Into the Black: NASA’s Secret Shuttle Missions – Part Four

"Into the Black" continues with a review of STS-38, the 37th flight of the space shuttle era and the seventh dedicated Department of Defense mission. Photo Credit: NASA

 The Secret History of NASA’s Middle Child: Part 4: The Mystery of the ‘Prowler’

‘High profile’ are two words which can easily be applied to Dick Covey’s NASA career. During his 16-year tenure as an astronaut, he rendezvoused with a crippled satellite, piloted the first post-Challenger mission and commanded the singular shuttle flight which restored NASA’s reputation in the eyes of politicians and public alike: the repair of the Hubble Space Telescope. Yet there is one aspect of Covey’s career which was far quieter and which continues to arouse debate to this day. Early in 1989, Covey replaced Brewster Shaw as the astronaut office’s lead representative on the Department of Defense Shuttle missions. On paper, the assignment looked relatively non-descript. In reality, it exposed Covey to the innermost details of the Shuttle’s most secret assignments…missions which, even today, remain shrouded in myth, mystery and rumor. 

The insights which Covey received were greater than those to which even the astronauts assigned to the classified flights were normally privy. “Each crew was read into the particular DoD program that they were supporting,” he explained to NASA’s oral historian, “but there needed to be someone who was aware of what all of those missions were going to be doing and working that interface with the appropriate agencies within the DoD to make sure that the crew issues that may cross all of those were being taken of.” Covey’s mandate was to manage the classified materials and the staff whose involvement with the missions demanded a level of security clearance beyond Top Secret. Many of the meetings attended by Covey were held in “special environments” and the crucial nature of his role is underlined by the fact that even the astronauts for one DoD mission did not necessarily know what their fellow astronauts, assigned to another DoD mission, might be working on. 

From STS-27 in December 1988 until his own flight, STS-38, in late 1990, Covey was thus involved on an intimate level with the planning and preparation of these secret flights and was exposed to details of classified payloads whose existence continues to be officially denied or concealed. Many observers considered the missions ‘boring’, since so little was known about them. In truth, they were quite the reverse. “There were exciting things going on in DoD space back then,” Covey recalled, cryptically. “There still are. And being a part of that, then, with my military background and being able to support all that was really very, very cool.” Indeed, more than one astronaut has said that his involvement in these missions was the crowning glory of his professional career, as an astronaut, as an active-duty military officer and as a patriot, since each flight placed a new element of the United States’ national security arsenal into orbit. 

Over time, some details have emerged. In the late 1990s, images of one classified payload (a pair of military communications satellites, launched by Mission 51J) were released and photographs of a second-generation Lacrosse radar-imaging sentinel, under construction, also trickled into the public domain. Speculation over the physical appearance and capabilities of these payloads has been rife and excitable: sketches of the gigantic Magnum satellites, with their vast ‘farms’ of antennas, are readily available on the Internet, and observations of the peculiar ‘disappearance’ and ‘reappearance’ of STS-36’s optically stealthy Misty satellite have been made by professional astronomers and amateur skywatchers alike. Then, in 1999, came the first mutterings that Dick Covey’s own DoD mission – a five-day flight in November 1990, thought to have carried a military telecommunications relay satellite for the National Reconnaissance Office – might also have launched a second, more covert payload, known only as ‘Prowler’. 

At the time of launch, the primary satellite for Covey’s mission was dubbed Air Force Program-658 (AFP-658) by the media and there was suspicion that it was a Magnum electronic intelligence platform, deployed atop a Boeing-built Inertial Upper Stage (IUS) booster. Saddam Hussein had invaded Kuwait only months earlier and the emplacement of this new intelligence monitor was expected to track the movement of his forces, in addition to the old enemy, the Soviet Union. However, when on-orbit images of Atlantis’ vertical stabilizer were revealed, many years later, they revealed no trace of the airborne support equipment – a doughnut-like ‘tilt table’ – known to have supported IUS-boosted satellites in the payload bay. More recently, it has become generally accepted that STS-38 deployed a member of the second-generation Satellite Data Systems (SDS-B) telecommunications relay satellites. It was not the first such launch from the Shuttle; in August 1989, the crew of Columbia were believed to have deployed a similar payload. 

In this view from STS-49, the repaired Intelsat 6-3 communications satellite drifts away into space, attached to an Orbus-21 solid rocket motor. Some observers have remarked that the SDS-B satellite, released on STS-38, closely resembled Intelsat-6, both in physical appearance, booster type and method of deployment. Photo Credit: NASA

Imagery and videotapes of an SDS-B under construction were released by the National Reconnaissance Office in the spring of 1998, as was the name of its prime contractor, Hughes, and its heritage seemed obvious: it was strikingly similar in appearance to the Syncom-4 military communications satellites, five of which were deployed from the Shuttle in a sideways, Frisbee-like motion. In a 2009 article for Air & Space magazine, Michael Cassutt quoted an Air Force source who was deeply familiar with the SDS-B project. “It’s strange,” he told Cassutt, “to work on a secret project for ten years, then see it on network television!” 

The Air Force began to develop the first-generation SDS in 1973 to offer America’s intelligence community with a network of orbiting relays, capable of transmitting real-time data and images from reconnaissance satellites which were out of range of ground stations. Another of their responsibilities was to support voice and data communications for covert military activities. The second-generation SDS-B operated in high-apogee and low-perigee orbits, ranging from as close as 480 km and as far as 38,000 km, at steep inclinations which achieved their highest point over the northern hemisphere. This enabled them to cover two-thirds of the globe; relay spy satellite data of the entire Soviet land mass and cover the entire North Polar Region in support of Air Force communications. Such wide coverage was not possible to geostationary-orbiting satellites.

