While developing the A-12 Oxcart, which would evolve into the SR-71, Annie Jacobsen explains (in Area 51), the CIA feared the Russians were watching from space:
Across the world, at NII-88, Sergei Korolev had designed a Soviet spy satellite called Object D, but the CIA did not know what exactly it was capable of. Also under way was a follow-on espionage platform called Zenit, a modified version of the Vostok spacecraft that had been equipped with cameras to photograph American military installations from space. The Russians took great delight in rubbing what they learned in the face of the State Department. Once, using diplomatic channels, they passed a simple sketch of the exact shape of Lockheed’s top secret airplane to the CIA, whose employees were baffled as to how the enemy could have known such a thing, in view of the fact that operations personnel had been very careful to avoid the orbiting Soviet snoopers. Was there a double agent among them? The CIA, ever paranoid about KGB infiltration, worried in private that there could be a spy inside Area 51. Lovick finally figured it out: the Russians were using infrared satellites. In the desert heat, which could reach 125 degrees Fahrenheit in the summer, the mock-up of the aircraft left a heat signature as it sat on the tarmac while technicians were waiting to hoist it up on the test pole. The sketch reflected that.