The quote as such, is as follows:
Dawn of War, page 98 wrote: Shortly afterwards, a flotilla of Naval and Inquisition vessels had joined the Ravenous Spirit in orbit and had proceeded to launch an unrelenting barrage of lance strikes, mass drivers and cyclone torpedoes, reducing the once green world to a primeval, molten state.
The passage identifying it as an exterminatus follows from here:
Dawn of War, page 161 wrote: "As I recall, you were the one who requested the assistance of the Inquisition in the performance of an exterminatus on cyrene - the systematic annihilation of all life on the planet - genocide by another name."
Parameters for the bombardment
As anyone who has had some knowledge of Star Wars BDZ incidents can tell you, melting a substantial portion of a planet's surface (IE crust) can be very energy intensive. But how intensive, and how do we determine this? The clue lies mainly in the manner in which the incident is phrased - that the planet is reduced to a "molten, primeval state."
Now, that by itself doesn't really tell us alot, ,aside from the fact the planet's surface is raised to the melting point. The context though suggests that the planet was reduced to such a state simialr to how the Earth was in the very early stages of its life. "Primeval Earth" on google does not turn up many results however (this being the only one I could find), but recalling my older "Cave sof Ice" bombardment analyis, I remembered discovering during that research that the Earth during that period was also quite molten.
That period is known as the Hadean era (or eon, either works.), named so for the hell-like conditions of the planet at that time. As a google search and browsing of some of the resulting links indicates that the earth at that peroid was in a mostly molten state. We can therefore infer that the conditions on cyrene would be similar as a result of the bombardment (IE a fair portion of the planet heavily molten.)
The next question of course is the depth to which the crust is molten. Again, this is not specifically indicated, but we can conclude based on the quote that since the planet would be made "molten", much of its solid mass would be affected. The obvious conclusion woudl be that much of the crust will be melted in the process of the bombardment.
This is perfectly likely, but it is worth noting that the crust is not the ONLY solid part that the bombardment would neccesarily affect. Part of the upper mantle also remains solid (which together with the crust is called the lithosphere.) The actual "depth" seems to vary tremendously.. I've seen as little as eighty kilometers well up to hundreds (300 km) of kilometers) Data on the lithosphere can be found in the google results here
That said, there are other considerations:
- most hatbitable planets also have a considerable quantity of water (water makes up 70% of the Earth's surface.) In a "molten, primeval" state, this almost certainly means that the vast majority of the planet's oceans and other bodies of water will be boiled away (reduced to vapor). In terms of energy, this will probably be alot smaller relative to melting most of the earth's crust (much less the lithosphere), but it serves as a useful lower-limit benchmark.
- while considerable melting is almost certain from the calc, its also quite likely that, given the weapons being used, there was a not-insiginifcant amount of vaporisation involved (Asteroid impacts will create lerge amounts of vapor) as well as fragments. While its not directly possible to calc vaporization, it could argualby increase the calc by up to nearly an order of magnitude, dpeending on the percentage of vaporization inferred.
- it is quite possible that lower levels of the mantle are also heated, since the only temperature increases as you go down fruther towards the core. Considering the mantle makes up most of the Earth's mass and extends down for thousands of kilometers, it can potentially add alot to the calc. However, I ignore this avenue for several reasons. First, I'm not really sure yet how the temperatures breakdown beyond the lithosphere. before it reaches melting point. The lower layers (the ashthenosphere) tend to be more plastic, rather than molten, but the temps and pressures also fudge with calcs, ,whch would entail more research than I currently wish to engage. Secondly, given the probable length of time of the bombardment, inefficiencies will probably dictate that the lower levels will get heated up regardless.
Indeed, inefficiencies themselves could contribute significantly to the calc, as noted here with regard to Base Delta Zero, inefficiencies could contribute to an orders of magnitude increase in calcs.
Numbers of shisp involved
We know there was one strike cruiser present, as well as a "flotilla" of Navy and Inquisition vessels. As previously discussed in the Ciaphas Cain novel and the misc 40K analyis thread, "flotilla" is another word for "squadron" so this tells us there is roughly a squadron of ships here. Now the exact kind of squadron is not specified.
The distribution of "squadrons" is as follows
Battleships and Grand Cruisers are 2-3 ships
Cruisers and batltecruisers are 2-4 ships
Escorts are 2-6 ships.
For the purposes of the calc, I am going to assume cruisers. AS far as I know, the Inquisition does not normally have its own battleships (but they do have cruisers), and in the navy, cruisers are much more common than battleships (and much more likely to respond quickly.) Moreover, if there were a couple of battleships replying, a strike cruiser would more than likely be superfluous in the bombardment. Escorts, of course, are ignored because while there would be more of them, they'd acutally contribute less overall firepower than the cruisers.
Nonetheless, I may do breakdowns for different kinds of "squadrons" based on this. Battleships will be the conservative one.
According to Battlefleet gothic it takes a single capital ship "hours" to conduct an exterminatus. Given the squadron dispostions above, the timeframes should be arguably much "less" in evey case (with 3-5 cruisers the timeframe should, arguably be 1/3 to 1/5th what it is for a single ship.)
There is a small problem with this: The "Index Astarrtes" entry for the blood ravens (written by Graham McNeill) specifies it took the fleet a whole week of pounding with "mass drivers, lance strikes, and cylconic torpedoes. It also specifies that "fleets of Inquistorial and naval vessels" appeared, implying much greater numbers than what hte novel itself implies.
