Stealth

This article contains information relevant to both the C# and VB6 versions of Aurora. Where differences exist, they are noted in the appropriate sections.

The concept of stealth is to operate or hide without giving enemy forces any indications as to the presence of your forces. In Aurora, ships can employ stealth construction techniques (such as Cloaking Devices and engines with thermal emission reduction), as well as stealthy tactics (moving slowly, staying away from enemy sensors) in an effort to achieve stealth.

Avoiding Detection

There are three ways to detect a ship - EM Sensors, Thermal Sensors, and Active Sensors. Enemies will have a mix of all three, so all three need to be considered. A good stealth ship design has a balance of all three, combined with the modules needed to do its actual mission (e.g., electronic intelligence-gathering or survey).

EM Emissions

Your ship's electromagnetic emissions will be picked up by enemy EM sensors. A ship emits an EM signature if it uses active sensors, or has active shields. Each ship's emissions will be added up, and that will be the ship's total EM strength. If you have multiple ships in a fleet, each one will have its own EM signature, and each one will need to be detected separately.

Active sensor signature = Grav Pulse Strength = Sensor strength * Sensor size * Sensor resolution
Shield signature = 3 * Current shield strength

Note that active sensors only emit when they are turned on, but they also only work when they are turned on. This means that your ship is likely to be almost blind against targets with low emissions of their own, such as enemy missiles. If you want to defend a stealth ship against enemy missiles, CIWS is usually best - it gives you some defensive capability, and their built-in sensors do not create any emissions. Armor also works, like always.

Thermal Emissions

Your ship's thermal emissions will be picked up by enemy thermal sensors. A ship emits a thermal signature if it is using its engines, but it will always have a thermal signature even if it's not moving. Moving more slowly will reduce the thermal signature, which can be very useful. In C# the signature of immobile ships is very small, but in VB6, ships that are not moving have their maximum possible thermal signature. As such, VB6 players should never allow a stealth ship to come to a halt near enemies.

Moving ship signature = Total engine power * Engine thermal reduction modifier * (current speed/max speed)
Immobile ship signature (C#) = 5% * ship size in HS
Immobile ship signature (VB6) = Total engine power * Engine thermal reduction modifier

Active Sensors

If an enemy is using active sensors, they can find you even if you have negligible emissions. The main ways to avoid this issue are either simply staying away from them (by using your own EM sensors to see their emissions), with a Cloaking Device, or with Sensor Jammer (C#) / ECM (VB6) modules.

Normally, your ship will be detected based on your ship's size in HS (for exact formulas, see the active sensors article). A cloaking device will reduce your ship's effective size by the listed percentage, so a 120 HS (6,000 ton) ship with a -75% cloak will appear on enemy active sensors as if it was only 30 HS (1,500 tons) instead.

A sensor jammer/ECM will reduce the range of enemy sensors. Unlike cloaking, this does not change your ship's apparent size on enemy sensors, it just changes the range of those sensors. This makes it less effective against large-resolution sensors, but more effective against small-resolution sensors.