Emissions, signatures and stealth

Published on June 18, 2026, 7:30 p.m.
Last changed on June 18, 2026, 7:45 p.m.

In various previous posts were mentioned the principles of entity and unit metabolism.

I go back to metabolisms here because each time they were mentioned, other types of waste were also alluded to - radiation, etc.

Now, I think I may have found an elegant segue into this unanswered question, via two distinct, yet heavily linked concepts:

Emission
Signature

At first, one might consider those two to be the same. And one might be right. But when they are considered in the light of detection mediums and mechanics, a very useful global rule seems to emerge - and very quickly: emission is a raw value emitted by a unit/entity, while signature is the "visibility" that results from the sum of said emissions.

Detection mediums can then be considered as "detection channels". I think this is great because:

It is extremely flavourful from a fluff perspective (see list below)
What's more, it also supports the engine's desire to feel realistic

Emission types

Without further ado, here is the current list of "channels" over which an entity will emit. All entities will have as many emission values as there are channels and each emission total will be the sum of the individual unit emissions.
And instead of coming up with yet another mechanic, why not use attributes? I mean, there's already quite a few so a few extra won't change that much…

The list as of today:

Channel	Attribute name	Attribute symbol	Unit	Comments
Optical	Optical emission	`EMOP`	m2/kg	Optical emission generated per unit mass through silhouette, reflection, glint, albedo, ultraviolet response and exposed surface contrast.
Thermal	Thermal emission	`EMTH`	W/kg	Thermal emission generated per unit mass through waste heat, infrared emission, stored warmth, hot surfaces and heat-flow contrast.
Gravitic	Gravitic emission	`EMGR`	kg/kg	Gravitic emission generated per unit mass through mass-shadow, inertia cues, density concentration and local gravity-gradient disturbance.
Radio	Radio emission	`EMRA`	W/kg	Radio emission generated per unit mass through radar return, microwave interaction, electrical leakage, resonance and RF emissions.
Neutrino	Neutrino emission	`EMNU`	Wν/kg	Neutrino emission generated per unit mass through weak-interaction output from fusion, fission, antimatter or exotic core activity
Magnetic	Magnetic emission	`EMMG`	A·m2/kg	Magnetic emission generated per unit mass through field distortion, current loops, induction traces, coils and magnetised materials.
High energy	High-energy emission	`EMHE`	W/kg	High-energy emission generated per unit mass through X-ray, gamma, hard radiation, energetic particles and shielding scatter.
Chronal	Chronal emission	`EMCH`	τc/kg	Chronal emission generated per unit mass through timing residue, causal strain, chronon traces and temporal coherence disturbance.
Tachyonic	Tachyonic emission	`EMTA`	τt/kg	Tachyonic emission generated per unit mass through superluminal traces, pre-echoes, reversed signals and causality-stressed activity.
Noetic	Noetic emission	`EMNO`	ψ/kg	Noetic emission generated per unit mass through mind-bearing structure, identity pressure, psionic resonance and noo-field activity.
H/space	H/space emission	`EMHS`	Hσ/kg	H-space emission generated per unit mass through hyperspatial boundary stress, transit residue, aperture scars and jump-wake pressure.
V/space	V-space emission	`EMVS`	Vσ/kg	V-space emission generated per unit mass through absence stress, locality thinning, void coupling and normal/void boundary disturbance.

So that's 12 channels in total; some are very very realistic while others, well, others are arguably linked to higher scientific/technical tiers and are outright science-fiction-esque.

Each of these attributes is intensive so depends fully on unit masses. However, they are not translated into extensive attributes; rather, they are used to enrich the metabolism expression (see below for more details).

Integration into unit metabolism

So a typical metabolism expression will thus look like this:

CONSUME#RESOURCE_POWER#e.attr('PWDT')@WASTE#WASTE_HEAT#e.attr('PWDT') * (1.0 - e.attr('ENEF'))@EMISSION_OPTICAL(e.attr('MASS') * e.attr('EMOP'))@EMISSION_THERMAL(e.attr('MASS') * e.attr('EMTH'))@EMISSION_RADIO(e.attr('MASS') * e.attr('EMRA'))@EMISSION_HIGH_ENERGY(e.attr('MASS') * e.attr('EMHE'))@EMISSION_GRAVITIC(e.attr('MASS') * e.attr('EMGR'))

For this imaginary unit, we learn that it emits over the following channels:

Optical
Thermal
Radio
High energy
Gravitic

It would seem to be obvious, but it is useful to mention: nearly all (if not all) units will emit over the optical and gravitic channels at the very least. Why? Well because they have mass and they are not singularities, so have volume. CQFD, as we say in French.

