Subject:      Spysats: going higher?
From:         [email protected] (Allen Thomson)
Date:         1995/05/09
Message-Id:   <[email protected]>
Newsgroups:   sci.space.policy

     Various IC officials have made statements over the past two years 
which seem to have strong implications for the future of US satellite 
reconnaissance.  Departing DCI Woolsey's valedictory statement to the 
SSCI is typical: 


    "Pursuant to a plan that I put together in 1992, before I became 
    DCI, at the request of my predecessor, Bob Gates, we are in the 
    midst of cutting the number of reconnaissance satellites nearly 
    in half, and making even deeper cuts in ground stations." 

      World Threat Assessment Brief: Statement for the Record by R. 
      James Woolsey, Director of Central Intelligence, to the Senate 
      Select Committee on Intelligence, 10 January 1995, as prepared. 
      [Excerpt] 

     Other people, notably DNRO Jeffrey Harris and Keith Hall, DASDC3I, 
have said similar things in interviews and congressional hearings.  Just 
what all this means in concrete terms has been something of a mystery, 
but I believe that there may be some indication of the way things will 
go in a recent publication by an IC official.  The November 1994 issue 
of Aerospace America contained an article ("The Space Business and 
National Security, an Evolving Partnership") by DDCI Adm. William 
Studeman which is remarkable for its frankness:

         "Desert Storm did reveal some key shortfalls, the most 
    important of which can be tied to an inability to move data 
    with absolute efficiency and to provide the necessary total 
    coverage of the battlefield.   A major one, of course, is the 
    inability of low-orbit imaging satellites to consistently dwell 
    or to acquire synoptic imagery in sufficient quantities to meet 
    intensive tactical demands.  Similarly, because of bandwidth 
    demands of other architecture issues, we are plagued by 
    problems with the dissemination of imagery. 
    
         "In looking to the future we have kept these shortfalls in 
    mind and have developed strategies that should overcome them. A 
    main issue, though, is cost.  We are carefully weighing the 
    tradeoffs that will allow us to provide -- in a resource 
    constrained environment -- collection assets that most 
    effectively address these deficiencies and other needs of 
    military leaders and policy makers." 

     If the governing requirements are to provide longer dwell and 
synoptic imagery for battlefield use, then physics allows two 
possible solutions:  multiply the number of satellites in low orbit or 
maintain a constellation of a few vehicles but raise their orbits 
significantly.  Since cost is a major constraint, the development of new 
multisatellite systems or procurement of many more of the very expensive 
current type seem to be ruled out, as Woolsey et al. said.  So it looks 
as if the future holds a migration of big spysats to altitudes higher 
than the < 1000 km where they now seem to live.   The NRO's continuing 
requirement for heavy-lift vehicles is consistent with this idea. 

     As Kepler tells us, higher orbits are slower and provide longer 
time-over-target.  The additional time can be used to look at a limited 
area repeatedly, or to scan a large field of view.  If current spysats 
have the ~3 meter aperture commonly quoted in the open literature,  then 
they could back off to ~5000 km altitude and still have a resolution of 
1 meter, which is sufficient for most military and general 
reconnaissance purposes.  Transmitting less data per square meter of
target also sidesteps the bandwidth problem mentioned by Studeman.

     I've run simulations for a number of high-altitude orbits to see 
what kind of coverage they provide, and there are several promising 
possibilities.  Current favorites are  ~5500 km x 500 km direct and 
retrograde-sunsynchronous Molniya orbits that give high resolution at 
perigee and long dwell at apogee.  Argument of perigee could be adjusted 
to suit the needs of the moment. 

     Going high has the added attraction of making satellites a bit less 
vulnerable than those closer in.  Five to ten Mm altitudes would 
complicate the acquisition problem because the 1/r^4 dependence of 
monostatic radar/lidar and 1/r^2 dependence of passive optics/IR make 
the satellites harder to locate from the ground or LEO.  Secondarily, an 
ASAT weapon capable of reaching that high needs to be more expensive 
than one designed to reach low altitudes.  OTOH, the rapid advance and 
spread of technology make these advantages uncertain and probably 
transient, so a wise NRO would not count on them to keep its satellites 
safe. 

    The problem of dissemination could be partially addressed by 
providing direct downlinks to mobile user stations, rather than (or in 
addition to) data relay through other satellites to a central processing 
facility as is now apparently done.  This approach also would make 
possible a decrease in the number of fixed ground stations, consistent 
with Woolsey's remarks.