A Spy Satellite You’ve Never Heard of Helped Win the Cold War

In the early 1970s, the Cold War had reached a particularly frigid moment, and U.S. military and intelligence officials had a problem. The Soviet Navy was becoming a global maritime threat-and the United States did not have a global ocean-surveillance capability. Adding to the alarm was the emergence of a new Kirov class of nuclear-powered guided-missile battle cruisers, the largest Soviet vessels yet. For the United States, this situation meant that the perilous equilibrium of mutual assured destruction, MAD, which so far had dissuaded either side from launching a nuclear strike, could tilt in the wrong direction.

It would be up to a top-secret satellite program called Parcae to help keep the Cold War from suddenly toggling to hot. The engineers working on Parcae would have to build the most capable orbiting electronic intelligence system ever.

It was becoming obvious what the challenges were," says Lee M. Hammarstrom, an electrical engineer who over a 40-year period beginning in the 1960s was in the thick of classified Cold-War technology development. His work included the kind of satellite-based intelligence systems that could fill the surveillance gap. The Soviet Union's expanding naval presence in the 1970s came on the heels of its growing prowess in antiaircraft and antiballistic missile capabilities, he notes. We were under MAD at this time, so if the Soviets had a way to negate our strikes, they might have considered striking first."

A Parcae satellite was just a few meters long but it had four solar panels that extended several meters out from the body of the satellite. The rod emerging from the satellite was a gravity boom, which kept the orbiter's signal antennas oriented toward Earth.NRO

Reliable, constant, and planetwide ocean surveillance became a top U.S. priority. An existing ELINT (electronic intelligence) satellite program, code-named Poppy, was able to detect and geolocate the radar emissions from Soviet ships and land-based systems, but until the program's last stages it could take weeks or more to make sense of its data. According to Dwayne Day, a historian of space technology for the National Academy of Sciences, the United States conducted large naval exercises in 1971, with U.S. ships broadcasting signals, and several types of ELINT satellites attempting to detect them. The tests revealed worrisome weaknesses in the country's intelligence-gathering satellite systems.

That's where Parcae would come in.

One of the big advances of the Parcae program was a three-satellite dispenser that could loft three satellites, which then functioned together in orbit as a group. Seen here are three Parcae satellites on the dispenser.Arthur Collier

Even the mere existence of the satellites, which would be built by a band of veteran engineers at the U.S. Naval Research Laboratory (NRL) in Washington, D.C., would remain officially secret until July 2023. That's when the National Reconnaissance Office declassified a one-page acknowledgment about Parcae. Since its establishment in 1961, the NRO has directed and overseen the nation's spy-satellite programs, including ones for photoreconnaissance, communications interception, signals intelligence, and radar. With this scant declassification, the Parcae program could at least be celebrated by name and its overall mission revealed during the NRL's centennial celebration that year.

Aspects of the Parcae program had been unofficially outed over the years by a few enterprising journalists in such venues as Aviation Week & Space Technology and The Space Review, by historians like Day, and even by a Russian military advisor in a Ministry of Defense journal. This article is based on these sources, along with additional interviews and written input from Navy engineers who designed, built, operated, and managed Parcae and its precursor satellite systems. They confirm a commonly held but nevertheless profound understanding about the United States during that era. Simply put, there was nothing quite like the paranoia and high stakes of the Cold War to spur engineers into creative frenzies that rapidly produced brilliant national-security technologies, including surveillance systems like Parcae.

A Spy Satellite with a Cosmic Cover Name

Although the NRO authorized and paid for Parcae, the responsibility to actually design and build it fell to the cold-warrior engineers at NRL and their contractor-partners at such places as Systems Engineering Laboratories and HRB Singer, a signal-analysis and -processing firm in State College, Pa.

Parcae was the third Navy satellite ELINT program funded by the NRO. The first was a satellite called GRAB, about as big as an exercise ball. GRAB stood for Galactic Radiation and Background experiment, which was a cover name for the satellite's secret payload; it also had a bona fide solar-science payload housed in the same shell [see sidebar, From Quartz-Crystal Detectors to Eavesdropping Satellites"]. On 22 June 1960, GRAB made it into orbit to become the world's first spy satellite, though there was no opportunity to brag about it. The existence of GRAB's classified mission was an official secret until 1998.

