Space

Subject: Re: Doubts about FAS "Lacrosse" homepage...
Date:  Mon, 27 Jan 1997 14:02:35 -0500
From: John Pike 
Organization:  Federation of American Scientists
Newsgroups:  sci.space.policy, alt.politics.org.cia
aufsj@imap2.asu.edu wrote:
> "Lacrosse" radar imagery satellite.  There were no disclaimers, so I
> would think that the data represents the best guesses of the people at
> FAS.
Yeah -- we have been working this one for several years now, and this
remains our current all-source best guess -- additional feedback is most
urgently solicited.
>  I have *very* grave doubts about what is portrayed, however.
>         http://www.fas.org/SPP/military/program/imint/lacrosse.htm
We have gone through a couple of renditions ourselves, and further
revisions are hoped for.
> In summary, I think that the spacecraft pictured is a SIGINT spinner
We do have a depiction of the Titan-2 singlet "spinner" @
    http://www.fas.org/spp/military/program/surveill/sbwass_a.htm
> and that some of the other data (like the orbit) don't make any
> sense at all for Lacrosse.
They may not make sense, but unless you have found a typo [entirely
possible] I think that we have displayed the correct data [there may be
a typo or two, as this is a pretty massive multi-year project, and we
aren't always able to catch or update everything].
>         First things first.  The drawing shows possible modes of data
> collection.  I recognized it as a copy of documents of the Canadian
> RadarSat 
>         http://radarsat.space.gc.ca/Graphics/RADARSAT/rsat-op.e.gif
> no hard data on Lacrosse modes.
That is correct, although the modes depicted are pretty generic to all
SAR.
> feature appears to be a large high-gain antenna, which is identified as
> the radar antenna. The problem, however, is that the state of the art in
> radar imagery birds (even back when Lacrosse was designed) is the use of
> an array.
Yes, our original depiction was of a pair of large planar arrays.
However:
1 - We developed information from a source who was pretty insistent that
the overall antenna configuration was more or less as depicted [we don't
build them, we just draw them].
2 - The thing that is funky about SAR is that, paradoxically, the higher
the resolution of the imagery, the smaller the actual antenna [to the
extent that there are relationships between antenna aperture and
resolution]. So we do depict a planar array, at the focal point of the
dish.
3 - Candidly, we are still at something of a loss to entirely apprehend
the functioning of this system, but I am guessing that the dish antenna
has something to do with lowering system noise or side lobes or jamming
rejection or something to that effect. I could be wrong.....
> addition, moving around that big dish antenna in some sort of scan
> pattern will complicate the heck-n-darn out of the lives of the people
> who have to keep that thing pointed in the right direction
That is why they get paid the big bucks, to make it all work!!!
>         The way to use a directional dish antenna is to NOT move it, at
> platform is set in motion, rolling or spinning
Lacrosse does not spin [the Titan-2 singlet does].
>         As to spacecraft size and weight and power and etc.?  There
> shouldn't really be any need for a large electrical supply from radar
> demands alone. The RadarSat only utilizes 2.5kw of power. Why would the
> bird on the FAS page, imagery or SIGINT, need those rather largish solar
> panels?
1 - The overall wingspan of the bird was specified in an AW&ST article,
and in the absence of evidence to the contrary, that is how we depicted
the thing.
2 - I will confess that we are still in the process of doing power
budgets for some of these things, and we have, over time, refined some
solar array dimensions.
3 - RADARSAT has a fairly low duty cycle [1%???] which means that most
of the time the radar is running on battery power rather than the direct
solar array power level. We presume that LACROSSE has a much higher duty
cycle [ie, it would need to take lotsa pix in rapid succession] and thus
needs lotsa juice...
>         If it is a SIGINT bird it would presumably be carrying a large
> amount of parameter electronics for the measurement of collected signal.
