I am thinking of making a story set in the First Extraplanetary War era of the "To The Planets Beyond Extended Edition" set during a military confrontation between an UNAPA Task Force sent to the Galilean Moons to conduct a ground invasion of those moons and a smaller Ganymedean Task Force. However, in the story, the UNAPA Task Force is intercepted near the moon/captured asteroid of Carpo.
UNAPA (Main) Ships
- Antimatter-catalysed nuclear pulse propulsion (first generation) engines (primary engines); Gas Core nuclear thermal engines (fourth generation; Open Cycle version) (secondary engines)
- 132 km/s exhaust velocity (Primary Engines); 45 km/s (Secondary Engines)
- 180 kN of thrust (primary engines); 4,500 kN (secondary engines) x3
- 70 – 120 km/s of delta v
- 707 - 1200 tonnes of wet mass
- 331 - 706 tonnes of dry mass
- 0.02 Earth gees - 0.03 Earth gees of acceleration (primary engines); 1.2 - 2 Earth gees of acceleration (secondary engines)
Ganymedean (Main) Ships
- Helium 3-Deuterium ICF (second generation) engines (primary engines); Gas Core nuclear thermal engines (fourth generation; Open Cycle version) (secondary engines)
- 110 km/s exhaust velocity; (Primary Engines); 45 km/s (Secondary Engines)
- 195 kN of thrust (primary engines); 4,500 kN (secondary engines) x3
- 50 – 100 km/s of delta v
- 817 - 1400 tonnes of wet mass
- 482 - 740 tonnes of dry mass
- 0.014 - 0.024 Earth gees of acceleration (primary engines); 1 - 1.7 Earth gees of acceleration (secondary engines)
Drones (Both Sides)
- Gas Core Nuclear Thermal (Third Generation; Closed Cycle; Mini-version) engines (Main Stage); UDMH/N204 Chemical engines (Terminal Attack Stages)
- 23 km/s exhaust velocity (Main Stage); 3.3 km/s (Terminal Attack Stages)
- 460 kN of thrust x5 (Main Stage); 1,830 kN of thrust (Terminal Attack Stages; 1 per stage) x8
- 30 - 37 km/s of delta v
- 60 - 80 tonnes of wet mass
- 12 - 22 tonnes of dry mass
- 3 - 4 Earth gees of acceleration (Main Stage); 2.3 - 3.11 Earth Gees of Acceleration (per Terminal Attack Stage); 19 - 25 Earth Gees of Acceleration (combined Terminal Attack Stages)
The spacecraft all have kinetic weaponry to attack each other, with 2 ships in each task force also equipped with drones. The kinetic weapons are all with depleted uranium rounds of ammunition, each slug being 41 kilograms, each coilgun being between 150 to 332 km of maximum range, with an exit velocity of 20 km/s. Effective range for these weapons is 45 to 115 km. And this is just the range that these craft can use to get a targeting solution or lock on hostile craft, since in a general sense, the range is technically infinite.
Each of the coilguns has 41 kilogram slugs fired at a rate of 3 rounds per second, with the burst duration being 5 seconds and an accuracy (on average) between 0.01 metres position error per kilometre of distance to 0.9 metres position error per kilometre of distance for both sides, depending on how advanced their targeting systems are. The slugs are assisted by a 30 kilogram (wet mass) liquid-fueled LH2/LOX guidance stage to assist in staying on the target. ECM effectiveness is basically around a 50% - 72% effectiveness in the sense that they can disrupt communication systems and disrupt the targeting solution of a hostile craft. So, in the former this means that if you want to contact the departure point, or another craft, communications are going to be affected. In the latter, you can miss and in a few millennia, the depleted uranium round will hit the surface of another object in who-knows-how-many years.
A clarification: this does not imply spacecraft in this setting use kinetics entirely. Some law enforcement spacecraft use directed energy weapons (or DEWs for short) spacecraft to target specific parts of a hostile spacecraft, but are impractical for large scale military use in an offensive sense. Military-grade DEWs are basically anti-drone defences, and since the two Task Forces have Drone Carriers in this situation, those are included and there are spacecraft designed specifically for this purpose. Anti-drone DEWs have a wavelength of 3600 nanometres, and require a series of large mirrors, which are vulnerable in combat, thus forcing spacecraft to conceal them away from combat and remove a fraction of the concealment in combat, depending on how much power is needed to dispose of incoming missiles or drone swarms (in this case, the latter is the target). On average, though, the power requirements are too large to be made into practical offensive DEWs in this setting (for now, that is).
In addition, the sensors of the spacecraft used in the manoeuvre (and throughout both wars in general) will be addressed in Part II. :/
UNAPA Task Force Composition
- 12 Space Dominance Vehicles (SDVs); 2 being Drone Carriers (100 - 120 drones each) and 8 Space Offence Vehicles (SOVs), 4 Space Defence Vehicles (SDeVs)
- 3 Space Control Vehicles (SCVs) with 3 battalions each SDV with a complement of Transatmospheric Vehicles (TAVs) and/or Transatmospheric Pods (TAPs), the former for regular armed forces and latter for rapid deployment Espatiers and SpecOps units.
Ganymedean Attacking Task Force Composition
- 6 Space Dominance Vehicles (SDVs); 2 being Drone Carriers (100 - 120 drones each) and 2 Space Offence Vehicles (SOVs), 2 Space Defence Vehicles (SDeVs)
Defences on UNAPA Task Force Target
- 1 Orbital Defence Platform (ODPs; anti-spacecraft/missile satellite network server(s))
- 8 - 12 SDVs ( 4 - 6 SOVs, 2 - 4 SDeVs, 2 Drone Carriers)
- 32 - 45 Orbital Guard Vehicles (OGVs)*
UNAPA Objective: Launch a ground assault on the moons of Europa, Ganymede, Callisto and Io.
Ganymedite Objective: Prevent the UNAPA ground assault by either destroying them or forcing them to turn back (by this, I refer to return to the point of origin via gravitational slingshot).
Soft Detection Time: 1.2 Days Post-Departure
Hard Detection Time: 3.1 (Brachistochone Transfer)- 87 Days (Hohmann Transfer) Post-Departure
Identification Time: 5.8 (Brachistochone Transfer) 97 Days (Hohmann Transfer) Post-Departure
Target Lock Time: 6.9 - 7.9 (Brachistochone Transfer) ~100 Days(Hohmann Transfer; Depends on positions of both objects at the time of departure) Post-Departure (Arrival)
In addition: the x[insert number of engines here] is an engine cluster, and only applies to secondary engines of main craft and drone engines.
Asterisk #1 = Law Enforcement Only; To be used to minimise civilian casualties, if any.
With this in mind, can such an intercept manoeuvre be pulled off in a realistic fashion?
NOTE: The following provides a Reddit link to the scenario itself: UNAPA vs Outer Solar System Perspectives Part I.