A second GRAB launched in 1961, and the pair of satellites monitored Soviet radar systems for the National Security Agency and the Strategic Air Command. The NSA, headquartered at Fort Meade, Md., is responsible for many aspects of U.S. signals intelligence, notably intercepting and decrypting sensitive communications all over the world and devising machines and algorithms that protect U.S. official communications. The SAC was until 1992 in charge of the country's strategic bombers and intercontinental ballistic missiles.

The Poppy Block II satellites, which had a diameter of 61 centimeters, were outfitted with antennas to pick up signals from Soviet radars [top]. The signals were recorded and retransmitted to ground stations, such as this receiving console photographed in 1965, designated A-GR-2800. NRO

The GRAB satellites tracked several thousand Soviet air-defense radars scattered across the vast Russian continent, picking up the radars' pulses and transmitting them to ground stations in friendly countries around the world. It could take months to eke out useful intelligence from the data, which was hand-delivered to NSA and SAC. There, analysts would examine the data for signals of interest," like the proverbial needle in a haystack, interpret their significance, and package the results into reports. All this took days if not weeks, so GRAB data was mostly relevant for overall situational awareness and longer-term strategic planning.

In 1962, the GRAB program was revamped around more advanced satellites, and rechristened Poppy. That program operated until 1977 and was partially declassified in 2004. With multiple satellites in orbit, Poppy could geolocate emission sources, at least roughly.

Toward the end of the Poppy program, the NRL satellite team showed it was even possible, in principle, to get this information to end users within hours or even less by relaying it directly to ground stations, rather than recording the data first. These first instances of rapidly delivered intelligence fired the imaginations, and expectations, of U.S. national-security leaders and offered a glimpse of the ocean-surveillance capabilities they wanted Parcae to provide.

How Parcae Inspired Modern Satellite Signals Intelligence

The first of the 12 Parcae missions launched in 1976 and the last, 20 years later. Over its long lifetime, the program had other cryptic cover names, among them White Cloud and Classic Wizard. According to NRO's declassification memo, it stopped using the Parcae satellites in May 2008.

Originally designed as an intercontinental ballistic missile (ICBM), the Atlas F was later repurposed to launch satellites, including Parcae. Peter Hunter Photo Collections

Initially, Parcae launches relied on an Atlas F rocket to deliver three satellites in precise orbital formations, which were essential for their geolocation and tracking functions. (Later launches used the larger Titan IV-A rocket.) This triple launching capability was achieved with a satellite dispenser designed and built by an NRL team led by Peter Wilhelm. As chief engineer for NRL's satellite-building efforts for some 60 years until his retirement in 2015, Wilhelm directed the development of more than 100 satellites, some of them still classified.

One of the Parcae satellites' many technical breakthroughs was a gravity-gradient stabilization boom, which was a long retractable arm with a weight at the end. Moving the weight shifted the center of mass of the satellite, enabling operators on the ground to keep the satellite antennae facing earthward.

The satellites generally worked in clusters of three (the name Parcae comes from the three fates of Roman mythology), each detecting the radar and radio emissions from Soviet ships. To pinpoint a ship, the satellites were equipped with highly precise, synchronized clocks. Tiny differences in the time when each satellite received the radar signals emitted from the ship were then used to triangulate the ship's location. The calculated location was updated each time the satellites passed over.

A GRAB satellite was prepared for launch in 1960. Peter Wilhelm is standing, at right, in a patterned shirt.NRO

Transmissions from the GRAB satellites were received in huts" [left], likely in a country just outside Soviet borders. In between the two banks of receivers in this photo is the wheel used for manually steering the antennas. These yagi antennas [right] were linearly polarized.NRO

The satellites collected huge amounts of data, which they transmitted to ground stations around the world. These stations were operated by the Naval Security Group Command, which performed encryption and data-security functions for the Navy. The data was then relayed via communications satellites to Naval facilities worldwide, where it was correlated and turned into intelligence. That intelligence, in the form of Ships Emitter Locating Reports, went out to watch officers and commanders aboard ships at sea and other users. A report might include information about, for example, a newly detected radar signal-the type of radar, its frequencies, pulse, scan rates, and location.

