for cool-down (and unobtainium realignment) at the moment when the bad guys actually showed up. – Sneftel Aug 27 '15 at 21:35
  • 1
    @Sneftel Plus, to reiterate SpaceIsBig42's second point: going around in hostile posture—i.e. ready for a fight—is at odds with a mission of peaceful exploration. – Lexible Aug 28 '15 at 02:02
  • I think there's also the question of efficiency- why waste valuable Dilithium on powering the shields all the time? They can raise the shields quickly enough that it's not necessary. – PointlessSpike Aug 28 '15 at 07:13
  • @Sneftel If ST was a bit harder on the sci-fi scale, cooling down would likely be the major factor. They have no way of cooling the whole ship when the shields are on - remember that even to fire their own weapons, they have to synchronize their phaser' phase to their shields. This would significantly limit the amount of radiative cooling available, and would probably result in heat buildup rather quickly. However, ST being as soft as it is, they'll probably either ignore the issue or "dump the heat to subspace". – Luaan Aug 28 '15 at 08:22
  • If ST was a bit harder on the sci-fi scale, then the moment they put the shields up they'd be effectively blind! If something as powerful as a weaponised bolt of of energy can't get in, then natural radiation/light sure can't. – Grimm The Opiner Aug 28 '15 at 12:11
  • Bonus Question: Why did nobody implement a shields-up-automation? (Probably they went out of budget after they bought all those cool red shirts.) – Chris Aug 28 '15 at 18:34
  • 1
    That quote seems to be saying that the 24-hour limit applies only to the backup generators. Presumably the main generators can keep the shields powered for much longer (and at 100% of nominal power, not just 65% like the backups). – Ajedi32 Aug 28 '15 at 19:10
  • 3
    @GrimmTheOpiner Ever worn sunglasses that let you see your environment while "deflecting" high energy UV radiation? – Hagen von Eitzen Aug 29 '15 at 09:44
  • "Continuous-duty rating" means "What power level a device can operate at indefinitely". The 24 hour limit is for the four backup generators. Unfortunately, we don't know what max the shields are capable of. If 750,000 MJ represents the shields operating at 125%, it doesn't make much sense to turn them off. If 750,000 MJ represents just the deflector shields, or the shields operating at 1-2% it makes sense why they have to raise shields. -- That said, I think we can assume that 'raising shields' puts them higher than 750,000 MJ, because otherwise, nothing about ST makes any sense at all. – Shane Aug 31 '15 at 16:39
  • @HagenvonEitzen there's definitely some sort of a point there, but running shields in the same way would require making assumptions about the frequencies any weapons directed against you would be operating at, assumptions which could be sidestepped. But shields are a universal Sci-Fi trope and Star Trek is no more guilty than any/many others! The only "shields" I can bring to mind that were explained differently were in the computer game "iWar". – Grimm The Opiner Sep 01 '15 at 15:07
34

Federation starships despite their appearance of near-infinite energy, expend the bulk of that energy in four ways: offensive weapons, defensive shielding, energy manipulation on-board ship for environmental controls, internal gravity, inertial dampeners and maintaining mobility through the use of the warp drive engines. Of the four, defense utilizes a great deal of the energy generated.

  • Technically, the shields are always up albeit in a reduced energy configuration. The deflector array is always in operation as long as the ship is in space, deflecting particles of matter which could have disastrous effects on the ship or its crew. This technology is commonly known as the navigational deflector.

The navigational deflector (also known just as the deflector, the deflector array, the deflector dish, the main deflector or the nav deflector for short) was a component of many starships, and was used to deflect space debris, asteroids, microscopic particles and other objects that might have collided with the ship. At warp speed the deflector was virtually indispensable for most starships as even the most minute particle could cause serious damage to a ship when it was traveling at superluminal velocities.

  • This low-intensity shielding, however is not the same as the main shields which protect the ship against attacks from spaceships and other potential threats. These shields require an enormous power drain on the ship's energy supplies and are thus only utilized when the ship is under attack, in an extreme environment, or attempting to prevent transporter-based technology from entering the ship.

  • Since the drain on ship's power is both considerable and requires significant crew to manage and maintain power management, raising the deflector screens to a defensive posture requires a call to red alert to bring out the proper crew and to set the ship up for proper emergency energy management.

Community
  • 1
Thaddeus Howze
  • 212,750
  • 23
  • 708
  • 994
  • A fourth way: the energy required to move around is substantial too, especially at higher warp factors. –  Aug 27 '15 at 22:16
  • 1
    Shields are often brought up under yellow alert, which is more of a caution state than an outright emergency state. So, I assume that is the minimum crew alert state for proper shield operation. – Ellesedil Aug 27 '15 at 23:59
5

As can be seen almost every few episodes, raising one's shields is generally seen as an aggressive move. All races do it only whenever a battle is imminent.

The Federation, in contrast to most other greater empires, is focused on exploration and peace. Flying around in a state of combat readiness is not something that tells people "we come in peace" but more "get ready, whenever our sensors detect you, we will attack you".

This is directly supported in Star Trek: The Motion Picture through this exchange while the Enterprise is approaching V'ger:

CHEKOV: Should I go to battle stations, sir?
KIRK: Negative, We'll take no provocative action.
DECKER: Recommend defensive posture, screens and shields.
KIRK: No, Mister Decker, ...that could also be misinterpreted as hostile.

If we compare permanently having shields with modern day ship warfare, you could say "the Federation ship has their ECM set to full and a target lock on us, but their weapons are not ready, yet."

