Thursday, 16 March 2017

Ad Astra: Breaching Pods

Does this count as stealth?
If you're a fan of science fiction and haven't already been watching The Expanse, do yourself a favour and take a look at the trailer to see what you've been missing. The series is great television, with a gripping storyline and good acting, while also being pretty damn scientifically accurate.

The second season's introductory two-parter involved an assault on an unregistered rotating space station, with an ex-Martian gunship and a cobbled-together Belter transport matched up against a single advanced stealth frigate. One character, Detective Miller, decided to join the assault teams, meaning he has to be on one of the breaching pods that will be launched towards the station. Before we see them on-screen, one character describes them as "a beer can taped to a rocket".

As you can see from the gif, he's not wrong.

Breaching pods are something that's been around in science fiction for a while – the earliest I know of were in Babylon 5. It's an important role, since most naval combat ends when the enemy force retreats, is destroyed, or is commandeered. There are also plenty of situations in which a fighting force might want to land troops on an enemy vessel before it's surrendered or been disabled. On Earth's seas, this involves something like small boats, scuba divers or submarines. But in space, you need much more specialised hardware.

Military Breaching Pod (TL9)
This is the kind of hardware employed by spaceborne military forces with funds only a government could provide. An unstreamlined SM+5 metallic laminate hull contains ten soldiers and their gear. A metallic hydrogen rocket with 1mps of deltaV ensures they can close the distance between them and the enemy craft quickly while leaving some propellant for manoeuvring, while defensive ECM makes it harder to target the vulnerable pod in flight. Once the pod reaches the enemy spacecraft, it latches on with an external clamp, then a reusable explosive charge (modelled by the forward missile launcher system) detonates to breach the hull. The front of the hull is more heavily armoured and reinforced against both the explosive charge, and impacts, since some situations may require a ballistic approach to the target.

[1] external clamp [$5k]
[2] major battery: one fixed-mount 20cm missile launcher (6d×5 (2) dDam) [$150k]
[3-6] advanced metallic laminate armour, ram (dDR 20, ×2 vs crushing) [$480k]

[1-2] advanced metallic laminate armour (dDR 10) [$120k]
[3-6, core] passenger seating (10 seats) [$50k]

[1-2] advanced metallic laminate armour (dDR 10) [$120k]
[3] defencive ECM (-2 to target) [$300k]
[4-5] fuel tank (1mps, 3 tons) [$20k]
[6] metallic hydrogen rocket (2G, 0.5mps/tank) [$90k]
[core] control room (Complexity 6, Comm/sensor 4, no stations) [$10k]

Improvised Breaching Pod (TL9)
This is a pale imitation of the pod above, cobbled together from scrap, spare parts and whatever can be found in the local breaker's yard. It might be found in the hands of terrorist groups, resistance armies, rebels, or pirates. The pod is an unstreamlined steel alloy tin can (or a whole cargo shipping container) fitted with seats for fourteen people and their gear. A simple monopropellant chemical rocket takes the pod to a maximum speed of about 250m/s (0.15mps), enough to close distance but not for speed or evasion, making it vulnerable to weapons fire while travelling. A breaching charge improvised from mining equipment blows the front of the pod open at the same time as the target's hull – these are single-use.

[1] external clamp [$5k]
[2] medium battery: one fixed-mount 16cm missile launcher (6d×4 (2) dDam) [$50k], plus 1 ton cargo
[3-4] steel armour (dDR 4) [$30k]
[5-6] passenger seating (4 seats) [$20k]

[1-2] steel armour (dDR 4) [$30k]
[3-6, core] passenger seating (10 seats) [$50k]

[1-2] steel armour (dDR 4) [$30k]
[3-5] fuel tank (0.45mps, 4.5 tons) [$30k]
[6] chemical rocket (3G, 0.15mps/tank) [$60k]
[core] control room (Complexity 6, Comm/sensor 4, no stations) [$10k]

Breaching Pod Table
TL Spacecraft dST/HP Hnd/SR HT Move LWt. Load SM Occ dDR Range Cost
9 Breaching Pod, Imp. 20 0/4 12 3G/0.15mps 30 2.4 +5 14SV 4 $315K
9 Breaching Pod, Mil. 20 0.4 12 2G/1mps 30 1 +5 10SV 20/10/10 $1.35M


  1. Nice to see the Expanse get more GURPS love. It's filling the whole that Battlestar Galactica left heh.

    Also my plasma torpedo from my Warheads R Us post was also a lose reference to the show heh.

  2. I do love me some breaching pods; did a very short one-off where the players were resisting inbound, so the stats never came up but should I ever look back again, there they are.