nickw@syma.sussex.ac.uk (Nick Watkins) (02/05/91)
From article <14230@ganymede.inmos.co.uk>, by conor@lion.inmos.co.uk (Conor O'Neill): > I realise that the real details are almost certainly classified, but I would > like to get some feel for the answers: Yes they are, so ALL that follows is based on open sources, and may be wrong. > 1) How many US/Allied spy satellites are likely to be targetted on the Gulf? Only US has spy satellites in coalition unless you count France which has SPOT. 4 KH11 & 1 Lacrosse are the usually quoted numbers, but these identifications are more uncertain than they are sometimes made out to be. KH11 are photographic, Lacrosse is radar. > 4) What sort of resolution? > Can they count buildings? (Yes, it seems) yes. > Can they count vehicles? (maybe?) yes. > Can they recognise different types of vehicles? yes. c.f leaked pictures of planes, ships. > Can they count men? reports suggest that they can, at least approximately. > Can they see an Iraqi soldier scratching his nose? Probably not. > 5) Are they affected by the dark, or by cloud cover, or is much of the > sensing done in the Infra Red? Radar isn't, apparently, I think IR will be affected by cloud cover though. Maybe somebody who knows about weather satellites can help. > 6) Can they really detect missile and airplane launches, > or is this done by AWACS? Only the geostationary (DSP) early warning satellites do this, q.v Aviation Week a couple of weeks ago. > 7) A point was made that if you knew when the satellite was due, you could > simply hide under a bridge for 10 minutes. How true is this, and > are the Iraqis likely to be able to determine enough orbital information > to do this? Depends on how good friends they remain with Russians, at a guess ? > 8) Any other information which is available about spy satellites. Go to library and do author search under D. Ball, J. Richelson & W. E. Burrows. Enjoy. Nick --
awtron@strawber.Princeton.EDU (Andrew Tron D-313 x3749) (02/07/91)
In article <4409@syma.sussex.ac.uk> nickw@syma.sussex.ac.uk (Nick Watkins) writes: >From article <14230@ganymede.inmos.co.uk>, by conor@lion.inmos.co.uk (Conor O'Neill): >> 5) Are they affected by the dark, or by cloud cover, or is much of the >> sensing done in the Infra Red? >Radar isn't, apparently, I think IR will be affected by cloud cover >though. Maybe somebody who knows about weather satellites can help. > Water does a very good job of absorbing infra-red. That's why you only see infra-red telescopes at very high altitudes (to get above the water vapour at lower altitudes) or in space. Infra-red images are useful for weather satellites: an infra-red image can give you the temperatere of the highest layer of cloud, which can then be translated to the height said cloud. This is useful for predicting the severity of thunderstorms (i.e high tops == severe thunderstorms). I got this info when I visited an FAA flight service station once. ------------------------------------------------------------------------------- Never trust a pilot with clean hands.| Andrew Tron at Princeton University Never address a major international | awtron@phoenix.princeton.edu (Internet) terrorist as "Bubbi". | uunet!phoenix!awtron (UUCP)
Gumley_LE@cc.curtin.edu.au (Liam Gumley) (02/07/91)
In article <4409@syma.sussex.ac.uk>, nickw@syma.sussex.ac.uk (Nick Watkins) writes: > From article <14230@ganymede.inmos.co.uk>, by conor@lion.inmos.co.uk (Conor O'Neill): >> I realise that the real details are almost certainly classified, but I would >> like to get some feel for the answers: >> 5) Are they affected by the dark, or by cloud cover, or is much of the >> sensing done in the Infra Red? > Radar isn't, apparently, I think IR will be affected by cloud cover > though. Maybe somebody who knows about weather satellites can help. Nothing classified here.... Visible sensors obviously only work during the daytime. Depending on the type of orbit, the satellite can be in sunlight for up to about 50% of the time (sun-synchronous orbit). I don't know the altitude of the KH-11, but I imagine it would be low, to maximise image spatial resolution. This probably means it does not have a sun-synchronous orbit. They are usually at an altitude of 850 km or so. Infrared sensors are usable both in the day and the night, although if you want to see targets such as vehicles or people, you would want to do it at night when the ground is cooler than the objects you are trying to see. Weather sensors have a different kind of emphasis than an recon imaging system would have. Meteorologists are typically more concerned about knowing the temperature of a given pixel accurately, rather than the spatial resolution of that pixel. Most kinds of clouds are either partly or completely opaque to both visible and infrared radiation - you can't see the ground through them. I don't know too much about radar, but at microwave wavelengths, clouds are pretty transparent. I imagine that synthetic aperture radar (SAR) technology would be used. Oceanographic SAR aims for height resolution on the scale of centimeters, so you can imagine the resolution defense sensors would be working at. Check out "Jane's all the world's satellites" - a pretty good reference. Cheers, Liam. -- tgumleyle@cc.curtin.edu.au #Liam E. Gumley, Department of Applied Physics, Curtin University of Technology# #Perth, Western Australia. >>>All opinions expressed are exclusively mine.<<<#
mcdonald@aries.scs.uiuc.edu (Doug McDonald) (02/08/91)
In article <7000.27b11bd8@cc.curtin.edu.au> Gumley_LE@cc.curtin.edu.au (Liam Gumley) writes: > >Visible sensors obviously only work during the daytime. No so. Have you ever noticed that you can see things at night? Modern electronic sensors can do even better. Moonlight gives enough light for anything. Starlight is sufficient for many purposes. Doug McDonald