[FPSPACE] Space Based Radar is doomed

[Allen Thomson]

> This is all shrouded in the mysts of classification, but presumably we're
talking about different kinds of synthetic aperture radars here for FIA and
SBR.

That was true initially, when, if I understand it aright,  SBR was mostly
supposed to be a "Moving Target Indicator" radar like JSTARS has and FIA was
to have a high-resolution "Synthetic Aperture Radar," son of LACROSSE.   MTI
and SAR, though distinct, are fairly close together technically, both
depending on heavy-duty Doppler processing to do their respective tricks.
(And indeed, it's possible to process SAR returns to get target velocity
information, which leads to some interesting MASINT appplications.)

> The FIA stuff is probably optimised for the reconnaissance mission, used
to look below the clouds to see things in detail.  SBR is focused on wider
areas, looking for moving vehicles and things like that.

The later versions of SBR seem to have decided to do it all, both MTI and
SAR.  I suspect the two capabilities were to be available as different
exclusive modes, so you couldn't do both at the same time.  But that
wouldn't be too awful if near-real-time viewing and switching were
available. Look over a broad area for moving dots that might be interesting,
switch to high-res to get more information on particular dots.  Actually,
you can do this kind of thing with with SAR in the "spotlight" mode, which
allows resolution vs area coverage trade-offs.

> I suspect that with FIA the idea was to develop a single bus for either
optical or radar recon, not to do both.  This is actually the path that the
Japanese appear to have taken.

That is suggested by the available literature.  I tend to be
skeptical/puzzled, because radar and optical hardware are pretty different
and one-size-fits-all would probably lead to serious compromises in one or
the other or both.  Maybe OK for a moderate-budget/moderate-requirements
program, but I wonder about the wisdom of it for FIA.