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Originally posted by DinoDoc
You're reaching Boris.
You're reaching Boris.
Sensor globes
Many people assume that the two globes set atop the command tower of a star destroyer are deflector shield generators. This is almost certainly wrong. The best evidence indicates that they are sensor systems instead.
At the climax of the Battle of Endor a concerted A-Wing attack led to the explosive destruction of one of these globes on the Executor. This damage also coincided with a breakdown of the bridge deflector shields, which is the reason for the common prejudice regarding the function of the globes.
On all other starships the deflector shield generators are hidden internal devices. They do not need to be perched up high away from the main hull. If the star destroyer globes were deflector shields or if shield generators took any advantage from being prominently placed on a vessel's outer hull then we would expect to see similar structures on rebel capital ships and other vessels. We do not. The domes must be some non-critical system which can afford exposure in a vulnerable location. Furthermore, if the globes really were deflector shield generators then they would themselves be sufficiently shielded to withstand missile attacks from mere starfighters.
The failure of Executor's bridge deflector shields coinciding with a globe's destruction may merely indicate that the damage to one system affected power to the other in an unanticipated way. Note that only one of the globes was damaged. If the globes on the command tower were the actual shield generators then both would have to be damaged or destroyed before the bridge shields were wholly lost. (It should also be noted that the globes on the bridge tower were only two out of at least eight that can be seen in that neighbourhood of the dorsal hull.) At best, Executor's demise says more about a flukey and synergistic system failures than any functional connection between globes and shields.
In fact there might not be any causal connection between the destruction of a globe and the failure of the bridge deflector shields. Early in the battle, [ROTJ novel p.170] Admiral Ackbar gave specific targeting orders for the Alliance capital ships:
"Concentrate your fire on their power generators. If we can knock out their shields, our fighters might stand a chance against them."
In other words, the shield failure was probably due to a power loss which was the deliberate result of the rebel heavy ships' bombardment. In fact it might only have been only a temporary shield failure, with the generators taking some time to recharge. The damage to the globe may have indirectly contributed to the ship's vulnerability, insofar as it might hamper raising the shields again once they were already down. The destruction of one scanner globe was a sign that the bridge deflector shields (which would otherwise protect the globes from starfighters) had already failed. This is a demonstration of Executor's vulnerability, not the cause of it.
Furthermore, there is evidence of at least one warship at the Battle of Endor which lost its bridge shields even though its globes were completely intact. This was one of the vessels with multiple bridge nodules on the face of the command tower. (It may be the intermediate-sized "communications ship" described in the novel.) In the closeup footage of the battle around this ship there are great gushes of flame coming from inside most of the bridges, exploding out into the void. Even though the shields are completely lost and the bridge regions have obviously been devastated by rebel bombardment, the globes atop the tower are serenely unharmed and presumably fully functional.
Although they're only second-order evidence, it is interesting to note that the official non-canon sources are divided. The roleplaying game seems silent on this matter. Computer games introduced the whole "shield globe" idea as a simplistic means of making large warships vulnerable to the player starfighters. However globe destruction was not always effectual in the games, eg. they don't alter the shielding of Victory-class destroyers. Essential Guide to Vehicles & Vessels and the SWCCG cards followed the computer games, but STAR WARS Incredible Cross Sections indicated that the antenna/globe area is concerned with targeting. Some novels attribute shield functions to the globes, while others call them "sensor domes."
To deduce the real purpose of the globes we must consider what functions of a starship actually would benefit from the high vantage of the top of the command tower. The fact that the location gives clear line of sight into space over a maximal angular field suggests a particular type of sensor system which is is blocked by the bulk of the vessel. Sensors of at least some other starships are in similarly prominent positions, eg. the sensor dish on the Millennium Falcon. Nobody dares to suggest that the Millennium Falcon's dish is a deflector shield generator.
On Earth military/naval sensor and communications dishes are often protected within polyhedral domes which closely resemble those of star destroyers. The surface of the globe is composed of a material which is transparent to the energy employed by the antenna within. An example is the 4MW radar of the AEGIS tracking system featured on the US Navy's Ticonderoga-class 172m guided-missile cruisers. It is likely that the star destroyer globes are analogous to these, albiet using forms of energy far beyond those known to our science. The common physical function of scanner-type devices in our world and in STAR WARS give rise to similar structures.
Mandel's 1978 Star Destroyer Imperator Class blueprints corroborate the designation of the globes with a sensory function. His work appears to be just as "official" and Lucasfilm-approved as the divergent reference material which appeared in the late 1980's through to present. The blueprints label the globes as "long-range scanners". Smaller-scale short-range scanners are probably distributed across the rest of the vessel's surface.
Positioning of the main scanner globes high atop the command tower has the effect of minimising long-range blind-spots. Lines of sight are uninterrupted in as many directions as possible; the emissions of the scanners are well away from most of the ship's bulk. However the tower globes cannot access all of the sky. Unless there are more scanners on the underside of the ship, there will be blind arcs across ventral directions.
In the escape from Hoth, Han Solo launched his starship into a strafing run across the surface of the star destroyer Avenger and hastily parked on the aft face of the command tower. This manoeuver makes best sense if the globes are the major scanners of the vessel, because Solo's landing site is one of the few sheltered blind-spots (apart from possible locations on the ventral surface). By moving into the blind-spot when the bridge crew were distracted by the threat of collision, the Falcon vanished from the scopes.
The particular uses of the globes may include the provision of targetting data for the ship's turbolaser batteries and other weapons systems. This would account for the rebels' repeatedly determined attacks on the globes of multiple Imperial ships during the Battle of Endor. Elimination of scanner globes dramatically reduces the accuracy of the Imperial warships' otherwise superior firepower. (Of course the real reason might instead be the fact that the globes are delicate enough to be vulnerable to starfighter fire, unlike most other parts of a huge warship.) Admiral Piett's immediate order for an intensification of firepower may partly be a recognition of the perilous damage to Executor's gunnery systems.
In accordance with its enhanced command and control capabilities, the Executor and other vessels of its class possess at least three pairs of scanner globes in addition to the conventional set on the bridge tower. One set are placed about half a kilometre behind the bridge, on the dorsal surface atop twin cylindrical towers. The spacing of these globes is equal to that of the couple on the bridge tower. There is no linear array between them. This implies that the globes operate independently of the linear array, dependently on a partner globe, and that the globes' spacing is an important characteristic of the function and physics of these devices (probably due to the exploitation of some kind of interferometric technology). However the separation distance isnt restricted to a constant value, because the other known pairs of globes are more widely spaced, sitting generally downhill and outboard from the command tower.
These supplementary scanner globes may help ameliorate the sensor shadow cast by the long fantail of the command ship, increasing the aft sky coverage by a few percent. They also cause a dramatic reduction in the number of sensor blind-spots near the hull, especially in the crevices of the crenulated dorsal terrain and on the sides of the bridge tower. However hull shadow considerations probably are not a primary concern, since the globes' size implies special long-range capabilities (which are not available on smaller vessels like the improvised warships of the Rebel Alliance). Nor can the extra globes be a mere backup system, because their placement is not as advantageous as those on the command tower. The most likely reason for their presence is that these larger starships have more power and space available to sustain these useful devices. The potential to direct the operation of one set of globes at a different part of the sky to the primary set must naturally improve the strength, range and overall effectiveness of the sensor system.
Studies of the proportions of the star destroyer models reveal that the sensor globes have a diameter of approximately 41m.
Those werent the shield generators
damn blasphemous x-wing games
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