Q & As About 'Star Wars': Why wasn’t the Death Star re-engineered after the Rebels exploited the flaw with the thermal exhaust port?

The Galactic Empire's Death Star 1 battle station in its final stages of construction. © 2016 Lucasfilm Ltd.

Why wasn’t the Death Star re-engineered after the Rebels exploited the flaw with the thermal exhaust port?

Actually, the Death Star was modified heavily after the destruction of Grand Moff Tarkin’s DS-1 at the Battle of Yavin.

Although the movies don’t address this - there’s a three-year time jump between A New Hope and The Empire Strikes Back - it’s extremely likely that the Emperor called his most senior advisors and formed an Imperial Death Star Investigative Committee to discover how a single Incom T-65 X-wing fighter was able to destroy the Empire’s ultimate weapon with two proton torpedoes.

Such an investigative body would have had access to archival copies of the DS-1 plans, perhaps provided by the Emperor himself. The original plans were destroyed along with the Imperial Citadel on Scarif shortly before the Battle of Yavin, but it’s not a stretch of the imagination to posit that Palpatine had his own backup copies of the plans in his personal archives.

An after-action report by Lord Vader would have established that:

1. The Rebels had acquired the technical readouts of DS-1 and found the weakness
2. Governor Tarkin was overconfident and should have launched more TIE Fighter squadrons at Yavin, instead of relying solely on Vader’s elite squad

Further investigation (which would have been classified EMPEROR’S EYES ONLY) would eventually have revealed that:

1. The Death Star concept was basically sound in principle, albeit with a need for modifications, such as a superlaser that did not need hours to recharge and had an ability to protect the battle station from attack by capital ships by allowing gunners to target objects smaller than planets or moons
2. Galen Erso had deliberately created the thermal exhaust port as a built-in “soft spot” that could be exploited by the Rebellion

Imagine how destructive (and almost invulnerable this Death Star might have been had the Emperor waited till it was complete. © 1983 Lucasfilm Ltd. (LFL)

We are never told when the Empire began work on the second Death Star; it’s possible that the DS-2 was already in the works at the time of the Battle of Yavin. Even allowing for the possibility that the Empire already had over a decade’s worth of experience at building moon-sized battle stations, I find it hard to believe that the Emperor commissioned the new and improved Death Star after the Battle of Hoth (3 ABY). It’s more likely that work was underway near the Endor moon at around the same time that the Empire completed DS-1; per Rogue One: A Star Wars Story, the main obstacle that project Director Orson Krennic faced was the weaponizing of the huge kyber crystal and that he needed Erso’s expertise to finish that process; every other component used in the Death Star’s construction was based on existing technologies.

Clearly, the likely scenario as to the removal of the Death Star’s known vulnerability is that the Death Star II was two-thirds complete at the time of the Battle of Yavin, and that construction was halted temporarily until the cause of its destruction was analyzed and reported on by the Imperial Death Star Investigative Committee. The station’s main reactor would have had to undergo a massive redesign, mainly in the areas of eliminating excess heat from the reactor and minimizing damage caused by Rebel starfighters such as the Incom T-65C X-wing.

Had Emperor Palpatine not gotten overconfident and not used the unfinished Death Star 2 as bait to draw out the Rebel armada at Endor, it’s likely that a finished battle station would have been nigh-impossible to destroy. With no “easy-to-exploit” vulnerability built-in, Moff Jerjerrod’s new battle station might have crushed “the insignificant Rebellion” and extended Palpatine’s rule for another decade or so.