Space history expert Sven Grahn describes on his website the fairly extensive efforts the US intelligence community undertook, as a joint effort between several agencies, to monitor signals from Soviet deep space probes starting in 1960. One technical barrier that made this especially difficult was the geographic location of the Russian ground station in the Crimea. Since the probes only transmitted when visible to the station, any intercept site would need to be as near as possible -- at least on the same meridian -- so it would rotate into view of the transmitter at the same time as the Crimean station. This was a bit complicated because of political changes, as the US lost access to deep space monitoring sites in Eritrea (Kagnew Station, code name STONEHOUSE) and Turkey just as they would have been useful for this effort (and probably a number of others). This was no doubt not just a US project, but likely operated in cooperation with at least the intelligence agencies of the UK -- the type of thing that would tend to be a closely held secret.
The newly released document describes NSA's effort to find the Soviet deep-space "broadband signal" that the planetary probes used to transmit data such as radar mapping imagery, video, and other high-rate telemetry. As the document portrays it, the search for this signal was ineffective for many years due to various factors, including the geographic problem mentioned above, unpredictable downlink schedules, and uncertainty as to the exact frequency used by the transmitter. (CIA technicians examined antenna waveguides on display models of the Soviet spacecraft at expositions to help narrow the options to the 5.6 to 6.3 Ghz range, which was only of limited help due to the huge potential frequency range in question). Several Soviet Mars and Venus probes successfully sent back large amounts of data and imagery during the 1960s and 70s, but western intelligence agencies were unable to intercept these potentially important signals. So when the Russians launched twin probes to Venus in 1983 (Venera 15 and 16) that featured large radar antennas and were intended to produce the first synthetic aperture radar maps of the planet's surface, the NSA and its divisions, particularly DEFSMAC, the Defense Special Missile and Astronautics Center, were determined to solve the technical puzzle once and for all.
Improvements in receiver sensitivity apparently allowed the intercept effort to be conducted farther from the Crimean ground station than in earlier cases, but what really made a breakthrough possible was a new computerized signal analyzer that operated like a super radio scanner, capable of monitoring tens of thousands of channels simultaneously. The mobile system belonged to NASA's Search for Extraterrestrial Intelligence program (although it may not have been built for this specific type of "extraterrestrial intelligence"...). It was apparently the first of its kind, built by the Jet Propulsion Laboratory as a prototype of systems intended to be used in future full-scale SETI efforts. The van-mounted system was also used to monitor signals from US deep space missions such as the Voyager probes. (The unit was intended to be sited at radio telescopes in various parts of the world to study the radio interference background in order to determine which bands might even be usable for future ETI-signal listening projects -- see Sullivan, 1984).
The mobile system was called Radio Frequency Interference Surveillance System (RFISS). According to a 1981 NASA document,
Science Utilization of the Radio Frequency Interference Surveillance System (SURFISS), a program sponsored by the [JPL] Director's Discretionary Fund, is designed to utilize JPL's 65,000-channel Radio Frequency Interference Surveillance System (RFISS) for radio astronomical studies. The RFISS is a unique microwave spectrum analyzer developed to detect radio frequency interference (RFI) at the DSN facility at Goldstone. It is a trailer-based microwave receiver and data processing system which includes a 65,000-channel spectrum analyzer. The receiver and spectrum analyzer are controlled by a Modcomp II computer, allowing the RFISS to process two 10-MHz channels into 32,000 channels, each with a resolution of 305 Mhz.
The RFISS was connected to the 26-m antenna receiver system at DSS 13 (Venus Station) in September 1981 in order to carry out the first step of the SURFISS program. Both S- and X-band signals were coupled to the RFISS for these tests. [Shaffer, 1981]The Director of the Jet Propulsion Laboratory when RFISS was used for the intercept operation was retired four-star Air Force general Lew Allen. Prior to becoming JPL director, Allen had headed the National Security Agency from 1973-77, after which he served as Air Force Chief of Staff from 1978-82.
