It was designed for a parachute snatch recovery, so it must not have had any sort of underwater signalling device aboard to help locate it. Even if the recovery pilot saw it actually hit the water, there was no GPS in those days, how did they know where exactly where it was? LORAN?

Finding that dude was a remarkable achievement, even more so than the remote sensing aspect was, in 1971. KEYHOLE data was already obsolete when I started in remote sensing in the late 70s. Everything was digital, right off the sensor platform.

Its taken 41 years to declassify this. I wonder what is possible now, when money is no object.