The Return of the Siege

This is the first part in a series about warfare in space. In this first post we will not get into the discussion about possible motives Space Settlements could have to wage war with each other. Rather we will discuss possible tactics Space Settlers could use in space wars.

Assuming that a conflict between Space governments escalates into an armed conflict, we have to consider what potential targets for attack are. It does not take much imagination to conclude that at least the following are potential targets: Solar Power Satellites, industrial stations, transport vessels and space habitats. The first three are relative easy to attack, and the destruction of those will have serious impact on the population of a space habitat which is dependent upon their services.

But what about space habitats as a potential target? Compared to the other targets, space habitats are quite large and will be designed in such fashion that their construction will not fall apart by the first blow. Further space habitats are closed structures, which can only be entered through secure airlocks. In this respect space habitats are quite similar to premodern cities with their fortified city walls. But with the important difference that unlike city walls, Space Habitats have no opening.

In premodern warfare sieges were a common tactic. A siege is nothing more than surrounding an enemy city or fortification by an army, and to isolate the population. The idea is that since most cities couldn’t be taken easily, it would better to cut of the citizens from outside supplies, until they had to give up and to surrender.

Besides surrender there are two other ways in which a siege can end. First, they besieged city is too well prepared, that it will take years before they have to give up due to attrition. Besieging a city draws many resources from the army, and if a siege takes too long, the besieging army has to give up.

Secondly, the besieging army can be defeated by an external force. If the city has allies, or is part of a larger nation, those will attempt to attack the besieging forces. Whether this will successful, depends on whether the besieging party has enough forces to defeat those reinforcements.

As a tactic in space warfare, sieges have certain advantages. There is no need to enter a space settlement, if one is able to cut off all supply lines of that settlement. And since the inhabitants of the settlement cannot leave, they are kept out of commission (as potential soldiers). From an ethical perspective, besieging a space settlement is less problematic than a massive attack which might kill several thousands, and even millions (in larger space habitats such as O’Neill cylinders) of people.

Even if one does not have an inherent commitment to basic ethical standards, it’s rational to avoid mass killings of civilians. First of all, the opposing party might lose its interests in peace negotiations, and instead the opponent might seek revenge. Secondly, parties which were initially neutral might be moved to such war crimes, to either impose sanctions or even to join the war at the opposing side. Thirdly, after defeat the political and military leaders might face prosecution for war crimes.

Though besieging space settlements can be attractive, if neither conquest nor destruction are the objectives; siege warfare has certain disadvantages. First, a substantial fleet is needed to effectively surround a space settlement. And by sending out a substantial force, one’s own settlements are left vulnerable. On a related note as long as the siege continues, those forces cannot be deployed for other operations.

How could space settlements defend themselves against a siege? First, space settlers should be prepared. By building up adequate reserves, they can endure long sieges albeit it on a lesser standard of living. If a space settlement is able to recycle its resources efficiently, then the main concern will be a guaranteed energy supply. The attackers might conquer or disable the settlements solar power satellites, and hence reduce the amount of energy available to the settlement.

Secondly, a space settlement could establish certain defensive capacity, either by installing weapons, such as high energy laser or particle-beam weapons, on the outside of the settlement, or by having a fleet of defense ships in the neighbourhood of the settlement.

Alternatively, if a space settlement is aware that some party is intending to siege them, it could send a military force to attack its opponents before they can strike. This defense strategy, however, requires adequate reconnaissance and well-trained forces.

A possibility would be a tactic, which we will call a reversed Trojan horse. The inhabitants of a space settlement could pretend to surrender, and invite their adversaries to enter the habitat. However, when the enemy is inside, the space settlers overpower them. If the besieging party is relatively small, the settlers could choose to allow all hostile soldier within their settlement. Otherwise they could allow only one unit to enter, which is subsequently taken hostage with the aim of forcing the besiegers to back off. This could be effective, especially if a high-ranking officer is among the hostages.

Whether the siege is a suitable strategy or tactic in space warfare, depends on what is at stake. In case of minor interests, this type of warfare is probably to costly. However, if the stakes are high, sieges are much more attractive.

Next installment in this series about warfare in space, is about piracy.

20 thoughts on “The Return of the Siege”

    1. I share your hope, but humans have waged for war for the most stupid reasons in the past. So we need to be prepared if we are attacked.

    1. That site is not bad, and it certainly contains great entries. However, it’s in our opinion too much oriented towards science fiction, and less to real space colonization.

      1. All the details are nicely cataloged and stored in binders with pictures (photoshopped of course) and then all conveniently swept under the rug.

          1. I suppose that would be the ideal war.
            I am thinking of The Hunger Games now. No real relation to your post. It just came to my mind.

  1. Siege warfare and blockades – although effective – have always been expensive and risky military options. They require great material resources and logistical planning. Only the most powerful of forces are so capable, and that’s why the “castle defense” of medieval times was successful for such a prolonged period.

