[World Building] A Future History of Space Force

[Verjigorm]

Originally Posted by Polydamas

If the battle is in Earth orbit, then any space-based weapons will be overwhelmed by missiles launched from earth as soon as a belligerent rotates into the right position and its missiles reach orbit. At least one nation has destroyed an object in Earth orbit with an anti-satellite missile whereas everyone's anti-satellite satellites, drones, and ROVs are secret and untested.

Lots of discussions of the likely merits of various weapons in space with a lot more evidence, thought, and math than in this thread, just saying (eg. Children of a Dead Earth, Attack Vector: Tactical, Project Rho).

Earth based missile systems work, but have the problem of needing to provide enough deltaV to get into orbit, and then intercept the target. They need to be pointed in the correct distance and be targeted. If a vessel maneuvers on the opposite side of earth from your land-based sensors, it could change it's orbit enough to approach from an unpredictable orbit, and it's missiles don't have to use nearly as much energy to get to the target.

A space based missile platform can target a lot of orbital infrastructure. Where an earth based missile would need around 8 to 9 mps to reach a GEO or EML1 target, a LEO based system can do that with three or less MPS. An excess of deltaV will be extremely useful for any sort of mission, whether you are attempting to get close to the target to interfere with it's comms or intercept it.

This is going to heavily influence the cost of the missile. Let's just use spaceships design as a rough benchmarking system: a missile with 18 fuel tank systems, 1 engine and 1 command center can have up to 6.75 mps of delta-v. This is enough to reach LEO and have a substantial amount of maneuver left over, but it can't reach higher or more distant orbits. A missile in LEO could target launch to *mars*(whether it is gonna survive the 9 month trip and be effective is a different story), as well as being able to intercept pretty much any target in cislunar space. To be able to target higher orbits, an earth based system would need to use staging, which increases the mass(and cost) of the missile substantially.