My reading of the discussion on the topic is that a big reason why this was believed to be debris or a decoy was because of its unusually light weight for its size. This could be explained by the great reduction in weight a beryllium mirror allows. The James Webb Space Telescope has a mirror that weights half as much as the Hubble mirror but has a collecting area 6 times as great. So this means a reduction in weight to area by a factor of 12 in regards to the mirror. The mirror makes up a big part of the weight though not all of course for a imaging satellite. Bob Clark --- Björn Gimle (GlocalNet) <bg_26934@glocalnet.net> wrote: > It is "generally" agreed that what amateurs have > observed is a decoy. > See http://www.satobs.org/seesat/Dec-2005/0052.html > and the Reply liked from there! > > ----- Original Message ----- > From: "Robert Clark" <bobbygc2001@yahoo.com> > To: <SeeSat-L@satobs.org> > Sent: Tuesday, May 01, 2007 3:54 AM > Subject: RE: Orbital surveillance satellites now > exceed 1 inch resolution? > > > > Thanks for the informative response. > > > > Your description on this page of the "Misty" > > satellite gives it as one of the lightest > satellites > > for its physical dimensions: > > > > USA 144: The Mystery Deepens - Flash Timings > Needed. > > "SRP Analysis Reveals Area to Mass Ratio. > > SRP analysis has yielded an accurate estimate of > the > > object's area to mass ratio - more precisely, its > kA/m > > value - area to mass ratio multiplied by a > constant > > which accounts for its shape and reflectivity. > > The value of k can be between 1 and 2. A value of > kA/m > > of about 0.135 m^2/kg appears to account for the > > object's historical rates of orbital decay. > > Assuming k = 1.5, then A/m = 0.09 m^2/kg - at > least an > > order of magnitude greater than that of most > payloads > > and rocket bodies. For comparison, consider: > > > > Compton GRO 0.004 m^2/kg > > Hubble ST 0.006 m^2/kg > > UARS 0.007 m^s/kg" > > http://www.satobs.org/seesat/Aug-2002/0045.html > > > > This passage describes it as having a large > surface > > area for the given weight. But note this means it > also > > has a very low weight for its given surface area. > > A key feature of the James Webb Space Telescope is > > also its low weight for the size of its mirror. > This > > is because of its beryllium mirror which allows > very > > thin mirror blanks. > > So this low weight of the Misty satellites is > > consistent with ligthweight, segmented beryllium > > mirrors. > > > > > > Bob Clark > > > > > > > > --- Ted Molczan <molczanssl@rogers.com> wrote: > > > >> 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 > >> > >> > > > > > > __________________________________________________ > > Do You Yahoo!? > > Tired of spam? Yahoo! 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