In spite of his achievements as an astronaut, one of Mike Mullaneâ€™s greatest regrets was losing the chance to fly into polar orbit, becoming one of the first humans to do so.
Unlike his first mission in August 1984, Mullaneâ€™s second flight would begin from an untried Shuttle launch complex in California and carry its own risks and uncertainties.
â€œI was looking forward to that so much,â€ he told an interviewer in January 2003, only days before the Columbia disaster, â€œbecause youâ€™re basically going to see the whole world!â€
Since the dawn of the space age, each US manned mission had flown from Cape Canaveral in Florida. That monopoly, however, was set to change in July 1986 with the launch of Discovery from Vandenberg Air Force Base, a 150-square-mile site midway between San Francisco and Los Angeles. It had been chosen to stage a series of military Shuttle missions carrying top-secret Department of Defense payloads into high-inclination polar orbits. Moreover, NASAâ€™s agreement to detail one of its orbiters to Vandenberg on a more-or-less permanent basis acknowledged the Air Forceâ€™s political support for the Shuttle during its development.
One of the most significant satellites destined to be launched from the Californian base was the state-of-the-art KH-12 imaging platform, which many observers felt could not reach its required polar orbit from Florida. In accordance with normal safety criteria, Shuttle missions could typically achieve maximum orbital inclinations of 57 degrees, although polar trajectories were technically feasible by executing â€˜doglegâ€™ manoeuvres during ascent. However, the additional energy needed for the orbiter and its attached External Tank to â€˜turnâ€™ at such high velocities during the dynamic climb to space would force a 30% reduction in payload capacity.
The implications, articulated by a high-ranking Air Force official during testimony to Congress in 1978, was that heavy KH-12 and other polar launches â€“needed to cover the majority of the Soviet and Chinese landmasses â€“ could not be effectively achieved from the East Coast. Additionally, in the run-up to the first Shuttle mission, and with NASAâ€™s rhetoric of routine, fortnightly missions ringing in its ears, the Department of Defense was already developing payloads whose size, weight and complexity specifically required the capabilities of the reusable spacecraft to reach orbit.
Safety concerns were yet another issue precluding polar flights from Florida, in that the trajectories of ascending Shuttles would cross heavily-populated South Carolina and the Great Lakes; furthermore, the jettisoned Solid Rocket Boosters would fall within an impact â€˜footprintâ€™ which included Brunswick in Georgia and the External Tank would follow a suborbital path across Canada, the North Pole, Russia, China and perhaps India. Aside from the risk of killing or injuring civilians, the chance of an abortive mission crash-landing in Soviet territory whilst carrying a highly-sensitive national-security payload did not bear thinking about.
Although Vandenbergâ€™s use for polar launches would have sidestepped many of these diplomatic difficulties, the sheer value of KH-12 in particular obliged NASA and the Air Force to design â€˜alternateâ€™ mission plans in which the satellite could be deployed as early as the first orbit, purely to avoid overflying Russia. At length, partly due to problems accommodating the KH-12 aboard the Shuttle and chiefly because the first Vandenberg launch was considered a test flight, it was decided to carry an experimental spacecraft before committing more sensitive payloads at a later date.
Known as â€˜Teal Rubyâ€™ and originally codenamed â€˜Air Force Program-888â€™, or â€˜AFP-888â€™, it was a bizarre contraption which would have evaluated infrared detectors for future early-warning satellites. â€œIt was a staring mosaic infrared sensor,â€ explained Jerry Ross, another crew member on the first Vandenberg mission, in a January 2004 interview, â€œthat was trying to be able to detect low-flying, air-breathing vehicles â€“ things like cruise missiles â€“ and a way to detect these approaching US territoriesâ€. Also aboard Discovery would have been an experimental infrared telescope called Cirris.
Teal Ruby required an orbit of 350-450 nautical miles, inclined at 72 degrees, which only a Vandenberg launch could safely and efficiently provide. After deployment from Discovery, its operational lifetime was constrained to just one year by a dwindling on-board supply of cryogenic coolant needed to keep its infrared sensors at sufficiently low temperatures. In shape and cost, it has been described as â€œa complete messâ€, with funding originally set at $80 million and three years allocated for its development. In reality, it took more than twice as long to build and cost almost half a billion dollarsâ€¦
The Vandenberg mission would also have added to the confusion already caused by a cryptic and somewhat clumsy combination of numbers and letters used to identify Shuttle flights since February 1984. Internally, it was variously labelled â€˜Sixty-Two-Alphaâ€™ or â€˜Mission 62Aâ€™. The first number denoted the financial year in which it was due to be flown (1986 in this case), while the second identified the launch site (with â€˜oneâ€™ reserved for Cape Canaveral and â€˜twoâ€™ for Vandenberg). The letter, lastly, highlighted the position of a particular flight in the launch pecking order to a specific year and from a specific site.
