“God, from the mount of Sinai, whose gray top
Shall tremble, he descending, will himself,
In thunder, lightning, and loud trumpets’ sound,
Ordain them laws.”
— John Milton, Paradise Lost, Datalinks
In SMAC, Orbital Defense Pods are military satellites. Which technically makes them base facilities, even though they’re logically more akin to expensive military units that exist entirely off-map. They rely on the eleventh-tier Self-Aware Machines technology to build and, like all the other satellites, can only be built at a base with an Aerospace Complex or by a faction that has built the Space Elevator.
They serve two purposes in the gameplay that are not replicated by any other mechanics in the player’s control. Their primary purpose is to serve as the equivalent of the old SDI in Civilization: nuke defense. Each pod has a 50% chance to shoot down an incoming Planet Buster, but it can only take one shot each turn. Since Planet Busters are very expensive, this greatly increases the cost necessary to launch a WMD attack, but it is still possible to “flood the zone” by launching many more missiles than the opponent has defensive satellites.
However, this is complicated by the fact that there’s another line of defense. If every pod has taken its shot and there are still Planet Busters incoming, it is possible to sacrifice an Orbital Defense Pod to intercept the missile before it hits its target. This is almost assuredly a good deal.
So this means that a faction that wants to start the SMAC-equivalent of nuclear Armageddon needs to launch somewhere between one and a half to two times the number of Planet Busters as the target has defensive satellites in order to soak up the defenses. Only then will subsequent missiles land. Since each Planet Buster costs at least twice as much as each Orbital Defense Pod, they serve as very effective defenses.
The second thing that Orbital Defense Pods can do is to sacrifice themselves for a 50% chance of taking out a rival’s satellite. Since Orbital Defense Pods cost the same as any other satellite, this isn’t usually a very good trade for the aggressor.
However, this math does serve to underline why the Space Elevator is so crucial to the dominance of space. Since the double production bonus applies to Orbital Defense Pods as well as any other kind of satellite, it means that the Space Elevator faction can trade minerals one-for-one on average against other factions’ economic facilities. The math works the same in the other direction, meaning that rivals need to spend four minerals to every one that they destroy.
Or it would be, anyway, if the game weren’t almost-inevitably decided by the point the player gets this technology. The first faction to the Space Elevator is almost assuredly going to be the first one to Orbital Defense Pods too. And then, building off the snowball, they can easily achieve a hammerlock on the flow of resources from space.
But the game was actually probably over long before even that. The orbital mini-game is fun to think about, but it almost never actually matters to the player’s overall experience. In practice, it’s just another fun subsystem to toy with before the player puts the game away through a victory type of his choosing.
Which is a shame. It’s clear after a moment of reflection that the Orbital Defense Pods have to be, themselves, Self-Aware Machines. That means that they’re intelligent and sentient. Presumably they want to live and know what it means to die. So there’s some real potential pathos there when the player gives the order to have the pod take a Planet Buster for his bases.
Also, the quote is just an awesome selection on Reynolds’s part. Orbital Defense Pods really do take on the aspect of Milton’s God in relation to the people of Planet. For one thing, they do live way up high. And when they’re displeased by the actions of the people below them, they swoop down with thunder and lightning to ordain their law. Thou shalt not place weapons of mass destruction atop rockets and hurl them toward His people.