Re: Space Geography

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On Fri, Sep 23, 2011 at 9:23 AM, Samuel Penn <sam@glendale.org.uk>
wrote:

> [...]
>   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.
>

Even if your sensors are limited in location and not spread across the
solar
system in question(1), "coming from a direction very close to the sun"
would
really have to be coming directly from the other side of the Sun, along
the
invader-sun-defense detector axis. With our current technology, we can
(and
are currently right now this very week(2)) in the process of
communication
with spacecraft on the far side of the Sun, and angularly close to it.
Granted, it is an active comms connection, but this is meant to be
illustrative that our perceived notions of the impossible from 10, 20,
30
years ago have been overcome, or significantly addressed. If this sort
of
trend continues...

(1) - one way around this is to set up a handful (3-4 minimum) of area
detectors in polar orbit around the Sun. Those could easily monitor the
ecliptic plane from 'above' or 'below' the Sun to see what is on the
'far'
side relative to the planet to be defended in question.

(2) - for those unaware, the MESSENGER spacecraft is currently in orbit
around Mercury. And Mercury is about to enter superior conjunction
(i.e., be
on the far side of the Sun from Earth) next week (specifically Day 272
+/- 1
day - for the non-DOY folks, Day 272 is Sept 29). The
Sun-spacecraft-Earth
angle is going to be <3 degrees (I don't have the exact number; the plot
I
have doesn't have that level of detail in the scale, but eyeball judging
suggests ~1 or 2 degrees).

Mk