Orbital Tug for use in the Tellus-Luna system
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Cargo: 20 tons (44,800 lb)

Delta V:  30*10^6 furlongs per fortnight
          0.11861 Tellurian Clarkes per second
          500,000,000 cm/s


Reaction mass: Water
Main driving projector: DC arcjet
Isp: 500 lb-s/lb
Power source: solar furnace & stirling cycle engine (reaction mass used as coolant)



Cargo:               20   T
Structure:            0.5 T
Equipment:            0.5 T
Gyrodynes:            0.5 T
Driving projectors:   0.5 T
Furnace & dynamo:     2   T
Tankage:              8   T     (11.25:1 tankage ratio)
Reaction mass:       87   T     (2.72:1 fuel:mass ratio)

TOTAL:              120   T


Instruments:
  Sun sensor
  Planet sensor
  Star sensor
Autopilot:
  Flip flop
  Timer (initial burn)
  Timer (capture or circularising burn)
  Sun, planet & star sensors & orientation logic (lunar braking)
  Programmed by a rotary switch (T-L/off/L-T) and two timer settings


Tug is orientated by Lunar or Tellurian orbit station for initial burn, orientation being maintained by gyrodyne.  A simple timer cuts the driving projector when a sufficiant delta V is expected to be achieved.


ORIENTATION LOGIC
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Aim: to line up the vessel with the sun (offsets can be added)

Sequence:
 1) Fast positive theta rotation until delta(sunsensor)    is negative & >threshold
 2) Fast positive phi   rotation until delta(sunsensor)    is negative & >threshold
 3) Slow negative theta rotation until delta(sunsensor)    is negative & >threshold
 4) Slow negative phi   rotation until delta(sunsensor)    is negative & >threshold
 5) Fast positive theta rotation until delta(planetsensor) is negative
 6) Fast positive phi   rotation until delta(planetsensor) is negative
 7) Slow negative theta rotation until delta(planetsensor) is negative
 8) Slow negative phi   rotation until delta(planetsensor) is negative
 9) Fast positive theta rotation until delta(starsensor)   is negative
10) Fast positive phi   rotation until delta(starsensor)   is negative
11) Slow negative theta rotation until delta(starsensor)   is negative
12) Slow negative phi   rotation until delta(starsensor)   is negative