The SR-71 was a hack, where the goal was to use 1960s technology to make an areal camera platform that could photograph targets protected by SAMs. The original

The SR-71 was a hack, where the goal was to use 1960s technology to make an areal camera platform that could photograph targets protected by SAMs. The original design brief was that it should be a stealth U2, but as the A-12/SR-71 project developed it became clear that that wasn't possible with the technology of the time, but that they could make a platform that flew so fast the SAMs wouldn't have time to lock, launch, and intercept. There were suborbital spy satellites available before the A-12 even flew: http://en.wikipedia.org/wiki/Corona_%28satellite%29 http://en.wikipedia.org/wiki/Corona_%28satellite%29 The problem was that the cost of the keyhole program was incredible, you needed a whole launch platform plus a whole recovery mission every time you wanted to take a picture. So the SR-71 was a cost-saving measure versus Keyhole. Currently the us military can get the information that the SR-71 could provide more easily and with less danger and cost.