News


Subject: More on Ofeq, and some speculation
From: thomsona@netcom.com (Allen Thomson)
Date: 1995/04/15
Message-Id: <thomsonaD72x0w.AHI@netcom.com>
Newsgroups: sci.space.policy


Looking at the orbit of the Ofeq-3 protospysat the Israelis
launched earlier this month, I've been struck by how several
accidents of geography and orbital mechanics have worked in
favor of Israel (and possibly one of its friends).

The first is the shape of the Mediterranean Sea and the
location of Israel. The Israelis can't launch in a direction
that would overfly or drop stages on nervous neighbors, so
they're constrained to an azimuth that takes their SLVs just
south of Crete and Sicily, near Tunis, and out over the Straits
of Gibraltar. This is just about the *only* trajectory currently
available to them, and it's remarkable how neatly it fits into
the local geography.

Due to the payload penalty that comes with a retrograde
orbit, the westward launch constraint is usually seen as a
severe handicap for Israel. As reported in an earlier message,
however, the resulting east-to-west orbit at 36 degrees
inclination can be phased to give extraordinarily good daylight
coverage of the Middle East. Ofeq-3's orbit is so phased, and
it makes a half-dozen or so daylight passes per day over Israel
and the surrounding countries. Putative US and Russian spysats
only get one or two passes per day from their higher inclination
orbits.

Although the natural evolution of Ofeq's orbit will "detune"
it for Mid-East coverage after several weeks, it will
subsequently cycle back into the proper phasing. An obvious way
to solve the detuning problem is to use a constellation of three
Ofeqs with ascending nodes spaced 120 degrees apart in longitude.
In that case, at least one satellite would provide good daylight
coverage at any given time (*). Moreover, a user in a different
part of the world could also use the satellites, which leads to
the last geographical coincidence and a bit of political
speculation.

As it turns out, the Cape of Good Hope is at 34 degrees
south latitude, and the properties of Ofeq-3's orbit that make
it very good for keeping an eye on Israel's neighbors make it
equally good for watching what's going on in and around South
Africa. The phasing of the orbit has to be different, but with
a constellation of three, both Israel and the South Africans
would enjoy uninterrupted multiple daytime passes.

Why single out the South Africans as possible co-users of
Ofeqs rather than other folks who live around 35 degrees north
or south of the Equator? (Here comes the speculation; be
warned.) Well, there is the long history of kind-of-covert
military cooperation between the two countries, including
development of significant technologies. More specifically,
there have been reports that South Africa's now canceled
Greensat program, which evolved from a spysat design, had much
in common with Ofeq. While the former South African government
might have preferred to build and launch its own satellites,
having the option to use the services of a country not
effectively under MTCR constraints could well have been
attractive. The lucky geographical/orbitological coincidences
described above would make it look like an even better deal,
since South Africa would only have to install a tracking antenna
under a dome and perhaps get cryptographic key material from the
Israelis. Quite likely such an arrangement could escape
detection for a long time, giving South Africa the advantage of
covert space-based surveillance of its neighbors and avoiding
international political problems.

Even if the above fantasy were true in The World That Was,
it probably isn't any more, as the apartheid regime and its
adversarial relations with most of the rest of the world have
disappeared. Nonetheless, it makes for entertaining speculation,
and perhaps would be worth researching a little more.


(*) No Usenet posting should be without footnotes: For those who
would like to see how the hypothetical three-Ofeq constellation
behaves, here are some orbital elements to feed to your tracking
programs. "OfeqA" is the real Ofeq-3, while B and C have had the
longitude of the ascending node increased by 120 and 240 degrees,
respectively.

OfeqA
1 23549U 95018 A 95096.85362148 .00113461 00000-0 33509-2 0 36
2 23549 143.3777 102.1910 0261160 83.0998 279.9378 15.06127287 200
OfeqB
1 23549U 95018 A 95096.85362148 .00113461 00000-0 33509-2 0 36
2 23549 143.3777 222.1910 0261160 83.0998 279.9378 15.06127287 203
OfeqC
1 23549U 95018 A 95096.85362148 .00113461 00000-0 33509-2 0 36
2 23549 143.3777 342.1910 0261160 83.0998 279.9378 15.06127287 206