By following this peculiar logic â€“ whose origins remain unclear, but which may have been connected to NASAâ€™s collective triskaidekaphobia following the ill-fated Apollo 13 mission â€“ Sixty-Two-Alpha was the first of two top-secret flights scheduled for launch from Vandenberg in 1986. The second, carrying the long-awaited KH-12, was expected to follow sometime in late September on Mission 62B. However, such a short turnaround time for Discovery was considered unlikely because Vandenberg did not possess the same sophisticated processing facilities as Cape Canaveral.
In fact, even before the Challenger disaster, NASA anticipated turnaround times between each Vandenberg flight to be around eight months, which might easily have pushed 62B into early 1987. The Department of Defense, it seemed, would be lucky to achieve just two missions per year â€“ a far cry from the ten or 20 annual launches envisaged when the Shuttle began flight operations in April 1981. The reasons for this overestimation are complicated, but can be attributed to problems with both the launch site itself and a number of key design changes needed to haul heavy payloads into high polar orbits.
Vandenbergâ€™s Shuttle operation centred on Space Launch Complex (SLC)-6, nicknamed â€˜Slick Sixâ€™, which had originally been built in the 1960s for the Air Forceâ€™s cancelled Manned Orbiting Laboratory project. The expectation was that upgrades to existing hardware would help to drive down development costs; however, unforeseen problems throughout the late 1970s and into the 1980s pushed the pricetag relentlessly upwards. Flame ducts had to be built for booster exhausts, as did a specialised payload preparation room, an assembly building, a three-mile-long Shuttle runway, a new launch tower and facilities for mating the orbiter to its Boeing 747 carrier aircraft.
Unlike Cape Canaveral, in which the stacking of the orbiter, its boosters and External Tank is undertaken in the gigantic Vehicle Assembly Building, preparations for missions at Vandenberg would have been conducted at the launch pad! â€œThe [boosters] were going to be stacked up out at the pad,â€ remembered Jerry Ross, â€œ[then] the External Tank would be mounted to those out at the pad and then the Shuttle would be brought out on this multi-tiered carrier from its processing facility several miles away and taken out to the launch pad and put in place once everything else was ready.
â€œI was out there once or twice to see the pad once it was pretty well configured and ready to do. The entire launch stack could be enclosed in, basically, a rollaway hangar type of facility and also the launch control centre was basically underneath the pad! It was buried in concrete, not directly underneath, but still right there, contiguous to the launch pad itself. That should have been a fairly noisy place to operate out of!â€
The dangers of acoustic, blast and thermal excesses on the base had been questioned as late as the autumn of 1985 and would be revisited during the Challenger inquiry: at just 1,200 feet from the pad, the launch control centre was far too close for the comfort of its 175 occupants. Vibrations experienced during launches â€“ exacerbated and reflected by the surrounding mountains â€“ could upset computers and cause major structural damage to ascending Shuttles, while unpredictable weather conditions, including ice, heavy rain and thick fog, posed additional hazards.
Regardless of the obstacles, Ross believed â€œit would have been a fascinating rideâ€, propelled by Discoveryâ€™s three main engines and a pair of specially-modified boosters with new, â€˜filament-woundâ€™ cases. â€œThat meant that, as opposed to solid-steel case segments of the solid-rocket motors, ours were going to be made out of a graphite-epoxy type of material,â€ he said. â€œThey had the same joint design as the steel cases, and since the graphite ones would have been more flimsy â€“ more flexible â€“ we always were wondering what would have happened to us had we tried to launch with those, considering the Challenger accident.
â€œThe reason for using the filament-wound solids is because they were a lighter weight. That would give us more weight capability [of around an extra 8,000 pounds] to orbit, since launching at a higher inclination you use less of the Earthâ€™s rotational velocity to help you get into orbitâ€. The new-style casings were built by Hercules Incorporated, subcontracting to NASAâ€™s booster manufacturer Morton-Thiokol, and employed a unique capture feature to eliminate rotation in the joints between each segment.
In addition to concerns about the reliability of the new, four-segment booster casings, there was also an alarming possibility that hydrogen could become trapped in the exhaust duct beneath the three main engines, perhaps triggering a fire or explosion which might destroy Discoveryâ€™s tail during launch. Only days before the Challenger disaster in January 1986, these concerns crystallised into additional costs as the Air Force acknowledged its latest technical hurdle in getting Vandenberg operational. By now, the site had swallowed close to three billion dollars for its Shuttle operation, more than twice as much as had been predicted in 1977.
