It was 1971 when US secret services discovered a nightmare: Soviet warships Kirov, armed with nuclear missiles, could evade radar. The answer? The Parcae Program, a constellation of spy satellites developed by the Naval Research Laboratory. Equipped with ELINT antennas and atomic clocks, these “orbital ears” triangulated every radio emission from the USSR, sending encrypted data to the aircraft carriers in 300 seconds. “It was like having Google Maps for the Navy, but in the 70's.“, he jokes Arthur Collier, former project manager. Yet, for 47 years, Parcae it remained a secret buried in classified documents. Have you ever heard of it?
Kirov: When the USSR Challenged the Balance of Terror
The battleships Kirov They were 28.000-ton monsters, armed with SS-N-19 nuclear missiles. In 1971, during secret exercises, the US realized that their spy satellites existing ones took weeks to process data from Soviet ships. Too late to react to an attack. The Pentagon feared that the USSR, thanks to these ships, could violate the MAD doctrine (Mutual assured destruction)1. A system was needed that could track every movement in real time.
Il Parcae Program was born from this urgency. “We had to move from strategic to tactical intelligence,” he explains Lee Hammarstrom, engineer of Naval Research Laboratory. Previous satellites, such as GRAB e poppy, collected data useful only for long-term analysis. Parcae would have instead provided precise coordinates within 2 minutes, directly connecting the space to the aircraft carriers' operations rooms.
“We weren’t playing chess. It was a game of Risk, with the survival of the species at stake.”
Ed Mashman, program engineer.
Parcae Technology: Atomic Clocks and the Trick of Gravity
The heart of the system was three spy satellites thrown together on a Atlas F, positioned in orbit at an altitude of 1.100 km. Each satellite had a steerable antenna and a gravity-gradient stabilization boom: an extendable rod with a weight at the end that, exploiting gravitational differences, kept the apparatus always facing Earth. “It looked like space origami,” he laughs Peter William, chief designer.
The real innovation was triangulation. The three satellites measured the arrival time of Soviet radar signals with clocks synchronized to the nanosecond. By comparing the delays, they calculated the position of the ship. with a margin of error of 500 meters. Today we would call it passive GPS, But unlike GPS, Parcae didn't transmit anything: it listened.
The data was encrypted and sent via Tactical Receiving Equipment, a secure protocol that made them accessible only to submarines and naval commands. A top secret Twitter. If a Kirov he turned on the radar, an alert came in in record time. There was only one problem: how to identify each ship, precisely, by its radar signature?
HULTEC: The Electronic “ID Card” of Enemy Ships
Today it is routine, but in the 70s it was a revolution. The system HULTEC (Hull-to-Emitter Correlation), developed by the NRL, matched each signal to a specific hull. “Each radar had a unique ‘signature,’ like a regional accent,” Hammarstrom explains. “A Kirov It emitted different frequencies than a submarine Delta, and Parcae recognized them”.
The raw data was processed by computers SEL 810, ancestors of artificial intelligence algorithms. These “minicomputers” (“mini” in a manner of speaking: they were still as big as refrigerators) filtered millions of signals, extracting only the relevant ones. Like looking for a needle in a haystack, while the haystack is on fire. The result? Reports like the Ships Emitter Locating Report, which indicated the type, position and potential threat of the ships.
“With HULTEC, we knew not only where the enemy was, but who was. A superpower in the shadows”
Dwayne Day, space historian.
Parcae Today: A Legacy Between Cybersecurity and Star Wars
Il Parcae Program was retired in 2008, but its legacy lives on today. The communication system Tactical Receiving Equipment It was adopted during the Gulf War to transmit satellite images in real time. HULTEC correlation techniques are used in cybersecurity to identify hackers by their digital “fingerprint”.
And in space? The principles of Parcae inspire modern satellites ELINT, like those of the constellation NROL-151, (those, unlike Parcae, are still classified). Parcae, however, taught us that espionage is not stealing secrets, but anticipating the future. A current lesson, while China and the USA launch new spy satellites for the next War (let's hope) Cold.
- The MAD doctrine, acronym for Mutual assured destruction (mutually assured destruction), is a military strategy developed during the Cold War. It is based on the idea that if two nuclear powers attacked each other, both would suffer catastrophic and inevitable damage, leading to the total destruction of both parties involved. ↩︎