It Just Goes

It was under an unusual shroud of quiet that Commander Ken Mattingly and Pilot Hank Hartsfield - the last two-man Shuttle crew - rode the bus to Pad 39A on 27 June 1982 for STS-4. Mattingly had previously flown on Apollo 16 with John Young, while Hartsfield was making his first space mission. Originally, when NASA intended to fly six test flights before declaring the Shuttle operational, Mattingly and

Hartsfield were assigned to the fifth (called the 'E') mission, and when the agency reduced the number to four they expected to be assigned an operational flight.

According to the initial plans, astronauts Vance Brand and Bob Overmyer - the 'D' crew - were in line for STS-4, but their roles were switched with those of Mattingly and Hartsfield and they were ultimately assigned as Commander and Pilot of Columbia's first operational mission, with the job of deploying two commercial satellites and overseeing the first Shuttle spacewalk. ''The idea of trying to get on an early test flight'', said Mattingly, ''was what every pilot wants to do. Of course, none of us thought that it was going to take so many years before that first flight took place.''

Concerns had been raised over their chances of launching safely, because on the previous night (26 June), a severe hailstorm damaged several thermal tiles and left water behind the covers of two RCS thrusters. Despite the chance of this freezing during ascent, it was decided that it would not present a problem.

Columbia lifted off precisely on time at 3:00 pm, right at the opening of a four-and-a-half-hour 'window', and was quickly arcing into the clear Florida sky, on course for a week-long mission. For Mattingly, who had endured a bone-jarring liftoff on board a Saturn V a decade earlier, the Shuttle, in comparison, was the smoothest ride in the world: ''It [the Saturn] feels just like it sounds. You get this staccato cracking and all that from the engines. Inside, it's the same thing. It's shaking and banging and pushing hard and there's no doubt that something really gigantic is going on. ... The Shuttle [was] not noisy; it doesn't shake. It just goes.''

Columbia's ascent, overall, was nominal, but several hydraulic sensors registered dramatic temperature drops in the nose landing gear wheel well - in one case from 25 Celsius to minus 15 Celsius - which took several hours to return to normal. Nothing like it had been seen on the three previous launches and it was attributed to rainwater from the storm having penetrated Columbia's wheel wells. Moreover, DFI measurements recorded moisture behind some thermal tiles.

This reinforced a decision by NASA managers, made before the launch, to orient the Shuttle in a belly-to-Sun attitude and so evaporate the water. This attitude was maintained for 12 hours, after which the astronauts began preparing for the 'normal' attitudes planned for their mission. With her belly facing the Sun and her payload bay and overhead windows aimed Earthwards, this presented some magnificent first views of orbital flight for both men. ''All of a sudden,'' Mattingly said later, ''it was like you pulled the shades back on a bay window and the Earth appeared!''

The ascent, however, had gone somewhat awry for Columbia's twin SRBs, whose parachutes had failed during their fall back to Earth. Both boosters sank after splashdown in the Atlantic Ocean and, although an underwater remote camera later photographed the wreckage, it was deemed too expensive to recover them. The cause of the failure was later traced to a new feature intended to separate the parachutes from the SRBs at the instant of splashdown; it was supposed to prevent the boosters being dragged through the water by their deflated canopies, and instead had prevented their deployment.

The system was active on the first three Shuttle missions, but was partially disabled for STS-4. During the launch of Mattingly and Hartsfield, frangible nuts

The desk-sized IECM is manoeuvred by the RMS on STS-4.

holding one of two risers for each parachute were replaced by two regular solid nuts that would not separate the riser. Preparations for Columbia's next mission, STS-5, would include the replacement of all frangible nuts with regular solid ones. As a result, when the Shuttle next lifted off in November 1982, both risers on each parachute remained attached to the boosters until they could be removed by recovery personnel. The fix was successful.

Meanwhile, despite the half-day 'hot soak' of Columbia's tiles in orbit, DFI data indicated that water still remained in several nooks and crannies. It was feared that, during cold periods, it could freeze and possibly crack the most sensitive tiles on areas of Columbia that endured maximum atmospheric heating during re-entry. As a result, another, 23-hour 'solar inertial' run was added to the astronauts' timeline for 29 June and resolved the problem. After the mission, several DFI-measured tiles were removed and checked for traces of water; none was found, thereby validating the solar inertial 'conditioning' attitude to resolve future incidents.

0 0

Post a comment