The simultaneous detection of signals from different kinds of emitters from a single location made it possible to identify the class of the ship doing the emitting and even the specific ship. This kind of granular maritime reconnaissance began in the 1960s, when the NRL developed a ship surveillance capability known as HULTEC, short for hull-to-emitter correlation.

Early Minicomputers Spotted Signals of Interest

To scour the otherwise overwhelming torrents of raw ELINT data for signals of interest, the Parcae program included an intelligence-analysis data-processing system built around then-high-end computers. These were likely produced by Systems Engineering Laboratories, in Fort Lauderdale, Fla. SEL had produced the SEL-810 and SEL-86 minicomputers used in the Poppy program.

These machines included a real-time interrupt capability," which enabled the computers to halt data processing to accept and store new data and then resume the processing where it had left off. That feature was useful for a system like Parcae, which continually harvested data. Also crucial to ferreting out important signals was the data-processing software, supplied by vendors whose identities remain classified.

The SEL-810 minicomputer was the heart of a data-processing system built to scour the torrents of raw data from the Poppy satellites for signals of interest. Computer History Museum

This analysis system was capable of automatically sifting through millions of signals and discerning which ones were worthy of further attention. Such automated winnowing of ELINT data has become much more sophisticated in the decades since.

The most audacious requirement for the Parcae system was that the intercept-to-report" interval-the time between when the satellite detected a signal of interest and when the report was generated-take no more than a few minutes, rather than the hours or days that the best systems at the time could deliver. Eventually, the requirement was that reports be generated quickly enough to be used for day-to-day and even hour-to-hour military decision making, according to retired Navy Captain Arthur Art" Collier. For six years, Collier served as the NRO program manager for Parcae. In a time of mutual assured destruction, he notes, if the intercept-to-report delay was longer than the time it took to fry an egg, national security leaders regarded it as a vulnerability of potentially existential magnitude.

Over time, the Ships Emitter Locating Reports evolved from crude teletype printouts derived from raw intercept data to more user-friendly forms such as automatically displayed maps. The reports delivered the intelligence, security, or military meaning of the intercepts in formats that naval commanders and other end users on the ground and in the air could grasp quickly and put to use.

Parcae Tech and the 2-Minute Warning

Harvesting and pinpointing radar signatures, though difficult to pull off, wasn't even the most sobering tech challenge. Even more daunting was Parcae's requirement to deliver sensor-to-shooter" intelligence-from a satellite to a ship commander or weapons control station-within minutes.

According to Navy Captain James Mel" Stephenson, who was the first director of the NRO's Operational Support Office, achieving this goal required advances all along the technology chain. That included the satellites, computer hardware, data-processing algorithms, communications and encryption protocols, broadcast channels, and end-user terminals.

From Quartz-Crystal Detectors to Eavesdropping Satellites

The seed technology for the U.S. Navy's entire ELINT-satellite story goes back to World War II, when the Naval Research Laboratory (NRL) became a leading developer in the then-new business of electronic warfare and countermeasures. Think of monitoring an enemy's radio-control signals, fooling its electronic reconnaissance probes, and evading its radar-detection system.

NRL's foray into satellite-based signals intelligence emerged from a quartz-crystal-based radio-wave detector designed by NRL engineer Reid Mayo that he sometimes personally installed on the periscopes of U.S. submarines. This device helped commanders save their submarines and the lives of those aboard by specifying when and from what direction enemy radars were probing their vessels.

In the late 1950s, as the Space Age was lifting off, Mayo and his boss, Howard Lorenzen (who would later hire Lee M. Hammarstrom), were perhaps the first to realize that the same technology should be able to see" much larger landscapes of enemy radar activity if the detectors could be placed in orbit. Lorenzen was an influential, larger-than-life technology visionary often known as the father of electronic warfare. In 2008, the United States named a missile-range instrumentation ship, which supports and tracks missile launches, after him.