The declassified NSA document describes their appropriation of the RFISS van for the Venera intercept mission:
(S//SI)With the Soviet spacecraft on their way to Venus, [-several words redacted-] obtained permission [redacted] to use the facility to cover the Venera satellites due to arrive at Venus in October. [-several words redacted-] allowed a search until 15 October,[-redacted-] NASA arranged for the pickup of the van. A USAF C-5A was flown in and the van loaded - it barely fit. It was flown to the [-several words redacted-], and towed to the observatory. By early October the van was hooked up. On 10 and 14 October Venera 15 and 16, respectively, arrived in orbit. The command link,[-redacted-] was active and monitored by a number of ground sites. The information from this link was relayed by DEFSMAC to collectors [-redacted-]. (The [-redacted-] was separated from the regular observatory personnel. The SETI specialists were given sanitized search parameters and limited feedback on results.)
So where was the observatory where this spooky activity went down? According to a helpful contemporary NASA report, it was Jodrell Bank, England. As the civilian report explains it,
Field tests have begun using an existing 216-channel spectrum analyzer...built at JPL originally as a radio frequency interference (RFI) surveillance system (RFISS)....Of particular interest are the presence and character of RFI at potential [SETI] observing sites. These interfering signals, not catalogued in advance, will cause long hours of delay while observers study a particular signal to determine whether it is of terrestrial origin, from a regularly passing satellite, or indeed from beyond the solar system....During September through November 1983, the Nuffield Radio Astronomy Laboratories at Jodrell Bank, England, made available to the SETI project a large amount of observing time on a new, moderately sensitive radio telescope at frequencies near 1420 Mhz. This opportunity came at a time when field tests were just beginning, and the required time was not available at other observatories....
Therefore, the JPL mobile spectrum analyzer was shipped to Jodrell Bank for several weeks (1) to collect RFI environment at a major observatory in a frequency band of critical importance, and (2) to determine how to improve the methods and associated software used to collect RFI data.The 12.8-m dish was used to scan the horizon and point at the Moon to gather RFI background data, as well as attempt some SETI scans within 25 parsecs of the Sun -- officially. But every time Venus broke the horizon, the intelligence search went into action. The NSA story continues:
(S//SI)However, the Soviets refused to cooperate. They spent the first several weeks adjusting the orbits of the two satellites over Venus's polar regions and made little use of the broadband data link to transmit back pictures. On October 15 the period allotted for the intercept ended. [-redacted-], probably interested in the effort, offered another week, beginning on 7 November, to search again for the signal. Personnel at the site spent the next three weeks adjusting and calibrating the equipment. While they waited, their frustration grew when the Soviets announced that on October 19 the first radar pictures covering a million square kilometers had been transmitted back to earth. On 8 November the [-several words redacted-] with the RFI van was turned on and the search began again.
The person who was "interested in the effort", and gave permission to extend it, may have been the Jodrell Bank director at the time, Dr Francis Graham-Smith. The radio observatory had a long history of monitoring Soviet deep-space probes (with and without Russian blessing) going back to the Bernard Lovell era, making the NSA/SETI mission just one of a series of such activities. But the highly covert measures taken in this case seem to imply that the SIGINT agencies didn't want the Soviets to know, during this especially rocky phase of the Cold War, just how much of an interest they were taking in Russian space data-transmission technology.
(S)Shortly after midnight on 9 November, Venus rose above the horizon. The antennas at [-several words redacted-] and at other sites, began listening. DEFSMAC coordinated the search. The [-redacted-] uplink in the Crimea passed instructions to the two Venera spacecraft to start the radar mapping of the surface of Venus. The two spacecraft began their mission. At 0635Z a teletypewriter at DEFSMAC clattered briefly with a crisp message [-redacted-] "We have it. [-redacted-] The twenty-one-year search was over.
It seems likely that there is an interesting thread of linkage between SETI and Cold War signals intelligence research, but it's equally probable that it will remain a murky connection for many years to come.
View the declassified NSA/SETI document at Governmentattic.org
Downs, GS and S Gulkis, "SETI Investigations at Jodrell Bank, England: September Through November 1983", TDA Progress Report 42-76 (Oct-Dec 1983)
Shaffer, RD, et al, "Radio Astronomy", TDA Progress Report 42-66 (Sept-Oct 1981)
Sullivan, "The Radio Frequency Interference Problem", SETI Science Working Group Report, 1984