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 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Fri Apr 27 2007 - 22:31:13 EDT