Subject: Re: Iraqi ASAT
From: thomsona@netcom.com (Allen Thomson)
Date: 1995/08/22
Message-Id: <thomsonaDDqCvJ.I8E@netcom.com>
Newsgroups: sci.space.policy,alt.war,alt.politics.org.cia
in <41b6kp$cjk@clarknet.clark.net> < johnpike@fas.org> (John Pike) wrote:
>prb@clark.net (Pat) wrote:
>>... look at higher orbits (Get above the AA fire),
>Well, you start to run into aperture problems, in that the current KH
>would seem to me to start to run into resolution problems above ~5000 km.
True, the 2.5 to 3 meter apertures thought to characterize
current US spysats give "only" one meter resolution at 5000 km.
This is just fine for the majority of tactical and strategic
reconnaissance requirements, as witness the choice of one meter
resolution for Helios. Even 1.5 - 2 meters, corresponding to
7,500 - 10,000 km altitude and a 2.5 m aperture, is still quite
usable for many purposes. A 2-meter Russian picture of San
Diego, for example, shows identifiable aircraft at the airport,
boats and ships, even buses on the highways. High orbits can
improve dwell times, and even, if made elliptical, help the
absentee ratio which John rightly emphasizes as being a big
problem for tactical use of small constellations of LEO
satellites.
As noted earlier on some of these newsgroups, a November 1994
Aerospace America article by the DDCI strongly implies that
higher altitudes for imaging satellites of more-or-less the
present design is the way the NRO is planning to go if it hasn't
done so already.
Whether migrating to higher altitudes would be much direct help
in avoiding any but the most primitive ASAT threats is a question
which should be studied.
>>make satellites more stealthy (Hard to see, hard to hit)
>Don't bet on it. You could paint them black to reduce the optical
>signature, but then it stands out like a sore thumb in infra-red, and the
>thermal control problem would be pretty intense [which is why they have
>those nice shiny gold/mylar thermal control reflectors which make them so
>visible at optical. It is really very hard to see just how one would put
>meaningful radar absorbing material on these things, particularly since
>countour control would be pretty hard to do....
Actually, if you're concerned about avoiding detection by
monostatic radars of VHF and higher frequencies, simply hiding
behind a reflective plate tilted to direct the return away from
the radar should work pretty well. That applies to optical
detection too, if you cant the plate so that the observer's line
of vision is reflected out into space. You can see the effect in
some of the pictures and paintings of HST being deployed: the
flat, shiny sunscreen on the front reflects space and looks,
surprise!, like space.
Full body absorptive stealth has its problems in both radar
and visible light -- remember that the Moon is as reflective as
asphalt -- and has been used to date apparently as an adjunct to
reflective designs. Otherwise F-117s and B-2s wouldn't look the
way they do. Things may change with the march of technology, but
it appears as if reflective principles are still on the top of
the stealth designers' toolkit.
The real difficulty with stealth in LEO, I think, is that all
stealth vehicles which have been revealed to date _are designed
and operated to be stealthy against specific kinds of sensors
encountered in specific geometries_. This is probably a fatal
problem for low-orbiting satellites, at least if they are
supposed to stay hidden for long periods of time.
If we only had to worry about a few, well-located and well-
characterized sensors -- for example the big Russian space
surveillance radars -- there might a chance to "fool all of them
all of the time." That, however, is far from being the actual
situation. For a LEO satellite, a large fraction of the sky (the
disk of the Earth, ignoring the possibility of space-based
detection systems) is the possible location of a wide and ill-
understood collection of sensors. Moreover, the satellite is
illuminated from a variety of directions over a very wide range
of frequencies and reflects or reradiates that energy in ways
which are difficult to predict and control.
As Greg Canavan at LANL has succinctly put it,*
"Observables can only be reduced by so much for low-altitude
satellites, which are continually observed from many angles
with many phenomenologies."
So even if a system designed and operated so as not to be
spotted by the Russian radars worked as intended, it would still
be at risk of detection by Russell Eberst and his binocular-
wielding friends, people doing radar and optical orbital debris
surveys, asteroid inventory projects, bistatic intercept off
radars and commercial transmitters, et lengthy cetera. Add to
this the ever-present danger of HUMINT compromises, and the
wisdom of depending on stealth to protect big, expensive, not-
easily-replaceable satellites becomes dubious indeed.
Expendable tactical satellites would be a different matter, of
course. In that case, the purpose would be to buy time, not
immortality, and stealth might well be a very useful component of
the satellite's capabilities, along with a certain amount of
maneuverability. Covert launch would be nice also, which is one
reason I hope Pegasus gets over its current problems.
The potential utility of stealthy tacsats has not escaped
foreign analysts; in the summary of an analysis of U.S. satellite
reconnaissance during Desert Storm,** a Russian writer notes
Factors which can lower the tendency of satellite reconnaissance
to reveal military operations and intent are the use of Stealth
technology (especially for small satellites), active maneuvering
and orbital servicing [I'm not sure how "orbital servicing,"
orbital'noye obsluzhivaniye" is supposed to fit in].
>>make them more maneuverable (New engines, new ideas)
>Well, the "KH-12" would seem to already have a fair amount of push-water
>on board [~10klb out of 40klb] but do the math -- this is enough for a
>few days of sky-dancing, or one giant leap to a ~5000 km orbit from
>nominal 800 km, but it really isn't going to help much in a multi-week
>attrition campaign.
One of the big problems with maneuver as a protective measure
is simply going to be getting warning and characterization of an
attack in time to command the appropriate maneuvers. Direct-
ascent ASATs aren't all that easy to detect and track. And, as
you say, a satellite can carry just so much gas, so it can't
afford to react to every false alarm or perform anticipatory
maneuvers too often.
>>or make them more economical.
>Well, one out of four ain't bad [the other three solutions all tend in
>the other direction], but there is no such thing as a cheap satellite --
>some are only more expensive than others.
>>s/c can be cost effective if they are built cheap
>Well, do the math -- in general:
> unit cost absentee Cost/effectiveness
> ratio
>S/C $100-2000 M 1:10 0.01 to 0.001
>UAV $ 10-20 M 1:1 1.00
I'm not sure I understand your Cost/effectiveness calculation,
so just one comment on spacecraft cost: if there's a reason why a
1-m resolution optical spysat needs to cost more than a few tens
of millions of dollars when procured in quantity, it's escaped
me. IMHO, this is one area where the much-esteemed market forces
would do wonders if the NRO were to join the country.
>>it's jus the NRO
>>has trouble with a s/c that doesnt cost a billion dollars.
> Their deformations make things even worse than they have to be, but
>the problem has more to do with their institutional imperative to get
>folks hooked on their toys than with their refusal to build cheap toys.
Well, sure: any business wants to be a monopoly -- just ask
Citizen Gates. There are excellent reasons for legislation
against this practice, and it would be a good thing if the same
reasoning that led to those laws were to be applied to the black
world.
>>however to data, s/c survivability has been greater then aircraft
>>survivability.
>And the issue at hand is whether this is a permanent operating factor.
Nothing is forever.
* An Entry-Level Conventional Radar-Driven [sic] Rocket Anti-Satellite"
by Gregory H. Canavan
Los Alamos National Laboratory
LA-UR-91-4122
** "O demaskiruyushchikh priznakakh kosmicheskikh sredstv razvedki"
"Reconnaissance Satellite Operations as Indicators of Military Intent"
(Lit: On the Revealing Characteristics of Space Reconnaissance Means)
by Major L.N. Doda
Voyenna mysl' (ISSN 0236-2058), No.10, 1992, pp. 42-47 and inside back
cover.