Planetary Defenses & missiles

As far as planetary defenses go, I think a lot of it will be determined by
the particular tech/background you are using.  Traveller has deep-sited
meson guns, Starfire has some beams & missiles, Star Wars has full
planetary shields and surface-to-orbit cannons, etc.  So, for this, I'll

stick to general ideas and the GZG background.

Planets have some advantages over spacecraft; they're messy, so you can
hide things on/in them pretty well, armor is practically free, power is
pretty easy (geothermal tap, etc), they're really big, with lots of places to
hide. Some disadvantages are that they're messy, with lots of obscuring
atmosphere to shoot/launch through, they're non-maneuvering (except in a

Lensman universe...), so they cannot choose the time & place of a battle

with as much freedom as a ship, and they've usually got things on them that
you don't want blown up. This may sound strange; who wants their ships'

bridge blasted? Nobody, but if you lose a ship, you've lost a bit of an

investment, probably recoupable. If you start losing cities (infrastructure),
you're losing the base upon which everything else is built.

By the time an invading fleet has destroyed the orbital
defenses/defending
fleet (or if there never were any), the planet is in trouble. The attackers
could drag a rock over and drop it from well out of PD range, and score a
pretty good, predictable hit on a target area. This could be used
on a small scale as anti-PD bombardment, or as a threat of further
destruction. As a threat, it's not good; If you really wanted to trash the
planet, that would have started immediately. If not, and the planet calls the
invaders' bluff, the invader is forced to either back off some, or
destroy that which he has come to capture - rarely acceptable, even with
a relatively high abundance of habitable planets.

As far as the GZG background goes, planets have a few options: apparently
beam weapons will fire into & out of a Terran-standard atmosphere.  I
would expect some degradation, but that depends on a lot of factors. Ortillery
is more effective (if not, why have it?), but requires mass that is unusable
for any other purpose. As I use the vector system for fighters

and MT missiles (they're both FAST!), I count launching or landing as one turn
of endurance. Thus, an MT missile spends it's launch turn expending endurance
clearing the atmosphere (no move). The second turn, it has the vector of the
launching body. It can maneuver as normal on the second turn. Fighters act in
a similar manner. SML range when fired from an atmosphere is halved. All of
these, of course, do not apply when dealing
with a body that has no/negligible atmosphere - Fortress Luna, anyone?

New MT missile notes: MASS 2, Cost 6, Thrust 36, Endurance 6. 2d6 damage, half
damage to any armor, remainder to hull. Ignores screens. May run
'inert' - expends no thrust, retains previous vector, may attack if 1
endurance remaining. Inert missiles are automatically destroyed by
fighters, ADS, PDS & class-1 batteries acting as PDS.  Each turn of
thrust expends 1 endurance. If no endurance remains, cannot attack. Comes in
long-range (9 turns endurance) and fast (48 Thrust).  Various other
warloads: EMP, KKM, EW, etc. These are shipkillers, and are currently
undervalued. but not by much, they can be shot down, and for the mass of 2,
you get 6 SM (SMR). Harder to take down all the SMs than 2 missiles.

New Fighter/Missile movement notes: Fighters/Missiles may spin freely,
and expend thrust in any direction. Essentially, they may alter their endpoint
by their Thrust rating. This must be plotted as normal. Fighters follow same
move rules as fighters. This frees up missile movement (no crew to

worry about squishing), and gets fighters into the vector system.

Comment?