Re: Planetary defenses

At 11:32 AM 9/25/98 -0700, you wrote:
>OK I've noticed that many people on this list seem to assume that
>orbital strikes, ortillery and woning orbit means it's pretty much all
>over for a planet, that it might as well roll over and die.
>
>I'd like to throw it back at everyone and ask, if you had to design a
>planetary defense to counter such a situation what could be done? How
>effective would be ground based wepons? Obviously they could be very
>effective against atmospheric craft but what about Stuff in space?

Actually, a friend and I have been working on that question in private
e-mail recently.  We are putting together a campaign game using GDW's
Imperium and Don Hawthorne's "Integration Packet 001" as starting point.

<http://www.wizard.net/~caw/intpackets.htm>

Instead of trying to design FT analogs for the ships in Imperium as
Hawthorne suggests, we'll probably just be using FB ships (FSE & NSL
respectively) for the tactical combat.

Anyway, since planetary defenses are fairly important in Imperium, we
will
be trying to make them effective in the campaign as well.  Since we are
trying to simulate a specific universe with a fairly well developed
technological background, some of our assumptions may not apply to a
more
general discussion of planetary defenses.

First of all, planetary defenses in the Imperium universe are not
perfect.
Massive orbital bombardment can neutralize or destroy it before it can
reply in kind.	If it fails to do so, the defenses can attack every ship
in
the fleet with a moderate chance of destroying each.  I interpret this
to
be an strategic level abstraction of a FT-style battle in which the
attacking fleet must damage or destroy a significant portion of the
defense
network quickly before its weapons can wear them down.	The levels of
firepower needed for a quick kill on a planetary defense are formidable;
the equivalent of up to 4 or 5 of their largest capital ships or 7 to 9
heavy cruisers.

Secondly, all inhabited planets possess some inherent level of planetary
defenses (depending on the size of the settlement) at no cost.	Players
can
expend resources to upgrade these basic defenses, effectively doubling
(or
more) their firepower and durability.  Any planetary defense is capable
of
striking down any starship that bombards or ground force that tries to
land
on the planet although some units (such as capital ships and jump
troops)
are more resistant to these attacks.

Third, the upgraded planetary defenses are not very expensive relative
to
starships.  In Imperium, a planetary defense marker is 10 resource
units;
less than the price of a heavy cruiser.  Part of this is probably the
result of the ship design assumptions in the Traveller universe; their
starships require a much higher proportion of their mass for FTL drives
and
fuel.  This same principle applies to non-FTL ships such as monitors
(capital ship firepower and defenses for light cruiser prices) as well.
Were we to simulate this properly, we would tinker with the FT 2.5
design
system to increase the mass requirements for drives.  As it is, we are
considering a quick hack method which is to adjust the economic system's
point conversion rate to allow a player twice as many FT points per RU
for
planetary defenses or monitors as we do for regular starships.

The ideas we have been kicking around are things like a swarm of SLM box
launchers in low orbit, discounts for some things like armor on ground
bases (hey, dirt is cheap), a few really large beam weapons with limited
arcs, a network of PDS-equipped satellites, etc.

One of the more radical options proposed would be to treat a planetary
defense network in the abstract as one big installation (or a sectional
installation) with the unusual array of weapons.  All ranges would be
measured to or from any point on the surface of the planet (I use a 12"
globe), not the center.  This cuts both ways; it gives the defenses a
large
"footprint" but makes it all equally vulnerable.  Not quite sure how
hull
points or thresholds fit in, maybe they would represent the strength of
dug-in defense installations and maybe they would represent the amount
of
bombardment the planet would be willing to put up with before throwing
in
the towel.

This would be a highly abstracted representation of what I visualize as
a
network of satellites, mine fields, hidden sensor arrays, bunkers,
dispersed launch silos, subterranean meson cannons, PDS air defense
launchers, fiber optic land lines, comsat links, etc.  This has the
advantage of being much easier to game than keeping individual stats for
60-bazillion tiny weapons platforms (plus decoys).

Fighters are also an important weapon for planetary defense, but since
they
are handled separately in Imperium, I've left them as a distinct system.
 I
would say that any planet can provide unlimited "free" base capacity for
any fighter squadrons based there.  (ie, not need to buy a hangar bay) 
I
would also assume that the fighters are aerospace vehicles and need not
worry greatly about launching.	Or you can have them spend a point of
endurance in taking off if you like.

Jeff