Re: [FT] Some thinking on sensor and operational level games

Thomas Barclay wrote:
> 
> Hi all
> 
> Just thinking about sensors and a game at a
> higher level than the tabletop FT. By higher, I
> mean longer time and distance scale, with more
> hide and seek. Brian posted his ideas and I
> skimmed them, but I'm working on my own so I
> thought I'd quiz the list intelligentsia.

	I'm going to take a stab at these. Bear in mind that I do NOT
have
professional qualifications in this area, I am operating on a roughly
University-level physics knowledge and my experience from a number of
these discussions in the past. My most frequent source will be a
professional astronomer who posts regularly on sfconsim-l (Bruce
Macintosh)

> Specifically:
> 1) At what range could one likely detect a
> starship with good passive sensors? By that, I
> mean optical (visible and not visible spectra)
> and other similar systems. Something that
> doesn't rely on "wazoo newtech".

	This depends on what you're trying to detect, so I'll split it
down a bit.

	1) If you want to detect heat emmissions alone (just the fact
that the
ship is at ~300K (it has a crew) and space isn't), then a ship-mounted
set of telescopes can do a full-sky scan to detect said ship at 1AU
(from the detector) in ~24 hours (using present-day telescopes
(near-infrared)). Using 1000km/MU and 15 minutes/turn, that means that
ships can be detected at 150,000MU within 96 turns, BY HEAT EMISSIONS
ALONE.

	2) Unless the ship is 100% black (even 99.99% isn't quite good
enough)
you will have a comparable range to detect a ship by reflected sunlight
(out at least to Mars orbit, possibly farther), within the same
timescale (again, present-day telescopes).

	3) If the ship is using a reaction drive, present-day scopes
could see
it out as far as Pluto orbit. 4 non-ship-mounted scopes could do a
full-sky survey in ~16 hours (64 turns) (roughly 4,500,000 MU). One
ship-mounted scope could do it in 72 hours (288 turns).

	These full-sky surveys will take awhile, but for a ship to
actually get
very close before being picked up, it would have to be moving at a
rather extreme velocity and have very high thrust.

> 2) How much does the answer to 1 depend on
> if the ship is thrusting?

	As above. A considerable change.

> 3) How much does the answer to 1 depend on
> if the ship has activated some kind of active
> sweep sensors or firecontrols?

	I haven't even considered this, because it depends too much on
what
exactly the active sensors look like. In any case, due to the inverse
square law, you can detect active sensor use at least twice as far away
as the active sensors can detect you (assuming the same detector, same
cross-section, etc.)

> 4) How much does the answer to 1 depend on
> mass of the vessel?

	Not much at all. Note that if they have a reaction drive, and
use it,
you can get thrust from the drive's spectrum, and the ship's mass from
the combination of thrust and acceleration.

> 5) How much does the answer to 1 depend on
> EMCON levels employed? (is silent/black running
> of any use in space?)

	Not really. Keeping your whole ship at 0 degrees centigrade
could help,
but it would have to include crew quarters, and that wouldn't be very
comfortable. Even so, the above (1AU) detection would then require the
'scopes of 2 ships (or, it would require us to make some advances in
technology over present-day telescopes, not impossible over the next 200
or so years).

> 6) I assume there are three phases to
> engaging an enemy:
> 
> 1) gross detection - there's something out
> there, even if it is too far away to tell what or
> how many
> 2) fine detection - we can tell how many,
> perhaps what thrust, what mass, are any
> emitting
> 3) lock-on - we  have a fire control solution

	I'm not sure that this quite applies. Now, passive detection
from 1
platform won't get you everything. 1 and part of 2, most likely.
However, detection from more than one platform will get you parallax,
which will get you all of 1 and 2, and some of 3 (if they're thrusting,
they're a known quantity. If they stop, they can be hit at an arbitrary
range, because now they're ballistic. Once you see a ship from its
thrusters, a dedicated scope can pick it up from heat alone at the same
range).

> I assume passive sensors will generally take you
> through phase 1 and maybe phase 2, but you
> definitely need to "go active"
> (sensors/firecontrol) to get 3.

	I'm not sure of this.

> 7) Does using active sensors increase your
> ranges for the first phase of detection? Or are
> they long enough that your pathetic amount of
> emitted energy just has no effect? I am sure
> active sensors would have some impact in the
> second stage, and obviously firecontrol is the
> third stage.

	No, IMO.

> 8) How feasible are recce fighters or stealthed
> drones or missiles with sensors and a link back
> to the ship to extend your active or passive
> detection radius? Would communications with
> such a drone or fighter not become
> problematic beyond <insert arbitrary range>?
> Or if you had to suddenly manouvre in combat,
> thus breaking  your hard to detect presumably
> direct laser link?

	Communications might be problematic, depending on laser spread.
Thrust
would be bad (the figures for thrust above assumed a space shuttle main
engine (not all THAT powerful, and on a Mass 1 or less ship in FT terms
I believe).

> 9) If I have ECM or an area jammer, I assume
> that I'm making detection level 1 easier and
> detection levels 2 and 3 harder. Turning on the
> jammer systems would mean people would
> quickly discover something was emitting out
> there, but exactly where (more than a general
> few mu area) might be significantly more
> difficult to pin down than without the jammer.
> So you'd never use ECM or Jammers until such
> time as you thought the enemy already knew
> you were there (otherwise why give up your
> invisibility). Is this right? Or don't I get how real
> EW jammers/ECM  work?

	This, I don't know about. I don't know much about EM myself.

	As for fire control, there were recently an interesting series
of
articles posted on sfconsim-l by a person whose job is in that area.
They generated some debate (mostly clarification), but are quite
informative. They're probably in the archives, or I could ask him for
permission to post them here.

> This is just some starting points for my thinking.
> But any input from people with solid ideas or
> some sort of domain expertise (or a keen
> interest) would be worthwhile.

Hope I was some help,