Laser Artillery | Magnitude: Asteroid Destruction
Asteroid Destruction with Starfighter Laser Weaponry
Starfighter laser cannons provide sufficient firepower to blast apart buildings & asteroids many times more massive than the fighters themselves. Destructive capacity in the demolition of asteroids may be indicative of the weapons magnitude & energy requirements[¹]:
" From "Deflection and Fragmentation of Near Earth Asteroids" by T.J. Ahrens and A.W. Harris, it is projected that a 1 kiloton buried explosive will fragment a 100m diameter asteroid (based on experiments with terrestrial igneous rock), a 1 megaton explosive will fragment a 1km diameter asteroid, and a 1 gigaton explosive will fragment a 10km diameter asteroid. Using these figures as a basis, we can produce an approximation Y = (d/100)³, where d is diameter in metres and Y is yield in kilotons." - Asteroid Destruction Calculator
From experiments with terrestrial igneous rock, it is projected that a 1 kiloton explosive will fragment a 100m diameter asteroid, a 1 megaton explosive will fragment a 1km asteroid, and a 1 gigaton explosive will fragment a 10km diameter asteroid[¹], correlating to a 'rule-of-thumb' approximation Y = (d/100)³, where d is diameter in metres and Y is yield in kilotons.
This approximation assumes the explosives are buried for efficient distribution of energy into the surrounding rocky mass, as it may require greater energy to destroy the same asteroids using less effectively positioned explosives. For our purposes here, "Explosive-Anti-materiel-Equivalent-Yield" (Expl-AM-Equiv Yield) describes the energy of a conventional chemical or nuclear explosive which might destroy a similar-sized asteroid to a laser-blast produced by a starfighters blaster cannon.
The table extrapolates the explosive power required to destroy rock asteroids of 10 meters through to 100 meters in diameter fromY = (d/100).
Ice asteroids are less than half as massive as similar sized rock asteroids and require some tens of times (an order of magnitude) less energy to completely demolish[²].
TIE/rb | H-s9.3 twin laser cannons
TIE/rb | H-s9.3 twin laser cannons
Footage shows a heavy TIE/rb-("brute") fighter destroy two massive asteroids in quick succession[¹] with its rapid-fire H-s9.3 twin laser cannon. The first asteroid was around a hundred meters wide (~ 260 ft by 367 ft) as it completely dwarfed the Millennium Falcon, and it would have massed over half a million tonnes amusing a typical rocky composition. Y= (d/100) indicates an explosive force equivalent to between half a kiloton and 1 kiloton of TNT might fragment such a massive rock, so because the asteroid was completely destroyed in three shots the Explo-AM Equiv. Yield of each blast falls within the range of 670 gigajoules (170 tonnes TNT) to 1.39 terajoules (333 tons TNT).
" According to the SW2ICS, the midship guns have a per-shot yield of 2 kilotons, which would be enough to pulverize a well-consolidated 100-150 metre wide asteroid, assuming that the force-coupling efficiency of an energy bolt is equal to the force-coupling efficiency of a centrally buried chemical explosive. Of course, this is not the case, nor is it even close, so the 100-150 metre figure should be treated as an extremely generous estimate. An energy beam primarily heats the target, and the only form of force coupling is secondary, through gas expansion caused by rapid vapourization. Realistically, a 2 kiloton energy beam of perhaps 0.01 second duration would probably be limited to fragmenting an asteroid of only a few dozen metres in size rather than 100-150 (with a lot of heating, melting, and vapourization), which is closer to what we see in the film. " - Star Wars Episode II: Revelations #2: The Technology
Apparent width of asteroid: ~ 70-80 m
Apparent height of asteroid: ~112 meters
Average diameter of asteroid: ~ 96 meters
Likely mass of asteroid: 200-500 thousand tonnes
A more conservative estimate could be derived by calculating as if each shot could individually blast-apart an asteroid closer to 30 meters diameter so that a three-shot burst might blast-apart a larger ~100 meter asteroid; this would reduce approximate per shot Explo-AM Equiv. Yield to ~110 gigajoules (27 tonnes TNT). Furthermore, if the asteroid was composed mostly of ice rather than rock then it would have massed considerably less, closer to two or three-hundred thousand tonnes, and it would have required an order of magnitude less energy to destruct. The "Asteroid Destruction Calculator" indicates a ~100 gigajoule (24 ton TNT) explosive force might totally fragment such an iceberg, translating to a per shot Explo-AM-Equiv. Yield of ~33 gigajoules.
