A ship can run its senors in either active or passive mode. A ship is much more likely to detect ships with active sensors, but is also much more likely to be detected.
A sensor check is made by rolling Sensors + Education and subtracting difficulty modifiers. The effect of the roll determines how much information is gathered. In some cases the GM may require a sensor roll to be rolled without giving the difficulty, particularly if their are multiple objects of varying difficulties to detect.
- Short < 10,000 KM +2
- Medium 10,000-50,000 KM +0
- Long 50,000KM to 1 AU -1
- Very Long > 1 AU -3
Active or Passive
Passive Sensors -1 (-2 at Very Long range)
Active Sensors + 0 (+1 at Medium and short ranges)
Target has Active Sensors +2
Target has active P-Plant +1
Target Jumping out of system +2
Capital Ships +1* (Larger ships and stations may have even greater mods)
Stealth Ships -4
Running Silent -1 (Non stealth ship attempting to be stealthy)
Information given from sensors
A standard sensor suite will have Radar/Lidar, EM, thermal and visual scanners. Even with good sensor rolls the amount of information given beyond long range can be quite limited. Common things to expect from sensor rolls are, size, speed, direction, power plant size, heat etc. Sensor readings can be further analyzed to attempt to determine composition etc.
Several advanced sensor types exist including Densitometers which can determine internal structure and makeup of an object and NAS which detects neural activity and intelligence.
Certain ships may be equipped with enhanced sensors which may give bonuses to detecting cloaked ships, scanning planets etc.
A certain amount of information can be gained without sending probes to take samples of a planet. The planets size and temperature are obvious, as well as weather and limited atmosphere information. An actual survey of a planet requires the use of probe drones.