Less obvious cases:

Reaction propulsion units will usually have optical emissions values far greater than simply explained by mass - due to ejecta. A fusion torch at full throttle is hard to hide, even at a distance!
Gravitic-related units (energy, propulsion) will emit far more intensely over the gravitic channel than their sole mass would suggest

Caveat: many of these of course depend on regime and so such a fusion torch unit will probably emit far less when used at 10% of its capacity. Likewise, a detection unit of the "active type" is likely to increase its emissions over the channel it detects over. There are many such cases - the summary of which being emissions can actually be quite dynamic!

Entity level integration

Using this formula, applied at entity level for each channel:

\sum_{i = 1}^{n} {Emission}_{i}

we get the signature of the entity over that channel. Simple sum.

Given how light this is (including individual emission calculations), the engine is very likely to be able to update an entity's signatures at runtime, ~~almost~~ in real time, taking into account factors such as:

Individual unit regime
Various modifiers such as environment, etc.
Crew skill rolls?
Stealth (see the very next section)

This feels promising!

Stealth

There ain't no stealth in space, mate.
A wise man

In the real world yes. But at the risk of repeating myself (too late I know), Adlumens tries to be pseudo-realistic. So while stealth probably deserves a full series of posts by itself, let's just check today's public state of the art (after a quick lookup on the Internet). Disclaimer: Bruno, no I did not ask you-know-who 8-}:

Radio/RF: broadband RAM, metamaterials, advanced shaping (flying-wing/tailless). All-aspect low RCS on B-21, J-36, NGAD. Tunable absorbers counter low-frequency/UHF radars.
Thermal/IR: cooled/masked exhausts, thermal coatings, active cooling. Reduced engine signatures key in 6th-gen fighters/bombers.
Optical/Visual: adaptive camouflage, metamaterial skins, low-visibility coatings. Still limited; mainly for drones/UAVs.
Acoustic: quiet propulsion, anechoic coatings (subs dominant), fluidic controls (emerging aircraft). Less mature for high-speed platforms.
Multi-Spectral Integration: AI-managed adaptive materials + EW for simultaneous suppression across channels. Pure stealth evolving into holistic signature management.

Blimey. So we're already quite good at it and if we extrapolate… well why not come up with a list of attributes that reduce not emissions, but individual signatures. The rule being:

All units contribute to emissions
Sums of emissions result in entity signatures over channels
Stealth units affect signatures by reducing them

Of course not all stealth units can reduce all signatures; some specialisation/flavour is in order. At the moment, I have split stealth units into two groups:

Group	Brief description
Individual	Stealth systems reduce, distort or delay the signatures by which a single entity is detected, identified and targeted. They may use coatings, geometry, damping, heat control, energetic containment, deception fields or exotic boundary effects. They do not guarantee invisibility; instead they lower confidence, shorten reliable detection windows, corrupt sensor fusion and make hostile tracking decisions slower, weaker or wrong.
Area/Volume	Area/volumetric stealth systems reduce, distort or delay the signatures by which a region becomes less reliably analysed or scanned. They may use energetic containment, deception fields or exotic boundary effects. They do not guarantee invisibility; instead they lower confidence, shorten reliable detection windows, corrupt sensor fusion and make hostile tracking decisions slower, weaker or wrong.

Group

Brief description

Individual

Stealth systems reduce, distort or delay the signatures by which a single entity is detected, identified and targeted. They may use coatings, geometry, damping, heat control, energetic containment, deception fields or exotic boundary effects. They do not guarantee invisibility; instead they lower confidence, shorten reliable detection windows, corrupt sensor fusion and make hostile tracking decisions slower, weaker or wrong.

Area/Volume

Area/volumetric stealth systems reduce, distort or delay the signatures by which a region becomes less reliably analysed or scanned. They may use energetic containment, deception fields or exotic boundary effects. They do not guarantee invisibility; instead they lower confidence, shorten reliable detection windows, corrupt sensor fusion and make hostile tracking decisions slower, weaker or wrong.

Stealth-related attributes

I will not list them all here, as the same patterns is respected across all detection channels/mediums. The patterns is:

Attribute	Group	Unit	Brief description
Signature reduction	Individual	Normalised	Reduction of signature value
Signature authority	Individual, intensive	kg/kg	Mass coverage provided per unit mass
Total signature authority	Individual, extensive	kg	Total mass coverage provided
Signature area reduction	Area/volume	Normalised	Reduction of signature value within affected volume
Signature area authority	Area/volume, intensive	m³/kg	Volume covered per unit mass
Total signature authority	Area/volume, extensive	m³	Total volume covered

I have tried to make variants within each group feel nice, with variants both specialised and "jack-of-all-trades-ish" and strongly specialised.

But but what about detection

Yes. I will cover that in a post soon. As you'd probably expect, more attributes! :-)

Thank you for reading. Now I can go back to planetary surfaces! :-)