Lorenzen's and Mayo's engineering concept of raising the periscope" for the purpose of ELINT gathering was implemented on the first GRAB satellite. The satellite was a secret payload that piggybacked on a publicly announced scientific payload, Solrad, which collected first-of-its-kind data on the sun's ultraviolet- and X-ray radiation.

That data would prove useful for modeling and predicting the behavior of the planet's ionosphere, which influenced the far-flung radio communication near and dear to the Navy. Though the United States couldn't brag about the GRAB mission even as the Soviet Union was scoring first after first in the space race, it was the world's first successful spy payload in orbit, beating by a few months the first successful launch of Corona, the CIA's maiden space-based photoreconnaissance program.

A key figure in the development of those user terminals was Ed Mashman, an engineer who worked as a contractor on Parcae. The terminals had to be tailored according to where they would be used and who would be using them. One early series was known as Prototype Analysis Display Systems, even though the prototypes" ended up deployed as operational units.

Before these display systems became available, Mashman recalled in an interview for IEEE Spectrum, Much of the data that had been coming in from Classic Wizard just went into the burn bag, because they could not keep up with the high volume." The intelligence analysts were still relying on an arduous process to determine if the information in the reports was alarming enough to require some kind of action, such as positioning U.S. naval vessels that were close enough to a Soviet vessel to launch an attack.

To make such assessments, the analysts had to screen a huge number of teletype reports coming in from the satellites, manually plotting the data on a map to discern which ones might indicate a high-priority threat from the majority that did not. When the prototype" display systems became available, Mashman recalls, the analysts could all of a sudden, see it automatically plotted on a map and get useful information out of it.... When some really important thing came from Classic Wizard, it would [alert] the watch officer and show where it was and what it was."

Data overload was even more of a problem aboard ship or in the field, so NRL engineers developed the capability to deliver the data directly to computers onboard ships and in the field. Software automatically plotted the data on geographic displays in a form that watch officers could quickly understand and assess.

These capabilities were developed during shoulder-to-shoulder work sessions between end users and engineers like Mashman. Those sessions led to an iterative process by which the ELINT system could deliver and package data in user-friendly ways and with a swiftness that was tactically useful.

Parcae's rapid-dissemination model flourished well beyond the end of the program and is one of Parcae's most enduring legacies. For example, to rapidly distribute intelligence globally, Parcae's engineering teams built a secure communications channel based on a complex mix of protocols, data-processing algorithms, and tailored transmission waveforms, among other elements.

The communications network connecting these pieces became known as the Tactical Receive Equipment and Related Applications Broadcast. As recently as Operation Desert Storm, it was still being used. During Desert Storm, we added imagery to the...broadcast, enabling it to reach the forces as soon as it was generated," says Stephenson.

Over the course of a 40-year career in national security technologies, Lee M. Hammarstrom rose to the position of chief scientist of the National Reconnaissance Office. U.S. Naval Research Laboratory

According to Hammarstrom, Parcae's communications challenges had to be solved concurrently with the core challenge of managing and parsing the vast amounts of raw data into useful intelligence. Coping with this data deluge began with the satellites themselves, which some participants came to think of as orbiting peripherals."

The term reflected the fact that the gathering of raw electronic signals was just the beginning of a complex system of complex systems. Even in the late 1960s, when Parcae's predecessor Poppy was operational, the NRL team and its contractors had totally reconfigured the satellites, data-collection system, ground stations, computers, and other system elements for the task.

This data density" issue had become apparent even with GRAB 1 in 1960. Those who saw the first data harvests were astonished by how much radar infrastructure the Soviet Union had put in place. Finding ways of processing the data became a primary focus for Hammarstrom and an emerging breed of electronic, data, and computer engineers working on these highly classified programs.

Collier notes that in addition to supporting military operations, Parcae was available to help provide maritime-domain awareness for tracking drug, arms and human trafficking as well as general commercial shipping."

Those who built and operated Parcae and those who relied on it for national security stress that so much more of the story remains classified and untellable. As they reminisced in interviews that can't yet be fully shared, engineers who made this spy satellite system real say they had not been more professionally and creatively on fire before or after the program. Parcae, though a part of the Cold War's prevailing paradigm of mutual assured destruction, proved to be a technological adventure that gave these engineers joy.

This article appears in the February 2025 print issue.