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.