Shield generator A shield generator , deflector generator , or shield emitter , was the physical component of starship s , space station s , and other installations , utilized for the generation of protective energy screens with which to defend against outside attacks . In combat situations , it was common for a vessel to target weapon s fire at an adversary ' s shield generators , in an attempt to disable or weaken their shield strength . Technical data . The Federation utilized mercassium , a synthetic composite , in the constructions of their shield generators , a technology they did not share . ( ) If shield strength were to be lowered to a dangerous level , shield emitters could be brought up to full power by taking the shields offline and recharging the emitters . However , as this tactic would leave the ship vulnerable for the duration of the recharge cycle , it was considered extremely dangerous , and was rarely used . ( ) Overview . In 2154 , Degra was able to knock out the shield generators of a Xindi - Reptilian warship , allowing the crew of to target the warship ' s weapons . Degra subsequently destroyed the warship , to prevent its crew from reporting the fact that Degra had entered into an alliance with the " Enterprise " crew . ( ) That same year , Commander Shran supplied the " Enterprise " crew with the coordinates of the shield generator of what appeared to be an Andorian battle cruiser which was attacking " Enterprise " . However , upon firing weapons at the coordinates , it was discovered that the attacking vessel ' s shields were still at maximum power . It was later determined that the vessel was not , in fact , Andorian , but was rather a Romulan vessel disguised as an Andorian ship . ( ) Later that year , in an attempt to retrieve Ambassador Soval , who had been abducted by Shran , Lieutenant Malcolm Reed , " Enterprise " s tactical officer , fired upon the shield generator of Shran ' s vessel , in an attempt to use the transporter to retrieve Soval . ( ) In 2367 , after an encounter with a Borg cube , the crew of the experienced difficulties in keeping the auxiliary aft shield generators online , although Commander Shelby estimated that they could be back to full operating capacity within three hours . ( ) Later that year , while engaged in combat with a Cardassian vessel , Captain Picard ordered Lieutenant Worf , the " Enterprise " s tactical officer , to concentrate weapons fire on the Cardassian s ' weapons and shield generators . The tactic was successful , and the Cardassian ship was forced to stand down . ( ) In 2368 , " Enterprise " engineering teams installed five new shield generators at the Human colony on Moab IV , in order to fortify the structure ' s structural integrity so that it could withstand the gravitational forces of a stellar core fragment passing near the planet . ( ) During the Cardassian occupation of Bajor , Bajoran Resistance fighters would often take small ships close to Cardassian freighter s , and overload their shield generators with directed phaser fire . In 2369 , Major Kira Nerys , first officer of Deep Space 9 , suggested using the same tactic with a runabout , in order to rescue Doctor Bashir , whose body had been taken over by the Kobliad criminal Rao Vantika , aboard the " Norkova " . The plan was overruled by Commander Sisko , however , as the " Norkova " was hauling a shipment of deuridium , and the risk of a hull breach spreading the substance throughout the Bajoran system was too high . ( ) The same year , Miles O ' Brien , Deep Space 9 ' s chief of operations , ordered the computer to restart all shield generator subsystems and received a 98 . 3 % efficiency report . With this task , O ' Brien tried to show Commander Sisko the " strange behavior " of the computer voice . ( ) In 2370 , Captain Picard , while posing as a member of Arctus Baran ' s mercenary group , disabled the shields of a Federation outpost on Calder II by targeting the outpost ' s shield generator with a phase - resonant pulse configured to a precise frequency . This allowed the group to beam up a series of archaeological artifacts without destroying the outpost . ( ) The same year , in an alternate quantum reality , a Cardassian attack on the " Enterprise " caused an overload in the ship ' s shield generators . This resulted in an inability of the crew to raise the shields , and major damage to the " Enterprise " . ( ) In 2371 in an alternate timeline , a Romulan Warbird attacked Deep Space 9 , starting