walkuere@amaranth.com wrote: > In Article<31D6B75A.11B6@fas.org>, <johnpike@fas.org> wrote: > > It is a bit difficult to imagine that NRO would go to all the trouble to > > make AFP-731 adequately stealthy in every other regard > you are good at SIGINT, you should already have all the data channels > "demuxed". Either look for a new data channel, or something unusual in the > previously existing channels. I think that I will attempt to defend my original proposition. The SDS birds have several GHz of bandwidth to play around with to get the images down from the Keyholes to the ground. The instantaneous bandwidth of the underlying imagery signal should only be many tens of MHz, so I am guessing that there is plenty of room for dummy traffic and fancy crypto and lotsa other things that would make it a pretty pointless task to attempt to reverse engineer things like Keyhole constellation size and current tasking priorities simply based on getting inside the downlink stream, which in any event is something that has a pretty dang small footprint on the ground to begin with, what with a largish EHF dish on the SDS birds for the downlink [and so this is not the sorta thing that one could normally get access to without, say, living in Ft Belvoir VA or Aurora CO] And the TTC bandwidth is trivial compared to the payload bandwidth, so if I can hide the imagery channel, hiding the TTC channel is easy. [I know that it is said that *ALL* US spacecraft use the S-band stuff for TTC, but if this was the *only* thing standing in the way of making AFP-731 and kindred spacecraft stealthy, surely they would contemplate making an exception in this case, particularly if I could drive the thing via SDS-2 and really didn't need to talk to the rest of the Satellite Control Network]. All of this would be one of the more highly sensitive things that had ever been attempted, and your caveat about "good at SIGINT" almost certainly doesn't apply in this case -- there are lotsa things that SIGINT ain't gonna tell you, and I am guessing that this is one of them. You do however raise an interesting point about the possibility of Russian HEO and GEO SIGINT birds inadvertently getting inside the EHF transmission path from a covert IMINT bird in MEO. This would provide one potential system vulnerability. However, I am guessing that due to the general absence of significant ground-traffic at EHF, it is unlikely that the Russian SIGINT birds have paid too much attention to this sorta thing [which does pose non-trivial technical challenges in terms of things like antenna configuration control]. In particular, my impression from contemplating tasking and operations of US SIGINT birds has led me to the belief that under normal circumstances such critters only hear things that they are listening for -- ie, that they are tasked against specific targets, which is about the onliest way that they would ever hope to extract anything useful from the great blooming buzzing confusion [did I get that phrase right??]. So I am guessing that they just flat out aren't set up to be listening to great big whacks of the vasty deep on the off chance that there is some previously unidentified EHF emitter lurking out there, and that in any event since EHF is kinda directional, the odds that they would manage to get a good fix on ole AFP-731 would be pretty remote, and I am also guessing that if one were clever [as I assume that the boyz out at Big Black are] one could probably fire up some sorta orbitology software and predict such windows of vulnerability to make sure that one was not transmitting modulated high-power wideband EHF from a piece of supposedly inert space debris during those periods during which someone might be listening in.... Anyone else have some thoughts to add??? -- John Pike Federation of American Scientists http://www.fas.org/ Public Eye http://www.fas.org/eye/ Intelligence Reform Project http://www.fas.org/irp/ Space Policy Project http://www.fas.org/spp/ Indeed I tremble for my country when I reflect that God is just. - Jefferson