The SDS-B featured a pair of 4.5 m dish antennas and a third, smaller dish for Ku-band downlink. Overall, the satellite measured 4 m long and 3 m wide, with a launch mass estimated at close to 3,000 kg. In total, three of this cylindrical SDS-Bs were deployed by the shuttle, on STS-28, STS-38 (Covey’s mission) in November 1990 and STS-53 in December 1992. Although it is unclear as to how they were deployed, some observers have assumed that they were released in a similar fashion to the Hughes-built Syncoms: in a ‘frisbee’ fashion. Others have noted that the solid rocket booster used for the SDS-B was an Orbus-21, physically identical to the motor later fitted to Intelsat 6-3 by spacewalking astronauts during STS-49 in May 1992. This has prompted alternative suggestions that the SDS-B was deployed ‘vertically’ from a special cradle in the payload bay, more like Intelsat 6-3 than the Syncom 4s. 

In whatever manner that SDS-B departed Atlantis, it is certain that the deployment was completed in the early hours of 16 November 1990, about seven hours after launch, after which the orbiter performed a separation burn to move to a safe distance in anticipation of the firing of the satellite’s motor. However, according to observer Ted Molczan, writing in February 2011, the delta-V of Atlantis’ burn was less than a tenth of what it should have been for a motor attached to a payload the size of an SDS-B. Moreover, he noted that the satellite itself lingered for some time in low-Earth orbit, rather than initiating its climb to geostationary altitude at the next available ascending node. 

Molczan explained that the second satellite, Prowler, was then deployed 22 hours later…after which Atlantis’ crew performed an unusual maneuver, by lowering their orbit, rather than raising it. “It also happened to arrest the separation from the SDS,” Molczan wrote, “and initiate a very gradual overtaking, perhaps to create the impression of a rough station-keeping maneuver [by Atlantis] to keep Soviet attention focused on the SDS.” It would also appear that the SDS-B finally fired its apogee motor during a 16.5-hour period which overlapped the firing of Prowler’s own motor. Detection by the Soviet-operated signals intelligence station at Lourdes, near Havana, might have been circumvented, Molczan continued, by timing the deployment of Prowler very carefully as Atlantis passed beyond the Cuban radar horizon. 


In the pre-Challenger era, many satellites based upon Hughes' HS-376 bus were deployed from the Shuttle. This view shows the general appearance of the payload, together with the spherical PAM-D booster at its base, and highlights the method of deployment. Was Prowler of similar design? Photo Credit: NASA

What was Prowler, what did it look like and what did it do? Even now, the fiction and the speculation greatly outweighs the facts and the hard evidence. A case has been advanced that it was based upon Hughes’ HS-376 bus – very much like the cylindrical communications satellites launched on several Shuttle missions in the early 1980s – with an attached Payload Assist Module (PAM)-D to boost it into geostationary orbit. Molczan suggested a total payload weight of around 4,500 kg – of which 1,300 kg was the satellite itself, together with 2,100 kg for the PAM-D and the remainder for the support hardware in Atlantis’ bay – and argued that the ability of the shuttle to carry both it and the SDS-B would have been well within its performance envelope. 

Nonetheless, the STS-38 was heavy, as evidenced by its orbital altitude, which did not venture much higher than about 250 km. “You can read a lot into that,” Dick Covey admitted to NASA’s oral historian. “We didn’t go very high because we couldn’t go very high, which says we probably had a heavy payload. That was the thing that was really unique about the whole mission.” Of course, for much of the first decade after the conjectured launch of Prowler, its existence was unacknowledged. The presence of two spent rocket motors – codenamed ‘1990-097C’ and ‘1990-097D’ – could be explained simply as representing the expended first and second stages of an IUS booster, without raising suspicion. 

As to Prowler’s nature, labels such as ‘geolocation platform’, ‘optically stealthy’ and ‘inspector’ have been banded around over the years and the consensus seems to be that it was some kind of low-observable satellite, employed to rendezvous and secretly inspect other nations’ satellites in geostationary orbit, 35,000 km above Earth. At face value, the mission seemed impossible. Some observers doubted that it was even possible, in 1990, to conduct unmanned rendezvous in geostationary orbit, long before it had been routinely performed in low-Earth orbit. Others countered that geostationary altitudes provide a more benign environment for tele-robotic operations and relative motion control and even wondered if Prowler might have performed radio frequency blocking; literally parking itself in front of a satellite’s antenna path to block its signals. Still others have gone further: that Prowler actually did attempt such blocking, albeit experimentally, on US communications satellites, and several analysts have argued that it could have positioned itself within 30 cm of a target.    

More than two decades later, the Department of Defense missions performed by the shuttle are far more than an insignificant footnote of history, for more details and more rumors continue to appear with every passing year. The flights once denigrated as ‘boring’ might actually have been some of the most exciting voyages ever undertaken by the reusable orbiters. The sense of pride harbored by so many military astronauts to have participated in these flights is tangible; a pride centered not only on completing an ambitious mission, or fulfilling an urgent national security need, but on setting to work a new masterpiece of technological prowess. As STS-38’s commander, Dick Covey was “read into” many of these levels of classification and restricted knowledge, sometimes more so than his fellow crew members. Families were kept out of the loop, as were other astronauts, and to this day, Covey knows many ‘things’ about his flight that remain Top Secret. “From that standpoint,” he said, “we still have a secret ‘ring’ [of people] and can nod at each other when we hear things or know things that we know that nobody else still knows about what we did and how we trained.”   

One interesting aspect of the STS-38 mission is that it included a rare move of two full-stack orbiters. On the left is space shuttle Columbia and on the right is Atlantis. Be sure to tune in tomorrow for the next "Into the Black" segment. Photo Credit: NASA

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