Preparing for each Shuttle flight takes several years, but the actual bringing together of the components begins with setting up the boosters on a Mobile Launch Platform (MLP) in the gigantic Vehicle Assembly Building (VAB). This 160-m-tall structure -the world's largest scientific building, so vast that clouds once formed in its upper reaches before an air-conditioning system was fitted - has dominated the swampy landscape of the Kennedy Space Center (KSC) on Merritt Island in Florida for the best part of four decades. It was used to assemble the massive Saturn V Moon rockets and, since 1980, the Shuttle.
Each SRB comprises six blocks, called 'segments', each of which is hauled with pinpoint precision into place, one on top of the other. To prevent a leakage of searing gases during ascent, a series of rubbery O-rings seal the joints between the segments. After propelling the Shuttle and ET to an altitude of about 45.7 km, explosive rockets at the nose and tail of each booster push them away and parachutes lower them to a gentle splashdown just off Cape Canaveral in the Atlantic Ocean. They are then recovered, refurbished and reused.
When the assembly of the SRBs is complete, the ET is moved into position between them and connected by a series of spindly attachment struts. Following checks of their mechanical and electrical compatibility, the Shuttle itself is moved from the nearby Orbiter Processing Facility (OPF), tilted on its tail and mated to the ET. In the early days of the programme, the Commander and Pilot of the mission boarded the vehicle while it was in a vertical position inside the VAB to rehearse pre-launch procedures. Nowadays, this is done by the entire crew after the Shuttle has been rolled to the pad.
The transfer of the 1.8-million-kg Shuttle stack from the VAB to one of two pads
Attached to her External Tank and Solid Rocket Boosters, and mounted on top of the crawler, Columbia is readied for her first launch.
of Launch Complex 39 - a distance of 5.6 km - takes six hours, with the aptly named 'crawler' inching the MLP and its precious, $2-billion national asset along a track made of specially imported Mississippi river gravels. Once the stack is 'hard-down' on the pad surface, further checks are conducted, payloads installed and the crew participates in a Terminal Countdown Demonstration Test (TCDT), essentially a full dress-rehearsal of the last part of the countdown, followed by a simulated main engine failure and emergency escape procedures.
By 20 February 1981, these preparations in readiness for STS-1 had long been completed; in fact, attached to her tank and boosters, Columbia had sat majestically on Pad 39A since 29 December the previous year. She had been at KSC for even longer. Her construction took almost five years from the start of work to build her cockpit in June 1974 to rollout of the finished article in March 1979. A week later, to the amazement of motorists in the sweltering California heat, Columbia was towed overland from prime contractor Rockwell International's Palmdale plant to Edwards Air Force Base.
By late March, she had been flown 'piggyback' on top of the modified 747 aircraft to KSC and ensconced in one of two bays in the OPF. The latter is positively dwarfed by the immense VAB and is still used to prepare the Shuttle fleet for their missions, to repair and refurbish them and to install and remove their payloads. It is, however, far more than just a spacecraft hangar; due to the extreme volatility of the propellants carried on board the Shuttle, the OPF is fitted with detectors that are so sensitive to explosions that visitors are forbidden from using camera flashes when taking photographs.
After her arrival at KSC, Columbia underwent a protracted period of pre-launch preparations that lasted almost two years. Although she was structurally 'complete', she was far from ready to fly. She had no main engines, her thermal protection system needed attention and her ET and SRB segments were not destined to arrive until the summer of 1979. By the end of the following year, however, significant progress had been made and in November Columbia rolled into the VAB for stacking. Following checks, she moved to the launch pad a few days after Christmas in readiness for launch the following spring.
The thermal protection system - particularly its thousands of tiles, each of which was individually designed and not interchangeable - had been the biggest headache during this time because of the sheer novelty of its design. ''When it took off on the back of the 747 from Palmdale, a whole bunch of the tiles came off as they went down the runway,'' former Shuttle manager Arnie Aldrich wryly recalled. ''That led to the requirement to have a better understanding of how the tiles were attached and how to know they were well attached and that problem took two years to solve.''
Much work still had to be done before Young and Crippen could even board the orbiter, however. One of the most critical exercises was a Wet Countdown Demonstration Test (WCDT), which lasted six days and culminated on 20 February 1981 in a 20-second firing of Columbia's engines. This Flight Readiness Firing (FRF) was necessary to demonstrate their ability to throttle between 94 and 100% thrust, and gimbal just as they would be expected to do in flight. Similar 'wet' - or fully fuelled - tests had been performed before the Saturn V launches, although on those occasions the engines had not been test-fired.
Preparations for the FRF proceeded in a manner not dissimilar to a real countdown: launch controllers started the clock at T — 53 hours when they powered-up the SRBs, ground-support equipment and Columbia herself. Four seconds before the simulated 'liftoff, the Shuttle's engines roared to life at 120-millisecond intervals, reaching 90% rated thrust within three seconds and hitting the 100% mark precisely at T— zero. Three seconds later, engineers simulated retracting the ET umbilical and the SRBs' hold-down posts; a further 15 seconds elapsed before shutdown commands were issued to all three engines. The test was a success and a significant milestone had been cleared.
According to the STS-1 press kit, released around this time, the launch was provisionally booked for ''no earlier than'' 17 March, but a number of technical issues and a human tragedy conspired to delay Columbia's first flight by several weeks. Following the FRF, engineers had to repair a section of super-light ablator insulation, which had become debonded from the ET during a test of its cryogenic propellants back in January. This pushed the target date for launch back to 5 April, followed by another delay until the 10th, caused by a strike against Boeing by machinists and aerospace workers.
Throughout March, the attention of the world's media focused on Young and Crippen as they maintained their proficiency training, participating in a TCDT and practising how to escape from Columbia in the event of a main engine failure seconds before launch. The biggest fear in such a scenario was the presence of invisible hydrogen flames, through which the pressure-suited astronauts would have to run to reach a slidewire escape basket that would whisk them from the 58-m level of the launch pad down to the ground and a waiting M-113 armoured personnel carrier.
Although Young and Crippen had not been directly involved in the Enterprise approach and landing runs - which had been conducted by two other teams of astronauts, Joe Engle and Dick Truly and Fred Haise and Gordon Fullerton - they nevertheless achieved proficiency in flying the Shuttle Training Aircraft (STA). This Grumman Gulfstream had been modified to fly almost exactly like the Shuttle, approaching the runway at several times the angle of a commercial aircraft and nearly twice the speed. The men also honed their skills in flight software laboratories, visual motion simulators, full-scale Shuttle mockups and on board Columbia herself.
It was just a few days after Young and Crippen had returned to Houston, following their TCDT, when the Shuttle claimed its first two lives. Several technicians working inside Columbia's aft compartment were rendered unconscious by a dangerous build-up of nitrogen gas; and although they were pulled out, one died that same day and another two weeks later. The cause was traced to a breakdown of communications: a warning sign had been mistakenly removed and a supervisor called away. Crippen would later pay a personal tribute to the two dead men, John Bjomstad and Forrest Cole, while in space.
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