Re: Space Geography

Another consideration to be accounted for is for the detection to be 
communicated by the sensor arrays to sentient recipients, which is 
likely to be at light speed. Unmanned sensor arrays are likely to be 
positioned such that there aren't (m)any blind spots in system, with 
built in redundancy (multiple sensor arrays with overlapping scan 
areas and communication lines to the sentient presence).

Assuming you arrive in-system 6 light hours out from your final 
target, and 1 light hour away from the nearest sensor array with a 
direct "line of sight" communication to the sentient presence at your 
final target, then the sensor array would detect you 1 hour after 
arrival and the sentient presence would become aware of your presence 
at some point from 6 hours after you arrive in system. It is unlikely 
that you will be travelling much faster than 0.2 light speed 
in-system, so it would take you a minimum of 30 hours to reach final 
target, in which time they will have been tracking your movements 
(course, speed, etc) giving them up to 24 hours to prepare their 
defences to meet you.

On arrival you would have a slight edge as you would be aware of 
in-system dispositions at "point x" in time due to light which has 
reached your arrival point. For instance, on arrival your sensors 
reveal that 6 hours ago, your final target was being circulated not 
by the single cruiser squadron you had anticipated and there is in 
fact a full battle group within 1 light hour of the target. You could 
then opt to abort and exit the system immediately before your 
presence has been registered by them (they will of course become 
aware of your arrival, but after you have left).

As others have said, the chances are that you will be detected 
regardless of where you "jump in". The real issue is how quickly the 
detection will occur. Once in system both sides will be limited by 
the speed of light in determining where your/their forces are - as 
you approach your target the information on both sides will get 
closer to "real time location".

For a good idea of what I'm talking about, try Jack Campbell's "Lost 
Fleet" series.

Tamsin

At 14:23 23/09/2011, Samuel Penn wrote:
>  On Fri, 23 Sep 2011 10:50:52 +0100, Roger Burton West
>  <roger@firedrake.org> wrote:
> > On Fri, Sep 23, 2011 at 05:48:00AM -0400, Indy wrote:
> >>But note that in general the background radiation is
> >>pretty low to begin with. On the flip side, contemporary technology
> >> has
> >>challenges just detecting Earth-crossing asteroids. It's pretty much
> >> all
> >>passive and optical.
> >
> > Part of the problem when it comes to spaceship detection is that
they
> > aren't relatively cool planets - in a world with realistic physics,
a
> > ship with enough power plant to run a space-drive and weapons and so
> > on
> > is seriously glowing, and will be obvious to anyone with an IR
> > detector
> > at several AU range. (Ask Ken Burnside about this...)
>
>  Some suggestions for stealth involve trying to shed your heat in one
>  direction - e.g., you point a non-radiating side towards the enemy
>  sensors, and radiate all your heat back in the opposite direction.
>
>  Ignoring the difficulty in doing this, it is foiled by having
multiple
>  sensors in the system, which makes it difficult to radiate in a
>  direction
>  which isn't being watched.
>
>  As far as coming in from the poles is concerned, if most civilian
>  traffic
>  tends to be on or near the ecliptic, then civilian sensors are
probably
>  going to be focused there, so such a technique might work against
soft
>  targets. Military sensors will undoubtedly scan the entire sky,
despite
>  the extra expense of doing this.
>
>  Coming from a direction very close to the sun might make it hard to
be
>  detected - which is another reason for a system to have lots of
sensors
>  spread throughout the system. There may be regions which are less
well
>  scanned than others though, so though you may not be able to avoid
>  detection, you might be able to delay it.
>
>
>--
>  Be seeing you,
>  Sam.