Thoughts on defending celestial bodies

Particularly crowded orbits full of infrastructure could be very useful hiding spots. One may expect to see many dormant defenses hidden in stations, and among satellites and debris, alongside those buried underground or surface-mounted.

Perhaps as a counter-strategy against high-flying shrapnel, invaders could lead their charge with squadrons of cleanup ships? Using broad whipple shields or magscoop capture or something

I would argue the opposite, if anything it makes them primary defences, seeing as a missile launched from long distance, even if moving at incredible speed, is visible due to background cross referencing and heat signatures, all the mass driver has to do is wait until the ideal interception moment occurs and fire off a slug, boom no more missile. If anything a better bet would be on the ground special forces insertion disabling the mass driver and as many systems as possible before subsequent attack occurs.  

Id say you would even more so need fleets, as i said above anything fired from extreme range makes interception time large enough to actively defend from such an attack. The only absolute killer is light-speed velocity projectiles, and those are thankfully out of our physical reach. Fleets give you far more options in terms of active attack and dynamic situational advantages as opposed to long range mass driver vs mass driver. They can get in close, dodge and lay down a much faster deadlier payload than something that needs to spend a month getting to it's target.

Im not so sure if anything a primary mass driver backing a defensive fleet sounds like an ideal scenario. And no once again any munitions fired "interplanetary style" can be tracked unless moving at ludicrous speeds that require star trek levels of science. Even if it is not a missile, a slug flying through space will still have to be fired from something, and that something will likely put out heat either in radiators or in the initial flash of the shot, it would then have to take a while to get there.

Honestly a good comparison is modern day ICBM's very long range and very destructive but slow and intercept able, only really being a threat en mass. Likewise anyone without a mass driver would be at a disadvantage. Space only makes this worse by adding months of travel time to anything you catapult at anything else. It is like trying to say that the best counter to a trebuchet is another trebuchet.

The two main threats i can see to an asteroid mounted mass driver is the aforementioned sabotage, and a far bloodier all out attack on the defending fleet(if there is one) and the subsequent mass driver itself. Ideal modes of attack would be ship launched drone and missile swarms, or perhaps fast attack landing ships which could try to close in and breach the asteroids defences using loopholes in the fields of fire, then deploy ground exoskeletons to traverse the surface and take out the defences point blank(this would be ideal for a minimising of internal damage to the target body, if there is a colony inside for example).

Finally after 500 years mankind can return to the ancient and wondrous art of fortress building.

So i have done some thinking and broken down a model of space fortress that i think acts as a good prototype. 

So for this example i am assuming a nice average sized 100 km3 rock more or less on the main orbital plain at a decent inclination and a "normal" eccentricity, Nausikaa 192 is a very good example. Tactically it is a stony asteroid and as such makes for a good fuel production stop with oxygen carbon and hydrogen mines for the synthesis of many useful propellants. Another important factor is it's rotation, why you might ask? i will get to that shortly, but for now it is good to know that Nausikaa has a rotational period of around 13 hours.

Moving on to the defensive break down, i am going to categorise defences into three broad categories.

First is the A type: Unconcealed adaptable platforms.

The two biggest examples of this has obviously got to be A) Your primary cargo mass driver, and B) your anti Kessler syndrome lasers.  

So A) has already been discussed a bit, bit essentially if you convert your mass driver by uh, not doing very much really, you turn it into a giant gun. This is great! If constructed ideally, it would stretch the length of your entire asteroid. Heck make it long enough and you get a two ended gun, all you have to do is flip the magnets and the firing chain and tah dah. Now this is were the rotation comes in, see what rotation really means, assuming you built the mass driver in a nice equatorial orientation, is your turret travertion rate. If we take the 13 hour period from Nausikaa and then opt for the double ended design, that gives us an average of two windows of ideal firing along the planetary inclination 6.5 hours apart. The downsides are obvious as well, it's big so it is easy to shoot at, it's complicated so sabotage is an issue, it is more or less the main cannon of your base(unless you have multiple in which case lucky you.) Assuming you want ideal coverage, six mass drivers are needed, one at every point of a hypothetical cube drawn around your base.

B) Is also a freebee, large lasers are pretty much the cheapest and longest standing solution to micro space debris, able to burn up or move that deadly dust out of your valuable shipping lanes. So obviously converting them into anti missile stations is not that much of a stretch, once more like the mass driver if their positions are well known then they will likely already be a target for attacking forces.

Finally C) is so laughably basic it is hardly worth mentioning, basically if you have a door to the outside of the asteroid, and the missile fits through the door, then presto you have an albeit make shift but bu no means ineffective rocket tube. Heck you keep the air lock pressurised and open the door fast enough, and you got yourself a gas ejection system!

So D)-F) are the more sneaky options that are undoubtedly meant to make the pointy bits come out the slim end and don't double as some other useful design. 
D) Is essentially a covered turret, be it laser, cannon or rail/coil gun you dig until you are within a few centimetres of the surface install a lid or hatch mechanism, and when you need it out comes the turret ready to burn or shoot down the would be attackers.

E) is in it's own way even more basic than D), simply bury some VLS tubes full of missiles and hook up the Fire Control lines. If you want to get fancy you could connect ammunition passages similar to many Russian deck launchers. The main challenge with both of these designs is the ejection mechanism, too fancy and your enemy will spot it with their telescopes, too basic and you spurt out have a ton of rock and potentially damage your turret. 

F) is by far the most morally questionable, in basic it's mentioned in the war crimes section of the info-logs, you take a civilian transport, fill it with weapons then open the cargo bay doors and viola a make shift torpedo boat. 

G/H/I are sneaky not in the pure sense as they can be hidden, but in the sense that they use the same facilities as civ ships, the only difference being that they are well, not. Any hanger that can resupply a comm satellite can resupply a drone. Any ship hanger can be converted into a space navel dockyard. Likewise any basic construction vehicle can become a makeshift fighter any cargo ship a carrier etc.


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