Every day for decades, engineer Phil Pressel would come home from work and be unable to tell his wife what he'd been doing all day.
Now, Pressel is free to speak about his life's work: designing cameras for a top-secret U.S. government spy satellite. Officially known as the KH-9 Hexagon, engineers called it "Big Bird" for its massive size.
Until the government declassified it last month, Hexagon had been a secret for 46 years.
"The challenge for this satellite, to design it, was to survey the whole globe," Pressel tells weekends on All Things Considered host Guy Raz.
It was a grand challenge for Pressel. Born in Belgium, he survived the Holocaust as a young boy when a French family hid him from the Nazis. Pressel says he never expected to come to America, much less become an engineer on a top-secret American spy satellite.
Hexagon's main purpose was, in a way, to prevent wars. It was designed to spot Soviet missile silos and troop movements.
"It permitted President Nixon, in the early 1970s, to sign the SALT-1 treaty, the Strategic Arms Limitation Treaty," Pressel says. Photos sent down from Hexagon enabled the U.S. to verify the Soviet Union's claims about its weapons stockpiles.
Those photos themselves were a technological marvel. Pressel says that even 40 years after its original launch, Hexagon is still one of the most complicated vehicles ever to orbit the earth because it used film.
"It was the last film-recovery system used for reconnaissance," he says. Each Hexagon satellite launched with 60 miles worth of film and an immensely complicated electromechanical system that controlled the cameras.
Once a reel of film was finished, it was loaded into a re-entry pod and sent back to earth. "And then at around 50,000 feet, a parachute would slow it down, and a C-130 airplane caught it in midair over the Pacific," Pressel says.
After all the film was sent back to earth, the satellite was abandoned, and a new one launched, he says. Nineteen of them went up before the program ended in 1986.
Pressel says he's immensely proud of the work he and his colleagues did on Hexagon. "We did all of this incredibly complicated work with slide rules, without microprocessors, without solid state electronics," he says.
"We used old technology, and it worked!"
GUY RAZ, host: Every day for decades, Phil Pressel, an engineer, would come home from work, and he couldn't tell his wife anything about what he'd been doing all day. Pressel was designing the cameras for a top-secret U.S. government spy satellite. For 46 years, the government kept the project under wraps. But now, that satellite, known as the KH-9 Hexagon, has been declassified, and Pressel can finally talk about his life's work. And Phil Pressel joins me now in the studio. Welcome to the program.
PHIL PRESSEL: Yeah. Hi, Guy.
RAZ: Phil, explain what this satellite was meant to do.
PRESSEL: The challenge for this satellite, to design it, was to survey the whole globe. Its main purpose, actually, was the ability to verify missile silos and whatever armaments that the Russians had, and it permitted President Nixon, in the early 1970s, to sign the SALT 1 Treaty; SALT being Strategic Arms Limitation Treaty.
RAZ: What was it able to verify?
PRESSEL: It verified the number of airplanes, tanks in one shot, because it orbited the Earth in a polar orbit. While the Earth was rotating beneath it, it could cover the whole Earth. Previous cameras took spotty pictures, and they could move tanks, move planes. And this way, we could count - I mean, the government - could count everything.
RAZ: It reminds me of President Reagan's famous dictum: trust, but verify.
RAZ: And this was the verify.
PRESSEL: This was the verify.
RAZ: You have described this as the most complicated vehicle ever sent into orbit at the time...
PRESSEL: Yes. Right.
RAZ: ...more complicated than the Apollo missions and those vehicles?
PRESSEL: Yes. This - it is believed by not only those of us who worked on it but by experts in the government and in industry that it still is the most complicated thing ever put up in orbit.
PRESSEL: Because it had film, and it was the last film recovery system that was used at the time.
RAZ: Actual film.
PRESSEL: Actual film. It was all mechanical and, most importantly, electronically controlled. The servile mechanisms controlled the speed of the film relative to the image of the Earth.
RAZ: OK. If this was orbiting the Earth and taking pictures on film, how did you actually get the film back to develop it?
PRESSEL: The film canisters were sent back to Earth in a re-entry vehicle that re-entered the atmosphere just like the astronauts used to do...
RAZ: Which was launched out of the satellite.
PRESSEL: Right. And then, at around 50,000 feet, a parachute slowed it down and a C-130 airplane caught it in midair over the Pacific...
PRESSEL: ...brought it back to Earth and then it was developed.
RAZ: Phil, you actually were not born in the United States. You came here as...
PRESSEL: I was born in Antwerp, Belgium.
RAZ: You came here as a child after the war.
PRESSEL: Yeah, yeah. I'm basically a Holocaust survivor.
RAZ: Could you ever have imagined that you would, as an adult, live in the United States and take part in what clearly was a critical program for the United States and its efforts during the Cold War?
PRESSEL: Absolutely not. I couldn't even conceive of living anywhere else but in Europe.
RAZ: Phil, I noticed you have an iPhone. And as you know, right here in the studio, you and I can go on your iPhone using Google Earth, and we can locate pretty much any location, at least in cities, around the world. You can really zoom in. I can find your house.
RAZ: You're - you live in San Diego.
RAZ: And that is pretty incredible technology. And if you think about it, it's available to everybody now.
RAZ: And your technology was just available to a secret select few people.
RAZ: Had you imagined that we would come this far as a...
PRESSEL: No. Could not imagine it. And the other thing is that we did all of this incredibly complicated work with slide rules, without microprocessors, without solid state electronics, without CCDs, LEDs, and we used old technology. And it worked.
RAZ: That's Phil Pressel. He designed the cameras for the recently declassified KH-9 Hexagon spy satellite. He joined me here in the studio. Phil, thanks for coming in.
PRESSEL: You're very welcome. Pleasure. Transcript provided by NPR, Copyright NPR.