This cleraly represents a contradiction of sorts - the "fleets" bit can be disregarded probably, but the timeframe (arguably) could not. I am, howver, inclined to give more credene to the "novel" depiction of events for several reasons
- In the novel it is identified as an Exterminatus, and the timeframe of Exterminatus is well defined both within battlefleet gothic as well as corrobroated by other sources. No source I am aware of has ever indicated it takes a week of actual bombardment to exterminate a planet, and the BFG refrence does include brute force weapons (mass drivers and fusion wepaons)
- The novel appears to present the incident from the viewpoint of Gabriel. This would be more consistent "in-universe", as Gabriel was present for the incident. The "Index Astartes" entry is written as if it were reporting an event secondhand.
- In addition to #2, the Index Astartes article also makes it abundantly clear that some or much of hte information is unknown (the Inquisitorial records on the incident are still sealed.) In fact, they flat out state that "only the Inquisition and Gabriel Angelos" know what happened. Which reinforces the idea that Gabriel's recollection of events is more accurate.
- The timeframe given in the article is "months." Now, this is arguably debatable, but "months" may not be very "rapid" a response time for the Imperium (the Imperium in Caves of Ice responded to the Necron bombardment with a flotilla of battleshisp in weeks) Again, its debatable, but this does not seem very likely.
- the Index Astartes article conflicts with both the novel and Battlefleet Gothic on separate points: Two against one.
- The "week long" timeframe can be more easily reconciled with "hours" (depending on circumstances) without bending over backwards for rationalization. Whereas you can rationalize a "week" as falling under "hours" only in a very loose sense. Moreover, from a logical standpoint, ,constantly firing for over a week is unrealistic - there would have to be reloading, resupplying of ammunition, allowance for maintenancec and cooldown, etc.
Nonetheless, to be conservative, I will further include the use of the week-long timeframe, even though I consider "hours" to be the reliable timeframe.
The first number will be ocean vaporizing, as specified before. Having done this previously, this will come out to roughly 4e27 joules. works well as a low limit baseline. In reality melting a significant portion of the crust will result in the oceans boiling off as a side effect (energy radiated away elsewhere, etc.)
Now, to calcualte the actual crust melting, I did two different ways.
The first way, I pulled the classic "one meter, one hour" figure from Mike's Base Delta Zero page. The energy figure is (of course) 2.2e24 joules. I then multiplied by an assumed 30-40 km crust depth, and then took 30% of that figure (only about 30% of the surface of the planet is "solid" from the top of the crust to the bottom - the crust under the oceans is only about 10 km thick at most..) To account for the "ocean crust" I take 2e24 J, multiply by 10 kilometers (10,000 meters) and then take 70% of that. the result for the first calc is between 2e28 and 2.64e28 joules. The energy for the "ocean crust" would be ~1.54e28 joules.
The total energy input would be at least between 3.5e28-4.2e28 joules.
The lazy calc was fairly straightfoward: it involved using the crustal mass figures pulled from the nineplanets, which is roughly 2.6e22 kg. multiplying that by the melting enegy from the BDZ page yielded an energy requirement of around ~5e28 joules.
Since there isn't much difference between the two I'll use the second figure.
Assuming 2 vessels (of any kind) + 1strike cruiser did it:
For 2 hours: Ocean vaporizing: 1.85e23 watts Complete crust melting: 2.32e24 watts
For 24 hours: Ocean vaporizing: 1.54e22 watts Complete crust melting: 1.93e23 watts
For one week:Ocean vaporizing: 2.2e21 watts Complete crust melting: 2.76e22 watts
Assumign 3 Battleships + stirke cruiser did it
For 2 hours: Ocean vaporizing: 1.4e23 watts Complete crust melting: 1.74e24 watts
For 24 hours: Ocean vaporizing: 1.17e22 watts Complete crust melting: 1.45e23 watts
For one week: Ocean vaporizing:1.67e21 watts Complete crust melting: 2.1e22 watts
Assuming 4 cruisers + strike cruiser did it
For 2 hours: Ocean vaporizing: 1.12e23 watts Complete crust melting: 1.4e24 watts
For 24 hours: Ocean vaporizing 9.33e21 watts Complete crust melting: 1.17e23 watts
For one week: Ocean vaporizing 1.33e21 watts Complete crust melting: 1.67e22 watts
Assuming 6 escorts + strike cruiser did it:
For 2 hours: Ocean vaporizing: 8e22 watts Complete crust melting: 1e24 watts
For 24 hours: Ocean vaporizing 6e21 watts Complete crust melting: 8.33e22 watts
For one week: Ocean vaporizing 9.52e20 watts Complete crust melting: 1.19e22 watts
The above do represent a fairly wide range of numbers, but none of them should be considered upper limits. But, rather, a range of lower limit values. I'm only considering the crust ATM (I'll do calcs for the lithosphere later, with more research permitting), it ignores any inefficiencies in the proceses (which, as noted, could significantly increase the calcs), and I'm also ignoring the fact that the "hours" timeframe applies to a single ship. Logically, with multiple ships in this case the bombardment should be over sooner (IE, with 4 vessels, the 2-24 hour timeframe would be between half an hour and 6 hours.)
Nonetheless, this does serve to indicate a nice level of consistency with other esablished calcs (IE the Caves of Ice bombardment, nova cannons and bombardment cannon calcs, etc.)
More to come...