Hi,
There are several considerations when deciding where to place reconnaissance
satellites. This has nothing to do with technology, but just plain physics.
- The ability to cover the target at vertical viewing angles.
- The ability to scan the entire orbited object.
- The amount of time it takes to return to the same point on the
orbited object.
- The limits of the observing optics (the extreme being diffraction
limited optics.)
So, if your target is at a fixed longitude, very low latitude, and your optics
are excellent, then geosynchronous orbits make sense for this role.
For Earth's orbit at the extreme end of the visible spectrum (400 nm) you
would need a ~8.75 m diffraction limited telescope to get 2 m resolution
(which is pretty poor.)
Maybe there is some way to PSB all these considerations (and any I've missed)
away.
I just don't see them ;-)
Cheers, Tony C.
> On 9-Mar-06, at 12:50 PM, Eric Foley wrote:
> Well, even if satellites today aren't able to do sub 2 meter
> themselves) is good enough that I personally have no doubt that
> orbital ones, in which it was posited that in the far future
> safe close to a well protected planet. Hammer's Slammers posits that
> So, if your target is at a fixed longitude, very low latitude, and
you
> would need a ~8.75 m diffraction limited telescope to get 2 m
Gravitic lenses for light focusing. I think that was the PSB Traveller used
to explain how a ship-mounted laser could cut through another ship at
five
light-seconds without an emitter 100 meters across ;-)
Cheers,
M.
Well, the exact PSB you decide to use isn't really that important. At some
point, one has to keep in mind that we're discussing a sci-fi future
where
the problem of how to travel faster than light -- which current physics
holds to be either impossible outside of maybe the outlandish theory of
dropping through a singularity of some sort and somehow managing to stay
alive in the process. I would tend to say that if we're going to play game
where this is not only a problem that's been solved but is made a trivial
element that we can abstract into a given, it's a little silly to say that we
won't also have developed a way to build spy satellites that doesn't force us
to still use giant physical glass lenses in the telescopes.
E
[quoted original message omitted]
Sure, but my point is that there are other, more important reasons than
range that make geosynchronous orbits sub-optimal for recon satellites.
The fact that you are fixed above a given point is a big negative. The fact
that most of the planet is either at a bad viewing angle or is completely
occulted is also a big negative. Long range is just another nail in the
coffin, IMO.
Cheers, Tony C.
> On 10-Mar-06, at 5:40 PM, Eric Foley wrote:
> Well, the exact PSB you decide to use isn't really that important. At
> some point, one has to keep in mind that we're discussing a sci-fi
> use giant physical glass lenses in the telescopes.
> role.
> five