by destroying the station ' s shield generators , in order to hinder the crew ' s ability to defend the station . Although the attack ultimately resulted in the destruction of the station , this timeline was negated by Chief O ' Brien , who traveled back in time and managed to warn the crew of the Romulans ' presence , thereby averting the attack . ( ) Later that year , newly promoted Captain Sisko ordered a complete overhaul of the ' s deflector shield generators , in preparation of an anticipated Tzenkethi attack . ( ) In 2372 , during the Klingon attack on Deep Space 9 , Chancellor Gowron ordered the station ' s shield generators targeted , resulting in the disabling of two of them . This allowed Klingon boarding parties to beam aboard the station . ( ) In 2373 , when the " Defiant " became trapped within an energy barrier surrounding a planet in the Gamma Quadrant , the crew encountered their own descendants , who claimed that , upon attempting to leave , the " Defiant " would be thrown back in time and crash on the planet . Jadzia Dax , collaborating with one of the colonists , Yedrin Dax , formulated a plan whereby the " Defiant " could safely leave the energy barrier , which included synchronizing the ship ' s shield generators . ( ) In 2374 , a sneak attack by the Jem ' Hadar on the " Defiant " resulted in the disabling of the ship ' s shield generators and impulse engine s . This allowed Jem ' Hadar soldiers to board and take over the ship . ( ) In 2375 , One , a Borg drone enhanced with 29th century technology , was able to access the ' s shield generators , reconfiguring the shields to disrupt a tractor beam with which a Borg sphere had locked onto " Voyager " . ( ) Later that year , Lieutenant Commander Worf conceived of a means by which Captain Picard could beam aboard the Son ' a collector while its shields were raised , by maneuvering their ship within one hundred meter s and transporting him between the collector ' s shield generators . ( ) The same year , the crew of Deep Space 9 was supplied with a new ship , whose shield generators had been completely reconfigured in order to negate the advantage of the Breen ' s energy dampening weapon s . ( ) Later that year , the crew of " Voyager " utilized spatial charge s to destroy the primary shield generator aboard a Borg sphere , as part of " Operation Fort Knox , " their attempt to steal a Borg transwarp coil . ( ) In 2376 , Captain Janeway suggested to Commander Chakotay that he perform a diagnostic of " Voyager " s shield generators , which was considered way overdue . Later , Lieutenant B ' Elanna Torres scored a direct hit to the aft shield generators of Penk ' s starship . ( ) That same year , Captain Janeway ordered the shield generators of a damaged Borg cube targeted , in an attempt to rescue members of her crew who were being held captive . The effort proved futile , however , as the cube ' s generators were too deep inside the vessel . Janeway subsequently ordered Harry Kim , who was also on the cube , to attempt to deactivate the generator , but he was discovered by an adolescent drone before he could complete his mission . ( ) In 2377 , Irina , a Terrellian pilot , interfaced a phase inverter designed to cause a system overload with her ship ' s shield generator . This severely injured her copilot , giving Irina an excuse to withdraw from the Antarian Trans - stellar Rally , which she planned to bomb in an attempt to sabotage a recently signed peace treaty . ( ) In the late - 24th century , Captain Janeway and the " Voyager " crew developed ablative generator s , extremely advanced shield emitters capable of forming a protective layer of near - impenetrable armor around the hull . Along with transphasic torpedo es , this technology was specifically designed to defend against the Borg . In 2404 , Janeway , at this point an admiral , traveled back in time to 2378 on an illegal mission to change history , and delivered this technology to the " Voyager " crew . Using the generators , the crew was able to successfully penetrate the Borg defenses protecting a transwarp hub , and enter a conduit bound for the Alpha Quadrant . ( ) Background information . The phrase " shields up , " which saw widespread use in " Star Trek " , probably had its origin in classical warfare , when infantry would raise their s to defend against incoming arrows or other projectiles . The order would be given when it was time for the soldier to raise his shield from the carry position . "