40K planetary/theatre shields

[Serafina]

Does 40K have planetary shields?

I only know of one instance (Gaunts Ghosts: Necropolis) where a theatre shield was deployed.
This shield protected an entire hive city against heavy bombarment for weeks.
At no point there was a danger of shield failure (such a risk is never mentioned). The shield only went down due to sabotage.

Single shells from the bombardment demolished the Great Imperial Basilika. As we speak about the IoM and it was a rich hive, it was a HUGE building (measurments in the km-range).
Thus, i estaminate at least a low-Kt yield for the big artillery shells used in the bombardment.

Given that at least a dozen of those shells hit the shield each second, together with hundreds of smaller shells and energy weapons, we have a lower range of several megatons hitting the shield each second.

However, the shield may be able to withstand way bigger firepower, as no one ever feared a shield failure.

Of course, those shields are rare and expensive. But if a hive city can afford one, what will Terra/Mars/Cadia/Nemesis Tessera have?

Now, the question:
Are there any other instances of plantetary or theatre shields? Or can anyone do a better analysis than mine?

[Lord Relvenous]

Connor MacLeod is the local 40k analyst. He covered Necropolis, so I'd look that up (it's linked to in the grand 40k sticky). That's a great place to look for past discussions on 40k. The answers to your questions are probably all there.

[Serafina]

Ok, i overlooked that while searching the 40K-sticky. So , screw my analysis.

The question still stands: Are there other known instances of such shields in 40K?

[Setzer]

In Straight Silver, I think, they mention a large portion of one conflict's frontline being shaped by shield emplacements.

[Lancer]

Wolf's Honor. The Governor's Palace of Charys, an agriworld, is protected by a much smaller void shield. Nothing else comes to mind at the moment, but I'm sure that there are other instances.

[Lazarus]

In Straight Silver, a somewhat bizarre situation existed where WWI-style trench warfare was viable again due to the technology of the planetary society being organically little in advance of mid-20th century, but bolstered by Imperial technology, notably shield generators which covered the front lines and presumably vital areas. They weren't kept online at all times though, so presumably they take quite some power to run. The capital hive on Herodor also had a shield generator, though it wasn't combat rated, designed more for weather control. It also didn't reach the ground, which is a feature I've not seen anywhere else. I've never heard of any reference to planetary shields though.

[Steel]

I haven't read it yet, but I think someone has mentioned that the entire theater was covered by shield, preventing orbital naval bombardment in the latest Dan Abnett titan book, if someone could confirm that. If that was the case then we're looking at a shield capable of repelling some quite substantial naval firepower.

[Black Admiral]

There is a theatre shield covering Spoiler

the Chaos forces' reserves of some sixty-plus Titans

But it's implied that's more to shield from observation than direct attack.

[open_sketchbook]

I've mentioned this before, but the Imperial approach to orbital defensive is usually ground-to-space defense lasers; take all the power you'd need to run a shield generator, and pipe it into a couple of frakking huge lasers instead. These weapons batteries are powerful enough that nine of them provided enough motivation for the Imperial Navy to have to land on the other side of Vraks and deploy the Krieg regiments, and they were never able to use orbital bombardment to effect the war, as I recall.

[Balrog]

IIRC there is a planetary-wide shield used in one of the Planetkill short stories, however Spoiler

it's just a trick to kill the population off, since it's powered only by human souls!

[Connor MacLeod]

As far as I know, ,aside from the example Balrog gave, there are no true planetary scale shields in 40K. I do believe Terra was protected by large forcefields which covered much of the Imperial Palace and other locales in the Horus Heresy, and the buildings there have been described as continent sized hives... which suggests that the larger void shields get to be hundreds or thousands of kilometers wide.

I dont know how large the mobile fortress monastaries are either like what the Imperial Fists and Dark Angels have, but I think the shield volumes might be similar there as well.

Connor MacLeod is the local 40k analyst. He covered Necropolis, so I'd look that up (it's linked to in the grand 40k sticky). That's a great place to look for past discussions on 40k. The answers to your questions are probably all there.

There are other folk who do analysis besides myself. I am merely the one who focuses most heavily on it.

[NecronLord]

IIRC there is a planetary-wide shield used in one of the Planetkill short stories, however Spoiler

it's just a trick to kill the population off, since it's powered only by human souls!

Actually, it's not. It's said to be somehow catalysed by that, but it continues to draw energy long after tha humans are dead, and they don't understand why it didn't work anyway. Given that it is supposedly somehow linked with some kind of C'tan/necron intelligence, it seems likely that it didn't actually need those people to die at all, and it solely refused to operate until it had influenced the humans into building the machine that consumed their entire population.

It's derived from necron technology, though, and supposedly able to resist the Planet Killer itself.

What is presumably the same kind of thing reappears on the World Engine, a mobile necron planet, in the latest space marine books. As I remember it, it resists a large IoM fleet's firepower, including planet killers, but one chapter of marines manages to ram a single ship through the shield while it's being bombarded, and interrupt the control systems long enough for the World Engine to be destroyed. Though they basically all die in doing so.

In a wider context, only the necrons seem to have the secret of shielding a planet fully with one energy field by technological means.

[Serafina]

Ok, so we never see a imperial planetary shield, but really big (contintent-sized) shields.

Any estaminations how much firepower they can take?

After reading Connors "Necropolis"-analysis, which states that they can propably full-sized nukes with ease, i would say that they are propably at least as powerfull as battleship-shields (given the increase in size, this is no surpirse).

[Connor MacLeod]

The defenses of Earth in the Horus Heresy took something like nearly two months (Though I doubt it was continuous) of sustained bombardment form Horus' fleet. I dont know how big the fleets were, but maybe hundreds or thousands of ships. It cracked the crust and shifted tectonic plates (supposeldy) and boiled off the oceans/eas (whatever there might have been.) but the areas under the shields were untouched.

At the very least its safe to say they probably stood off at least e27 watts, probably more (days of bombardment by hundreds of 40K warships, even if only part of the time, would probably exceed that number quite a bit.)

Edit: In the novel "Draco" the Emperor's palace is a single continent sized construct.