Thus energy consumption aside, it is not something the Federation wants to do because it projects the wrong image about them and their intentions.

ApproachingDarknessFish
  • 17,056
  • 9
  • 88
  • 108
Thomas
  • 10,115
  • 6
  • 41
  • 67
  • I dunno... in "A Matter of Honor", Riker tells a Klingon that the Enterprise raising shields is "normal procedure when entering into a suspicious situation. It's not an act of aggression." Kirk isn't one to follow SOP, of course. – Sneftel Jul 16 '18 at 21:32
  • I'm sorry, the Federation is not focused on peace, it is quite expansionist, and all of its exploration is carried out by its military, who also controls most foreign relations. But you're right on the first count. – einpoklum Jul 16 '18 at 21:38
1

If shields are up, they can be analyzed for weaknesses by enemies. They might not help when they are needed the most.

Edit

Copied explanation and references from https://memory-alpha.fandom.com/wiki/Shield_frequency

A shield frequency, shield harmonic, or shield modulation refers to the frequency settings of the shield emitters on a particular starship. If an enemy force were to obtain this frequency, they can modify their weapons to bypass the shields entirely. (Star Trek Generations) Shield functionality can be regained by remodulating the shields. (VOY: "Equinox, Part II") In order for two starships to merge their shield envelopes, the frequencies of their shields must be matched. (VOY: "Equinox") Federation shield frequencies operate in the Megahertz ranges. (Star Trek Generations)

In less than ideal sensor conditions, a ship can be identified by the pattern of its shield harmonics. (VOY: "Innocence")

In 2366, when the non-corporeal Koinonians drained antimatter from the antimatter pods to use it as energy to create their replica of Marla Aster, it was stopped by increasing the shield harmonics to match the antimatter containment effectively severing the Koinonian beam. (TNG: "The Bonding")

In 2371, Lursa and B'Etor were able to inflict severe damage on the USS Enterprise-D after learning its shield frequencies through modifications of Geordi La Forge's VISOR. They were then able to adjust their Bird-of-Prey's disruptors and torpedoes to pass through the Enterprise's shields. (Star Trek Generations)

The Vidiian starship that attacked the USS Voyager in 2371 was capable of continuously matching Voyager's shield frequencies, allowing them to clamp directly onto the hull. (VOY: "Fury")

In 2372, a shuttlecraft piloted by Tom Paris penetrated the shields of a Pralor starship by matching shield harmonics with those of the Pralor subspace defense field. (VOY: "Prototype")

In 2375, One, an advanced Borg drone with 29th century technology, remodulated Voyager's shields to break the ship free of a Borg sphere's tractor beam. (VOY: "Drone")

Later that year, Lieutenant Commander Tuvok developed a new shield modulation which was hoped would be effective against the weapons of Devore warships. (VOY: "Counterpoint")

In 2376, the USS Equinox successfully engaged the USS Voyager after learning its shield frequencies. Although Voyager remodulated its shields several times, each time the new frequencies were passed to the Equinox by their EMH, which had been switched with that of Voyager. (VOY: "Equinox, Part II")

While aboard a Borg installation, Janeway monitored the shield modulation of a Borg drone as it passed through one of the ship's internal force field. By adjusting her bio-dampener to the modulation of 324.95 she was able to walk through the force field, however her bio-dampener was destroyed in the process. (VOY: "Dark Frontier")

Community
  • 1
osundblad
  • 119
  • 4
0

As previously stated, all shield generators have a duty cycle. After this duty cycle it us mandatory for the units to go through a cooldown process. The deflector shields actually ARE up continuously: I believe the stated power level is somewhere between 5 and 15% of full strength. This is to protect the crew from radiation and small debris. The main navigational deflector dish clears the ship's path of larger objects. Furthermore, having the shields always raised at full strength interferes with several sensors used for scientific purposes. The Technical Manual states that fact, and states that "sensor windows" are periodically opened in the shields, but that the results obtained by scanning through these "windows" are of reduced quality. Think of it like this: the reason the Hubble telescope is mounted on a satellite is because it will get a clearer picture. If it was on earth, the atmosphere would interfere with image clarity.

dr scott
  • 9
  • 1
-2

It always made sense to me that if a ship locked onto the Enterprise, or fired torpedoes or any number of other scenarios, the computer should be programmed to automatically raise shields. It also always seems strange that the shields are set to some frequency creating a weakness to be exploited, instead of randomly cycling through frequencies.

But, if they resolved all these weaknesses, wouldn't it remove a lot of tension in the plot? Also wouldn't it eliminate a huge amount of plot points used in the TV show and movies if the Enterprise didn't get blasted now and then from not manually raising shields in time before getting shot at?

In response to the comment made to my answer - The shields do not automatically raise in every episode or movie. In Wrath of Khan the enterprise is shot at before Kirk has time to raise the shields after the Reliant locks on to fire causing damage and death. In the Next Generation TV Series when Warf is traveling through dimensions, he fails to raise shields in time causing people to die. In one episode (related to my shield frequency comment) Geordi's visor gets hacked so the Klingons know the shield frequency, instead of randomly changing the frequency the shields operate at continuously. There are a number of examples of this plot device.

If the shields and defense systems worked the way technology likely would look in 300 years, it would make for a boring show. A torpedo fired at the Enterprise would get shot down by automatic phasers while simultaneously raising shields without human intervention. Instead the show is something we can all follow.

Doug
  • 1