Thorn Deep Space Decoy Drone

[Nelson Cunnington]

Haven't done one of these for a while, so forgive me if I've missed anything important. I dare say all the bright young things are using the GURPS Spacecraft rules by now, anyway.

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Thorn (หนาม) Decoy Drone

Prior to the Pacific War, the TSA's Aerospace Force Command identified a need to improve the electronic warfare capabilities of its major military vehicles, in order to increase survival rates of its outnumbered forces in the projected conflict with China. To this end, the Thorn decoy drone was rapidly developed.

Up to this point, deception was widely held to be of little use in space warfare, owing to the high visibility of maneuvering spacecraft (amateur spacecraft spotters can and do track large spacecraft halfway across the Solar System using quite modest instruments). It was common wisdom that since a spacecraft could be detected and even imaged at distances far greater than the effective range of space weapons, deception wasn't even possible. TSA analysts hoped that advantage could be obtained during combat when the most sensitive sensors tended to be shielded and the more robust combat sensors might be confused by the fog of war. Any advantage was likely to be temporary, but even a couple of minutes of confusion might work to a smaller force's advantage.

The Thorn was designed to mimic the EM spectrum and navigational characteristics of the TSA's SDVs and LSDVs to maximise target confusion during an engagement. Numerous small antennae on the boxy hull radiate radio traffic similar to encrypted communications and control signals, larger antennae simulate tracking and acquisition radar, and reflective surfaces simulate the long-range appearance of passive sensors. In addition, angular dimples at the nose and tail form radar reflectors that radically increase the vehicle's radar signature.

A relatively low thrust chemical rocket enables the Thorn to maneouvre in the manner of a much larger vehicle. This by itself would not be enough to convincingly mimic an SDV, since the visual characteristics of a small rocket and a large pulse fusion drive are radically different, and could be readily discriminated by even the most damaged VIR sensor used by the most confused ship's AI. To aid the deception the drone is fitted with a pair of multispectral lasers whose frequencies match those of the opposing force's optical sensor filters. The lasers' simulated spectra are actively tuned to match the visual and infra-red spectrum of a pulse fusion drive, and are focussed on the opposing force's sensors at an intensity to match a drive at the same distance.

In the event, only a limited deployment of Thorns was achieved before war broke out. Chinese PLAN-SF histories have downplayed the effect of the few drones encountered during the deep space aspect of the conflict, though analysts have speculated that the Thorns should have have had a disproportionate effect on the PLAN-SF's human-based command and control. More speculative experts have it that PLAN-SF have developed more capable models of the TSA original.

Crew: Unmanned. Infomorph in unmanned controls has Astrogation, Electronics Operation (Communications, Sensors, ECM), Piloting (High-Performance Spacecraft).

Design: Unstreamlined box hull (2.65 spaces, nanocomposite, heavy frame); cDR/cPF 10/1F, 10/1S, 10/1B (nanocomposite armour).

Modules: New unmanned controls; small PESA; small radar; 0.02 compact metal-oxygen rocket; 0.33 tank (ultralight metal/oxygen); 0.75 New RTG; 1 ECM-2 module.

Statistics: EMass 48; CMass 51.5; LMass 54.9; Cost M$31. cHP 13. Size Modifier +2/+4. HT 12. Maintenance Interval: 3.6 hrs. RRA 0.015

Performance: sAccel 0.11 G. Burn Endurance: 4 x 100 seconds. Burn Points 37. DeltaV: 0.11


Design Notes: This design uses the ECM-2 module (10 tons, 1 space, M$20, 5 MW), which has the effect of "makes a small spacecraft look like a big spacecraft". This module is deliberately designed (in game terms) to be somewhat limited; as long as the decoy doesn't accelerate it can deceive all opposing forces, but if it accelerates, it can only focus its drive-mimicking lasers on two craft at once. The GM should determine whether this will continue to deceive individual spacecraft or the opposing force as a whole if there are more spacecraft than the module can handle. (My suggestion is that a flock of jinking AKVs may be more readily confused than an SDV.)

For more advanced models, add M$10 for each doubling of opposing forces that can be deceived this way, with no increase in mass or power, up to a limit of sixteen. But note, two decoys may match courses to increase their effective limit.

Using in a THS Space Combat game:

First determine if decoys will be effective for either side; pre-encounter espionage can both reduce and enhance the probability of deceptive techniques working. If decoys are effective, then the GM or referee should work to hide the results of opposing force die-rolls, reporting only movement, acceleration, and deployment of AKVs, or anything else that may reasonably positively identify an SDV or decoy as such. Note that firing energy weapons will not positively identify an SDV; outside of Bollywood sensies, beam weapons in a vacuum do not leave tracks pointing back to their origins.

Effective decoys may be unmasked by a spacecraft not under fire scanning the decoy for one round at effective range; five rounds at long range; or ten rounds at extreme range. An encounter at short range automatically unmasks the decoy. To add uncertainty the GM may call for an opposed roll of scanning Sensor skill vs decoy ECM skill to determine if the scan is accurate. (An SDV may attempt to appear to be a decoy.)