These estimates range by more than an order of magnitude, from 33 GJ to 1,390 GJ. The fire-rate of the H-s9.3 twin laser cannon is 300 shots per minute even at this magnitude[¹],,so the sustained (time average) firepower of the weapon is on the order of 165 (low end) to 7,000 (high-end) gigawatts.
Weapon System: H-s9.3 twin laser cannons
Platform: TIE/rb-"brute" heavy starfighter (twin-cannon pod-mount)
Fire Rate per minute:
Fire Rate per minute: >300
Explosive-anti-materiel-equivalent Yield per shot
High-est = 1,390 gigajoules (333 tons TNT)
Low--est = 33 gigajoules (8 tons TNT)
High-est = 7,000 gigawatts
Low--est = 165 gigawatts
Comparison to Earth
A short barrage from a H-s9.3 twin laser cannon can obliterate a one-hundred-meter wide asteroid so it's not unreasonable to speculate that the H-s9.3 twin laser cannon might just as easily demolish a city block:
"Since the spacing of streets in grid plans varies so widely among cities, or even within cities, it is difficult to generalize about the size of a city block. However, as reference points for US cities, the standard square blocks of Portland, Houston, and Sacramento are 264 by 264 feet (80 m × 80 m), 330 by 330 feet (100 m × 100 m), and 410 by 410 feet (120 m × 120 m) respectively (to the street center line)." - Wikipedia
"Engineers use a typical city block as 100,000 sq. ft. for calculation estimates, which is about 17 blocks per mile" - How Big is a City Block?
The most powerful non-nuclear weapons on Earth include the "American GBU-43/B Massive Ordnance Air Blast" (MOAB, commonly known as "Mother of All Bombs") and the "Russian Aviation Thermobaric Bomb of Increased Power" (ATBIP) nicknamed "Father of All Bombs" (FOAB). The respective yields of these weapons are theoretically sufficient to demolish rock-asteroids between 22 meters and 36 meters in diameter, which mass up to 20,000 tonnes. In this regard, the H-s9.3 twin laser cannon may possess even greater anti-materiel destructive firepower than the most-powerful non-nuclear weapons available on Earth, as a short barrage from the weapon could destroy a much larger asteroid weighing closer to half a million tonnes.
Below: scale-images compare Portland House and the iconic White House buildings on Earth to the larger of two asteroids destroyed by a H-s9.3 twin laser cannon:
Slave 1 | midship laser cannon
Slave 1 | midship laser cannons
"Unlike its seismic charges, Slave-1's midship guns were clearly designed for ship to ship combat. Their rate of fire was quite high (I estimate one shot every 3 frames at 24 fps, which averages out to roughly 480 shots per minute), which is appropriate for that task. It is unknown whether the firing rate of these guns is linked to their yield (ie- if the high refire rate comes at a cost in per-shot yield). However, at the yield setting used in this incident, each shot was capable of pulverizing asteroids larger than Obi-Wan's starfighter."- Star Wars Episode II: Revelations #2: The Technology
If Slave I's laser cannons achieve a maximum per shot yield of, for example, 4 gigajoules, perhaps sufficient for the demotion of multi-meter rock-asteroids, at a fire-rate of 480 shots per minute, then the weapons time-average firepower is 32 gigawatts. The weapons energy requirements necessitate a power source many orders of magnitude more productive than nuclear-fission; for comparison, the Bruce Nuclear Generating Station on Earth occupies 9.3 square kilometres of land and yields a peak production of around 6 gigawatts, which is just a small fraction of the power needed to operate Slave 1's midship lasers at this magnitude.
Turbolaser Artillery | scale comparison
Turbolaser Artillery | scale comparison
The heaviest turbolasers aboard an Imperial MKI 'Imperator'-class star destroyer are mounted in fifty meter wide turrets, each one around ten-thousand times more massive & more powerful than the H-s9.3 twin laser cannon on a TIE/rb starfighter. Assuming destructive ability scales accordingly then the heaviest turbolaser on a star destroyer might obliterate an asteroid that is over two-thousand meters wide & which weighs billions of tonnes. Destruction of the multi-kilometre asteroid correlates to an Expl-AM Equiv. Yield of ~10 megatons.
Imperial MKI 'Imperator'-class star destroyer, heavy turbolaser
Arquitens-class heavy quad laser battery
AT AT heavy laser cannons
Star Wars References
SOLO: A Star Wars Story
STAR WARS Episode II Attack of the Clones
Deflection and Fragmentation of Near Earth Asteroids" by T.J. Ahrens and A.W. Harris
The Asteroid Destruction Calculator
Star Wars Episode II: Revelations #2: The Technology by Mike Wong (mechanical engineer)
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