Fire, Fusion and Steel addenda

Sensor Options and Exotic Sensors

by

bmac@astro.ucla.edu

Sensor Options

High or Low-powered active sensors

Active sensors may be designed to trade off required input power for size - achieving greater sensitivity in a small package by use of a higher-powered beam, for example. High-power active sensors of a given sensitivity have the price as a normal sensor of the same sensitivity, but the designer may decrease the surface area by any factor between 2 and 5, increasing the power consumption by the same factor. High-power sensors have a volume of 10m3 per m2 of area.

Similarly, low-power active sensors decrease the input power by a factor of 2 to 5, increasing the surface area by the same amount. Low-power sensors have a volume of 2.5 m3 per m2 of area.

Continous sensor formula

Mathematically inclined users can calculate the area of sensors of arbitrary sensitivity by using the following formula:
Area = Base Area * 100 ^ (sensitivity-13)
(the ^ signifies exponentiation.)

The base area is found on the following table:

TL PEMS base area AEMS base area
8 50,000
9 1,000
10-11 2 5,000
12-13 1 2,500
14-15 0.5 1,000
The minimum diameter and firing range (for PEMS) is taken from the nearest PEMS on table 198 in Fire, Fusion and Steel. Sensors may not be constructed with greater or lesser sensitivity than those on Table 198 and Table 201 at a given TL.

Exotic Sensors

There are three types of exotic sensors available: Neutrino sensors, Gravitic Sensors, and Neural Activity Scanners.

Neural Activity Scanners

Neural Activity Scanners detect and classify life forms based on brain activity. They are extremely short-ranged, expensive, and fragile. At each TL two basic models are available - a lightweight (portable) model and a somewhat larger ranged device.

TL Range MW Vol MCr
13 0.010 0.004 0.002 0.02
13 0.100 40.0 50.0 20.0
14 0.050 0.005 0.002 0.02
14 0.200 50.0 50.0 20.0
15 0.100 0.006 0.002 0.02
15 0.400 60.0 50.0 20.0
Range: Typical range in km
MW: power required in MW
Vol: volume in m3. All NAS mass 2 tonnes per m3
Antenna area (m2) = MW x 100

Neutrino Scanners

Neutrino scanners attempt to detect neutrinos emitted by nuclear power plants. Pracitcal high-efficiency neutrino sensors are made possible by the increasing mastery of nuclear forces at TL12; however, they are generally too short ranged to be useful in starship combat. In addition, they function only as scanners - dececting targets but not providing a precise enough position for fire control. Neutrino scanner volume is given by the following table:

Sensitivity Volume at TL12-13 Volume at TL14-15 Typical Range
8 10.0 5.0 50 km
8.5 50.0 20.0 160 km
9 500.0 200.0 500 km
9.5 50000.0 20000.0 1600 km
Neutrino scanners mass 2 tonnes per m3 and cost MCr 5/m3. They require 0.1 MW per m3. They require no surface area.

For detection purposes, neutrino signature can be calculated by totalling the power of all nuclear (fusion, fission, and fusion+) power plants on the vehicle and comparing to table 13. At TL13+, power plants can be constructed with neutrino shielding. Neutrino shielding requires 0.1 m3 per m3 of power plant volume, masses 1 tonne per m3, cost MCr 1.0 per m3 and require 0.01 MW per m3, and reduces the neutrino signature by 1.0.

Gravitic scanners

Gravitic scanners detect both static gravitational fields and gravitational radiation. The ability of grav sensors to detect static fields is limited to strong fields or anomalies such as those caused by large mineralogical anomalies, or large astronomical objects. Their ability to detect graviational radiation, however, gives them some sensitivity to the gravity waves produced by thruster plates and contra-grav propulsion. Like neutrino scanners, they are not accurate enough to provide a fire-control solution, and are somewhat short-ranged. Despite the impressions of certain science-fiction authors, gravitational radiation travels only at the speed of light.

Gravitic scanner volume is given by the following table:

Sensitivity Volume by TL12-13 Volume by TL14-15 Typical Range
7.0 --- 0.01 5 km
7.5 0.5 0.05 16 km
8 5.0 0.50 50 km
8.5 100.0 5.00 160 km
9 5000.0 100.0 500 km
9.5 500000.0 2000.0 1600 km
10.0 --- 200000.0 5000 km
Mass is 2 tonnes per m3. Price is MCr 8 per m3. Power required is 0.01 MW per m3. Antenna area is 0.5 m2 per m3.

Gravitic sensors operating on a planetary surface or on a ship with active thruster plates have their sensitivity reduced by 0.5

The gravitic signature of a vehicle may be calculated from the following table:

Thrust (kn) Signature
1 - 10 -2.0
10 - 100 -1.5
100 - 1,000 -1.0
1,000 - 10,000 -0.5
10,000 - 100,000 0.0
100,000 - 1,000,000 0.5
1,000,000 - 10,000,000 1.0
10,000,000 - 100,000,000 1.5
100,000,000 -1,000,000,000 2.0
(As a rule of thumb, thrust in kn = (G-rating)*(size in Td)*(100.) Vehicles propelled by contra-grav instead of thruster plates have their signature reduced by 0.5.
© 1997 bmac@astro.ucla.edu. Traveller is a trademark of Imperium Games. Permission granted to reproduce electronically on the World Wide Web. Permission is *not* granted to Imperium Games to reproduce this text in any printed supplement without prior consultation with the author.