â€œWe were training at Los Alamos in New Mexico,â€ said Mike Mullane of the day Challenger exploded, â€œin a facility that didnâ€™t have easy access to a TV. We knew they were launching and somebody finally got a television. We watched the launch and they dropped it away within probably 30 seconds and we then started to turn back to our training. Somebody said â€˜Letâ€™s see if theyâ€™re covering it further on one of the other channelsâ€™, started flipping channelsâ€¦ there was the explosion and we knew right then that the crew was lost and something terrible had happened.
â€œI was crushed that I lost this mission,â€ he continued sadly, â€œbut that was minor compared to the trauma of Challengerâ€.
As a presidential investigation got underway, inevitable scrutiny was cast not only on the boosters â€“ with profound implications for the future of the filament-wound casings â€“ but also on more generic safety problems. The Air Force had already put in place plans to fit 54 outward-firing igniters inside each of the Shuttleâ€™s main engines to remove concentrations of hydrogen. Eventually, following a $7.3 million study, it was decided to employ steam to solve the problem: storing hot water in pipes, recirculating it through boilers to keep its temperature stable and spraying it into the main engine duct just before launch.
However, the loss of Challenger sounded the death-knell for polar-orbiting Shuttle flights from Vandenberg. The filament-wound casings, which had been conceived to be light enough to carry heavier payloads into higher-inclination orbits, would have required additional fixes to meet one of the Rogers Commissionâ€™s recommendations. These fixes, unfortunately, would have added extra weight and virtually cancelled-out any advantages in terms of their lifting capacity. By February 1987, the Air Force accepted that Rogers-enforced structural changes meant the Shuttle could no longer effectively haul heavy payloads in the 32,000-pound range into polar orbits.
Already, in the summer of the previous year, recommendations had been made to mothball Slick Six until at least 1991, pending the construction of a new orbiter and the final resolution of lingering hydrogen-concentration problems. Ultimately, with the reduction in the Shuttleâ€™s payload capacity to polar orbit and the suspension of manned missions, it became more prudent to reassign some Department of Defense payloads to expendable rockets. By this point, with a few exceptions, the military was seeking a way out of its dealings with NASA at the earliest opportunity.
â€œThe Air Force had been forced to use the Shuttle system for launching its satellites,â€ said Jerry Ross, â€œand it was looking to get out of that deal. Since we knew we were not going to be flying for a while, and they wanted to get their important military satellites into space, they very quickly [rejected] that forced marriage and went off and started building their own rockets.
â€œIn fact, it as we went further and the [booster] joint design came into question and we had this large backlog of satellites that needed to be launched and weâ€™d lost one of the orbiters, it was evident that we werenâ€™t going to be launching out of Vandenberg anytime soonâ€. Ironically, it was one of Rossâ€™ crewmates on the 62A mission, Air Force Undersecretary Edward â€˜Peteâ€™ Aldridge, who pressed for a return to using expendable rockets and ultimately terminated the Shuttle effort at Vandenberg in December 1989.
As for the remainder of the original crew, Pilot Guy Gardner, together with Mullane and Ross, eventually flew a Department of Defense mission in December 1988, although it launched from Cape Canaveral and deployed a top-secret radar-imaging satellite. Sixty-Two-Alphaâ€™s Commander, four-time Shuttle veteran Bob Crippen, moved up to a managerial role at NASA Headquarters in Washington and the other three crew members â€“ Dale Gardner, Brett Watterson and Aldridge â€“ returned to their respective military services.
In terms of its Shuttle operation, Vandenberg and Slick Six were indeed stricken by bad luck, costing more than four billion dollars and failing to achieve even a single launch. To this day, some observers feel it was for the best. The catastrophic failure of booster joints during Challengerâ€™s final flight have led Jerry Ross to doubt how well the â€œflimsyâ€ filament-wound cases would have performed during a â€˜realâ€™ ascent. Moreover, Vandenbergâ€™s unpredictable weather would have caused excessive ice build-up on the External Tank which, as Columbia has demonstrated, could have cripped the orbiterâ€™s heatshield and triggered disaster.
That, of course, is to leave untouched the other unknowns surrounding the site: the vibration and acoustic effects, the hydrogen-concentration problems and the ever-present, obvious dangers of strapping seven astronauts atop several million pounds of highly-explosive propellants. Perhaps, say the superstitious among us, the Air Force might well have taken heed of the popular cultural myth that Slick Six was built on an ancient Chumash Indian burial ground, whose vengeful descendants had cursed to failure all future occupants of the site.
NASAspaceflight.com Features writer Ben Evans is the author of the newly released Springer Praxis publication ‘Space Shuttle Columbia – Her Missions and Crews.’
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