[FPSPACE] What satellite bus was most used?

[Allen Thomson]

Matt Billie said,

> The National Museum of the US Air Force  website  credits the odd-looking 
> Lockheed Research Satellite with being the basis  for
 a large number of different missions, although I haven't found any of 
them.

[ http://www.wpafb.af.mil/museum/space_flight/sf6b.htm ]

I'm not totally sure, but I think this was used as the bus for some of the 
USAF's early low earth orbit electronic intelligence (ELINT) satellites.