    In space, it would be much cheaper and easier to redirect small asteroids as offensive weapons. The only downside to this option is its extended delivery time, but sieges and blockades have a similar limitation. Just the threat of using kinetic energy impactors would severely stress potential space settlement targets because an adequate system of defense would be quite costly.

    1. >>In space, it would be much cheaper and easier to redirect small asteroids as offensive weapons.

      Only, it is not quite easy to redirect an asteroid. The basic problem is how does one apply the required force to redirect such asteroid. It would take specialized trained personal to conduct such operation.

      >>Just the threat of using kinetic energy impactors would severely stress potential space settlement targets

      In order to maximize the kinetic impact, it would be better to keep the mass of the projectile low, and instead maximize its speed (after all T = mv²/2).

      >>because an adequate system of defense would be quite costly.

      I wouldn’t say that. Firstly, a space settlement is a heavy structure, and if properly designed the structure won’t break at the first blow. Hence a highly energetic object is required.

      Though such an attack might not destroy the settlement, this does not rule out massive damage will be done to the settlement. The repair costs could be of such extent, that the inhabitants could be forced to surrender.

      Secondly, if the inhabitants are able to detect the threat in time, they could destroy it by a particle-beam weapon. (This will be discussed in another post).

      1. Actually, redirecting asteroids (i.e. changing their orbital trajectory by using space tugs, gravity tractors, solar sails, or mass drivers) shouldn’t be that difficult or expensive compared to the siege/blockade alternative. From:

        “Former Apollo astronaut Rusty Schweickart has talked with Universe Today numerous times, and emphasizes that the technology needed to divert an asteroid exists today. ‘That is, we do not have to go into a big technology development program in order to deflect most asteroids that would pose a threat of impact,’ he said.”

        And considering the average velocity of asteroids, at roughly 25 kilometers/second, the mass required to damage man-made space structures would be very small (unless such structures were expensively armored). From:

        “Micrometeoroids pose a significant threat to space exploration.[5] Their velocities relative to a spacecraft in orbit average 10 kilometers per second (22,500 mph),[5] and resistance to micrometeoroid impact is a significant design challenge for spacecraft and space suit designers (See Thermal Micrometeoroid Garment).”

        This comment you wrote is exactly my point: “Though such an attack might not destroy the settlement, this does not rule out massive damage will be done to the settlement. The repair costs could be of such extent, that the inhabitants could be forced to surrender.”

        Particle beam and laser weapons would be a very, very expensive system of defense against kinetic impactors. The power costs alone would be huge.

        1. It’s certainly possible to divert an asteroid, and the velocity of an kinetic impactor is more important than its mass. However, successfully diverting an asteroid towards a specific target does require an expensive logistic operation.

          If you do it wrong, your impactor will miss its target. First you need to calculate the correct force to be applied to the asteroid, and secondly (the difficult part) you have to install the diversion devices in the right way.

          Diverting an asteroid towards a specified target is something different, than deflecting it from, say, Earth. In the latter case the specific direction is quite irrelevant as long as its away from Earth.

          The construction of a particle beam weapon is expensive, but once built its operational costs are quite low. And you are going to build them anyway (I will elaborate that claim in a future post).

          1. True, although look at the effect of terror weapons in human history. They don’t have to be precise. Just the threat they pose can have tremendous consequences. Space colonists would get pretty unnerved if someone was hurling big rocks in their direction. What’s that old saying? “It’s far easier to destroy than to build.”

            1. >>“It’s far easier to destroy than to build.”

              Absolutely true. After all the universe tends towards increasing entropy.

              >>Space colonists would get pretty unnerved if someone was hurling big rocks in their direction.

              An attack won’t come out of the blue, but is rather the next step in an ongoing dispute. So they might expect some kind of attack.

              If the attack ends in a near miss, the terror effect would be quite large. But if the asteroid misses the settlement with, say, a 100 km or more, the colonists might have a cynist attitude of “You can hit right”.

    2. And there’s even third mode of protection. A space habitat is movable. And so if an asteroid on collision course is detected in time, the settlement can be moved away from the line of attack. Cheap and effective.

      1. I’ll see your movable space habitat, and raise you with this:

        Redirect an asteroid, perhaps a mile in diameter, towards the orbit of a space habitat. Explode a nuclear weapon buried inside it at the optimum distance to create a “shotgun” blast of debris towards the target.

        Sorry for the poker reference, but I love strategy and tactics!

        1. No apologies needed, I love tactics and strategies too.

          A mile in diameter is probably to big, since the greater an asteroid is, the easier to detect it is (and the sooner it will be detected). And if you have a sufficient forceful nuclear explosive (say about a gigaton) an asteroid of just a few hundred meter would suffice.

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