No, the SIGINT birds do a bent-pipe dump of whatever they collect, and
it gets sorted out on the ground. LACROSSE dumps through TDRSS [why do
you think they built that second ground station at WSMR??]
>         The bird listed is in a 400mile 57degree inclination orbit. This
> means that the platform is flying into and out of the sun all the time at
> varying intervals.  It not only needs to use a lot of electricity, but it
> needs to recharge its batteries (there's more weight!) quickly
Point well taken.
>Why would anyone fly an imagery bird in a classic ELINT orbit?
Because when the first one was launched, the Titan pads at VAFB were
offline due to that April 1986 explosion, and this was the highest
inclination that the Shuttle could reach from KSC.
> For starters, IIRC, the maximum latitude under the ground track will
> correspond to the inclination.  Since known radar imagery systems (like,
> once again, our canuck cousin RadarSat) image only relatively closely
> along the ground track, this orbit makes no sense.
But this is a high-res system, and if you play with the SAR equations
you will conclude that high-res imagery is produced at high angles of
obliquity [aka, looking closer to the horizon].
>On the other hand, if this is a SIGINT bird
LACROSSE is not a SIGINT bird, period.
> Presumably, if one were to go to 57 latitude and go up approx 400 miles,
> one would have a horizon that reached to the pole. 
This works equally well for active radar and passive SIGINT...
>         Oh yeah. On that last point.  If it doesn't make sense to put
> Lacrosse into a SIGINT orbit, then what kind of orbit would you expect it
> in?  How about an imagery orbit?
The actually observed situation is that Lacrosse is not in imagery
orbits, but rather in the mid-inclination LEO orbits. In fact, as your
line of analysis indicates, this is sensible, as it facilitates
higher-resolution imaging of northern latitudes.
> advantage of a radar imagery bird is that it *can* take pictures in the
> dark.
1 - The optical imagers have night-vision capabilities.
2 - The real advantage of LACROSSE SAR is both night and clouds [nacht
und niebel???] -- and if one contemplates the CORONA imagery, you will
come to appreciate that clouds are the true bane of the squint's
existence, and some locales are famed for "demon cloud" obscuration.
This is particularly the case given the LACROSSE real-time targetting
assignment, which cannot await nice weather....
> In order to maximize its usefulness, wouldn't one expect it to be
> placed into an orbit that mimics that of its compatriot optical imagery
> birds, except that it arrives every time in the middle of the night?
This is already achieved by default by the KEYHOLE birds.
>         At any rate, that is a quick summary of why I think the satellite
> listed on the FAS page is NOT a Lacrosse, but rather a SIGINT spinner.
> Any other thoughts out there?  Am I missing the proverbial boat here
While you have raised some interesting points, and I would welcome a
continued dialog on these thorny matters, let me make a couple of
overall responses.
1 - Your epistemological conceit is misplaced -- the problem is not one
of trying to figure out the identity of the depicted spacecraft, but
rather one of trying to get a handle on the level of fidelity of the
depiction. [There have been some other instances where we were
confronted with "leaked" artwork and had to try to associate the
configuration with the program, but that is another story altogether].
2 - The major parameters of LACROSSE [notably its orbit] are not in
dispute, so while you might attempt to mount arguments as to why Big
Black has made some horrible orbitological plans, I don't think that it
is a useful line of inquiry to suggest that the spacecraft identified as
LACROSSE are in fact some other program entirely, and that the actual
LACROSSE spacecraft reside unobserved in completely different orbits
[having arrived there without the benefit of publicly recognized
launches].
3 - You have, however, raised some interesting points that we have
struggled with for several years now, and I look forward to the insights
of others as well.
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John Pike
Federation of American Scientists  http://www.fas.org/
 Space Policy Project              http://www.fas.org/spp/
 Public Eye                        http://www.fas.org/eye/
 Intelligence Reform Project       http://www.fas.org/irp/
Indeed I tremble for my country when I reflect that God is just.
  - Jefferson