RE: Orbital surveillance satellites now exceed 1 inch resolution?

From: Ted Molczan (
Date: Fri Apr 27 2007 - 22:30:17 EDT

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    Robert Clark asked:
    >  I copied below a post I sent to some space oriented 
    > discussion lists about the possibility of large segmented 
    > mirrors being used on surveillance satellites. One objection 
    > to this idea was that satellites large enough to have mirrors 
    > this size, 6.5 meters, would have been noted by amateur 
    > satellite watchers.
    >  Have there been cases where a satellite was
    > *inexplicably* brighter than expected?
    No. Four satellites of KH-11 lineage are in orbit, tracked fairly regularly by
    hobbyists. One or two Misty satellites (essentially stealthy versions of KH-11)
    may also be in orbit, but there is no way to be certain because they intended to
    be nearly invisible, and seem pretty effective doing so.
    If technological advances of the sort you describe are going to appear in IMINT
    satellites, I believe they are more likely to do so as part of the FIA (Future
    Imagery Architecture) program, which is believed to be years away from
    operational launches.
    An apparent FIA technology development satellite was launched in 2006 Dec, from
    VAFB, aboard a Delta II, into a 58.5 deg, 370 km orbit. Reuters has reported
    that the satellite is related to the FIA optical program, but that it failed
    soon after reaching orbit, apparently due to a faulty computer. Hobbyist
    tracking to-date has detected no orbital manoeuvres, without which, the
    satellite will decay by about 2008 Feb.
    By the way, in your post, you mentioned that spy satellites frequently have
    elliptical orbits, and can lower their orbits to 150 km at closest approach. The
    KH-8 film-return satellites operated with a perigee of about 130 km +/- 10 km.
    The last of those orbited in 1984. 
    KH-8's direct successor, the KH-11, was introduced in 1976, and approximately
    doubled the perigee height to about 280 km +/- 20 km, enabled by doubling the
    diameter of the primary mirror compared with that of the KH-8.
    Although KH-11 and its successors are manoeuvrable, they do so infrequently
    (several times per year), and only to counter the effects of orbital
    perturbations, mainly drag and solar gravity. I am not aware of any instance of
    their having dropped their perigee below approximately 260 km. The satellites in
    the eastern KH plane tend to raise their perigee as they age, up to about 330
    km. In recent years, those that have remained in orbit after the launch of their
    successors, have operated with a 400 km perigee. For some reason, the western
    plane KHs generally have maintained the 280 km perigee, even in retirement.
    Ted Molczan
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